Pathophysiology

Fig.9

The pathogenesis of acute dystonia is not fully understood. It is thought to be related to dopamine-receptor blockade (D2), which disrupts the dopaminergic-cholinergic balance in the basal ganglia (substantia nigra) leading to a relative excess of cholinergic output.

Antidopaminergic drugs with anticholinergic properties are therefore less likely to produce an acute dystonic reaction because they disrupt the neurotransmitter balance less markedly.

Alternatively, nigrostriatal dopaminergic activity may be increased in response to dopamine receptor blockade or dopamine receptor hypersensitivity.

Acute dystonia can be dose related but is often idiosyncratic.