Acute Dystonic Reactions



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

Content by Dr Nabil El Hindy, Dr Íomhar O' Sullivan. Last review Dr ÍOS 24/03/24.