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Question 1
Correct
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A 33-year-old individual presents to the emergency department in an intoxicated state after a night of drinking. Although there are no immediate medical concerns, the patient is visibly under the influence of alcohol, exhibiting unsteady gait, reduced social inhibition, and mild slurring of speech. Additionally, the patient is observed to be urinating frequently.
What is the probable mechanism behind the increased frequency of urination in this patient?Your Answer: Suppression of antidiuretic hormone (ADH) release from the posterior pituitary gland
Explanation:Polyuria, or excessive urination, can be caused by a variety of factors. A recent review in the BMJ categorizes these causes by their frequency of occurrence. The most common causes of polyuria include the use of diuretics, caffeine, and alcohol, as well as diabetes mellitus, lithium, and heart failure. Less common causes include hypercalcaemia and hyperthyroidism, while rare causes include chronic renal failure, primary polydipsia, and hypokalaemia. The least common cause of polyuria is diabetes insipidus, which occurs in less than 1 in 10,000 cases. It is important to note that while these frequencies may not align with exam questions, understanding the potential causes of polyuria can aid in diagnosis and treatment.
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This question is part of the following fields:
- Renal System
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Question 2
Incorrect
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A 78-year-old male visits his doctor complaining of fresh red blood in his stool, tenesmus, and a change in bowel habit that has persisted for 7 weeks. The patient has a medical history of hypertension and takes amlodipine and amlodipine without any allergies. During a digital rectal examination, an irregular mass is detected in the anterior aspect of the rectum. The patient is immediately referred for a flexible sigmoidoscopy, which reveals an adenocarcinoma in the anal canal below the pectinate line.
In this patient, what is the lymph node region where metastatic spread is most likely to occur initially?Your Answer: Inferior mesenteric nodes
Correct Answer: Superficial inguinal nodes
Explanation:The lymphatic drainage of the anal canal below the pectinate line is provided by the superficial inguinal nodes. These nodes also drain the lower limbs, scrotum/vulva, and the rectum below the pectinate line. The ileocolic nodes primarily drain the ileum and proximal ascending colon, while the inferior mesenteric nodes drain the hindgut structures. The internal iliac nodes drain the inferior rectum, anal canal above the pectinate line, and pelvic viscera. The para-aortic nodes do not directly drain the portion of the rectum below the pectinate line, but they do drain the testes/ovaries.
Lymphatic drainage is the process by which lymphatic vessels carry lymph, a clear fluid containing white blood cells, away from tissues and organs and towards lymph nodes. The lymphatic vessels that drain the skin and follow venous drainage are called superficial lymphatic vessels, while those that drain internal organs and structures follow the arteries and are called deep lymphatic vessels. These vessels eventually lead to lymph nodes, which filter and remove harmful substances from the lymph before it is returned to the bloodstream.
The lymphatic system is divided into two main ducts: the right lymphatic duct and the thoracic duct. The right lymphatic duct drains the right side of the head and right arm, while the thoracic duct drains everything else. Both ducts eventually drain into the venous system.
Different areas of the body have specific primary lymph node drainage sites. For example, the superficial inguinal lymph nodes drain the anal canal below the pectinate line, perineum, skin of the thigh, penis, scrotum, and vagina. The deep inguinal lymph nodes drain the glans penis, while the para-aortic lymph nodes drain the testes, ovaries, kidney, and adrenal gland. The axillary lymph nodes drain the lateral breast and upper limb, while the internal iliac lymph nodes drain the anal canal above the pectinate line, lower part of the rectum, and pelvic structures including the cervix and inferior part of the uterus. The superior mesenteric lymph nodes drain the duodenum and jejunum, while the inferior mesenteric lymph nodes drain the descending colon, sigmoid colon, and upper part of the rectum. Finally, the coeliac lymph nodes drain the stomach.
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This question is part of the following fields:
- Haematology And Oncology
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Question 3
Incorrect
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A 67-year-old man visits his GP complaining of alterations in his vision. In addition to decreased sharpness, he describes object distortion, difficulty discerning colors, and occasional flashes of light. He has a history of smoking (40-pack-year) and a high BMI. Based on these symptoms, what is the most probable diagnosis?
Your Answer: Diabetic retinopathy
Correct Answer: Age-related macular degeneration
Explanation:Age-related macular degeneration (AMD) is characterized by a decrease in visual acuity, altered perception of colors and shades, and photopsia (flashing lights). The risk of developing AMD is higher in individuals who are older and have a history of smoking.
As a natural part of the aging process, presbyopia can cause difficulty with near vision. Smoking increases the likelihood of developing cataracts, which can result in poor visual acuity and reduced contrast sensitivity. However, symptoms such as distortion and flashing lights are not typically associated with cataracts. Similarly, retinal detachment is unlikely given the patient’s risk factors and lack of distortion and perception issues. Since there is no mention of diabetes mellitus in the patient’s history, diabetic retinopathy is not a plausible explanation.
Age-related macular degeneration (ARMD) is a common cause of blindness in the UK, characterized by degeneration of the central retina (macula) and the formation of drusen. The risk of ARMD increases with age, smoking, family history, and conditions associated with an increased risk of ischaemic cardiovascular disease. ARMD is classified into dry and wet forms, with the latter carrying the worst prognosis. Clinical features include subacute onset of visual loss, difficulties in dark adaptation, and visual hallucinations. Signs include distortion of line perception, the presence of drusen, and well-demarcated red patches in wet ARMD. Investigations include slit-lamp microscopy, colour fundus photography, fluorescein angiography, indocyanine green angiography, and ocular coherence tomography. Treatment options include a combination of zinc with anti-oxidant vitamins for dry ARMD and anti-VEGF agents for wet ARMD. Laser photocoagulation is also an option, but anti-VEGF therapies are usually preferred.
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This question is part of the following fields:
- Neurological System
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Question 4
Incorrect
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A geriatric medicine trainee has developed a research project that they aim to publish in a high impact factor journal.
Two groups of elderly patients with hypertension are randomly assigned to receive treatment with amlodipine or lisinopril for a six week period.
At the end of the six week trial period, each participant is asked to rate the effectiveness of their specific treatment on lowering their blood pressure. The rating scale is from 1-5, where 1 indicates 'very ineffective' and 5 indicates 'very effective'.
As the data is not normally distributed, what statistical test should be utilized to determine if there is a significant difference between the two treatments?Your Answer:
Correct Answer: Mann-Whitney U test
Explanation:The appropriate statistical test for comparing ordinal, interval, or ratio scales of unpaired data is the Mann-Whitney U test. This test is necessary when dealing with non-normally distributed data, such as Likert items. In contrast, the chi-squared test is used to compare percentages, while the student’s t-test (paired or unpaired) requires normally distributed data and/or paired observations. As the data in this scenario involves two different groups receiving different interventions, the Mann-Whitney U test is the most appropriate choice.
Types of Significance Tests
Significance tests are used to determine whether the results of a study are statistically significant or simply due to chance. The type of significance test used depends on the type of data being analyzed. Parametric tests are used for data that can be measured and are usually normally distributed, while non-parametric tests are used for data that cannot be measured in this way.
Parametric tests include the Student’s t-test, which can be paired or unpaired, and Pearson’s product-moment coefficient, which is used for correlation analysis. Non-parametric tests include the Mann-Whitney U test, which compares ordinal, interval, or ratio scales of unpaired data, and the Wilcoxon signed-rank test, which compares two sets of observations on a single sample. The chi-squared test is used to compare proportions or percentages, while Spearman and Kendall rank are used for correlation analysis.
It is important to choose the appropriate significance test for the type of data being analyzed in order to obtain accurate and reliable results. By understanding the different types of significance tests available, researchers can make informed decisions about which test to use for their particular study.
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This question is part of the following fields:
- General Principles
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Question 5
Incorrect
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A 25-year-old man arrives at the emergency department after experiencing multiple episodes of vomiting following a night of heavy drinking. During the clinical examination, the doctor observes dry mucous membranes and reduced skin turgidity. As part of the diagnostic process, an arterial blood gas test is conducted, and the results are as follows:
pH 7.49
PaO2 9 kPa
PaCO2 5.5kPa
Bicarbonate 30mM
What could be the possible cause of this patient's arterial blood gas findings?Your Answer:
Correct Answer: Hypokalaemia
Explanation:Metabolic alkalosis can be caused by hypokalaemia, which occurs when there is a low level of potassium in the blood. Vomiting is another cause of metabolic alkalosis, as it leads to the loss of acid from the stomach. However, vomiting was not provided as an option. On the other hand, hypokalemia can also cause metabolic acidosis, as the body tries to replace potassium by exchanging it for hydrogen ions through the H+K+ATPase transporter in the alpha-intercalated cells of the cortical collecting duct. Uraemia, methanol toxicity, and aspirin toxicity are known causes of metabolic acidosis with raised anion gap. Aspirin can also cause respiratory alkalosis by directly stimulating the respiratory centres in the brainstem.
Understanding Metabolic Alkalosis and Its Causes
Metabolic alkalosis is a condition that occurs when there is a loss of hydrogen ions or a gain of bicarbonate in the body. This condition is mainly caused by problems in the kidney or gastrointestinal tract. Some of the common causes of metabolic alkalosis include vomiting, diuretics, liquorice, carbenoxolone, primary hyperaldosteronism, Cushing’s syndrome, and Bartter’s syndrome.
The mechanism of metabolic alkalosis is primarily due to the activation of the renin-angiotensin II-aldosterone (RAA) system. This system is responsible for the reabsorption of sodium ions in exchange for hydrogen ions in the distal convoluted tubule. When there is a loss of sodium and chloride ions due to vomiting or diuretics, the RAA system is activated, leading to an increase in aldosterone levels.
In cases of hypokalaemia, where there is a shift of potassium ions from cells to the extracellular fluid, alkalosis occurs due to the shift of hydrogen ions into cells to maintain neutrality. Understanding the causes and mechanisms of metabolic alkalosis is crucial in diagnosing and treating this condition.
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This question is part of the following fields:
- General Principles
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Question 6
Incorrect
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A 50-year-old man undergoes a colonoscopy and a colonic polyp is identified. It is located on a stalk in the sigmoid colon and has a lobular appearance. What is the most likely cause of this condition?
Your Answer:
Correct Answer: Dysplasia
Explanation:The majority of colonic polyps mentioned earlier are adenomas, which can be accompanied by dysplasia. The severity of dysplasia is directly proportional to the level of clinical apprehension.
Understanding Colonic Polyps and Follow-Up Procedures
Colonic polyps can occur in isolation or as part of polyposis syndromes, with greater than 100 polyps typically present in FAP. The risk of malignancy is related to size, with a 10% risk in a 1 cm adenoma. While isolated adenomas seldom cause symptoms, distally sited villous lesions may produce mucous and electrolyte disturbances if very large.
Follow-up procedures for colonic polyps depend on the number and size of the polyps. Low-risk cases with 1 or 2 adenomas less than 1 cm require no follow-up or re-colonoscopy for 5 years. Moderate-risk cases with 3 or 4 small adenomas or 1 adenoma greater than 1 cm require a re-scope at 3 years. High-risk cases with more than 5 small adenomas or more than 3 with 1 of them greater than 1 cm require a re-scope at 1 year.
Segmental resection or complete colectomy may be necessary in cases of incomplete excision of malignant polyps, malignant sessile polyps, malignant pedunculated polyps with submucosal invasion, polyps with poorly differentiated carcinoma, or familial polyposis coli. Screening from teenager up to 40 years by 2 yearly sigmoidoscopy/colonoscopy is recommended. Rectal polypoidal lesions may be treated with trans anal endoscopic microsurgery.
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This question is part of the following fields:
- Gastrointestinal System
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Question 7
Incorrect
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A 70-year-old man is being examined on the geriatric ward during the morning ward round. He reports feeling fine this morning. He has a medical history of atrial fibrillation, recurrent falls, severe asthma and diverticulosis.
During the examination, the doctor notices twitching of the facial muscles when tapping his face. Other than that, no abnormalities are found.
What could be causing the facial muscle twitching in this patient?Your Answer:
Correct Answer: Denosumab
Explanation:Denosumab has been known to cause hypocalcaemia, which can be identified through the examination finding of facial twitching upon tapping of the face, also known as Chvostek’s sign. This is due to the drug’s ability to inhibit the formation, function, and survival of osteoclasts, which are responsible for releasing calcium into the blood through bone resorption.
On the other hand, lithium is a mood stabilizer that can cause hypercalcaemia by resetting the setpoint for PTH. However, since there is no mention of the patient being on lithium in their medical history, this is unlikely to be the cause of their condition.
Rhabdomyolysis, which can result in hypercalcaemia, is often seen in patients who have experienced falls or prolonged bed rest, particularly in geriatric wards where patients may be less mobile.
Thiazide-like diuretics, such as indapamide, can also cause hypercalcaemia by increasing urinary calcium resorption. However, this usually resolves once the diuretic is discontinued.
Finally, milk-alkali syndrome is a condition characterized by high blood calcium levels caused by excessive intake of calcium and absorbable alkali, often through dietary supplements or antacids taken to prevent osteoporosis.
Denosumab for Osteoporosis: Uses, Side Effects, and Safety Concerns
Denosumab is a human monoclonal antibody that inhibits the development of osteoclasts, the cells that break down bone tissue. It is given as a subcutaneous injection every six months to treat osteoporosis. For patients with bone metastases from solid tumors, a larger dose of 120mg may be given every four weeks to prevent skeletal-related events. While oral bisphosphonates are still the first-line treatment for osteoporosis, denosumab may be used as a next-line drug if certain criteria are met.
The most common side effects of denosumab are dyspnea and diarrhea, occurring in about 1 in 10 patients. Other less common side effects include hypocalcemia and upper respiratory tract infections. However, doctors should be aware of the potential for atypical femoral fractures in patients taking denosumab and should monitor for unusual thigh, hip, or groin pain.
Overall, denosumab is generally well-tolerated and may have an increasing role in the management of osteoporosis, particularly in light of recent safety concerns regarding other next-line drugs. However, as with any medication, doctors should carefully consider the risks and benefits for each individual patient.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 8
Incorrect
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During your placement on the respiratory ward, you observe an influenzae outbreak. Besides haemagglutinin, what is the other antigenic determinant of this illness?
Your Answer:
Correct Answer: Neuraminidase
Explanation:The major antigenic determinants of influenzae are haemagglutinin (HA) and neuraminidase (NA). HA attaches to sialic acid residues on the cell surface, while NA catalyzes the cleavage of glycosidic linkages to sialic acid bonds, enabling new progeny viruses to exit the cell. Therefore, the correct answer is neuraminidase.
Respiratory Pathogens and Associated Conditions
Respiratory pathogens are microorganisms that cause infections in the respiratory system. The most common respiratory pathogens include respiratory syncytial virus, parainfluenza virus, rhinovirus, influenzae virus, Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, Mycoplasma pneumoniae, Legionella pneumophilia, and Pneumocystis jiroveci. Each of these pathogens is associated with specific respiratory conditions, such as bronchiolitis, croup, common cold, flu, community-acquired pneumonia, acute epiglottitis, atypical pneumonia, and tuberculosis.
Flu-like symptoms are often the first sign of respiratory infections caused by these pathogens, followed by a dry cough. Complications may include haemolytic anaemia, erythema multiforme, lymphopenia, deranged liver function tests, and hyponatraemia. Patients with Pneumocystis jiroveci infections typically have few chest signs and develop exertional dyspnoea. Mycobacterium tuberculosis can cause a wide range of presentations, from asymptomatic to disseminated disease, and may be accompanied by cough, night sweats, and weight loss.
Overall, understanding the different respiratory pathogens and their associated conditions is crucial for proper diagnosis and treatment of respiratory infections.
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This question is part of the following fields:
- General Principles
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Question 9
Incorrect
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Olivia is a 19-year-old female who has recently started college. She attends a party and has many alcoholic drinks and wakes the next morning with a severe headache. She puts this down to being hungover, however, by the next day the headache is worse and she has a widespread non-blanching purpuric rash. She attends the emergency department who suspect meningitis and would like to perform a lumbar puncture to obtain a cerebrospinal fluid (CSF) sample. The doctor would like to take the sample from the cauda equina to avoid spinal cord injury, at which level does the spinal cord terminate?
Your Answer:
Correct Answer: L1/L2
Explanation:CSF Analysis for Meningitis
Cerebrospinal fluid (CSF) analysis is an important diagnostic tool for meningitis. The appearance, glucose level, protein level, and white cell count in the CSF can provide clues to the type of meningitis present. Bacterial meningitis typically results in cloudy CSF with low glucose levels and high protein levels, along with a high number of polymorphs. Viral meningitis, on the other hand, usually results in clear or slightly cloudy CSF with normal or slightly raised protein levels and a high number of lymphocytes. Tuberculous meningitis may result in slightly cloudy CSF with a fibrin web and a high number of lymphocytes, along with low glucose and high protein levels. Fungal meningitis typically results in cloudy CSF with high protein levels and a high number of lymphocytes. In cases of suspected tuberculous meningitis, PCR may be used in addition to the Ziehl-Neelsen stain, which has low sensitivity. It is important to note that mumps and herpes encephalitis may also result in low glucose levels in the CSF.
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This question is part of the following fields:
- General Principles
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Question 10
Incorrect
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A 42-year-old man is admitted to the gastroenterology ward with a flare-up of his Crohn's disease. He has been experiencing up to 6 bowel movements per day for the past 2 weeks and has lost around 5kg in weight.
What are the expected biochemical abnormalities in this clinical scenario?Your Answer:
Correct Answer: Metabolic acidosis, normal anion gap, hypokalaemia
Explanation:Prolonged diarrhoea can lead to a normal anion gap metabolic acidosis and hypokalaemia. This is due to the loss of potassium and other electrolytes through the gastrointestinal tract. The anion gap remains within normal limits despite the metabolic acidosis caused by diarrhoea. It is important to monitor electrolyte levels in patients with prolonged diarrhoea to prevent complications.
Understanding Metabolic Acidosis
Metabolic acidosis is a condition that can be classified based on the anion gap, which is calculated by subtracting the sum of chloride and bicarbonate from the sum of sodium and potassium. The normal range for anion gap is 10-18 mmol/L. If a question provides the chloride level, it may be an indication to calculate the anion gap.
Hyperchloraemic metabolic acidosis is a type of metabolic acidosis with a normal anion gap. It can be caused by gastrointestinal bicarbonate loss, prolonged diarrhea, ureterosigmoidostomy, fistula, renal tubular acidosis, drugs like acetazolamide, ammonium chloride injection, and Addison’s disease. On the other hand, raised anion gap metabolic acidosis is caused by lactate, ketones, urate, acid poisoning, and other factors.
Lactic acidosis is a type of metabolic acidosis that is caused by high lactate levels. It can be further classified into two types: lactic acidosis type A, which is caused by sepsis, shock, hypoxia, and burns, and lactic acidosis type B, which is caused by metformin. Understanding the different types and causes of metabolic acidosis is important in diagnosing and treating the condition.
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This question is part of the following fields:
- Renal System
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Question 11
Incorrect
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You are giving a lecture to a group of high school students on the pathophysiology of pemphigus vulgaris.
Halfway through your talk, you briefly mention the importance of cadherins, transmembrane proteins that are crucial for cell-cell adhesion, and explain that they rely on certain ions to function properly.
What specific ions are you referring to?Your Answer:
Correct Answer: Calcium ions
Explanation:Cadherins require calcium ions for their proper functioning.
Understanding Cadherins: Proteins that Play a Vital Role in Cell Adhesion
Cadherins are a type of transmembrane proteins that are crucial for cell adhesion. They are also known as ‘calcium-dependent adhesion’ proteins. These proteins are responsible for maintaining the integrity of tissues and organs by binding cells together. Cadherins are found in various tissues and organs, including epithelial tissues and neurons.
One of the most well-known cadherins is E-cadherin, which is found in epithelial tissues. Dysfunction of E-cadherin is often associated with tumour metastasis. Another type of cadherin is N-cadherin, which is found in neurons. It plays a crucial role in the development and maintenance of the nervous system. Desmoglein is another type of cadherin that is found in desmosomes, which are structures that hold cells together in tissues such as the skin. Pemphigus vulgaris is a disease that is caused by the formation of antibodies against desmoglein 3.
In summary, cadherins are essential proteins that play a vital role in cell adhesion. They are found in various tissues and organs and are responsible for maintaining the integrity of tissues and organs by binding cells together. Dysfunction of cadherins can lead to various diseases, including cancer and autoimmune disorders.
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This question is part of the following fields:
- General Principles
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Question 12
Incorrect
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A 63-year-old woman is referred to dermatology for evaluation of a concerning lesion on her arm. She reports that it was previously a uniform shape and approximately 5 mm in size, but has since grown and become irregular in shape with multiple colors. A biopsy confirms advanced melanoma and she is started on ipilimumab. What is the mechanism of action for this medication?
Your Answer:
Correct Answer: Blockage of Cytotoxic T Lymphocyte-associated Protein 4 (CTLA-4)
Explanation:Ipilimumab is a type of immune checkpoint inhibitor that is used to treat melanoma by blocking CTLA-4. Other immune checkpoint inhibitors, such as nivolumab and pembrolizumab, block PD-1 and can be used to treat various cancers including melanoma, Hodgkin’s lymphoma, and non-small cell lung cancer. Atezolizumab and durvalumab are examples of immune checkpoint inhibitors that block PD-L1 and can be used to treat lung and urothelial cancer. Alkylating agents like cyclophosphamide exert their effect by cross-linking DNA, while medications like vincristine and vinblastine inhibit the formation of microtubules.
Understanding Immune Checkpoint Inhibitors
Immune checkpoint inhibitors are a type of immunotherapy that is becoming increasingly popular in the treatment of certain types of cancer. Unlike traditional therapies such as chemotherapy, these targeted treatments work by harnessing the body’s natural anti-cancer immune response. They boost the immune system’s ability to attack and destroy cancer cells, rather than directly affecting their growth and proliferation.
T-cells are an essential part of our immune system that helps destroy cancer cells. However, some cancer cells produce high levels of proteins that turn T-cells off. Checkpoint inhibitors block this process and reactivate and increase the body’s T-cell population, enhancing the immune system’s ability to recognize and fight cancer cells.
There are different types of immune checkpoint inhibitors, including Ipilimumab, Nivolumab, Pembrolizumab, Atezolizumab, Avelumab, and Durvalumab. These drugs block specific proteins found on T-cells and cancer cells, such as CTLA-4, PD-1, and PD-L1. They are administered by injection or intravenous infusion and can be given as a single-agent treatment or combined with chemotherapy or each other.
However, the mechanism of action of these drugs can result in side effects termed ‘Immune-related adverse events’ that are inflammatory and autoimmune in nature. This is because all immune cells are boosted by these drugs, not just the ones that target cancer. The overactive T-cells can produce side effects such as dry, itchy skin and rashes, nausea and vomiting, decreased appetite, diarrhea, tiredness and fatigue, shortness of breath, and a dry cough. Management of such side effects reflects the inflammatory nature, often involving corticosteroids. It is important to monitor liver, kidney, and thyroid function as these drugs can affect these organs.
In conclusion, the early success of immune checkpoint inhibitors in solid tumors has generated tremendous interest in further developing and exploring these strategies across the oncology disease spectrum. Ongoing testing in clinical trials creates new hope for patients affected by other types of disease.
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This question is part of the following fields:
- Haematology And Oncology
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Question 13
Incorrect
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During an inguinal hernia repair, the surgeon identifies a small nerve while mobilizing the cord structures at the level of the superficial inguinal ring. Which nerve is this most likely to be if the patient is in their 60s?
Your Answer:
Correct Answer: Ilioinguinal
Explanation:Neuropathic pain after inguinal hernia surgery may be caused by the entrapment of the ilioinguinal nerve. This nerve travels through the superficial inguinal ring and is commonly encountered during hernia surgery. The iliohypogastric nerve, on the other hand, passes through the aponeurosis of the external oblique muscle above the superficial inguinal ring.
The Ilioinguinal Nerve: Anatomy and Function
The ilioinguinal nerve is a nerve that arises from the first lumbar ventral ramus along with the iliohypogastric nerve. It passes through the psoas major and quadratus lumborum muscles before piercing the internal oblique muscle and passing deep to the aponeurosis of the external oblique muscle. The nerve then enters the inguinal canal and passes through the superficial inguinal ring to reach the skin.
The ilioinguinal nerve supplies the muscles of the abdominal wall through which it passes. It also provides sensory innervation to the skin and fascia over the pubic symphysis, the superomedial part of the femoral triangle, the surface of the scrotum, and the root and dorsum of the penis or labia majora in females.
Understanding the anatomy and function of the ilioinguinal nerve is important for medical professionals, as damage to this nerve can result in pain and sensory deficits in the areas it innervates. Additionally, knowledge of the ilioinguinal nerve is relevant in surgical procedures involving the inguinal region.
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This question is part of the following fields:
- Neurological System
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Question 14
Incorrect
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A 53-year-old man comes to the emergency department complaining of chest discomfort. He has no significant medical history and is generally healthy.
Upon examination, the patient is found to have tachycardia and an ECG confirms supraventricular tachycardia. The on-call cardiologist is consulted and, after further evaluation, suggests starting flecainide.
What is the mechanism of action of flecainide?Your Answer:
Correct Answer: Blockage of the Nav1.5 sodium channel
Explanation:Flecainide method of action is the blockage of Nav1.5 sodium channels in the heart. It is classified as a class Ic antiarrhythmic drug, which has the strongest effect on the initiation phase of depolarisation.
Verapamil and diltiazem, which are class IV antiarrhythmic drugs, block L-type calcium channels, specifically the Cav1.2 unit. Amiodarone, on the other hand, exhibits some calcium-channel blocking effects, among other effects, and blocks the Kv11.1 potassium channel.
Flecainide does not block the Cav2.3 calcium channel, which refers to R-type calcium channels that are poorly understood and sparsely found in the body.
Flecainide: A Sodium Channel Blocker for Cardiac Arrhythmias
Flecainide is a type of antiarrhythmic drug that belongs to the Vaughan Williams class 1c. It works by blocking the Nav1.5 sodium channels, which slows down the conduction of the action potential. This can cause the QRS complex to widen and the PR interval to prolong. Flecainide is commonly used to treat atrial fibrillation and supraventricular tachycardia associated with accessory pathways like Wolff-Parkinson-White syndrome.
However, it is important to note that flecainide is contraindicated in certain situations. For instance, it should not be used in patients who have recently experienced a myocardial infarction or have structural heart disease like heart failure. It is also not recommended for those with sinus node dysfunction or second-degree or greater AV block, as well as those with atrial flutter.
Like any medication, flecainide can cause adverse effects. It may have a negative inotropic effect, which means it can weaken the heart’s contractions. It can also cause bradycardia, proarrhythmic effects, oral paraesthesia, and visual disturbances. Therefore, it is important to use flecainide only under the guidance of a healthcare professional and to report any unusual symptoms immediately.
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This question is part of the following fields:
- General Principles
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Question 15
Incorrect
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A 28-year-old woman presents with fatigue, low energy, and lethargy. She has a medical history of migraine, ulcerative colitis, depression, and generalized anxiety disorder.
During the physical examination, slight pallor is noted in her eyes, but otherwise, everything appears normal.
The results of her blood test from this morning are as follows:
- Hemoglobin (Hb): 98 g/l
- Platelets: 300 * 109/l
- White blood cells (WBC): 6 * 109/l
- Mean corpuscular volume (MCV): 112
- C-reactive protein (CRP): 5 mg/L
- Erythrocyte sedimentation rate (ESR): 5 mm/hr
- Thyroid function test (TFT): normal
Based on these findings, what is the most likely cause of her symptoms and abnormal blood results?Your Answer:
Correct Answer: Long-term use of sulfasalazine
Explanation:Sulphasalazine is the likely cause of megaloblastic anaemia in this patient, as her blood results indicate macrocytic anaemia and she has a history of ulcerative colitis for which she is taking the medication. Microcytic anaemia is commonly caused by poor iron intake, while sickle cell anaemia causes microcytic anaemia. Long-term use of sumatriptan is not associated with macrocytic anaemia. Although hypothyroidism can cause macrocytic anaemia, this option is incorrect as the patient’s thyroid function tests are normal.
Aminosalicylate Drugs for Inflammatory Bowel Disease
Aminosalicylate drugs are commonly used to treat inflammatory bowel disease (IBD). These drugs work by releasing 5-aminosalicyclic acid (5-ASA) in the colon, which acts as an anti-inflammatory agent. The exact mechanism of action is not fully understood, but it is believed that 5-ASA may inhibit prostaglandin synthesis.
Sulphasalazine is a combination of sulphapyridine and 5-ASA. However, many of the side effects associated with this drug are due to the sulphapyridine component, such as rashes, oligospermia, headache, Heinz body anaemia, megaloblastic anaemia, and lung fibrosis. Mesalazine is a delayed release form of 5-ASA that avoids the sulphapyridine side effects seen in patients taking sulphasalazine. However, it is still associated with side effects such as gastrointestinal upset, headache, agranulocytosis, pancreatitis, and interstitial nephritis.
Olsalazine is another aminosalicylate drug that consists of two molecules of 5-ASA linked by a diazo bond, which is broken down by colonic bacteria. It is important to note that aminosalicylates are associated with a variety of haematological adverse effects, including agranulocytosis. Therefore, a full blood count is a key investigation in an unwell patient taking these drugs. Pancreatitis is also more common in patients taking mesalazine compared to sulfasalazine.
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This question is part of the following fields:
- Gastrointestinal System
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Question 16
Incorrect
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A 72-year-old man presents to his physician with a gradual yellowing of his skin. During the examination, the physician observes jaundiced sclerae and palpates a round mass under the right costal margin, measuring approximately 4 cm in diameter. The patient's abdomen is soft, non-tender, and not distended.
The physician orders a blood test, which reveals the following results:
- Bilirubin: 180 ”mol/L (3 - 17)
- ALP: 98 u/L (30 - 100)
- ALT: 36 u/L (3 - 40)
- ÎłGT: 71 u/L (8 - 60)
- Albumin: 43 g/L (35 - 50)
What clinical sign is evident, and what is the probable diagnosis?Your Answer:
Correct Answer: Courvoisier's sign indicating biliary tract cancer
Explanation:If a patient has painless jaundice and a palpable gallbladder in the right upper quadrant, it is unlikely to be caused by gallstones and more likely to be a malignancy. This is known as Courvoisier’s sign, and the most common cancers associated with it are cholangiocarcinoma and adenocarcinoma of the pancreatic head.
Rovsing’s sign is a sign of acute appendicitis, where palpation of the left lower quadrant causes pain in the right lower quadrant.
Virchow’s sign is the presence of a palpable left supraclavicular lymph node, which is a sign of metastatic gastric cancer.
Understanding Cholangiocarcinoma
Cholangiocarcinoma, also known as bile duct cancer, is a serious medical condition that can be caused by primary sclerosing cholangitis. This disease is characterized by persistent biliary colic symptoms, which can be accompanied by anorexia, jaundice, and weight loss. In some cases, a palpable mass in the right upper quadrant may be present, which is known as the Courvoisier sign. Additionally, periumbilical lymphadenopathy (Sister Mary Joseph nodes) and left supraclavicular adenopathy (Virchow node) may be seen.
One of the main risk factors for cholangiocarcinoma is primary sclerosing cholangitis. This condition can cause inflammation and scarring of the bile ducts, which can lead to the development of cancer over time. To detect cholangiocarcinoma in patients with primary sclerosing cholangitis, doctors often use a blood test to measure CA 19-9 levels.
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This question is part of the following fields:
- Gastrointestinal System
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Question 17
Incorrect
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A 75-year-old male has been admitted to the stroke ward after experiencing a stroke 2 days ago. During a mini mental state examination, it was observed that the patient struggled with repeating sentences. Upon further assessment, the doctor discovered that the patient had difficulty with speech repetition. Nevertheless, the patient had no issues with speech comprehension or production during conversation.
What could be the probable cause of the patient's symptoms?Your Answer:
Correct Answer: Conduction aphasia
Explanation:The patient is likely experiencing conduction aphasia, which is characterized by fluent speech but poor repetition ability. This is caused by an impairment to the arcuate fasciculus, which connects Broca’s and Wernicke’s areas. While comprehension is usually preserved in this type of aphasia, patients may struggle with repeating words or phrases. Broca’s aphasia, global aphasia, and primary progressive aphasia are less likely explanations for the patient’s symptoms.
Types of Aphasia: Understanding the Different Forms of Language Impairment
Aphasia is a language disorder that affects a person’s ability to communicate effectively. There are different types of aphasia, each with its own set of symptoms and underlying causes. Wernicke’s aphasia, also known as receptive aphasia, is caused by a lesion in the superior temporal gyrus. This area is responsible for forming speech before sending it to Broca’s area. People with Wernicke’s aphasia may speak fluently, but their sentences often make no sense, and they may use word substitutions and neologisms. Comprehension is impaired.
Broca’s aphasia, also known as expressive aphasia, is caused by a lesion in the inferior frontal gyrus. This area is responsible for speech production. People with Broca’s aphasia may speak in a non-fluent, labored, and halting manner. Repetition is impaired, but comprehension is normal.
Conduction aphasia is caused by a stroke affecting the arcuate fasciculus, the connection between Wernicke’s and Broca’s area. People with conduction aphasia may speak fluently, but their repetition is poor. They are aware of the errors they are making, but comprehension is normal.
Global aphasia is caused by a large lesion affecting all three areas mentioned above, resulting in severe expressive and receptive aphasia. People with global aphasia may still be able to communicate using gestures. Understanding the different types of aphasia is important for proper diagnosis and treatment.
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This question is part of the following fields:
- Neurological System
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Question 18
Incorrect
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Samantha is a 60-year-old female who is well known to the emergency department due to regular admissions of intoxication and related incidents. The last time she was admitted was because of a fall after a drinking binge, it was later discovered that this was caused by visual impairment and balance issues. Before treatment could be initiated, she self-discharged.
This admission she was found roaming the streets with no clothes on, no idea of how she got there or who she was. Whilst in the department she would constantly ask where she was and when she could home, despite being told numerous times.
Which of the following would you expect to see in this patient?Your Answer:
Correct Answer: Confabulation
Explanation:Withdrawal from alcohol can lead to hallucinations, often in the form of visual images such as rats or bugs crawling on or around the patient.
Understanding Korsakoff’s Syndrome
Korsakoff’s syndrome is a memory disorder that is commonly observed in individuals who have a history of alcoholism. This condition is caused by a deficiency in thiamine, which leads to damage and haemorrhage in the mammillary bodies of the hypothalamus and the medial thalamus. Korsakoff’s syndrome often follows untreated Wernicke’s encephalopathy, which is another condition caused by thiamine deficiency.
The primary features of Korsakoff’s syndrome include anterograde amnesia, which is the inability to acquire new memories, and retrograde amnesia. Individuals with this condition may also experience confabulation, which is the production of fabricated or distorted memories to fill gaps in their recollection.
Understanding Korsakoff’s syndrome is crucial for individuals who have a history of alcoholism or thiamine deficiency. Early diagnosis and treatment can help prevent further damage and improve the individual’s quality of life. Proper nutrition and abstinence from alcohol are essential for managing this condition.
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This question is part of the following fields:
- Psychiatry
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Question 19
Incorrect
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A man in his 50s is diagnosed with pernicious anaemia. What is the probable cause for this condition?
Your Answer:
Correct Answer: Autoimmune antibodies to parietal cells
Explanation:The destruction of gastric parietal cells, often due to autoimmune factors, is a primary cause of pernicious anaemia. In some cases, mixed patterns may be present and further diagnostic assessment may be necessary, particularly in instances of bacterial overgrowth.
Pernicious anaemia is a condition that results in a deficiency of vitamin B12 due to an autoimmune disorder affecting the gastric mucosa. The term pernicious refers to the gradual and subtle harm caused by the condition, which often leads to delayed diagnosis. While pernicious anaemia is the most common cause of vitamin B12 deficiency, other causes include atrophic gastritis, gastrectomy, and malnutrition. The condition is characterized by the presence of antibodies to intrinsic factor and/or gastric parietal cells, which can lead to reduced vitamin B12 absorption and subsequent megaloblastic anaemia and neuropathy.
Pernicious anaemia is more common in middle to old age females and is associated with other autoimmune disorders such as thyroid disease, type 1 diabetes mellitus, Addison’s, rheumatoid, and vitiligo. Symptoms of the condition include anaemia, lethargy, pallor, dyspnoea, peripheral neuropathy, subacute combined degeneration of the spinal cord, neuropsychiatric features, mild jaundice, and glossitis. Diagnosis is made through a full blood count, vitamin B12 and folate levels, and the presence of antibodies.
Management of pernicious anaemia involves vitamin B12 replacement, usually given intramuscularly. Patients with neurological features may require more frequent doses. Folic acid supplementation may also be necessary. Complications of the condition include an increased risk of gastric cancer.
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This question is part of the following fields:
- Gastrointestinal System
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Question 20
Incorrect
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A 22-year-old university student with a history of primary sclerosing cholangitis presents to the gastroenterologists with symptoms suggestive of ulcerative colitis. She has been experiencing bloody diarrhoea and fatigue for the past three months, with an average of seven bowel movements per day. Her medical history includes a childhood hepatitis A infection and an uncomplicated appendicectomy three years ago. She also has a family history of hepatocellular carcinoma.
During examination, stage 1 haemorrhoids and a scar over McBurney's point are noted. Given her medical history, which condition warrants annual colonoscopy in this patient?Your Answer:
Correct Answer: Primary sclerosing cholangitis
Explanation:Annual colonoscopy is recommended for individuals who have both ulcerative colitis and PSC.
Colorectal Cancer Risk in Ulcerative Colitis Patients
Ulcerative colitis patients have a significantly higher risk of developing colorectal cancer compared to the general population. The risk is mainly related to chronic inflammation, and studies report varying rates. Unfortunately, patients with ulcerative colitis often experience delayed diagnosis, leading to a worse prognosis. Lesions may also be multifocal, further increasing the risk of cancer.
Several factors increase the risk of colorectal cancer in ulcerative colitis patients, including disease duration of more than 10 years, pancolitis, onset before 15 years old, unremitting disease, and poor compliance to treatment. To manage this risk, colonoscopy surveillance is recommended, and the frequency of surveillance depends on the patient’s risk stratification.
Patients with lower risk require a colonoscopy every five years, while those with intermediate risk require a colonoscopy every three years. Patients with higher risk require a colonoscopy every year. The risk stratification is based on factors such as the extent of colitis, the severity of active endoscopic/histological inflammation, the presence of post-inflammatory polyps, and family history of colorectal cancer. Primary sclerosing cholangitis or a family history of colorectal cancer in first-degree relatives aged less than 50 years also increase the risk of cancer. By following these guidelines, ulcerative colitis patients can receive appropriate surveillance and management to reduce their risk of developing colorectal cancer.
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This question is part of the following fields:
- Gastrointestinal System
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Question 21
Incorrect
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Which one of the following statements regarding gastric acid secretions is false?
Your Answer:
Correct Answer: The intestinal phase accounts for 60% of gastric acid produced
Explanation:Understanding Gastric Secretions for Surgical Procedures
A basic understanding of gastric secretions is crucial for surgeons, especially when dealing with patients who have undergone acid-lowering procedures or are prescribed anti-secretory drugs. Gastric acid, produced by the parietal cells in the stomach, has a pH of around 2 and is maintained by the H+/K+ ATPase pump. Sodium and chloride ions are actively secreted from the parietal cell into the canaliculus, creating a negative potential across the membrane. Carbonic anhydrase forms carbonic acid, which dissociates, and the hydrogen ions formed by dissociation leave the cell via the H+/K+ antiporter pump. This leaves hydrogen and chloride ions in the canaliculus, which mix and are secreted into the lumen of the oxyntic gland.
There are three phases of gastric secretion: the cephalic phase, gastric phase, and intestinal phase. The cephalic phase is stimulated by the smell or taste of food and causes 30% of acid production. The gastric phase, which is caused by stomach distension, low H+, or peptides, causes 60% of acid production. The intestinal phase, which is caused by high acidity, distension, or hypertonic solutions in the duodenum, inhibits gastric acid secretion via enterogastrones and neural reflexes.
The regulation of gastric acid production involves various factors that increase or decrease production. Factors that increase production include vagal nerve stimulation, gastrin release, and histamine release. Factors that decrease production include somatostatin, cholecystokinin, and secretin. Understanding these factors and their associated pharmacology is essential for surgeons.
In summary, a working knowledge of gastric secretions is crucial for surgical procedures, especially when dealing with patients who have undergone acid-lowering procedures or are prescribed anti-secretory drugs. Understanding the phases of gastric secretion and the regulation of gastric acid production is essential for successful surgical outcomes.
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This question is part of the following fields:
- Gastrointestinal System
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Question 22
Incorrect
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A 35-year-old woman presents with sudden chest pain and difficulty breathing. She recently returned from a trip to Italy with her family. She has no significant medical history but takes oral contraceptives. On examination, her pulse is 100 bpm, temperature is 37°C, oxygen saturation is 95%, respiratory rate is 28/min, and blood pressure is 116/76 mmHg. Chest examination is unremarkable and chest x-ray is normal. What is the most appropriate diagnostic test to confirm the diagnosis?
Your Answer:
Correct Answer: CT pulmonary angiogram (CTPA)
Explanation:Diagnosis of Pulmonary Embolism in a Woman with Chest Pain and Dyspnoea
This woman is experiencing chest pain and difficulty breathing, with a rapid heart rate and breathing rate. However, there are no visible signs on chest examination and her chest x-ray appears normal. Despite having no fever, her oxygen levels are lower than expected for a healthy person. To rule out a pulmonary embolism, doctors must consider risk factors such as recent air travel and use of oral contraceptives.
The gold standard for diagnosing a pulmonary embolism is a CT pulmonary angiogram, as it can detect even large saddle embolus near the pulmonary arteries. While VQ scanning was previously used, it can miss these larger emboli. Additionally, doctors may perform Doppler ultrasounds of the venous system to check for deep vein thrombosis.
This presentation is not indicative of atypical pneumonia, such as Legionella, as the patient’s temperature would be expected to be high and chest signs would be present. Overall, a thorough evaluation is necessary to accurately diagnose and treat a pulmonary embolism in a patient with chest pain and dyspnoea.
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This question is part of the following fields:
- Respiratory System
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Question 23
Incorrect
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You are interested in investigating the prevalence of side-effects associated with statins, as you suspect they are more widespread than commonly reported and often go unreported by patients. While conducting your research, you come across a study that examines the long-term effects of statin therapy, which was conducted post-market release. What kind of study design would this be?
Your Answer:
Correct Answer: Clinical trial, Phase 4
Explanation:When a study has more than three phases, the final phase is typically postmarketing surveillance. This phase is responsible for monitoring the long-term effects of treatment.
Phase 4 clinical trials are conducted after a treatment has been proven effective and licensed for use. These trials provide more detailed information about the treatment’s side effects and long-term risks and benefits when used on a larger scale.
Pilot studies are preliminary investigations that aim to determine the feasibility of crucial components of a main study, usually a randomized controlled trial (RCT).
In a case-control study, subjects with an outcome of interest are matched with those who do not have the outcome of interest. The prevalence of exposure to a potential risk factor is then compared between cases and controls. If the prevalence of exposure is more common among cases than controls, the exposure may be a risk factor for the outcome under investigation.
Phase 3 trials are designed to test a drug’s efficacy, effectiveness, and safety in a sufficiently large sample population. At this stage, the drug is presumed to have some effect.
Most phase 3 trials, and some phase 2 trials, are randomized. Phase 4 trials are less likely to be randomized as they require a very large sample size.
Phases of Clinical Trials
Clinical trials are conducted to determine the safety and efficacy of new treatments or drugs. These trials are commonly classified into four phases. The first phase involves determining the pharmacokinetics and pharmacodynamics of the drug, as well as any potential side effects. This phase is conducted on healthy volunteers.
The second phase assesses the efficacy and dosage of the drug. It involves a small number of patients affected by a particular disease. This phase may be further subdivided into IIa, which assesses optimal dosing, and IIb, which assesses efficacy.
The third phase involves assessing the effectiveness of the drug. This phase typically involves a larger number of people, often as part of a randomized controlled trial, comparing the new treatment with established treatments.
The fourth and final phase is postmarketing surveillance. This phase monitors the long-term effectiveness and side effects of the drug after it has been approved and is on the market.
Overall, the phases of clinical trials are crucial in determining the safety and efficacy of new treatments and drugs. They provide valuable information that can help improve patient outcomes and advance medical research.
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This question is part of the following fields:
- General Principles
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Question 24
Incorrect
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A 56-year-old man is sent home following an uneventful left total hip replacement. He has been prescribed a direct factor Xa inhibitor for thromboprophylaxis.
What is the probable medication that the patient has been prescribed?Your Answer:
Correct Answer: Apixaban
Explanation:Apixaban directly inhibits factor Xa, while bivalirudin and dabigatran directly inhibit thrombin. On the other hand, enoxaparin is a type of low molecular weight heparin that indirectly inhibits factor Xa by forming a complex with antithrombin III, leading to irreversible inactivation of factor Xa.
Direct oral anticoagulants (DOACs) are medications used to prevent stroke in non-valvular atrial fibrillation (AF), as well as for the prevention and treatment of venous thromboembolism (VTE). To be prescribed DOACs for stroke prevention, patients must have certain risk factors, such as a prior stroke or transient ischaemic attack, age 75 or older, hypertension, diabetes mellitus, or heart failure. There are four DOACs available, each with a different mechanism of action and method of excretion. Dabigatran is a direct thrombin inhibitor, while rivaroxaban, apixaban, and edoxaban are direct factor Xa inhibitors. The majority of DOACs are excreted either through the kidneys or the liver, with the exception of apixaban and edoxaban, which are excreted through the feces. Reversal agents are available for dabigatran and rivaroxaban, but not for apixaban or edoxaban.
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This question is part of the following fields:
- Haematology And Oncology
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Question 25
Incorrect
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A senior citizen arrives at the emergency department complaining of abdominal pain, constipation, and confusion. The blood tests reveal hypercalcemia, and the junior doctor suggests that a potential cause of this is an elevated level of parathyroid hormone (PTH) in the bloodstream. Can you provide the most accurate explanation of the functions of PTH?
Your Answer:
Correct Answer: Increases bone resorption, increases renal reabsorption of calcium, increases synthesis of active vitamin D
Explanation:The primary function of PTH is to elevate calcium levels and reduce phosphate levels. It exerts its influence on the bone and kidneys directly, while also indirectly affecting the intestine through vitamin D. PTH promotes bone resorption, enhances calcium reabsorption in the kidneys, and reduces phosphate reabsorption. Additionally, it stimulates the conversion of vitamin D to its active form, which in turn boosts calcium absorption in the intestine.
Maintaining Calcium Balance in the Body
Calcium ions are essential for various physiological processes in the body, and the largest store of calcium is found in the skeleton. The levels of calcium in the body are regulated by three hormones: parathyroid hormone (PTH), vitamin D, and calcitonin.
PTH increases calcium levels and decreases phosphate levels by increasing bone resorption and activating osteoclasts. It also stimulates osteoblasts to produce a protein signaling molecule that activates osteoclasts, leading to bone resorption. PTH increases renal tubular reabsorption of calcium and the synthesis of 1,25(OH)2D (active form of vitamin D) in the kidney, which increases bowel absorption of calcium. Additionally, PTH decreases renal phosphate reabsorption.
Vitamin D, specifically the active form 1,25-dihydroxycholecalciferol, increases plasma calcium and plasma phosphate levels. It increases renal tubular reabsorption and gut absorption of calcium, as well as osteoclastic activity. Vitamin D also increases renal phosphate reabsorption in the proximal tubule.
Calcitonin, secreted by C cells of the thyroid, inhibits osteoclast activity and renal tubular absorption of calcium.
Although growth hormone and thyroxine play a small role in calcium metabolism, the primary regulation of calcium levels in the body is through PTH, vitamin D, and calcitonin. Maintaining proper calcium balance is crucial for overall health and well-being.
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This question is part of the following fields:
- Neurological System
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Question 26
Incorrect
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As the physician in charge of the health of a 70-year-old man who came in for his yearly check-up, you discover that he smokes 15 cigarettes daily and has a medical history of hypertension and hypercholesterolemia. During the examination, you hear a left-sided carotid bruit while auscultating. A recent duplex ultrasound showed that the left internal carotid artery has a 50% stenosis. What is the final step in the pathogenesis of this man's condition?
Your Answer:
Correct Answer: Smooth muscle proliferation and migration into the tunica intima
Explanation:Understanding Atherosclerosis and its Complications
Atherosclerosis is a complex process that occurs over several years. It begins with endothelial dysfunction triggered by factors such as smoking, hypertension, and hyperglycemia. This leads to changes in the endothelium, including inflammation, oxidation, proliferation, and reduced nitric oxide bioavailability. As a result, low-density lipoprotein (LDL) particles infiltrate the subendothelial space, and monocytes migrate from the blood and differentiate into macrophages. These macrophages then phagocytose oxidized LDL, slowly turning into large ‘foam cells’. Smooth muscle proliferation and migration from the tunica media into the intima result in the formation of a fibrous capsule covering the fatty plaque.
Once a plaque has formed, it can cause several complications. For example, it can form a physical blockage in the lumen of the coronary artery, leading to reduced blood flow and oxygen to the myocardium, resulting in angina. Alternatively, the plaque may rupture, potentially causing a complete occlusion of the coronary artery and resulting in a myocardial infarction. It is essential to understand the process of atherosclerosis and its complications to prevent and manage cardiovascular diseases effectively.
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This question is part of the following fields:
- Cardiovascular System
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Question 27
Incorrect
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A 27-year-old man comes to his doctor for a routine check-up before participating in a local 20-mile cycling race. He has been training for over a year and is determined to win. He has been experiencing occasional headaches on both sides of his head for the past three weeks, but they come and go and are not accompanied by aura, photophobia, or phonophobia. He has some redness and tenderness on his abdomen, but no masses are felt. His bowel and bladder function are normal. He had flu-like symptoms last week but is feeling much better now. His blood test results are as follows, and his hematocrit level is higher than normal:
Hemoglobin: 198 g/L
Platelets: 250 * 10^9/L
White blood cells: 6 * 10^9/L
Which of the following best explains his symptoms and blood test results?Your Answer:
Correct Answer: Secondary polycythemia due to erythropoietin use
Explanation:Athletes who use EPO are at risk of developing polycythemia. Cyclists are known to frequently use EPO, which can cause localized erythema on the abdomen from repeated injections. The patient’s headaches are not migrainous as they lack associated symptoms such as aura, photophobia, or phonophobia. Renal cell carcinoma is the primary type of kidney cancer in adults and typically presents with flank pain, haematuria, and a flank mass. Other symptoms may include weight loss, night sweats, fever, and malaise.
Polycythaemia is a condition that can be classified as relative, primary (polycythaemia rubra vera), or secondary. Relative polycythaemia can be caused by dehydration or stress, such as in Gaisbock syndrome. Primary polycythaemia rubra vera is a rare blood disorder that causes the bone marrow to produce too many red blood cells. Secondary polycythaemia can be caused by conditions such as COPD, altitude, obstructive sleep apnoea, or excessive erythropoietin production due to certain tumors or growths. To distinguish between true polycythaemia and relative polycythaemia, red cell mass studies may be used. In true polycythaemia, the total red cell mass in males is greater than 35 ml/kg and in women is greater than 32 ml/kg. Uterine fibroids may also cause polycythaemia indirectly by causing menorrhagia, but this is rarely a clinical problem.
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This question is part of the following fields:
- Haematology And Oncology
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Question 28
Incorrect
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A 65-year-old female presents to the emergency department with a three-week history of gradual-onset left knee pain. She has a known history of hyperparathyroidism, but is not on any regular medications.
Upon examination, there are no visible changes to the joint and the temperature over the knee is normal. However, she experiences tenderness over passive and active movement, but no restriction of joint movement.
A joint radiograph reveals no fracture but chondrocalcinosis. Further, a joint aspiration under polarised light shows positively birefringent rhomboid-shaped crystals.
What is the underlying pathology, given the likely diagnosis?Your Answer:
Correct Answer: Calcium pyrophosphate dihydrate deposition
Explanation:The most probable diagnosis for this patient is pseudogout, which is characterized by the deposition of calcium pyrophosphate dihydrate crystals in the synovium, resulting in pain during movement. The knee joint is commonly affected, and the presence of rhomboid-shaped crystals that are positively birefringent in polarised-light microscopy of joint aspirate confirms the diagnosis. Radiography may also reveal chondrocalcinosis.
A fracture would require a history of trauma and would be visible on the radiograph, neither of which is present in this case, making it an unlikely diagnosis.
Reactive arthritis is associated with immune-mediated destruction of the joint, but there is no recent history of diarrhoea, coryza, conjunctivitis, or urethritis, which are commonly associated with this condition. The light microscopy of joint aspirate and radiography findings do not support this diagnosis.
Joint infection typically presents with a hot, swollen joint that rapidly develops after a history of trauma. The joint aspirate would be expected to contain turbid fluid and grow organisms. However, none of these features are present in this patient, making joint infection an unlikely diagnosis.
Understanding Pseudogout
Pseudogout, also known as acute calcium pyrophosphate crystal deposition disease, is a type of microcrystal synovitis that occurs when calcium pyrophosphate dihydrate crystals are deposited in the synovium. This condition is commonly associated with increasing age, but younger patients who develop pseudogout usually have an underlying risk factor such as haemochromatosis, hyperparathyroidism, low magnesium or phosphate levels, acromegaly, or Wilson’s disease.
The knee, wrist, and shoulders are the most commonly affected joints in pseudogout. Diagnosis is made through joint aspiration, which reveals weakly-positively birefringent rhomboid-shaped crystals, and x-rays, which show chondrocalcinosis. In the knee, linear calcifications of the meniscus and articular cartilage can be seen.
Management of pseudogout involves joint fluid aspiration to rule out septic arthritis, followed by treatment with NSAIDs or intra-articular, intra-muscular, or oral steroids, similar to the treatment for gout. Understanding the risk factors and symptoms of pseudogout can help with early diagnosis and effective management of this condition.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 29
Incorrect
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A 20-year-old male presents to the emergency department with a three day history of dizziness and headache. He has no significant past medical history and is on no medications. He is studying computer science at university and lives in poorly ventilated student accommodation with eight other people. He follows a vegetarian diet.
His observations are heart rate 110 beats per minute, respiratory rate 23/minute, oxygen saturation 96% on room air, blood pressure 98/66 mmHg and temperature 37.2ÂșC.
On examination, he has an ataxic gait. Neurological, cardiovascular, abdominal, ENT and respiratory examinations are otherwise normal.
Urinalysis is normal.
An ECG demonstrated sinus tachycardia.
A chest x-ray is unremarkable.
Blood gas:
pH 7.25 (7.35-7.45)
PaO2 10.2 kPa (10-14)
PaCO2 5.4kPa (4.5-6)
HCO3 15 mmol/L (22-26)
SaO2 87% (94-98%)
Hb 112g/L (130-180)
Lactate 3.1 mmol/L (<2)
BE -3.5 (-2 - +2)
Glucose 5.3 mmol/L (4-6)
COHb 26% (<2%)
MetHb 0.2% (< 2%)
A CT head is normal.
What is the likely diagnosis and what could explain the low oxygen saturation reading on the arterial blood gas?Your Answer:
Correct Answer: Left shift of oxygen dissociation curve
Explanation:Carbon monoxide poisoning results in a leftward shift of the oxygen dissociation curve, leading to a decrease in the oxygen saturation of haemoglobin. This is due to the high affinity of carbon monoxide for haemoglobin, which competes with oxygen for binding. As a result, oxygen delivery to the tissues is impaired, causing hypoxia. The patient’s elevated carboxyhaemoglobin level, dissociation between peripheral and blood gas saturations, lactic acidosis, dizziness, headache, and ataxia all indicate carbon monoxide poisoning. The decreased partial pressure of environmental oxygen, alveolar destruction, and low haemoglobin are not the causes of his hypoxia.
Carbon monoxide poisoning occurs when carbon monoxide binds to haemoglobin and myoglobin, leading to tissue hypoxia. Symptoms include headache, nausea, vomiting, vertigo, confusion, and in severe cases, pink skin and mucosae, hyperpyrexia, arrhythmias, extrapyramidal features, coma, and death. Diagnosis is made through measuring carboxyhaemoglobin levels in arterial or venous blood gas. Treatment involves administering 100% high-flow oxygen via a non-rebreather mask for at least six hours, with hyperbaric oxygen therapy considered for more severe cases.
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This question is part of the following fields:
- General Principles
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Question 30
Incorrect
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A 26-year-old arrives at the emergency department with a dislocated shoulder after playing basketball. The joint is relocated, but he experiences pain and limited mobility in his affected arm. During the examination, it is observed that his right shoulder's flexion, extension, abduction, and external rotation are weakened. Additionally, he reports a loss of sensation in the lateral upper arm on the right side.
Which muscle/s receive innervation from the affected nerve in this case?Your Answer:
Correct Answer: Deltoid and teres minor
Explanation:The axillary nerve is responsible for supplying the deltoid and teres minor muscles, which allow for flexion, extension, abduction, and external rotation of the shoulder joint. Damage to this nerve can result in a loss of sensation over the ‘regimental badge’ area of the upper arm and impaired shoulder movement.
The biceps brachii, brachialis, and coracobrachialis muscles are innervated by the musculocutaneous nerve and are responsible for forearm flexion and shoulder adduction. Damage to this nerve would cause sensory impairment of the lateral aspect of the forearm.
The serratus anterior muscle is innervated by the long thoracic nerve and is responsible for stabilizing and upwardly rotating the scapula. Damage to this nerve would cause ‘winging’ of the scapula.
The supraspinatus and infraspinatus muscles are innervated by the suprascapular nerve and are responsible for initiating the first 15 degrees of abduction at the shoulder joint and externally rotating the shoulder, respectively.
The trapezius muscle is innervated by the accessory nerve and the ventral rami of the C3 and C4 spinal nerves. It acts to rotate and stabilize the scapula to enable movements of the upper limb.
Upper limb anatomy is a common topic in examinations, and it is important to know certain facts about the nerves and muscles involved. The musculocutaneous nerve is responsible for elbow flexion and supination, and typically only injured as part of a brachial plexus injury. The axillary nerve controls shoulder abduction and can be damaged in cases of humeral neck fracture or dislocation, resulting in a flattened deltoid. The radial nerve is responsible for extension in the forearm, wrist, fingers, and thumb, and can be damaged in cases of humeral midshaft fracture, resulting in wrist drop. The median nerve controls the LOAF muscles and can be damaged in cases of carpal tunnel syndrome or elbow injury. The ulnar nerve controls wrist flexion and can be damaged in cases of medial epicondyle fracture, resulting in a claw hand. The long thoracic nerve controls the serratus anterior and can be damaged during sports or as a complication of mastectomy, resulting in a winged scapula. The brachial plexus can also be damaged, resulting in Erb-Duchenne palsy or Klumpke injury, which can cause the arm to hang by the side and be internally rotated or associated with Horner’s syndrome, respectively.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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