Background
- 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 those below:
| Antipsychotics | Antiemetics |
|---|---|
| Phenothiazines (e.g. Prochlorperazine) |
Prochlorperazine |
| Butyrophenones (e.g. Haloperidol) |
Metoclopramide |
| Thioxanthenes (e.g. Thiothixene) |
Examples
History points
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!
Examination points
- 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 Mx to prevent respiratory compromise. O2
- IV access
- Treat with centrally acting anticholinergic:
- 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, another Dx 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