A 17-year-old girl presents with sudden-onset blindness while preparing for her school exit examinations.
Which of the following suggests an ocular rather than a psychogenic cause for blindness?
D. Non-organic visual loss may be psychogenic (conversion phenomenon) or secondary to malingering. It is more common among younger age groups and females, with the most frequently reported complaints being a reduction of visual acuity with or without loss of field. Absence of underlying optic nerve pathology is suggested by the demonstration of normal evoked potentials. On visual fi eld testing the patients may have an inconsistent spiral fi eld. When the patient acknowledges sighting the stimulus at some point on a horizontal axis, the examiner then moves around the fi eld in a circle (clockwise or anticlockwise). This will produce a progressively constricting fi eld and when the same horizontal axis is reached again, the stimulus will only be sighted at a much closer point to the centre. Some patients may have tubular vision. In the presence of true visual fi eld loss, the area of constricted field expands with increasing distance of the testing screen. In non-organic visual loss such field defects remain unchanged in width when tangent screen testing is performed at varying distances. This produces what is known as ‘tubular fields’. Simple tests of proprioception such as the finger–nose test are easily performed by blind patients; in non-organic visual loss, patients may be incapable of carrying out these tests. Intact vision (acuity at least 6/60) will elicit a positive optokinetic nystagmus (eyes moving with a black/white striped drum rolling in front of the eyes). The absence of such nystagmus indicates an ocular rather than psychogenic cause for visual loss.
Which of the following culture-bound syndromes is closely associated with social phobia?
D. Taijin Kyofusho (or anthropophobia: a fear of interpersonal relationships) could be considered as a cultural expression of social phobia among Japanese. Hikikomori, manifest by complete withdrawal from social life, is very closely related. Patients show severe obsession and fear of social contact with extreme self-consciousness regarding appearance, blushing, stuttering, or emitting offensive odours. Brain fag syndrome (known as studiation madness in the Caribbean) is characterized by variety of medically unexplained somatic symptoms, anxiety, depression, and fatigue. Symptoms may be triggered by the effort of reading; it is seen in students from a West African background. Dhat syndrome is characterized by complaints of discharge of semen in urine with no urological cause; this may be associated with fatigue and anxiety of loss of fertility and reproductive potency. Frigophobia (Pa-Leng) is a chronic anxiety state with phobia for cold; the patients may dress compulsively in heavy clothes and may become housebound for the fear of ‘cold attack’. Arctic hysteria or Piboloktoq is an acute dissociative episode of disruptive behaviour characterized by an irritable prodromal period and subsequent wild, excited, and risky behaviour.
Which of the following mechanisms is proposed to underlie hypersalivation seen in patients taking clozapine?
B. Both muscarinic M3 and M4 receptors are expressed in salivary glands. In general, stimulation of these receptors leads to increased salivation. Clozapine has antagonistic properties at muscarinic receptors (M1 to M3, and M5) but acts as an agonist at the M4 receptor. Olanzapine also has direct M4-agonistic properties and can produce hypersalivation; pirenzepine, an M4 antagonist, alleviates hypersalivation. In addition, clozapine may exacerbate salivation through its alpha-2 antagonism.
Which of the following can increase levels of clozapine via alterations in hepatic metabolism?
E. Clozapine is mostly metabolized via the CYP1A2, 3A4, and 2C19 enzymes. Cigarette smoking and caffeine induce CYP1A2; this can reduce clozapine levels in plasma. Rifampicin, carbamazepine, and phenytoin induce CYP3A4 and thus reduce clozapine levels. Erythromycin inhibits CYP3A4 and ciprofloxacin inhibits CYP1A2; both increase clozapine levels.
All of the following neuroendocrine changes are noted in depression EXCEPT:
C. Depression is associated with many neuroendocrine changes in hypothalamic-pituitaryadrenal cortex axis. Raised cortisol (measured in blood or saliva), abnormal dexamethasone suppression test (non-suppression of cortisol levels after overnight dexamethasone administration), and abnormal dexamethasone–corticotrophin releasing hormone (CRH) response (mediated via reduced ACTH response to CRH infusion), raised CRH levels in cerebrospinal fluid and down regulated CRH receptors are some of the reported changes.
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