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Question 1
Incorrect
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What does the term glycaemic index mean?
Your Answer: A measurement of how much glucose a food contains
Correct Answer: A measurement of how rapidly the carbohydrate in the food enters the blood
Explanation:The Glycaemic Index Method is a commonly used tool by dieticians and patients to determine the impact of different foods on blood glucose levels. This method involves calculating the area under a curve that shows the rise in blood glucose after consuming a test portion of food containing 50 grams of carbohydrate. The rationale behind using the GI index is that foods that cause a rapid and significant increase in blood glucose levels can lead to an increase in insulin production. This can put individuals at a higher risk of hyperinsulinaemia and weight gain.
High GI foods are typically those that contain refined sugars and processed cereals, such as white bread and white rice. These foods can cause a rapid increase in blood glucose levels, leading to a surge in insulin production. On the other hand, low GI foods, such as vegetables, legumes, and beans, are less likely to cause a significant increase in blood glucose levels.
Overall, the Glycaemic Index Method can be helpful in making informed food choices and managing blood glucose levels. By choosing low GI foods, individuals can reduce their risk of hyperinsulinaemia and weight gain, while still enjoying a healthy and balanced diet.
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This question is part of the following fields:
- Clinical Sciences
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Question 2
Incorrect
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Which of the following statements about research variables is accurate?
Your Answer: Dependent variables are affected by all other variables in a study
Correct Answer: Changes in a dependent variable may result from changes in the independent variable
Explanation:Understanding Variables in Research
Variables are characteristics, numbers, or quantities that can be measured or counted. They are also known as data items and can vary between data units in a population. Examples of variables include age, sex, income, expenses, and grades. In a typical study, there are three main variables: independent, dependent, and controlled.
The independent variable is the one that the researcher purposely changes during the investigation. The dependent variable is the one that is observed and changes in response to the independent variable. Controlled variables are those that are not changed during the experiment.
Dependent variables are affected by independent variables but not by controlled variables. For instance, in a weight loss medication study, the dosage of the medication is the independent variable, while the weight of the participants is the dependent variable. The researcher splits the participants into three groups, with each group receiving a different dosage of the medication. After six months, the participants’ weights are measured.
Understanding variables is crucial in research as it helps researchers to identify the factors that influence the outcome of their studies. By manipulating the independent variable, researchers can observe how it affects the dependent variable. Controlled variables help to ensure that the results are accurate and reliable.
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This question is part of the following fields:
- General Principles
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Question 3
Incorrect
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A 28-year-old woman comes to her outpatient appointment after being diagnosed with Grave's disease. This condition is known for having three distinct signs, in addition to thyroid eye disease. What are the other signs?
Your Answer: Thyroid arthritis & pretibial myxoedema
Correct Answer: Thyroid acropachy & pretibial myxoedema
Explanation:Grave’s disease is commonly linked to several other conditions, including thyroid eye disease, thyroid acropachy, and pretibial myxoedema.
This autoimmune disease, known as Grave’s thyroiditis, is caused by antibodies that target the thyroid stimulating hormone (TSH) receptor, leading to prolonged stimulation.
One of the most noticeable symptoms of Grave’s disease is exophthalmos, which occurs when TSH receptor antibodies bind to receptors at the back of the eye, causing inflammation and an increase in glycosaminoglycans. This results in swelling of the eye muscles and connective tissue.
Pretibial myxoedema is a skin condition that often develops in individuals with Grave’s disease. It is characterized by localized lesions on the skin in front of the tibia, which are caused by an increase in glycosaminoglycans in the pretibial dermis.
Thyroid acropachy is another condition associated with Grave’s disease, which involves swelling of soft tissues, clubbing of the fingers, and periosteal reactions in the extremities.
Graves’ Disease: Common Features and Unique Signs
Graves’ disease is the most frequent cause of thyrotoxicosis, which is commonly observed in women aged 30-50 years. The condition presents typical features of thyrotoxicosis, such as weight loss, palpitations, and heat intolerance. However, Graves’ disease also displays specific signs that are not present in other causes of thyrotoxicosis. These include eye signs, such as exophthalmos and ophthalmoplegia, as well as pretibial myxoedema and thyroid acropachy. The latter is a triad of digital clubbing, soft tissue swelling of the hands and feet, and periosteal new bone formation.
Graves’ disease is characterized by the presence of autoantibodies, including TSH receptor stimulating antibodies in 90% of patients and anti-thyroid peroxidase antibodies in 75% of patients. Thyroid scintigraphy reveals a diffuse, homogenous, and increased uptake of radioactive iodine. These features help distinguish Graves’ disease from other causes of thyrotoxicosis and aid in its diagnosis.
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This question is part of the following fields:
- Endocrine System
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Question 4
Incorrect
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A 19-year-old female comes to the clinic complaining of an itchy rash surrounding her belly button. She reports that the rash appeared a few days after getting her navel pierced. Upon examination, there is a vesicular rash with an erythematous base.
What are the primary cells involved in the disease affecting this patient?Your Answer: Classical complement pathway
Correct Answer: Th1 lymphocytes
Explanation:Th1 cells play a role in the cell mediated response, which is seen in contact dermatitis, a type 4 delayed hypersensitivity reaction. This reaction occurs due to the activation of Th1 lymphocyte cells and presents as a delayed reaction after exposure to the allergen.
Th2 lymphocytes, on the other hand, are involved in the humoral (antibody) process and activate B-cells.
Antigen presenting cells, such as macrophages and dendritic cells, process antigenic material and present them to lymphocytes.
The classical complement pathway is activated by antigen-antibody complexes (IgM/IgG). In systemic diseases like systemic lupus erythematosus, anti-glomerular basement membrane (anti-GBM) disease, and anti-neutrophil cytoplasmic autoantibody (ANCA)-associated glomerulonephritis, the presence of autoantibodies and the autoantibody-mediated involvement of the classical pathway of the complement cascade is the cause of glomerulonephritis.
T-Helper Cells: Two Major Subsets and Their Functions
T-Helper cells are a type of white blood cell that play a crucial role in the immune system. There are two major subsets of T-Helper cells, each with their own specific functions. The first subset is Th1, which is involved in the cell-mediated response and delayed (type IV) hypersensitivity. Th1 cells secrete cytokines such as IFN-gamma, IL-2, and IL-3, which help activate other immune cells and promote inflammation.
The second subset is Th2, which is involved in mediating humoral (antibody) immunity. Th2 cells are responsible for stimulating the production of antibodies, such as IgE in asthma. They secrete cytokines such as IL-4, IL-5, IL-6, IL-10, and IL-13, which help activate B cells and promote the production of antibodies.
Understanding the functions of these two subsets of T-Helper cells is important for developing treatments for various immune-related disorders. For example, drugs that target Th1 cells may be useful in treating autoimmune diseases, while drugs that target Th2 cells may be useful in treating allergies and asthma.
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This question is part of the following fields:
- General Principles
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Question 5
Correct
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A 32-year-old female patient arrives at the emergency department with suspected pulmonary embolism. The patient has a history of multiple deep vein thromboses on separate occasions and has few risk factors for thrombosis, but a significant family history of DVT. The consultant suspects an inherited thrombophilia.
What could be the possible diagnosis in this scenario?Your Answer: Factor V Leiden
Explanation:The most probable diagnosis for this case is factor V Leiden, which is the most common inherited thrombophilia. This condition causes resistance to activated protein C, which normally breaks down clotting factor V to prevent excessive clotting. As a result, individuals with factor V Leiden have an increased risk of developing blood clots, particularly deep vein thrombosis.
Antiphospholipid syndrome is another thrombophilia, but it is an acquired autoimmune disorder that is less common than factor V Leiden. It is characterized by inappropriate clotting and miscarriage, which are not present in this case.
Haemophilia A and von Willebrand disease are bleeding disorders that increase the risk of excessive bleeding, not clotting. Therefore, they are unlikely to be the cause of the patient’s thrombosis.
Protein C deficiency has a similar mechanism and presentation to factor V Leiden, but it is less common. Hence, it is not the most probable diagnosis in this case.
Thrombophilia is a condition that causes an increased risk of blood clots. It can be inherited or acquired. Inherited thrombophilia is caused by genetic mutations that affect the body’s natural ability to prevent blood clots. The most common cause of inherited thrombophilia is a gain of function polymorphism called factor V Leiden, which affects the protein that helps regulate blood clotting. Other genetic mutations that can cause thrombophilia include deficiencies of naturally occurring anticoagulants such as antithrombin III, protein C, and protein S. The prevalence and relative risk of venous thromboembolism (VTE) vary depending on the specific genetic mutation.
Acquired thrombophilia can be caused by conditions such as antiphospholipid syndrome or the use of certain medications, such as the combined oral contraceptive pill. These conditions can affect the body’s natural ability to prevent blood clots and increase the risk of VTE. It is important to identify and manage thrombophilia to prevent serious complications such as deep vein thrombosis and pulmonary embolism.
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This question is part of the following fields:
- Haematology And Oncology
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Question 6
Incorrect
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You are attending a seminar on adolescent eating disorders.
What hormonal alteration is common in post-pubertal teenagers with extreme undernourishment?Your Answer: Increased total triiodothyronine (T3)
Correct Answer: Hypogonadotrophic hypogonadism
Explanation:Endocrine System Adaptations during Starvation
During periods of starvation or severe malnutrition, the body undergoes various adaptations to cope with reduced food intake. One of the systems affected is the endocrine system, which experiences several changes. Glucagon levels increase, stimulating gluconeogenesis, while aldosterone, epinephrine, norepinephrine, and growth hormone levels also rise. Conversely, insulin production decreases, and there is a reduction in free and total T3, contributing to a lower metabolic rate. Prolonged starvation can also lead to a decrease in free T4. Hypogonadotrophic hypogonadism may occur, causing infertility, menstrual disturbances, amenorrhea, premature ovarian failure, and osteoporosis in women. Men may experience infertility, erectile dysfunction, and osteoporosis.
In summary, the endocrine system undergoes significant adaptations during starvation or severe malnutrition. These changes include alterations in hormone levels, such as increased glucagon and decreased insulin production, as well as reduced free and total T3. Hypogonadotrophic hypogonadism may also occur, leading to various reproductive and bone-related issues. these adaptations is crucial in managing individuals experiencing starvation or malnutrition.
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This question is part of the following fields:
- Paediatrics
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Question 7
Correct
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A 50-year-old male comes to the clinic with recent aggressive behaviour, depression, chorea and athetosis. His father had similar symptoms at the age of 70. It is suspected that he has a neurodegenerative disorder with trinucleotide repeat expansion.
What is the most likely trinucleotide repeat present in this case?Your Answer: CAG
Explanation:Huntington’s disease is a genetic disorder that causes progressive and incurable neurodegeneration. It is inherited in an autosomal dominant manner and is caused by a trinucleotide repeat expansion of CAG in the huntingtin gene on chromosome 4. This can result in the phenomenon of anticipation, where the disease presents at an earlier age in successive generations. The disease leads to the degeneration of cholinergic and GABAergic neurons in the striatum of the basal ganglia, which can cause a range of symptoms.
Typically, symptoms of Huntington’s disease develop after the age of 35 and can include chorea, personality changes such as irritability, apathy, and depression, intellectual impairment, dystonia, and saccadic eye movements. Unfortunately, there is currently no cure for Huntington’s disease, and it usually results in death around 20 years after the initial symptoms develop.
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This question is part of the following fields:
- Neurological System
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Question 8
Incorrect
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Which one of the following relationship descriptions regarding the scalene muscles is incorrect?
Your Answer: The anterior scalene inserts into the first rib
Correct Answer: The subclavian artery passes posterior to the middle scalene
Explanation:The middle scalene is located posterior to the subclavian artery.
The Scalene Muscles and Thoracic Outlet Syndrome
The scalene muscles are a group of three paired muscles located in the neck that play a role in elevating the ribs and tilting the neck. The scalenus anterior and medius muscles elevate the first rib and laterally flex the neck to the same side, while the scalenus posterior muscle elevates the second rib and tilts the neck to the opposite side. These muscles are innervated by spinal nerves C4-6 and originate from the transverse processes of C2 to C7, inserting into the first and second ribs.
The scalene muscles are important because the brachial plexus and subclavian artery pass between the anterior and middle scalenes through a space called the scalene hiatus or fissure. The subclavian vein and phrenic nerve pass anteriorly to the anterior scalene as it crosses over the first rib. However, the scalenes are at risk of adhering to the fascia surrounding the brachial plexus or shortening, which can cause compression of the brachial plexus when it passes between the clavicle and first rib. This condition is known as thoracic outlet syndrome.
In summary, the scalene muscles play an important role in the neck and chest, but can also cause issues if they become adhered or shortened, leading to thoracic outlet syndrome. It is important to be aware of this condition and seek medical attention if experiencing symptoms such as pain, numbness, or tingling in the arm or hand.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 9
Correct
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What is the structure utilized by bacteria to penetrate dense mucus?
Your Answer: Flagella
Explanation:Cell Surface Projections
Flagella, fimbriae, and pili are all types of cell surface projections found in bacteria. Flagella are composed of flagellin and have a motor pump at the base that propels the filamentous structure to allow bacteria to move. This movement is important for bacteria such as Helicobacter pylori to penetrate through gastric mucus. Fimbriae and pili are short projections that aid in attachment. They can be used to attach to an epithelial layer, which increases virulence, or to attach to other bacteria, which facilitates the exchange of genetic material.
In contrast, microvilli are cell surface projections found on the apical surfaces of human epithelial cells, such as enterocytes. They increase the surface area for absorption, allowing for more efficient nutrient uptake. Overall, these cell surface projections play important roles in bacterial movement, attachment, and nutrient absorption in human cells.
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This question is part of the following fields:
- Microbiology
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Question 10
Correct
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A 33-year-old is visiting the tuberculosis clinic for a medication check-up. He is currently undergoing treatment for active tuberculosis and is following directly observed therapy, which he is adhering to.
During the appointment, the patient reports experiencing a recent onset of painful and burning sensations in his hands and feet. Upon examination, the patient's radiological results show improvement, and he has gained weight. However, he has a sensory deficit that follows a glove and stocking distribution.
Which medication is most likely causing this patient's adverse reaction?Your Answer: Isoniazid
Explanation:Isoniazid is the correct option as it can lead to peripheral neuropathy, which is evident in this patient’s distal ‘burning’ sensation and peripheral sensory deficit. Isoniazid is known to be a pyridoxine (vitamin B6) antagonist, which is why pyridoxine is co-prescribed to prevent this adverse effect.
While Ethambutol can potentially cause peripheral neuropathy, it is much rarer and is more likely to cause optic neuropathy with associated visual disturbances, making it a less likely/incorrect option.
Pyrazinamide is not known to cause peripheral neuropathy, making it an incorrect option. Its main documented adverse effects are diarrhoea, vomiting, hyperuricemia, and gout.
Pyridoxine is co-prescribed with isoniazid to prevent peripheral neuropathy, making it an incorrect option.
Tuberculosis is a bacterial infection that can be treated with a combination of drugs. Each drug has a specific mechanism of action and can also cause side-effects. Rifampicin works by inhibiting bacterial DNA dependent RNA polymerase, which prevents the transcription of DNA into mRNA. However, it is a potent liver enzyme inducer and can cause hepatitis, orange secretions, and flu-like symptoms.
Isoniazid, on the other hand, inhibits mycolic acid synthesis. It can cause peripheral neuropathy, which can be prevented with pyridoxine (Vitamin B6). It can also cause hepatitis and agranulocytosis, but it is a liver enzyme inhibitor.
Pyrazinamide is converted by pyrazinamidase into pyrazinoic acid, which inhibits fatty acid synthase (FAS) I. However, it can cause hyperuricaemia, leading to gout, as well as arthralgia and myalgia. It can also cause hepatitis.
Finally, Ethambutol inhibits the enzyme arabinosyl transferase, which polymerizes arabinose into arabinan. However, it can cause optic neuritis, so it is important to check visual acuity before and during treatment. The dose also needs adjusting in patients with renal impairment.
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This question is part of the following fields:
- General Principles
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Question 11
Incorrect
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A 45-year-old businessman comes to his GP complaining of fever, headache, and diarrhoea. He denies having any coughs, nausea, or vomiting. He has a good health history. However, he recently returned from a business trip to India three weeks ago. He has been consuming the same food and drinks as his family since his return, and they are all healthy. During the examination, the man seems dehydrated and has tenderness in the right upper quadrant.
What do you think is the probable diagnosis?Your Answer: Hepatitis C
Correct Answer: Hepatitis A
Explanation:Understanding Hepatitis A: Symptoms, Transmission, and Prevention
Hepatitis A is a viral infection that affects the liver. It is usually a mild illness that resolves on its own, with serious complications being rare. The virus is transmitted through the faecal-oral route, often in institutions. The incubation period is typically 2-4 weeks, and symptoms include a flu-like prodrome, abdominal pain (usually in the right upper quadrant), tender hepatomegaly, jaundice, and deranged liver function tests.
While complications are rare, there is no increased risk of hepatocellular cancer. An effective vaccine is available, and it is recommended for people travelling to or residing in areas of high or intermediate prevalence, those with chronic liver disease, patients with haemophilia, men who have sex with men, injecting drug users, and individuals at occupational risk (such as laboratory workers, staff of large residential institutions, sewage workers, and people who work with primates).
It is important to note that the vaccine requires a booster dose 6-12 months after the initial dose. By understanding the symptoms, transmission, and prevention of hepatitis A, individuals can take steps to protect themselves and others from this viral infection.
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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 30-year-old patient visits their GP with complaints of muscle wasting in their legs, foot drop, and a high-arched foot. The patient has a medical history of type 1 diabetes mellitus. The GP observes that the patient's legs resemble 'champagne bottles'. The patient denies any recent trauma, sensory deficits, or back pain.
What is the probable diagnosis?Your Answer: Cauda equina syndrome
Correct Answer: Charcot-Marie-Tooth disease
Explanation:Charcot-Marie-Tooth syndrome is characterized by classic signs such as foot drop and a high-arched foot. The initial symptom often observed is foot drop, which is caused by chronic motor neuropathy leading to muscular atrophy. This can result in the distinctive champagne bottle appearance of the foot.
Diabetic neuropathy is an incorrect answer as it typically presents with significant sensory deficits in a ‘glove and stocking’ pattern.
Cauda equina syndrome is also an incorrect answer as it typically results in more severe symptoms such as loss of bladder control and significant sensory deficits, as well as back and spine pain. While foot drop may be present, it is unlikely to cause atrophy of the distal muscles.
CIDP is another incorrect answer as patients with this condition typically experience significant proximal and distal atrophy, which would not lead to the champagne bottle appearance. Additionally, sensory symptoms are present but less noticeable than the motor symptoms.
Charcot-Marie-Tooth Disease is a prevalent genetic peripheral neuropathy that primarily affects motor function. Unfortunately, there is no known cure for this condition, and treatment is mainly centered around physical and occupational therapy. Some common symptoms of Charcot-Marie-Tooth Disease include a history of frequent ankle sprains, foot drop, high-arched feet (also known as pes cavus), hammer toes, distal muscle weakness and atrophy, hyporeflexia, and the stork leg deformity.
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This question is part of the following fields:
- Neurological System
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Question 13
Incorrect
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A man in his early fifties comes to the clinic with symptoms of progressive paralysis and difficulty in swallowing. Upon examination, it is found that he has spastic paralysis in his arms and reduced knee reflexes. The diagnosis is confirmed as amyotrophic lateral sclerosis (ALS). What type of cell death is responsible for the combination of upper and lower motor neuron lesions seen in ALS?
Your Answer: Betz cells of the motor cortex
Correct Answer: Motor cortex neuronal cells and anterior horn cells
Explanation:Upper motor lesion signs are caused by damage to neuronal cells in the motor cortex, while lower motor lesion signs are caused by damage to anterior horn cells. This is why ALS, which involves damage to both areas, presents with mixed signs. If only one of these areas were damaged, it would result in only one type of motor neuron lesion sign. Multiple sclerosis often involves multiple lesions in the brain.
Motor neuron disease is a neurological condition that is not yet fully understood. It can manifest with both upper and lower motor neuron signs and is rare before the age of 40. There are different patterns of the disease, including amyotrophic lateral sclerosis, progressive muscular atrophy, and bulbar palsy. Some of the clues that may indicate a diagnosis of motor neuron disease include fasciculations, the absence of sensory signs or symptoms, a combination of lower and upper motor neuron signs, and wasting of small hand muscles or tibialis anterior.
Other features of motor neuron disease include the fact that it does not affect external ocular muscles and there are no cerebellar signs. Abdominal reflexes are usually preserved, and sphincter dysfunction is a late feature if present. The diagnosis of motor neuron disease is made based on clinical presentation, but nerve conduction studies can help exclude a neuropathy. Electromyography may show a reduced number of action potentials with increased amplitude. MRI is often used to rule out cervical cord compression and myelopathy as differential diagnoses. It is important to note that while vague sensory symptoms may occur early in the disease, sensory signs are typically absent.
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This question is part of the following fields:
- Neurological System
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Question 14
Correct
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A 28-year-old, first-time pregnant woman is currently in the second stage of labor, actively pushing to deliver her baby. The estimated weight of the baby is slightly above average, which has caused a prolonged second stage of labor. Eventually, the baby is delivered, but the patient experiences a second-degree perineal tear. The tear is immediately sutured to prevent bleeding. What is a risk factor for perineal tears?
Your Answer: Primigravida
Explanation:The only correct risk factor for perineal tears is being a primigravida. Other factors such as IUGR, spontaneous vaginal delivery, and caesarian section do not increase the risk of perineal tears. However, macrosomia and instrumental delivery are known risk factors for perineal tears.
Understanding Perineal Tears: Classification and Risk Factors
Perineal tears are a common occurrence during childbirth, and the Royal College of Obstetricians and Gynaecologists (RCOG) has provided guidelines for their classification. First-degree tears are superficial and do not require any repair, while second-degree tears involve the perineal muscle and require suturing by a midwife or clinician. Third-degree tears involve the anal sphincter complex and require repair in theatre by a trained clinician, with varying degrees of severity depending on the extent of the tear. Fourth-degree tears involve the anal sphincter complex, rectal mucosa, and require repair in theatre by a trained clinician.
There are several risk factors for perineal tears, including being a first-time mother, delivering a large baby, experiencing a precipitant labour, and having a shoulder dystocia or forceps delivery. It is important for healthcare providers to be aware of these risk factors and to provide appropriate care and support during childbirth to minimize the risk of perineal tears. By understanding the classification and risk factors associated with perineal tears, healthcare providers can better prepare for and manage this common complication of childbirth.
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This question is part of the following fields:
- Reproductive System
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Question 15
Incorrect
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A 35-year-old woman presents to the Emergency Department with progressive weakness of her lower limbs. Her symptoms started three days previously when she noticed her legs felt heavy when rising from a seated position. This weakness has progressed to the point now where she is unable to stand unassisted and has now started to affect some of the muscles of her abdominal wall and lower back. She is otherwise well, apart from suffering a diarrhoeal illness 12 days previously. Neurological examination of the lower limbs identifies generalised weakness, reduced tone and absent reflexes; sensory examination is unremarkable.
Which of the following organisms is most likely to have caused this patient's diarrhoeal symptoms?Your Answer: Bacillus cereus
Correct Answer: Campylobacter jejuni
Explanation:The correct answer for the trigger of Guillain-Barre syndrome is Campylobacter jejuni. The patient’s symptoms of ascending muscle weakness without sensory signs and absent reflexes and reduced tone suggest a lower motor neuron lesion, which is likely due to GBS. GBS is an autoimmune-mediated demyelinating disease of the peripheral nervous system that is often triggered by an infection, with Campylobacter jejuni being the classic trigger. None of the other options are associated with GBS. Bacillus cereus can cause food poisoning from rice, resulting in vomiting and diarrhoea. Escherichia coli is common among travellers and can cause watery stools and abdominal cramps. Shigella can cause bloody diarrhoea with vomiting and abdominal pain.
Understanding Guillain-Barre Syndrome and Miller Fisher Syndrome
Guillain-Barre syndrome is a condition that affects the peripheral nervous system and is often triggered by an infection, particularly Campylobacter jejuni. The immune system attacks the myelin sheath that surrounds nerve fibers, leading to demyelination. This results in symptoms such as muscle weakness, tingling sensations, and paralysis.
The pathogenesis of Guillain-Barre syndrome involves the cross-reaction of antibodies with gangliosides in the peripheral nervous system. Studies have shown a correlation between the presence of anti-ganglioside antibodies, particularly anti-GM1 antibodies, and the clinical features of the syndrome. In fact, anti-GM1 antibodies are present in 25% of patients with Guillain-Barre syndrome.
Miller Fisher syndrome is a variant of Guillain-Barre syndrome that is characterized by ophthalmoplegia, areflexia, and ataxia. This syndrome typically presents as a descending paralysis, unlike other forms of Guillain-Barre syndrome that present as an ascending paralysis. The eye muscles are usually affected first in Miller Fisher syndrome. Studies have shown that anti-GQ1b antibodies are present in 90% of cases of Miller Fisher syndrome.
In summary, Guillain-Barre syndrome and Miller Fisher syndrome are conditions that affect the peripheral nervous system and are often triggered by infections. The pathogenesis of these syndromes involves the cross-reaction of antibodies with gangliosides in the peripheral nervous system. While Guillain-Barre syndrome is characterized by muscle weakness and paralysis, Miller Fisher syndrome is characterized by ophthalmoplegia, areflexia, and ataxia.
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This question is part of the following fields:
- Neurological System
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Question 16
Incorrect
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A pair arrives at the infertility clinic after unsuccessful attempts to conceive despite regular unprotected vaginal intercourse with ejaculation. The wife has a child from a previous relationship three years ago and has no history of fertility issues. Her gynecological history is unremarkable. The husband seems normal except for having a severe cough. What is the probable reason for their inability to conceive?
Your Answer: Obstruction of tubes due to endometriosis
Correct Answer: Congenital bilateral absence of the vas deferens in the male
Explanation:The couple is attempting to conceive through vaginal intercourse with regular, unprotected sex where the ejaculate enters the vagina. The wife has successfully conceived before, and there have been no previous fertility issues, indicating that the male partner may be the cause of the problem. The husband’s chesty cough may indicate a lung disease, such as cystic fibrosis, which is linked to male infertility due to the congenital absence of the vas deferens.
Understanding Absence of the Vas Deferens
Absence of the vas deferens is a condition that can occur either unilaterally or bilaterally. In 40% of cases, the cause is due to mutations in the CFTR gene, which is associated with cystic fibrosis. However, in some non-CF cases, the absence of the vas deferens is due to unilateral renal agenesis. Despite this condition, assisted conception may still be possible through sperm harvesting.
It is important to understand the underlying causes of absence of the vas deferens, as it can impact fertility and the ability to conceive. While the condition may be associated with cystic fibrosis, it can also occur independently. However, with advancements in assisted reproductive technologies, individuals with this condition may still have options for starting a family. By seeking medical advice and exploring available options, individuals can make informed decisions about their reproductive health.
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This question is part of the following fields:
- Reproductive System
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Question 17
Correct
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A 75-year-old male with a history of atrial fibrillation and diverticulitis presents to the emergency department with severe abdominal pain. After thorough investigation, including mesenteric angiography, it was found that the left colic flexure was experiencing ischemia. Which artery provides direct supply to this region through its branches?
Your Answer: Inferior mesenteric artery (IMA)
Explanation:The inferior mesenteric artery supplies the distal 1/3 of the transverse colon, while the proximal two thirds are supplied by the middle colic artery, a branch of the SMA. The left colic artery, a branch of the IMA, supplies the remaining distal portion. Although the left colic artery is the primary supplier, collateral flow from branches of the middle colic artery also contributes. The left colic flexure, located between the end of the SMA and the start of the IMA’s blood supply, is a watershed region that can be susceptible to ischemia due to atherosclerotic changes or hypotension.
The splenic artery directly supplies the spleen and also has branches that supply the stomach and pancreas. There is no such thing as the AMA or PMA.
The Transverse Colon: Anatomy and Relations
The transverse colon is a part of the large intestine that begins at the hepatic flexure, where the right colon makes a sharp turn. At this point, it becomes intraperitoneal and is connected to the inferior border of the pancreas by the transverse mesocolon. The middle colic artery and vein are contained within the mesentery. The greater omentum is attached to the superior aspect of the transverse colon, which can be easily separated. The colon undergoes another sharp turn at the splenic flexure, where the greater omentum remains attached up to this point. The distal 1/3 of the transverse colon is supplied by the inferior mesenteric artery.
The transverse colon is related to various structures. Superiorly, it is in contact with the liver, gallbladder, the greater curvature of the stomach, and the lower end of the spleen. Inferiorly, it is related to the small intestine. Anteriorly, it is in contact with the greater omentum, while posteriorly, it is in contact with the descending portion of the duodenum, the head of the pancreas, convolutions of the jejunum and ileum, and the spleen. Understanding the anatomy and relations of the transverse colon is important for medical professionals in diagnosing and treating various gastrointestinal conditions.
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This question is part of the following fields:
- Gastrointestinal System
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Question 18
Correct
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What is the mechanism of action of heparin in elderly patients?
Your Answer: Activates antithrombin III
Explanation:Unfractionated heparin works by activating antithrombin III, which then forms a complex that inhibits several clotting factors including thrombin, factors Xa, Ixa, Xia, and XIIa.
Heparin is a type of anticoagulant medication that comes in two main forms: unfractionated heparin and low molecular weight heparin (LMWH). Both types work by activating antithrombin III, but unfractionated heparin forms a complex that inhibits thrombin, factors Xa, IXa, XIa, and XIIa, while LMWH only increases the action of antithrombin III on factor Xa. Adverse effects of heparins include bleeding, thrombocytopenia, osteoporosis, and hyperkalemia. LMWH has a lower risk of causing heparin-induced thrombocytopenia (HIT) and osteoporosis compared to unfractionated heparin. HIT is an immune-mediated condition where antibodies form against complexes of platelet factor 4 (PF4) and heparin, leading to platelet activation and a prothrombotic state. Treatment for HIT includes direct thrombin inhibitors or danaparoid. Heparin overdose can be partially reversed by protamine sulfate.
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This question is part of the following fields:
- General Principles
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Question 19
Correct
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Which nerve provides the motor supply to the brachialis muscle?
Your Answer: Radial and musculocutaneous nerve
Explanation:The Brachialis Muscle: Anatomy and Innervation
The brachialis muscle is responsible for flexing the forearm and is located in the anterior half of the humerus and intermuscular septa. It attaches to the coronoid process and tuberosity of the ulna at the elbow joint. The main nerve supply for the brachialis muscle is the musculocutaneous nerve, with C6 and radial nerve also playing a role. Additionally, the lateral part of the brachialis muscle is supplied by branches from the C7 root. Overall, the brachialis muscle is an important muscle for forearm flexion and is innervated by multiple nerves.
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This question is part of the following fields:
- Clinical Sciences
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Question 20
Incorrect
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A 67-year-old man presents to his doctor with a one month history of speech difficulty. He reports experiencing pronunciation difficulties which he has never had before. However, his reading ability remains intact.
During the consultation, the doctor observes occasional pronunciation errors when the patient is asked to repeat certain words. Despite this, the patient is able to construct meaningful sentences with minimal grammatical errors. He also demonstrates the ability to comprehend questions and respond appropriately.
The doctor performs a cranial nerve examination which yields normal results.
Which area of the brain may be affected by a lesion to cause this presentation?Your Answer: Hypoglossal nerve
Correct Answer: Arcuate fasciculus
Explanation:Conduction dysphasia is characterized by fluent speech but poor repetition ability, with relatively intact comprehension. This is a typical manifestation of conduction aphasia, which is caused by damage to the arcuate fasciculus connecting Broca’s and Wernicke’s areas. Patients with this condition may be aware of their pronunciation difficulties and may become frustrated when attempting to correct themselves.
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 21
Incorrect
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A 24-year-old man visits his GP clinic and requests a referral to a plastic surgeon. He is worried that his ears are too large compared to his face. This has caused him to become reclusive and he has lost his employment. Upon examination, his ears seem to be of normal size. What is the most suitable term for this conduct?
Your Answer: Hypochondriasis
Correct Answer: Dysmorphophobia
Explanation:Understanding Body Dysmorphic Disorder
Body dysmorphic disorder, also known as dysmorphophobia, is a mental health condition that affects a person’s perception of their physical appearance. Individuals with this disorder have a distorted body image, which causes them to obsess over perceived flaws or defects in their appearance. Even if there is only a slight physical abnormality, the person’s concern is excessive and can lead to significant distress or impairment in their daily life.
According to the Diagnostic and Statistical Manual (DSM) IV criteria, the preoccupation with the imagined defect must cause clinically significant distress or impairment in social, occupational, or other important areas of functioning. It is important to note that this preoccupation is not better accounted for by another mental disorder, such as dissatisfaction with body shape and size in Anorexia Nervosa.
Body dysmorphic disorder can have a significant impact on a person’s mental health and quality of life. It is important for individuals who may be experiencing symptoms of this disorder to seek professional help from a mental health provider. With proper treatment, individuals with body dysmorphic disorder can learn to manage their symptoms and improve their overall well-being.
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This question is part of the following fields:
- Psychiatry
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Question 22
Incorrect
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A 78-year-old man is undergoing evaluation for a cognitive impairment and suspected movement disorder. Various scans are ordered to aid in the assessment.
The scan findings are as follows:
MRI head reveals typical age-related alterations
SPECT scan shows decreased dopaminergic activity in the substantia nigra
Based on the above results, what is the probable diagnosis?Your Answer: Pseudodementia
Correct Answer: Parkinson's disease
Explanation:Neurodegenerative diseases are a group of disorders that affect the nervous system and lead to progressive deterioration of its functions. Parkinson’s disease is a common example of a basal ganglia disorder, which is characterized by the loss of dopamine-producing neurons in the substantia nigra. This results in motor symptoms such as bradykinesia, muscle rigidity, tremor, and postural instability, as well as cognitive, mood, and behavioral changes.
Alzheimer’s dementia, on the other hand, is not associated with a movement disorder but is characterized by atrophy of the medial temporal lobe and temporoparietal cortex, which can be seen on CT and MRI scans.
Huntington’s disease is another basal ganglia disorder, but it primarily affects the striatum, leading to a loss of striatal volume on CT and MRI scans. The movement disorder seen in Huntington’s disease is chorea, which is characterized by jerky, uncontrollable limb movements.
Multi-system atrophy is a rare neurodegenerative disease that affects the basal ganglia and cerebellum, leading to autonomic dysfunction, ataxia, and Parkinsonism. However, cognitive impairment is uncommon in this disorder.
Parkinson’s disease is a progressive neurodegenerative disorder that occurs due to the degeneration of dopaminergic neurons in the substantia nigra. This leads to a classic triad of symptoms, including bradykinesia, tremor, and rigidity, which are typically asymmetrical. The disease is more common in men and is usually diagnosed around the age of 65. Bradykinesia is characterized by a poverty of movement, shuffling steps, and difficulty initiating movement. Tremors are most noticeable at rest and typically occur in the thumb and index finger. Rigidity can be either lead pipe or cogwheel, and other features include mask-like facies, flexed posture, and drooling of saliva. Psychiatric features such as depression, dementia, and sleep disturbances may also occur. Diagnosis is usually clinical, but if there is difficulty differentiating between essential tremor and Parkinson’s disease, 123I‑FP‑CIT single photon emission computed tomography (SPECT) may be considered.
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This question is part of the following fields:
- Neurological System
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Question 23
Incorrect
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A 50-year-old woman visits a sexual health clinic for routine cervical screening and is found to have a polypoid lesion arising from the ectocervix. What is the typical epithelium found in this region?
Your Answer: Pseudostratified columnar epithelium
Correct Answer: Stratified squamous non-keratinized epithelium
Explanation:The ectocervix is typically covered by stratified squamous non-keratinized epithelium. If a patient presents with the described symptoms, it is important to investigate further for potential cervical cancer or cervical polyps, which can be discovered during routine gynaecological examinations. Pseudostratified columnar epithelium is not found in the cervix, while simple columnar epithelium is typically found in the endocervix. Simple squamous non-keratinized epithelium is not present in the ectocervix, which has multiple layers of squamous epithelium.
Anatomy of the Uterus
The uterus is a female reproductive organ that is located within the pelvis and is covered by the peritoneum. It is supplied with blood by the uterine artery, which runs alongside the uterus and anastomoses with the ovarian artery. The uterus is supported by various ligaments, including the central perineal tendon, lateral cervical, round, and uterosacral ligaments. The ureter is located close to the uterus, and injuries to the ureter can occur when there is pathology in the area.
The uterus is typically anteverted and anteflexed in most women. Its topography can be visualized through imaging techniques such as ultrasound or MRI. Understanding the anatomy of the uterus is important for diagnosing and treating various gynecological conditions.
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This question is part of the following fields:
- Reproductive System
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Question 24
Incorrect
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A 55-year-old male has been suffering from chronic pain for many years due to an industrial accident he had in his thirties. The WHO defines chronic pain as pain that persists for how long?
Your Answer:
Correct Answer: 12 weeks
Explanation:Chronic pain is defined by the WHO as pain that lasts for more than 12 weeks. Therefore, the correct answer is 12 weeks, and all other options are incorrect.
Guidelines for Managing Chronic Pain
Chronic pain is defined as pain that lasts for more than 12 weeks and can include conditions such as musculoskeletal pain, neuropathic pain, vascular insufficiency, and degenerative disorders. In 2013, the Scottish Intercollegiate Guidelines Network (SIGN) produced guidelines for the management of chronic, non-cancer related pain.
Non-pharmacological interventions are recommended by SIGN, including self-management information, exercise, manual therapy, and transcutaneous electrical nerve stimulation (TENS). Exercise has been shown to be effective in improving chronic pain, and specific support such as referral to an exercise program is recommended. Manual therapy is particularly effective for spinal pain, while TENS can also be helpful.
Pharmacological interventions may be necessary, but if medications are not effective after 2-4 weeks, they are unlikely to be effective. For neuropathic pain, SIGN recommends gabapentin or amitriptyline as first-line treatments. NICE also recommends pregabalin or duloxetine as first-line treatments. For fibromyalgia, duloxetine or fluoxetine are recommended.
If patients are using more than 180 mg/day morphine equivalent, experiencing significant distress, or rapidly escalating their dose without pain relief, SIGN recommends referring them to specialist pain management services.
Overall, the management of chronic pain requires a comprehensive approach that includes both non-pharmacological and pharmacological interventions, as well as referral to specialist services when necessary.
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This question is part of the following fields:
- Neurological System
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Question 25
Incorrect
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A 25-year-old female visits her doctor at 24 weeks of pregnancy. She underwent a sexual health screening that included a complement fixation test for herpes simplex virus, which came back positive. The doctor explains to her that the antibody tested for is typically the first antibody produced in response to an infection and may indicate a recent or new herpes virus infection. The patient is curious if her baby will be immune to herpes if she has developed antibodies during pregnancy.
What specific herpes simplex virus antibody was tested in this patient, and what counseling should be provided to her?Your Answer:
Correct Answer: IgM has been tested for - it does not cross the placenta
Explanation:The antibody that fixes complement but does not pass to the fetal circulation is IgM. Complement fixation tests are used to detect IgM and IgG class antibodies against specific microbial antigens, indicating a humoral immune response. IgM is the first antibody released in response to infection and is used in herpes simplex virus complement fixation testing. It does not cross the placenta. IgA is the predominant antibody in breast milk, while IgG is the only antibody that crosses the placenta. Therefore, options regarding IgG would be incorrect in this scenario.
Immunoglobulins, also known as antibodies, are proteins produced by the immune system to help fight off infections and diseases. There are five types of immunoglobulins found in the body, each with their own unique characteristics.
IgG is the most abundant type of immunoglobulin in blood serum and plays a crucial role in enhancing phagocytosis of bacteria and viruses. It also fixes complement and can be passed to the fetal circulation.
IgA is the most commonly produced immunoglobulin in the body and is found in the secretions of digestive, respiratory, and urogenital tracts and systems. It provides localized protection on mucous membranes and is transported across the interior of the cell via transcytosis.
IgM is the first immunoglobulin to be secreted in response to an infection and fixes complement, but does not pass to the fetal circulation. It is also responsible for producing anti-A, B blood antibodies.
IgD’s role in the immune system is largely unknown, but it is involved in the activation of B cells.
IgE is the least abundant type of immunoglobulin in blood serum and is responsible for mediating type 1 hypersensitivity reactions. It provides immunity to parasites such as helminths and binds to Fc receptors found on the surface of mast cells and basophils.
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This question is part of the following fields:
- General Principles
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Question 26
Incorrect
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A 70-year-old man visits his doctor for his yearly hypertension check-up. He is presently on the highest possible dose of ramipril, amlodipine, and indapamide. During the check-up, his blood pressure is recorded as 156/95 mmHg. The doctor advises him on lifestyle changes and suggests doxazosin. Can you explain the mechanism of action of this medication?
Your Answer:
Correct Answer: Alpha-1 antagonist
Explanation:Doxazosin is an alpha-1 antagonist that specifically targets the peripheral vasculature. By blocking these receptors, it can effectively decrease blood pressure, peripheral vascular resistance, and vasoconstriction, making it a useful antihypertensive medication.
The options of alpha-2 antagonist, beta-1 antagonist, and beta-2 antagonist are incorrect. Alpha-2 receptors inhibit the release of norepinephrine, acetylcholine, and insulin, and there is no significant use for alpha-2 antagonists in mainstream healthcare. Beta-1 receptors affect the heart, and beta-2 receptors work peripherally, affecting peripheral vascular resistance and bronchoconstriction. Antagonists of these receptors would respectively decrease heart rate and myocardial contractility or cause non-specific effects on both beta-1 and beta-2 receptors.
Adrenoceptor Antagonists: Types and Examples
Adrenoceptor antagonists are drugs that block the action of adrenaline and noradrenaline on specific receptors in the body. There are two main types of adrenoceptor antagonists: alpha antagonists and beta antagonists. Alpha antagonists block the action of adrenaline and noradrenaline on alpha receptors, while beta antagonists block their action on beta receptors.
Examples of alpha antagonists include doxazosin, which blocks alpha-1 receptors, and tamsulosin, which acts mainly on urogenital tract by blocking alpha-1a receptors. Yohimbine is an example of an alpha-2 antagonist, while phenoxybenzamine, previously used in peripheral arterial disease, is a non-selective alpha antagonist.
Beta antagonists include atenolol, which blocks beta-1 receptors, and propranolol, which is a non-selective beta antagonist. Carvedilol and labetalol are examples of mixed alpha and beta antagonists.
Overall, adrenoceptor antagonists are important drugs that can be used to treat a variety of conditions, including hypertension, heart failure, and angina.
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This question is part of the following fields:
- General Principles
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Question 27
Incorrect
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A 15-year-old boy presents with diplopia and headache. Imaging reveals acute hydrocephalus and a space occupying lesion in the base of the 4th ventricle. What type of cell proliferation would be expected on biopsy?
Your Answer:
Correct Answer: Ependymal cells
Explanation:Childhood tumours of the central nervous system (CNS) frequently develop at the base of the 4th ventricle. Oligodendrocytes are accountable for creating the myelin sheath in the CNS. The formation of the blood-brain barrier is a crucial function of astrocytes. Schwann cells are responsible for creating the myelin sheath in the peripheral nervous system.
The nervous system is composed of various types of cells, each with their own unique functions. Oligodendroglia cells are responsible for producing myelin in the central nervous system (CNS) and are affected in multiple sclerosis. Schwann cells, on the other hand, produce myelin in the peripheral nervous system (PNS) and are affected in Guillain-Barre syndrome. Astrocytes provide physical support, remove excess potassium ions, help form the blood-brain barrier, and aid in physical repair. Microglia are specialised CNS phagocytes, while ependymal cells provide the inner lining of the ventricles.
In summary, the nervous system is made up of different types of cells, each with their own specific roles. Oligodendroglia and Schwann cells produce myelin in the CNS and PNS, respectively, and are affected in certain diseases. Astrocytes provide physical support and aid in repair, while microglia are specialised phagocytes in the CNS. Ependymal cells line the ventricles. Understanding the functions of these cells is crucial in understanding the complex workings of the nervous system.
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This question is part of the following fields:
- Neurological System
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Question 28
Incorrect
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A 28-year-old man visits his GP with complaints of bilateral numbness in his hands and feet, along with a feeling of muscle weakness that has been progressively worsening for the past 15 months. The man admits to avoiding hospitals and his GP, and has not reported these symptoms to anyone else. Upon examination, reduced bicep reflexes are noted bilaterally. Nerve conduction studies reveal evidence of peripheral nerve demyelination. What is the most probable underlying diagnosis?
Your Answer:
Correct Answer: Chronic inflammatory demyelinating polyneuropathy
Explanation:Chronic inflammatory demyelinating polyneuropathy (CIDP) is a condition where the inflammation and infiltration of the endoneurium with inflammatory T cells are thought to be caused by antibodies. This results in the demyelination of peripheral nerves in a segmental manner.
CIDP is characterized by generalized symptoms and chronicity, and nerve conduction tests can reveal demyelination of the nerves. Guillain Barré syndrome (GBS) is an incorrect answer as it is more acute and often triggered by prior infection, particularly Campylobacter gastrointestinal infection. Diabetic neuropathy is also an incorrect answer as it typically presents as a focal peripheral neuropathy with sensory impairment. Multiple sclerosis (MS) is another incorrect answer as it involves the central nervous system and can present with additional signs/symptoms such as visual impairment and muscle stiffness. MS is diagnosed using an MRI scan and checking for oligoclonal bands in the cerebrospinal fluid.
Understanding Chronic Inflammatory Demyelinating Polyneuropathy
Chronic inflammatory demyelinating polyneuropathy (CIDP) is a type of peripheral neuropathy that is caused by antibody-mediated inflammation resulting in segmental demyelination of peripheral nerves. This condition is more common in males than females and shares similar features with Guillain-Barre syndrome (GBS), with motor symptoms being predominant. However, CIDP has a more insidious onset, occurring over weeks to months, and is often considered the chronic version of GBS.
One of the distinguishing features of CIDP is the high protein content found in the cerebrospinal fluid (CSF). Treatment for CIDP may involve the use of steroids and immunosuppressants, which is different from GBS.
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This question is part of the following fields:
- Neurological System
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Question 29
Incorrect
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A 35-year-old man visits his GP complaining of a painful, erythematous, vesicular rash on the anteromedial aspect of his left arm and a small area of his left chest. The patient reports that he first experienced pain in the affected area three days ago and noticed the rash yesterday morning. He attributes his current stressful state to work-related issues, which were exacerbated by a recent COVID-19 infection that required him to take 10 days off. The patient confirms that he had chickenpox during his childhood. Based on this information, where is the virus responsible for his symptoms most likely to have been dormant in his nervous system?
Your Answer:
Correct Answer: T1 dorsal root ganglion
Explanation:After the primary infection (usually chickenpox during childhood), the herpes zoster virus remains inactive in the dorsal root or cranial nerve ganglia. The patient’s rash, which appears in the left T1 dermatome, indicates that the virus has been dormant in the T1 dorsal root ganglion. Although herpes zoster can reactivate at any time, it is more commonly associated with older age, recent viral infections, periods of stress, or immunosuppression.
Shingles is a painful blistering rash caused by reactivation of the varicella-zoster virus. It is more common in older individuals and those with immunosuppressive conditions. The diagnosis is usually clinical and management includes analgesia, antivirals, and reminding patients they are potentially infectious. Complications include post-herpetic neuralgia, herpes zoster ophthalmicus, and herpes zoster oticus. Antivirals should be used within 72 hours to reduce the incidence of post-herpetic neuralgia.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 30
Incorrect
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A 7-year-old girl is brought to the child assessment unit by her father. She has been experiencing lower leg pain for over 3 weeks. He reports that she has been tripping more than usual but attributes it to her new carpet. Lately, she has been having difficulty getting out of bed and sometimes complains of feeling tired. The child appears to be in good health but has a runny nose. During the examination, she falls off the bed and lands on the floor. She uses her arms and legs to help herself up as she tries to stand.
What is the observed sign in this scenario?Your Answer:
Correct Answer: Gower's sign
Explanation:Children with Duchenne muscular dystrophy typically exhibit a positive Gower’s sign, which is due to weakness in the proximal muscles, particularly those in the lower limbs. This sign has a moderate sensitivity and high specificity. While idiopathic toe walking may also be present in DMD, it is more commonly associated with cerebral palsy and does not match the description in the given scenario. The Allis sign, also known as Galeazzi’s test, is utilized to evaluate for hip dislocation, primarily in cases of developmental dysplasia of the hip. Tinel’s sign is a method used to identify irritated nerves by tapping lightly over the nerve to elicit a sensation of tingling or ‘pins and needles’ in the nerve’s distribution.
Dystrophinopathies are a group of genetic disorders that are inherited in an X-linked recessive manner. These disorders are caused by mutations in the dystrophin gene located on the X chromosome at position Xp21. Dystrophin is a protein that is part of a larger membrane-associated complex in muscle cells. It connects the muscle membrane to actin, which is a component of the muscle cytoskeleton.
Duchenne muscular dystrophy is a severe form of dystrophinopathy that is caused by a frameshift mutation in the dystrophin gene. This mutation results in the loss of one or both binding sites, leading to progressive proximal muscle weakness that typically begins around the age of 5 years. Children with Duchenne muscular dystrophy may also exhibit calf pseudohypertrophy and Gower’s sign, which is when they use their arms to stand up from a squatted position. Approximately 30% of patients with Duchenne muscular dystrophy also have intellectual impairment.
In contrast, Becker muscular dystrophy is a milder form of dystrophinopathy that typically develops after the age of 10 years. It is caused by a non-frameshift insertion in the dystrophin gene, which preserves both binding sites. Intellectual impairment is much less common in individuals with Becker muscular dystrophy.
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This question is part of the following fields:
- Neurological System
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