1. Dystonic Drug Reaction
Presentation
Patients arrive with peculiar posturing or difficulty speaking, and are usually
quite upset and worried that they are having a stroke. Often there is no
history offered at all--the patient may not be able to speak, may not be aware
he took any phenothiazines or butyrophenones (e.g., Haldol has been used to
cut heroin), may not admit he takes psychotropic medication, or may not
make the connection between symptoms and drug (e.g., one dose of
Compazine given for vomiting). Acute dystonias usually present with one or
more of the following symptoms:
• buccolingual: protruding or pulling sensation of tongue
• torticollic: twisted neck, or facial muscle spasm
• oculogyric: roving or deviated gaze
• tortipelvic: abdominal rigidity and pain
• opisthotonic: spasm of the entire body
These acute dystonias can resemble partial seizures, the posturing of
psychosis, or the spasms of tetanus, strychnine poisoning, or electrolyte
imbalances. More chronic neurologic side effects of phenothiazines, including
the restlessness of akathisia, tardive dyskinesias, and Parkinsonism, do not
usually respond as dramatically to drug treatment as the acute dystonias.
What to do:
• Give 2mg of benztropine (Cogentin) or 50mg of diphenhydramine
(Benadryl) iv, and watch for improvement of the dystonia over the next
five minutes. This step is both therapeutic and diagnostic. Benztropine
produces fewer side effects (mostly drowsiness), and may be slightly
more effective, but diphenhydramine is more likely to be on hand in
the ED.
• Instruct the patient to discontinue the offending drug, and arrange for
followup if medications must be adjusted. If the culprit is long-acting,
prescribe benztropine (Cogentin) 2mg or diphenhydramine (Benadryl)
25mg po q6h for 24 hours to prevent a relapse.
What not to do:
• Do not persist with treatment in the face of a questionable response or
no response, but get on with the workup to find another etiology for
the dystonia (tetanus, seizures, hypomagnesemia, hypocalcemia,
alkalosis, muscle disease, etc.).
• Do not use intravenous diazepam first, because it relaxes spasms due
to other etiologies, and thus leaves the diagnosis unclear.

2. Discussion
The extrapyramidal motor system depends on excitatory cholinergic
neurotransmitters and inhibitory dopaminergic neurotransmittors, the latter
susceptible to blockage by phenothiazine and butyrophenone medications.
Anticholinergic medications restore the excitatory-inhibitory balance. One
intravenous dose of benztropine or diphenhydramine is relatively innocuous
and rapidly diagnostic, and is probably justified as an initial step in any
patient with a dystonic reaction.