- 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:
Points to note on historyDifferential 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).
- 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.
- 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.