A patient on therapy for his CNS illness develops the following abnormality what is the possible cause ?

Extrapyramidal symptoms due to D2 blockade in the limbic system are closely related to antipsychotic potency of typical antipsychotic drugs. Acute Muscular dystonia: It is the earliest appearing symptom(within hours)and may manifest as Toicollis, locked jaw, oculogyric crisis or spasm of other muscles. Central anticholinergics are useful in the treatment. Note : Oculogyric crisis is thespasm of the extraocular muscles, causing upward and outward detion of the eyes which is treated by Central anticholinergic agents.