Acute Dystonic Reactions



Clinical Presentation

Antipsychotics Antiemetics
Phenothiazines (e.g. Prochlorperazine) Prochlorperazine
Butyrophenones (e.g. Haloperidol) Metoclopramide
Thioxanthenes (e.g. Thiothixene  
  • Patient has usually taken a neuroleptic drug either for treatment of a psychiatric disorder, as an antiemetic or as a substance of abuse.
  • Dystonic reactions occur within 6 hours of ingestion and up to the first week after exposure to the offending drug.
  • Children are more susceptible than adults, occurring twice as often in males.
  • Characteristic motor spasms include:
Acute Dystonia

Points to note on history

Differential diagnosis includes: seizures, hysteria (pseudoseizures), tetanus and chronic dystonias, therefore consider:
  • History of prior seizures or epilepsy
  • Whether or not responsive to verbal stimuli
  • Muscular spasm versus tonic-clonic motor activity
  • Recent ingestion of antipsychotic or antiemetics (see table above)
  • Tetanus status and recent wounds
  • Family history of chronic dystonias, e.g. cerebral palsy
  • Beware of meningitis/encephalitis in children which may mimic seizures/dystonic reactions!

Points to note on examination

  • Dystonic reactions are rarely life threatening
  • Exclude respiratory compromise secondary to spasm of the laryngeal musculature
  • Acute dystonias may cause dislocation of the mandible

The diagnosis of acute dystonic reaction is a clinical one based on characteristic signs and symptoms in combination with of ingestion of above mentioned drugs. The diagnosis is confirmed by a rapid resolution of symptoms in response to treatment given (see below).


Immediate Management

  • Airway stabilisation to prevent respiratory compromise. O2
  • IV access
  • Treat with centrally acting anticholinergic:
    • Benztropine 1-2mg IV bolus or
    • Procyclidine 5-10mg IV bolus repeated in 20minutes (max. dose 20mg)
  • Dramatic resolution of symptoms occurs within 5 minutes and complete resolution usually within 15 minutes.
  • Diazepam 5-10mg IV bolus repeated at regular intervals may help in cases of dystonic reactions not amenable to adequate doses of anticholinergic medication.
  • If symptoms are not settling with the above standard treatment, other diagnoses should be considered.

Disposition

  • There are no criteria for admission and patients can be discharged once symptoms have settled.
  • Advice patient that symptoms may recur with continued usage of the offending medication.
  • This may be treated with procyclidine 5mg PO tds.
  • Diazepam may also be effective in such cases but has side effects of drowsiness and respiratory depression.
  • Warn patients not to drive or perform tasks that require full alertness whilst on sedative medications.

Content by Dr Nabil El Hindy, Dr Íomhar O' Sullivan 04/05/2002. Reviewed by Dr ÍOS 08/01/204, 18/05/2005, 14/05/2007. Next review 14/05/2008