Pharmacological and non-Pharmacological Causes

The reported incidence of dystonia in studies ranges from 2.3% to 64% depending on risk factors listed previously.

Two to three percent of patients commenced on neuroleptics will develop acute dystonia within days of initiating therapy. If highly potent neuroleptics e.g. haloperidol, are used, this can increase to over 50%.

Half of acute dystonic reactions occur in the first 48 hours, 90% within four days.

There also appears to be a diurnal pattern with 80% of reactions occurring between the hours of 1200-2300.

Non-pharmacological causes

Arterio-venous malformation, cerebrovascular accident, cerebral tumour, encephalitis and spinocerebellar degeneration can all present with acute dystonia.

Learning bite

Risk factors for acute dystonia include family history, young age, male sex, previous history of drug induced dystonia and cocaine use. (Evidence Grade 2B).