see also:

• Parkinson's disease
• serotonin syndrome
• neuroleptic malignant syndrome (NMS)

• acute extrapyramidal reactions are quite common neurologic reactions in some patients who take medications which block dopamine D2 receptors
• they are often sufficiently disturbing for the patient that they seek urgent medical attention
• dystonia is considered the third most common movement disorder after Parkinson's disease and essential tremor
• “extrapyramidal symptoms” include:
  • acute dystonic reactions
    • oculogyric crisis
    • oromandibular dystonia
    • Meige's syndrome - blepharospasmodic contractions with oromandibular dystonia
    • laryngeal dystonia
    • truncal dystonia
  • akathisia
    • usually sudden onset acute motor restlessness, anxiety
    • commonly occurs after rapid IV push of certain medications such as metoclopramide
  • pseudoparkinsonism
    • drug-induced parkinsonism (rigidity, bradykinesia, tremor, masked facies, shuffling gait, stooped posture, sialorrhoea, and seborrhoea; greater risk in the elderly)
  • tardive dyskinesia
    • dopamine D2 receptor blocking medications if taken for a sufficiently long period in susceptible patients may also cause an irreversible disabling movement disorder of the face called tardive dyskinesia
• other forms of dystonia:
  • blepharospasm - often stress-related
  • writer's cramp
  • spasmodic torticollis
  • many other forms of recurrent or chronic dystonias (see at blottom)

• medications which block dopamine D2 receptors include:
  • anti-emetics such as metoclopramide (Maxolon)
  • phenothiazines including prochlorperazine (Stemetil) and chlorpromazine (Largactil)
  • butyrophenone type antipsychotic agents including haloperidol and droperidol (Droleptan)
  • other antipsychotics such as olanzapine, risperidone, quetiapine
• other medications at risk:
  • SSRI/SNRI antidepressants
  • erythromycin
  • carbamazepine
• risk factors:
  • age < 30 yrs
  • male
  • PH or FH of dystonic reactions
  • recent cocaine or alcohol use
  • Rx with a potent dopamine D2 receptor antagonist (e.g. haloperidol)

• benztropine / benzatropine (Cogentin) im or iv
  • NB. NOT helpful for treating akathisia - consider propranolol or diazepam

• see 2023: The Dystonias for details on the classification of other types of dystonias

• lead poisoning

• presumably from pathology involving basal ganglia and the GABA producing Purkinje neurons, and/or cerebellum
• stroke (CVA)
• brain injury
• meningitis
• encephalitis
• Parkinson's disease
• Huntington's disease

• early-onset or dopa-responsive dystonia
• many inherited dystonias