Extrapyramide

Extrapyramide, or extrapyramidal system, is a collection of neural structures and pathways that influence movement outside the pyramidal tracts of the corticospinal system. The term contrasts with the pyramidal system, which mediates fine voluntary movements through direct corticospinal projections. Extrapyramidal circuits involve the basal ganglia—primarily the caudate nucleus, putamen, and globus pallidus—along with the substantia nigra, subthalamic nucleus, and associated thalamic connections. These networks help regulate muscle tone, posture, and automatic or learned movements, integrating motor control with cognitive and limbic inputs. Neurotransmitters such as dopamine and acetylcholine modulate activity within these loops, shaping initiation and suppression of movement.

Clinically, disturbances of extrapyramidal control can produce movement disorders referred to as extrapyramidal symptoms (EPS). These include acute dystonia, drug-induced parkinsonism, akathisia, and tardive dyskinesia. EPS most commonly arise as adverse effects of dopamine D2 receptor antagonists used in antipsychotic therapy, though several other medicines can contribute. Management typically involves adjusting or switching the offending medication and providing symptomatic treatments, such as anticholinergic agents for dystonia or parkinsonism and amantadine for tardive dyskinesia in selected cases.

In contemporary usage, the term extrapyramidal reflects functional circuitry rather than strict anatomy, acknowledging that these pathways form complex loops linking the cortex, basal ganglia, brainstem, and thalamus to regulate movement, posture, and motor learning.