Drug-induced dystonia is a serious reaction characterized by atypical repetitive or sustained muscle movements or spasms of the face (tongue, jaw, cheeks), neck, shoulder, back, trunk, and/or limbs, resulting in often-painful postures. Torticollis, opisthotonos (dystonic back arching), trismus, jaw opening, grimacing, blepharospasm, and oculogyric crisis (characteristic unidirectional upward eye deviation) can all be manifestations of drug-induced dystonia. These reactions can be delayed (tardive dystonia) or acute (acute dystonic reactions).

When acute dystonic reactions affect the neck region, difficulty swallowing, speaking, or breathing can ensue, which can be a medical emergency. Onset of acute dystonic reactions may occur within minutes or hours of drug intake, toxic exposure, or rapid dose increase, with most cases occurring within 5 days.

Drug-induced dystonia is most commonly caused by neuroleptics, especially high-potency neuroleptics, but also antiemetics. The pathophysiology is most often linked with blockage of dopamine receptors. Other risk factors for acute dystonia include young age, male sex, cocaine use, and history of acute dystonic reaction.

Related topics: Drug-induced movement disorders, Drug-induced muscle spasm