Movement disorders after head injury: diagnosis and management.

Head injury can cause extrapyramidal movement disorders such as tremors, parkinsonism, dystonia, chorea, myoclonus, and tics. Pure adventitious movements are rare, but combinations with paresis, spasticity, apraxia, or ataxia occur in approximately 20% of cases of severe head injury, in many cases appearing or evolving in the months following the injury. Tremors may improve in time but many of the other syndromes tend to persist. Reversible causes such as medications or metabolic derangements are occasionally identifiable. Some of these adventitious movements can be improved using neuroactive drugs, botulinum toxin injections, or stereotactic brain surgery.