What are the most common extrapyramidal side effects associated with antipsychotic medications?

Common Extrapyramidal Side Effects of Antipsychotic Medications

The most common extrapyramidal side effects (EPS) associated with antipsychotic medications include acute dystonia, drug-induced parkinsonism, akathisia, and tardive dyskinesia. 1, 2

Primary Types of Extrapyramidal Side Effects

1. Acute Dystonia

• Characterized by involuntary motor tics or muscle spasms
• Typically affects the face, extraocular muscles (oculogyric crisis), neck, back, and limb muscles
• Usually occurs after the first few doses or after dose increases
• Laryngeal dystonia is rare but potentially life-threatening (presents as choking sensation, difficulty breathing, or stridor)
• Treatment: anticholinergic medications (benztropine) or antihistamines 1, 3

2. Drug-induced Parkinsonism

• Clinically resembles idiopathic Parkinson's disease
• Features include:
  • Bradykinesia (slowness of movement)
  • Tremor (especially at rest)
  • Rigidity
  • Postural instability
• Generally appears within the first three months of treatment
• Treatment options:
  • Reducing antipsychotic dose
  • Adding anticholinergic agent (benztropine 1-2 mg/day)
  • Adding amantadine
  • Switching to an atypical antipsychotic 1, 2, 3

3. Akathisia

• Subjective feeling of restlessness and anxiety
• Objective signs include motor restlessness and inability to sit still
• Typically occurs within the first few days of treatment
• Can be difficult to manage
• Treatment approaches:
  • Reducing antipsychotic dose
  • Beta-blockers (especially propranolol)
  • Benzodiazepines
  • Anticholinergics (less effective for akathisia) 1, 2, 3

4. Tardive Dyskinesia

• Characterized by rapid involuntary movements:
  • Facial movements (blinking, grimacing)
  • Chewing or tongue movements
  • Extremity or truncal movements
• Occurs in approximately 5% of young patients per year
• More common with older "typical" antipsychotics
• Respiratory dyskinesia is often undiagnosed and can lead to recurrent aspiration pneumonia
• Prevention and early detection are crucial 1, 2

Risk Factors for Developing EPS

• Age (elderly and very young patients at higher risk)
• Male sex
• Previous history of tremors
• Previous use of antipsychotics
• Polypharmacy
• Substance abuse
• Higher doses of antipsychotics 2

Mechanism of EPS Development

EPS primarily occur due to blockade of dopamine D2 receptors in the nigrostriatal pathway, which is critical for normal motor function. This blockade creates an imbalance between dopaminergic and cholinergic activity in the basal ganglia, leading to various movement disorders 2, 4.

Prevention and Management

• Use the lowest effective dose of antipsychotic medication
• Consider atypical antipsychotics which generally have lower EPS risk
• For high-risk patients, prophylactic anticholinergic therapy may be indicated, though routine prophylaxis is not recommended
• Regular monitoring for abnormal movements, especially during prolonged treatment
• Prompt recognition and treatment of EPS when they occur 2, 5

Important Considerations

• EPS can significantly impact quality of life and medication adherence
• Patients experiencing acute EPS are at greater risk for developing tardive dyskinesia later
• Neuroleptic malignant syndrome, while rare, is a potentially life-threatening condition associated with antipsychotic use that includes rigidity as a key feature 1, 6, 7

Remember that while atypical antipsychotics generally have a lower risk of causing EPS compared to conventional antipsychotics, they can still cause these side effects, especially at higher doses or when used in combination with other medications 5, 6.