Etiology

• Acquired
  • Drugs: dopamine antagonists
    • High-potency typical antipsychotics (e.g., haloperidol) are more likely than atypical antipsychotics to induce acute dystonia.
    • Metoclopramide
  • Neurologic disorders: Huntington disease
  • Metabolic: Wilson disease
  • Psychogenic: conversion disorder

Clinical features

Focal dystonia

Affects a single region of the body

Conditions

• Spasmodic torticollis: cervical dystonia
  • The most common isolated focal dystonia. Predominantly affects the sternocleidomastoid muscle and trapezoid muscle.
  • Abnormal head movements or fixed head posture
• Blepharospasm: eye dystonia (e.g., increased blinking or involuntary eye closure); usually bilateral, symmetrical
• Writer's dystonia (writer's cramp): non-painful contractions of hand muscles that are provoked by specific tasks (e.g., writing)

Generalized dystonia

Affects the trunk and at least two additional regions of the body

Conditions

• Neuroleptic-induced acute dystonia

Treatment

• Levodopa/carbidopa: A trial should be taken in all patients with childhood-onset dystonia to distinguish dopa-responsive dystonia from the other forms.
• Anticholinergics (benztropine, trihexyphenidyl) or antihistamines (diphenhydramine)
• Periodic botulinum toxin injections: for focal dystonia
• Deep brain stimulation
• Treatment of underlying disorder of acquired dystonia (e.g., cessation of the causative drug)
• Supportive measures: physiotherapy, ergotherapy