Extrapyramidal reaction
Background
- Adverse effect of antipsychotics.
- More common with high-potency typical antipsychotics, but can also occur with atypical agents
- Due to antagonism of dopamine-2 receptors in basal ganglia
Clinical Features
- Early-onset syndromes
- hours to days after drug initiation
- reversible
- Acute Dystonic reaction
- involuntary, uncoordinated skelatal muscle contraction
- Akathisia
- subjective sensation of intense motor restlessness
- may be misdiagnosed as manifestation of psychiatric disease
- Parkinsonism
- onset weeks to months after starting medication
- similar presentation to Parkinson's disease (e.g. cogwheel regidity, pill-rolling tremor, shuffling gait, bradykinesia)
- Tardive dyskinesia
- usually irreversible or only partially reversible
- associated with prolonged use of antipsychotics
- sterotyped, repetitive facial movements (e.g. tongue protrusion, grimacing, lip smacking)
Differential Diagnosis
- Neuroleptic malignant syndrome
- Serotonin syndrome
- Hypocalcemia
- Strychnine toxicity
- Acute tetanus
- Parkinson's disease
- Mono amine oxidase inhibitor toxicity
- Phencyclidine toxicity
- Anti-NMDA receptor encephalitis
Evaluation
Management
- Stop or reduce offending agent
- may need to discuss with psychiatrist to prescribe new medication or for recs on taper
- Acute dystonia, akasthisia, parkinsonism
- diphenhydramine 25-50mg PO or IV
- OR benztropine 1-2mg PO or IV/IM
- continue PO antihistamines for 2 days after stopping antipsychotic
- +/- benzodiazepines
- Tardive dyskinesia
- may only be partially reversible, so minimize occurrence, stop or reduce offending agent promptly
- Do NOT give anticholinergics, will exacerbate symptoms