A 30-year-old man who was recenlty started on haloperidol 30 mg/day developed hyperpyrexia, muscle rigidity, akinesia, mutism, sweating, tachycardia and increased blood pressure. The investigations showed increased WBC count, increased creatinine phophokinase. This is no history of any other drug intake or any signs of infection. The most likely diagnosis is:

Ans is 'b' i.e. neuroleptic malignant syndrome It is a case of neuroleptic malignant syndrome due to intake of high dose of haloperidol (The usual dose of haloperidol is 2-20 mg/day)The syndrome may develop in upto 1% of patient using antipsychotic and is more common in high doses, the elderly and those with organic brain disease, hyperthyroidismClinical features includeFeverconfusion or fluctuating consciousness Muscular rigidityAutonomic unstability manifested by labile pulse, blood pressure and respiratory rate.Urinary incontinence or retentionLaboratory diagnosisRaised plasma creatine kinase concentration and sometimes myoglobinema with potential nephrotoxicity LeucocytosisTreatmentCessation of antipsychotic therapyAside from cessation of antipsychotic treatment and supportive care specific t/t is unsatisfactory Dopaminergic agonists bromocriptine or dantrolene are beneficial in some cases.Patient is actively rehydratedEven when recognized and treated the condition carries a mortality of 12-15%, through cardiac arrhythmias rhabdomyolysis or respiratory failure.The condition usually lasts for 5-7 days after the antipsychotic is stopped but may continue longer when a depot preparation has been used.