Synopsis
Recognise patterned twisting movement and posture, identify acute drug-induced and secondary causes and combine targeted injection, rehabilitation, oral and surgical treatment around function and pain.
- Dystonia consists of sustained or intermittent muscle contractions causing abnormal, often repetitive movements or postures that are patterned, twisting and sometimes tremulous.
- It may be focal, segmental, multifocal, hemidystonic or generalised and is classified further by age at onset, temporal pattern and whether it is isolated, combined or secondary.
- Movement is often action-induced and worsens with a specific task, fatigue or stress; overflow recruits nearby muscles and a geste antagoniste or sensory trick may transiently improve it.
- Common focal syndromes include cervical dystonia, blepharospasm, laryngeal dystonia and task-specific hand dystonia such as writer's cramp.
- Antipsychotics and dopamine-blocking antiemetics can cause an acute oculogyric, jaw, neck or truncal reaction within hours to days, or tardive dystonia after longer exposure.
- Young-onset generalised dystonia requires assessment for genetic disease, Wilson disease and dopa-responsive dystonia; a specialist levodopa trial can be transformative in the last condition.
- Sudden fixed painful posture is not automatically dystonia: stroke, seizure, tetany, tetanus, structural disease, orthopaedic deformity and functional dystonia need appropriate positive or exclusionary assessment.
- Botulinum toxin is the main treatment for many functionally significant focal dystonias and must be delivered by an experienced injector with product-specific dosing and goals.
- Oral trihexyphenidyl, baclofen, clonazepam or other medicines have selected roles, particularly in generalised disease, but anticholinergic, cognitive, sedation and dependence burdens often limit use.
- Deep-brain stimulation, commonly targeting the globus pallidus internus, is considered for severe medication-refractory generalised or selected segmental disease through a specialist multidisciplinary service.
Key red flags
Forceful blinking, jaw opening or closing, lower facial contraction or task-dependent strained or breathy voice reflects focal cranial network involvement; swallowing and airway impact determines urgency.
Within hours or days of a dopamine blocker, painful torticollis, jaw spasm, tongue protrusion, opisthotonus or sustained upward eye deviation occurs, sometimes with frightening laryngeal involvement.
Investigation priorities
Demonstrate pattern, task dependence, overflow, mirror movement, null point and sensory trick and define the muscles causing disability.
Management branches
Painful oculogyric, jaw, neck, tongue, truncal or laryngeal posturing follows a dopamine-blocking medicine.
- Use ABCDE, identify stridor, tongue or jaw obstruction and swallowing compromise, call anaesthetic support for airway involvement and stop the suspected culprit.
- Use the stocked emergency anticholinergic, such as imported benztropine, with route-specific reassessment and continued airway observation.
- Observe according to severity and culprit half-life, document the adverse drug reaction accurately and communicate future antiemetic or antipsychotic avoidance and alternatives.
- If the posture does not respond as expected, revisit seizure, tetany, tetanus, structural neurological disease and functional presentations rather than repeatedly dosing blindly.
Key medicines
Benztropine injection for acute dystoniaGive 1–2 mg intramuscularly or intravenously; a repeat may follow non-response after 30 minutes IM or 10 minutes IV. Confirm the imported product and prescribed maximum: reported daily limits are 4–6 mg, rather than permission for repeated unsupervised doses.UK procyclidine injection has been discontinued; benztropine is an unlicensed import. Prioritise airway support and monitor confusion, tachycardia, retention and cumulative anticholinergic effects. No established dose-equivalence with procyclidine is available; do not substitute doses milligram-for-milligram.
Botulinum toxin type AUse product-specific units, muscle selection and intervals, commonly around twelve weeks, through an expert clinic.Toxin products are not interchangeable. Local or remote weakness, dysphagia, dysphonia, dry eye and antibody-related loss of response require careful targeting and follow-up.