Extrapyramidal signs and symptoms (EPS) refer to movement and posture disturbances resulting from dysfunction of the basal ganglia or cerebellum, rather than the pyramidal (corticospinal) tract. These disturbances manifest as abnormalities in muscle tone, coordination, voluntary and involuntary movements, and posture.

Common extrapyramidal manifestations include:

• Asynergy: Impaired coordination between muscles during voluntary movements

• Ataxia: Unsteady gait or poor balance due to cerebellar dysfunction

• Athetosis: Slow, writhing, involuntary movements

• Blepharoclonus: Rapid eyelid twitching

• Chorea: Sudden, irregular, unpredictable movements

• Dysarthria: Impaired articulation of speech

• Dysdiadochokinesia: Difficulty performing rapidly alternating movements

• Dystonia: Sustained muscle contractions causing abnormal postures

• Muscle rigidity and spasticity: Increased tone with resistance to passive movement

• Myoclonus: Brief, shock-like involuntary jerks

• Spasmodic torticollis: Abnormal, sustained neck posture

• Tremors: Rhythmic, oscillatory movements

Pathophysiology

• Basal ganglia dysfunction: Interferes with the regulation of motor activity, resulting in involuntary movements, rigidity, and abnormal postures. Disorders include Parkinson’s disease, Huntington’s disease, drug-induced parkinsonism, and dystonias.

• Cerebellar involvement: Causes poor coordination, ataxia, dysdiadochokinesia, and intention tremor due to disruption of the cerebellar circuitry controlling smooth, purposeful movement.

• Neurotransmitter imbalance: Dopamine, GABA, acetylcholine, and glutamate pathways are critical; disruption produces various EPS manifestations.

• Drug-induced EPS: Antipsychotics and antiemetics that block dopamine D2 receptors in the basal ganglia can precipitate parkinsonism, dystonia, akathisia, or tardive dyskinesia.

Examination Technique

Patient Observation

• Assess gait, posture, spontaneous movements, facial expression, and speech.

Motor Tests

• Tremor: Observe at rest and during action (resting vs. intention tremor).

• Rigidity: Passively move limbs to assess “lead-pipe” or “cogwheel” resistance.

• Bradykinesia: Ask the patient to perform rapid alternating movements.

• Dystonia/Athetosis/Chorea: Observe for involuntary movements at rest and during activity.

• Ataxia: Finger-to-nose, heel-to-shin, and tandem walking tests.

• Dysdiadochokinesia: Rapid alternating movements (e.g., pronation-supination of hands).

• Blepharoclonus: Observe eyelids at rest and during conversation.

• Spasmodic torticollis: Assess neck posture and rotation abnormalities.

Clinical utility

• Diagnostic tool: Helps localize lesions in basal ganglia, cerebellum, or related pathways.

• Monitoring disease progression: EPS are hallmark features in Parkinsonism, Huntington’s disease, and drug-induced movement disorders.

• Guiding therapy: Detection informs pharmacologic (dopaminergic or anticholinergic drugs) and rehabilitative interventions.

Differential Diagnosis

Pediatric considerations

• EPS may result from congenital basal ganglia disorders or metabolic conditions.

• Careful observation is essential, as children may not be able to describe movement abnormalities.

Geriatric considerations

• High prevalence of Parkinsonism, drug-induced EPS, and neurodegenerative disorders.

• Age-related changes may mimic mild EPS, requiring careful differentiation.

Limitations

• EPS may be subtle or fluctuate, requiring repeated assessments.

• Differentiating drug-induced vs. primary neurological causes can be challenging.

• Requires experience to distinguish between types of involuntary movements.

Patient counseling

• Explain the neurological basis of observed movement or posture abnormalities.

• Reassure patients that some EPS are reversible with medication adjustments.

• Discuss physical therapy and occupational therapy for functional support.

• Encourage monitoring for progression or emergence of new symptoms.

Conclusion

Extrapyramidal signs and symptoms are critical markers of basal ganglia and cerebellar dysfunction. Comprehensive assessment aids in localizing lesions, diagnosing movement disorders, monitoring disease progression, and guiding treatment. Accurate recognition is essential for both clinical management and rehabilitation planning.

References

1. Jankovic J. Parkinson’s Disease and Movement Disorders. 6th ed. Philadelphia, PA: Wolters Kluwer; 2021.

2. Kandel ER, Schwartz JH, Jessell TM. Principles of Neural Science. 5th ed. New York: McGraw-Hill; 2013.

3. Ropper AH, Samuels MA, Klein JP. Adams and Victor’s Principles of Neurology. 11th ed. New York: McGraw-Hill; 2021.

4. Fahn S, Jankovic J, Hallett M. Principles and Practice of Movement Disorders. 2nd ed. Philadelphia: Elsevier; 2011.