Extrapyramidal symptoms

Overview

Extrapyramidal symptoms (EPS) refer to a group of movement disorders that result from dysfunction or disruption of the extrapyramidal system—a network of brain structures involved in regulating motor control and coordination. EPS commonly occurs as a side effect of certain medications, particularly antipsychotic drugs, but may also arise from underlying neurological conditions. These symptoms include tremors, rigidity, bradykinesia, dystonia, akathisia, and tardive dyskinesia. EPS can be temporary or persistent and may significantly impact a person's quality of life if not recognized and managed promptly.

Causes

The primary cause of extrapyramidal symptoms is the use of dopamine-blocking medications, particularly those that affect the basal ganglia. Common causes include:

• Antipsychotic medications: Especially first-generation (typical) antipsychotics like haloperidol, fluphenazine, and chlorpromazine

• Second-generation (atypical) antipsychotics: May cause EPS, though less frequently (e.g., risperidone, paliperidone)

• Antiemetic drugs: Such as metoclopramide and prochlorperazine

• Neurological disorders: Parkinson’s disease, Wilson’s disease, or basal ganglia damage due to stroke or trauma

• Drug interactions: Concomitant use of medications affecting dopamine transmission

EPS risk is higher with high-dose, long-term use, rapid dose escalation, or individual sensitivity to dopaminergic blockade.

Symptoms

Extrapyramidal symptoms vary depending on the type and severity of motor system involvement. Common presentations include:

1. Dystonia:

• Sudden, involuntary muscle contractions

• Twisting movements or abnormal postures (e.g., torticollis, oculogyric crisis)

2. Akathisia:

• Intense inner restlessness

• Inability to sit still, constant pacing or leg tapping

3. Parkinsonism:

• Tremors (especially resting tremor)

• Bradykinesia (slowness of movement)

• Muscle rigidity and stooped posture

• Shuffling gait

4. Tardive dyskinesia:

• Involuntary, repetitive movements—often of the face, tongue, lips, or limbs

• May appear after months or years of antipsychotic use

• Can be irreversible in some cases

Symptoms may occur acutely (hours to days), subacutely (weeks), or chronically (months to years after exposure to the causative agent).

Diagnosis

Diagnosis of extrapyramidal symptoms is clinical and based on observation of movement patterns, medication history, and neurological examination. Key steps include:

• Medical history: Assess for use of antipsychotics, antiemetics, or other dopamine-blocking drugs

• Neurological exam: Evaluate motor function, coordination, muscle tone, and tremor characteristics

• Standardized rating scales:

  • Simpson–Angus Scale (for parkinsonism)

  • Barnes Akathisia Rating Scale

  • Abnormal Involuntary Movement Scale (AIMS) for tardive dyskinesia

• Exclusion of other causes: Rule out Parkinson’s disease, Huntington’s disease, or structural brain disorders

Treatment

Treatment of EPS depends on the type of symptoms, severity, and the underlying cause. Common strategies include:

• Discontinuing or reducing the causative medication: Often the first and most effective step

• Switching to an atypical antipsychotic: Drugs like clozapine or quetiapine have lower EPS risk

• Medications for specific symptoms:

  • Anticholinergics (e.g., benztropine, trihexyphenidyl) for parkinsonism or dystonia

  • Beta-blockers (e.g., propranolol) or benzodiazepines (e.g., lorazepam) for akathisia

  • Tetrabenazine or valbenazine for tardive dyskinesia

• Physical therapy: To improve mobility and manage rigidity

• Monitoring: Regular follow-up to assess response and prevent progression

Prognosis

The prognosis for extrapyramidal symptoms depends on the type of EPS and how early it is recognized and managed. Acute symptoms such as dystonia or akathisia often resolve quickly once treatment is adjusted. Parkinsonism may improve gradually over weeks. Tardive dyskinesia is more difficult to reverse and may persist long after discontinuation of the offending drug. Early intervention and proper medication management are key to preventing long-term complications and preserving quality of life.