Which of the following is an advantage of using CT scan over MRI scan for diagnostic purposes?
D. Immediate availability, especially in head injury units, and ability to enable early detection of haemorrhages make CT scan the preferred diagnostic modality in emergency scenarios.
Reference:
Choose one of the following conditions where CT scan of brain is the investigation of choice:
A. MRI is more sensitive than CT for the detection of lesions of the spinal cord, cranial nerves, and posterior fossa structures. Diffusion MR is the most sensitive technique for detecting acute ischemic stroke and is useful in the detection of encephalitis and abscesses. CT is the investigation of choice for suspected acute stroke, haemorrhage, and intracranial or spinal trauma. CT is also more sensitive than MRI for visualizing lesions of the bone.
A patient with bipolar disorder recently stabilized on medications is brought to you with a history of fever for 4 days and blurred vision, muscle fasciculation, hyperactive tendon refl exes, and persistent nausea and vomiting for the last 2 days.
Which one of the following may be implicated?
B. In this case, a patient’s bipolar disorder has been stabilized on a particular medication. It is likely that this medication is lithium because the symptoms described here are consistent with lithium toxicity. This might have been precipitated by dehydration associated with fever. Other causes that may precipitate lithium toxicity are diarrhoeal illnesses, vomiting and fluid loss, and medications such as diuretics, NSAIDS and ACE inhibitors.
A patient who has chronic schizophrenia is on a depot antipsychotic medication. Your consultant asks for an ECG.
Which of the following will be of most interest to him?
D. Prolonged QT interval can predispose to serious ventricular arrhythmia called torsades de pointes (polymorphic ventricular arrhythmia). Many antipsychotics share the propensity to prolong QT interval. A troublesome change in heart rate is not observed clinically with most antipsychotics. Non-specific PR changes can occur with antipsychotic treatment.
Which of the following medications has the highest propensity to cause QT prolongation on ECG?
A. ECG abnormalities occur in approximately 25% of all patients on antipsychotics. The most commonly reported changes are the prolonged QT interval (suggestive of repolarization disturbances), depressed ST segments, and abnormal T waves. A prolonged QTc is more likely to be seen in patients with chronic schizophrenia treated with antipsychotics in doses greater than 200 mg chlorpromazine equivalents a day. Thioridazine, pimozide, sertindole, and droperidol prolong QTC interval to a higher extent than other antipsychotics. TCAs share this propensity with antipsychotics. This predisposes to a fatal form of arrhythmia called torsades de pointes (polymorphic ventricular arrhythmia) leading to sudden death.
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