Extrapyramidal side effects (EPS) are drug-induced movement disorders and are commonly associated with the use of certain antipsychotic medications, particularly the older, typical antipsychotics. These side effects occur due to the drug’s impact on the extrapyramidal system, which helps regulate motor control and muscle movement. The main types of extrapyramidal side effects include:
- Acute Dystonia: Sudden, often painful muscle spasms or contractions, usually affecting the head, neck, and eyes. Symptoms can include abnormal postures, muscle stiffness, oculogyric crisis (prolonged upward deviation of the eyes), and laryngospasm.
- Akathisia: A feeling of inner restlessness and a compelling need to be in constant motion. It manifests as fidgeting, tapping feet, rocking back and forth, and an inability to sit still.
- Parkinsonism: Symptoms resembling Parkinson’s disease, including tremor, bradykinesia (slowness of movement), rigidity, and a shuffling gait. Facial expressions may become less animated (mask-like facies).
- Tardive Dyskinesia (TD): A late-onset syndrome characterized by repetitive, involuntary, purposeless movements. Common manifestations include lip smacking, tongue protrusion, chewing or sucking movements, and facial grimacing. TD can be irreversible and is more likely with long-term use of antipsychotics.
- Neuroleptic Malignant Syndrome (NMS): Although rare, NMS is a serious and potentially life-threatening reaction to antipsychotics. Symptoms include severe muscle rigidity, fever, altered mental status, and autonomic dysfunction (such as irregular blood pressure and heart rate).
The risk of developing EPS depends on several factors, including the type of antipsychotic (with typical antipsychotics having a higher risk than atypical antipsychotics), dosage, duration of treatment, and individual patient susceptibility. Management of EPS may involve reducing the dose of the antipsychotic, switching to a different medication, or adding medications that help alleviate these symptoms, such as anticholinergic agents. Early recognition and intervention are important to prevent progression and improve patient outcomes.