What is the treatment for pseudoparkinsonism?

Treatment of Pseudoparkinsonism

For pseudoparkinsonism (drug-induced parkinsonism), the first-line treatment options include lowering the dosage of the causative antipsychotic medication, switching to another antipsychotic medication with lower EPS risk, or treating with an anticholinergic medication. 1

Understanding Pseudoparkinsonism

Pseudoparkinsonism is a form of drug-induced extrapyramidal symptoms (EPS) characterized by:

• Parkinsonian symptoms similar to idiopathic Parkinson's disease
• Typically appears within the first three months of antipsychotic treatment
• Commonly caused by first-generation (typical) antipsychotics
• Presents with rigidity, bradykinesia, tremor, and postural instability

Treatment Algorithm

Step 1: Evaluate and Modify Antipsychotic Therapy

• Reduce antipsychotic dose to the lowest effective dose that controls psychotic symptoms 2
• Consider switching to an atypical antipsychotic with lower EPS risk:
  • Quetiapine or olanzapine have lower EPS profiles 2
  • Clozapine has the lowest risk but is reserved for treatment-resistant cases due to risk of agranulocytosis 1

Step 2: If symptoms persist, add pharmacological treatment

Option A: Anticholinergic Medications

• Trihexyphenidyl:

  • Initial dose: 1 mg daily
  • Gradually increase by 2 mg increments every 3-5 days
  • Typical effective dose: 5-15 mg daily in divided doses 3
  • Maximum benefit often achieved at 6-10 mg daily
  • Best tolerated when divided into 3 doses taken at mealtimes 3

• Special considerations for anticholinergics:

  • Elderly patients: Start at lower doses (0.5 mg) and titrate slowly 2
  • Monitor for anticholinergic side effects (dry mouth, blurred vision, constipation, urinary retention)
  • Avoid in patients with glaucoma, prostatic hypertrophy, or cognitive impairment

Option B: Amantadine

• Alternative to anticholinergics with fewer cognitive side effects
• Indicated for drug-induced extrapyramidal reactions 4
• Typical dose: 100 mg 2-3 times daily
• Advantages: Fewer anticholinergic side effects, may help with negative symptoms

Step 3: Monitoring and Maintenance

• Regular assessment for abnormal movements using standardized scales like AIMS every 3-6 months 2
• Consider discontinuation of antiparkinsonian medication after 2-4 weeks if symptoms are controlled 5
• Long-term use of antiparkinsonian agents is generally not recommended unless symptoms recur upon discontinuation

Important Clinical Considerations

Risk Factors for Developing Pseudoparkinsonism

• Elderly patients
• Very young patients
• Males
• Previous history of tremors
• Previous use of antipsychotics
• Patients on high doses of antipsychotics 2

Avoiding Common Pitfalls

1. Don't use anticholinergics prophylactically in all patients on antipsychotics - only use when EPS symptoms develop or in high-risk patients 5

2. Avoid first-generation antipsychotics when possible, especially in elderly patients and those with Parkinson's disease 6

3. Don't continue antiparkinsonian medications indefinitely - attempt gradual withdrawal after symptoms are controlled for 2-4 weeks 5

4. Beware of anticholinergic burden - monitor for cognitive effects, especially in elderly patients 2

5. Don't overlook non-antipsychotic causes of parkinsonism - consider other medications that may cause similar symptoms (calcium channel blockers, metoclopramide) 7

By following this structured approach, pseudoparkinsonism can be effectively managed while minimizing additional medication burden and side effects. The goal is to achieve a balance between controlling psychotic symptoms and minimizing drug-induced movement disorders.