A patient of schizophrenia was staed on haloperidol 5 mg. Next day, he presented with uprolling of eyes. Complete neurological examination revealed no spasticity or any other abnormality. Visual acuity and opthalmoscopic findings are normal. Most likely diagnosis is

Acute muscular dystonias Bizarre muscle spasms, mostly involving lingua-facial muscles -grimacing, tongue thrusting, toicollis, locked jaw; occurs within a few hours of a single dose or at the most in the first week of therapy. It is more common in children below 10 years and in girls, paicularly after parenteral administration; overall incidence is 2%. It lasts for one to few hours and then resolves spontaneously. One of the central anticholinergics, promethazine or hydroxyzine injected i.m. clears the reaction within 10-15 min. REF KD TRIPATHHI 8TH ED.