Extrapyramidal side effects

Extrapyramidal Side Effects

Extrapyramidal side effects (EPSE) are drug-induced movement disorders that include various symptoms such as tremors, rigidity, bradykinesia, and tardive dyskinesia. These effects are primarily associated with the use of antipsychotic medications, particularly the typical antipsychotics, which are known to affect the extrapyramidal system of the brain.

Pathophysiology

The extrapyramidal system is a neural network that is part of the motor system causing involuntary reflexes and movement, and modulation of movement (i.e., coordination). It is distinct from the pyramidal system, which is responsible for voluntary movements. The extrapyramidal system includes the basal ganglia and related structures.

Antipsychotic medications, especially the first-generation or typical antipsychotics, block dopamine D2 receptors in the brain. This blockade can lead to a decrease in dopaminergic activity in the nigrostriatal pathway, which is part of the extrapyramidal system, resulting in movement disorders.

Types of Extrapyramidal Side Effects

1. Acute Dystonia

Acute dystonia is characterized by sustained muscle contractions, often leading to twisting and repetitive movements or abnormal postures. It can occur within hours to days of starting antipsychotic treatment.

2. Akathisia

Akathisia is a state of restlessness and an urgent need to move. Patients often describe it as an inner restlessness and may have difficulty sitting still. It can occur within days to weeks of starting treatment.

3. Parkinsonism

Drug-induced parkinsonism resembles idiopathic Parkinson's disease and includes symptoms such as tremor, rigidity, and bradykinesia. It typically occurs within weeks to months of starting antipsychotic therapy.

4. Tardive Dyskinesia

Tardive dyskinesia is characterized by repetitive, involuntary movements, often of the face and tongue, and sometimes the limbs. It usually develops after long-term use of antipsychotics and can be irreversible.

Management

Management of extrapyramidal side effects involves several strategies:

• Dose Adjustment: Reducing the dose of the antipsychotic medication can sometimes alleviate symptoms.
• Switching Medications: Switching from a typical antipsychotic to an atypical antipsychotic, which has a lower risk of EPSE, may be beneficial.
• Medications: Anticholinergic medications such as benztropine or diphenhydramine can be used to treat acute dystonia and parkinsonism. Beta-blockers like propranolol are often used for akathisia.
• Monitoring: Regular monitoring for the development of tardive dyskinesia is important, especially in patients on long-term antipsychotic therapy.

Prevention

Preventive strategies include using the lowest effective dose of antipsychotics, choosing atypical antipsychotics when possible, and regularly assessing patients for early signs of EPSE.

Also see

• Antipsychotic
• Parkinson's disease
• Dopamine receptor
• Basal ganglia
• Tardive dyskinesia

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