Extrapyramidal Symptoms (EPS)

Overview

Extrapyramidal symptoms (EPS) are a group of movement-related side effects that arise when certain medications interfere with the brain's dopamine pathways. The name comes from the extrapyramidal motor system, a network of brain circuits that helps control and smooth out voluntary movement. When these circuits are disrupted, movements can become stiff, slow, jerky, or restless.

EPS are most often linked to antipsychotic medicines used for conditions such as schizophrenia and bipolar disorder, but they can also follow certain anti-nausea and stomach drugs. The symptoms range from mild and reversible to long-lasting, and some types appear within hours of starting a drug while others develop after months or years. Recognizing EPS early matters because adjusting the medication can often relieve or prevent them.

Symptoms

EPS are usually grouped into several distinct patterns, and a person may have more than one type at the same time:

• Acute dystonia: Sudden, sustained muscle contractions causing twisting postures, a turned neck, eye rolling, or a tightening of the jaw and tongue, often within hours or days of starting a drug.
• Drug-induced parkinsonism: Tremor, muscle stiffness, slowed movement, and a shuffling walk that resemble Parkinson disease.
• Akathisia: An intense inner restlessness and an urge to keep moving, pacing, or shifting the legs.
• Tardive dyskinesia: Repetitive, involuntary movements of the face, lips, tongue, or limbs that tend to appear after long-term use.

Severe acute dystonia affecting the throat or breathing muscles is a medical emergency.

Causes

Most EPS are caused by medications that block dopamine, a brain chemical that helps coordinate movement. When dopamine signaling drops in the motor circuits, movement control becomes unbalanced.

• Antipsychotic medicines: Older (first-generation) antipsychotics carry the highest risk, but newer agents can also cause EPS, especially at higher doses.
• Anti-nausea and gut motility drugs: Medicines such as metoclopramide and prochlorperazine block dopamine and can trigger EPS.
• Other drugs: Certain antidepressants and other agents occasionally contribute.

The risk depends on the specific drug, the dose, how long it is taken, and individual factors. EPS are considered drug-induced movement disorders and are not a sign that the underlying mental health condition is worsening.

Risk Factors

• Use of first-generation (typical) antipsychotics
• Higher medication doses or rapid dose increases
• Long duration of treatment (especially for tardive dyskinesia)
• Older age, which raises the risk of tardive dyskinesia
• Being younger or male, which raises the risk of acute dystonia
• Use of more than one dopamine-blocking drug at the same time

Diagnosis

EPS are diagnosed mainly through a careful history and physical examination rather than a single test. A clinician will look at:

• Medication review: Which dopamine-blocking drugs are being taken, at what dose, and for how long.
• Timing: When the movements began in relation to starting or changing a medication.
• Movement examination: Observing for tremor, stiffness, restlessness, or involuntary movements, sometimes using standardized rating scales.

Other causes of abnormal movement, such as Parkinson disease or essential tremor, may need to be ruled out, especially when the link to medication is unclear.

Treatment

Treatment depends on the type of EPS and how severe it is, and it is guided by the prescribing clinician.

• Acute dystonia: Often responds quickly to anticholinergic or antihistamine medicines given by injection or mouth.
• Drug-induced parkinsonism: Usually improves when the responsible drug is lowered or switched; anticholinergic medicines may help.
• Akathisia: May ease with a dose reduction or a change in medication; certain medicines can reduce the restlessness.
• Tardive dyskinesia: Specific approved medications can reduce the involuntary movements; the offending drug is reviewed carefully because stopping it abruptly can temporarily worsen symptoms.

Never stop or change a prescribed medication on your own. Work with your prescriber, who can balance the benefit of the medicine against the movement side effects.

Prevention

• Use the lowest effective dose of dopamine-blocking medications
• Favor agents with a lower EPS risk when appropriate
• Have movement side effects monitored regularly during treatment
• Report new stiffness, restlessness, tremor, or facial movements early
• Avoid combining several dopamine-blocking drugs when possible

When to See a Doctor

Contact your prescriber promptly if you develop new tremor, stiffness, restlessness, or involuntary movements after starting or changing a medication. Seek emergency care right away if you have:

• A sudden locked jaw, twisted neck, or eyes fixed upward that will not relax
• Difficulty breathing, swallowing, or speaking
• High fever with severe muscle stiffness, confusion, and a racing heart, which can signal a rare but dangerous reaction

Related Topics

Frequently Asked Questions

References

1. National Institute of Neurological Disorders and Stroke (NINDS).
2. MedlinePlus, U.S. National Library of Medicine. Drug-induced tremor and movement disorders.
3. National Institute of Mental Health (NIMH). Mental Health Medications.
4. StatPearls, National Library of Medicine. Extrapyramidal Symptoms.