The sciatic neve originates in the sacral plexus, mainly from spinal segments L5-S2. It supplies muscles that cause extension of the thigh and flexion of the leg. It divides into two main branches, the tibial nerve and common peroneal nerve, which are responsible for all foot movements. Anterior thigh and medial leg sensory loss is typical of a femoral nerve lesion. The femoral nerve also mediates flexion of the hip.

Type I pneumocyte: The cell responsible for the gas (oxygen and carbon dioxide) exchange that takes place in the alveoli. It is a very thin cell stretched over a very large area. This type of cell is susceptible to a large number of toxic insults and cannot replicate itself.
Type II pneumocyte: The cell responsible for the production and secretion of surfactant (the molecule that reduces the surface tension of pulmonary fluids and contributes to the elastic properties of the lungs). The type 2 pneumocyte is a smaller cell that can replicate in the alveoli and will replicate to replace damaged type 1 pneumocytes. Alveolar macrophages are the primary phagocytes of the innate immune system, clearing the air spaces of infectious, toxic, or allergic particles that have evaded the mechanical defences of the respiratory tract, such as the nasal passages, the glottis, and the mucociliary transport system. The main role of goblet cells is to secrete mucus in order to protect the mucous membranes where they are found. Goblet cells accomplish this by secreting mucins, large glycoproteins formed mostly by carbohydrates.

Fundoscopy findings of cotton wool spots and retinal tears, accompanied by a history of blurred vision, are characteristic of retinitis. Cytomegalovirus is known to cause retinitis.

The most likely cause for acute breathlessness is due to papillary muscle rupture which causes mitral regurgitation.

Spinal cord hemisection, also known as Brown-Sequard syndrome, is associated with symptoms affecting one spinothalamic and one corticospinal tract. Symptoms include ipsilateral paralysis, loss of vibration and position sense, and hyperreflexia below the level of the lesion. Contralateral loss of pain and temperature sensation is also seen, usually beginning 2-3 segments below the level of the lesion.

The patient most likely has Klinefelter’s syndrome.
Klinefelter syndrome (KS) refers to a group of chromosomal disorders in which the normal male karyotype, 46,XY, has at least one extra X chromosome. XXY aneuploidy, the most common human sex chromosome disorder. It is also the most common chromosomal disorder associated with male hypogonadism and infertility.
Klinefelter syndrome is characterized by hypogonadism (micro-orchidism, oligospermia/azoospermia), gynecomastia in late puberty, hyalinization and fibrosis of the seminiferous tubules, elevated urinary gonadotropin levels, and behavioural concerns.

Human-papilloma virus (HPV) can lead to cervical cancer. There are many different types, but the types associated with cervical cancer most commonly are 16, 18, 31, 33, and 35. The vaccination against HPV protects against the most common types of HPV that are seen in cervical cancer and is recommended for children/young teens. Cervical cancer has a clear association with HPV, making this the best answer over all of the other answer choices.

Dermatitis herpetiformis (DH), or Duhring’s disease, is a chronic blistering skin condition,characterised by blisters filled with a watery fluid. Despite its name, it is neither related to nor caused by herpes virus: the name means that it is a skin inflammation having an appearance similar to herpes.
Dermatitis herpetiformis is characterized by intensely itchy, chronic papulovesicular eruptions, usually distributed symmetrically on extensor surfaces (buttocks, back of neck, scalp, elbows, knees, back, hairline, groin, or face)
Dermatitis herpetiformis is an autoimmune condition associated with HLA-DR3.
HLA-A3 is associated with haemochromatosis. HLA-B5 is most commonly associated with Behcet’s disease. HLA-DR4 is associated with both type 1 diabetes mellitus and rheumatoid arthritis. HLA-B27 is most commonly associated with several diseases, most commonly ankylosing spondylitis.

Sildenafil (Viagra) is a phosphodiesterase type V inhibitor used in the treatment of impotence.

Contraindications:
– Patients taking nitrates and related drugs such as nicorandil
– Hypotension
– Recent stroke or myocardial infarction (NICE recommend waiting 6 months)

Side-effects:
Visual disturbances e.g. cyanopsia, non-arthritic anterior ischaemic Neuropathy
Nasal congestion
Flushing
Gastrointestinal side-effects
Headache

The patient is in a suitable age for developing temporal arteritis and the fact that she’s unable to comb her hair indicates scalp tenderness or proximal muscle weakness. A high ESR together with increased CRP supports the diagnosis. Temporal artery biopsy is also useful to establish the diagnosis.

Interferon alfa alone, not interferon alfa and ribavirin, has been shown to achieve HBeAg seroconversion for patients with HBeAg-positive chronic hepatitis B.

The patient’s chronic renal failure causes decreased renal hydroxylation of vitamin D which leads to decreased calcium absorption in the gut. Simultaneously, there is also decreased renal excretion of phosphate, and this combination of factors results in increased PTH levels.

Malingering is not considered a mental illness. In the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), malingering receives a V code as one of the other conditions that may be a focus of clinical attention. The DSM-5 describes malingering as the intentional production of false or grossly exaggerated physical or psychological problems. Motivation for malingering is usually external (e.g., avoiding military duty or work, obtaining financial compensation, evading criminal prosecution, or obtaining drugs).

Malingering should be strongly suspected if any combination of the following factors is noted to be present: (1) medicolegal context of presentation; (2) marked discrepancy between the person’s claimed stress or disability and the objective findings; (3) lack of cooperation during the diagnostic evaluation and in complying with the prescribed treatment regimen; and (4) the presence in the patient of antisocial personality disorder (ASPD).

This patient is be pretending to be sick in order to get morphine.

Assess the need for oxygen therapy in people with:
– very severe airflow obstruction (FEV1 below 30% predicted)
– cyanosis (blue tint to skin)
– polycythaemia
– peripheral oedema (swelling)
– a raised jugular venous pressure
– oxygen saturations of 92% or less breathing air.

Also consider assessment for people with severe airflow obstruction (FEV1 30–49% predicted).

Consider long-term oxygen therapy for people with COPD who do not smoke and who:
have a partial pressure of oxygen in arterial blood (PaO2) below 7.3 kPa when stable or have a PaO2 above 7.3 and below 8 kPa when stable, if they also have 1 or more of the following:
– secondary polycythaemia
– peripheral oedema
– pulmonary hypertension.

Urea breath test is the most sensitive test to determine if there has been RESOLUTION/ERADICATION of the infection with H. pylori. The best test for initial diagnosis would be EGD with biopsy.

A cohort study is a particular form of longitudinal study that samples a cohort (a group of people who share a defining characteristic, typically those who experienced a common event in a selected period, such as birth or graduation), performing a cross-section at intervals through time.
The relative risk (RR) or risk ratio is the ratio of the probability of an outcome in an exposed group to the probability of an outcome in an unexposed group. Relative risk is used in the statistical analysis of the data of experimental, cohort and cross-sectional studies, to estimate the strength of the association between treatments or risk factors, and outcomes.

A precordial thumb is not routinely recommended because of its very low success rate for cardioversion of a shockable rhythm. It’s only recommended when there is a delay in getting the defibrillator.

Pulsus paradoxus is defined as the exaggerated fall in systolic blood pressure during inspiration by greater than 10 mmHg. Cardiac tamponade is the classic cause of pulsus paradoxus. Kussmaul’s sign (a rise in the jugular venous pressure on inspiration) is mostly seen in constrictive pericarditis. Hypotension, muffled heart sounds and raised JVP can be seen in both conditions.

The chance of two carriers of a recessive gene having a child that is homozygous for that disease (that is both genes are transmitted to the child) is 25%. Therefore, the chances of this couple having a child with CF are 25%(1/4) x 1/20 = 1/80.

Thioridazine has a quinidine-like action on the heart and is known to cause cardiac arrhythmias including prolonged PR and QT intervals and widening of QRS complexes. Intravenous magnesium sulphate is regarded as the treatment of choice for this arrhythmia.

Soluble guanylyl cyclase (GC-1) is the primary receptor of nitric oxide (NO) in smooth muscle cells and maintains vascular function by inducing vasorelaxation in nearby blood vessels. GC-1 converts guanosine 5′-triphosphate (GTP) into cyclic guanosine 3′,5′-monophosphate (cGMP), which acts as a second messenger to improve blood flow.

A t test is a type of statistical test that is used to compare the means of two groups. It is one of the most widely used statistical hypothesis tests in pain studies. There are two types of statistical inferences: parametric and nonparametric methods. Parametric methods refer to a statistical technique in which one defines the probability distribution of probability variables and makes inferences about the parameters of the distribution. In cases in which the probability distribution cannot be defined, nonparametric methods are employed. T tests are a type of parametric method; they can be used when the samples satisfy the conditions of normality, equal variance, and independence. In this case the data is parametric, comparing two independent samples from the same population.

Carbon monoxide (CO) poisoning:
It is considered as the great imitator of other diseases as the patients present with a myriad of symptoms. The carbon monoxide diffuses rapidly across the pulmonary capillary membrane binding to the haem molecule with a very high affinity (240 times that of oxygen) forming carboxy-haemoglobin (COHb). Non-smokers have a baseline COHb of ,3% while smokers have a baseline COHb of 10-15%.

Clinical features of carbon monoxide toxicity:
Headache: 90% of cases (most common clinical feature)
Nausea and vomiting: 50%
Vertigo: 50%
Confusion: 30%
Subjective weakness: 20%
Severe toxicity: ‘pink’ skin and mucosa, hyperpyrexia, arrhythmias, extrapyramidal features, coma, death
Cherry red skin is a sign of severe toxicity and is usually a post-mortem finding.
Management
• 100% oxygen
• Hyperbaric oxygen therapy (HBOT)

The use of Hyperbaric oxygen therapy (HBOT) for treatment mild to moderate CO poisoning is not routine.
The selection criteria for HBOT in cases of CO poisoning include:
• COHb levels > 20-25%
• COHb levels > 20% in pregnant patient
• Loss of consciousness
• Severe metabolic acidosis (pH <7.1)
• Evidence of end-organ ischemia (e.g., ECG changes, chest pain, or altered mental status)

Primary hyperparathyroidism (PHPT) is diagnosed based upon levels of blood calcium and parathyroid hormone (PTH). In most people with PHPT, both levels are higher than normal. Occasionally, a person may have an elevated calcium level and a normal or minimally elevated PTH level. Since PTH should normally be low when calcium is elevated, a minimally elevated PTH is considered abnormal and indicates PHPT.

Pseudomembranous colitis is caused by a C. difficile infection that causes membranes to form on the colon wall. It is caused most commonly by broad-spectrum antibiotics. This would include cephalosporins, broad-spectrum penicillin, and clindamycin. Macrolides and quinolones have also been reported as potential aetiologies, but much less commonly.

The given history suggests a small fibre painful peripheral sensory neuropathy, the most common cause of which is diabetes. Joint position sense and vibratory sensation are carried through large fibres, and therefore are not currently affected. Sensory nerves are affected more often than motor, so reflexes usually remain in tact.

Vitamin B12 deficiency causes impairment of joint position and vibratory sensation.

Chronic inflammatory demyelinating polyneuropathy (CIPD) causes a large fibre peripheral neuropathy with areflexia.

In syringomyelia there is impaired pain and temperature noted in the upper limbs.

Finally, with alcoholic polyneuropathy, all fibre types are affected (sensory and motor loss). It is usually gradual with long term alcohol abuse and may be accompanied by a nutritional deficiency. In addition, pain is a more dominant feature.

West Nile virus (WNV) is a single-stranded RNA flavivirus transmitted via the culex mosquito. This previously ‘tropical’ disease has became topical in recent years following a large scale outbreak in the New York area. Incidence of neurological involvement is around 1%, although some suggest that the incidence of meningoencephalitis in America is higher than in other parts of the world. Risk factors for neurological involvement include increasing age, and immunosuppression. The usual picture is of sudden onset fever and myalgia with nausea and vomiting and a non-specific rash. Transient meningitis is occasionally seen. Frank meningoencephalitis is seen in two-thirds of cases with neurological involvement; 15% progress to coma. A flaccid paralysis similar to acute Guillain–Barré is increasingly recognised.
Diagnosis is initially clinical with subsequent serological confirmation. Treatment is supportive; results from trials of antivirals have yielded disappointing results.

This patient has a poorly controlled T2DM with an underlying diabetic nephropathy. The histological findings are Kimmelstiel-Wilson lesions (nodular glomerulosclerosis) and hyaline arteriosclerosis. This is due to nonenzymatic glycosylation.

Diabetic nephropathy is the chronic loss of kidney function occurring in those with diabetes mellitus. Protein loss in the urine due to damage to the glomeruli may become massive, and cause a low serum albumin with resulting generalized body swelling (edema) and result in the nephrotic syndrome. Likewise, the estimated glomerular filtration rate (eGFR) may progressively fall from a normal of over 90 ml/min/1.73m2 to less than 15, at which point the patient is said to have end-stage kidney disease (ESKD). It usually is slowly progressive over years.

This man has gingivostomatitis, a characteristic feature of primary herpes simplex virus infection. Herpetic gingivostomatitis is often the initial presentation during the first (primary) herpes simplex infection. It is of greater severity than herpes labialis (cold sores) which is often the subsequent presentations. Primary herpetic gingivostomatitis is the most common viral infection of the mouth.
Primary herpetic gingivostomatitis (PHGS) is caused predominantly by HSV-1 and affects mainly children. Prodromal symptoms, such as fever, anorexia, irritability, malaise and headache, may occur in advance of disease. Sub-mandibular lymphadenitis, halitosis and refusal to drink are usual concomitant findings.

The history and ECG findings are adequate to begin cardiac revascularization of this patient. There is no need for cardiac markers to confirm the diagnosis. Further delay in starting definite treatment is not recommended.