ekstrapiramidal

Ekstrapiramidal is a term used to describe neural pathways and motor control mechanisms outside the pyramidal tract, specifically outside the corticospinal tract. It encompasses circuits involving the basal ganglia, thalamus, and related structures that regulate movement, muscle tone, and motor learning. Disturbances in these pathways can lead to a range of movement abnormalities, both from disease and from medication effects.

Extrapyramidal symptoms (EPS) are movement disorders commonly linked to drugs that block dopamine receptors, especially typical antipsychotics. Common EPS include parkinsonism (tastering slowed movement, rigidity, tremor, and reduced facial expression), akathisia (inner restlessness and an urge to move), dystonia (sustained muscle contractions causing abnormal postures), and tardive dyskinesia (late-onset, often repetitive, involuntary movements of the face, tongue, or limbs). The onset can be acute or develop after weeks to months, with higher risk associated with older age, female sex, higher antipsychotic dose, and longer exposure.

Pathophysiology centers on reduced dopaminergic activity in the nigrostriatal pathway, leading to an imbalance with cholinergic signaling. Atypical antipsychotics generally carry a lower risk of EPS due to broader receptor profiles. Management of EPS typically involves reducing or changing the causative medication, or using anticholinergic drugs (such as benztropine or trihexyphenidyl), amantadine, or, for tardive dyskinesia, vesicular monoamine transporter 2 (VMAT2) inhibitors. In focal dystonias, botulinum toxin may be employed.

The concept of ekstrapiramidal is related to broader movement disorders arising from basal ganglia dysfunction, including conditions like Parkinson’s disease, and is distinguished from signs attributable to the pyramidal (corticospinal) motor system.