Opisthotonus: Revisiting a classic movement disorder.

Opisthotonus is characterized by backward arching of the trunk, associated with retrocollis, caused by involuntary contractions of extensor paraspinal muscles. Classical etiologies include tetanus, strychnine intoxication, dystonia (particularly tardive dystonia and neurodegeneration with brain iron accumulation), seizures, and functional movement disorders (MDs). Inborn errors of metabolism, epileptic encephalopathies and other gene mutations should be considered in newborns and infants presenting with opisthotonus. We surveyed 1216 consecutive patients presenting for evaluation in a tertiary care center for MDs and identified 17 (1.4%) with opisthotonus. Functional opisthotonus represented the most common cause, present in 9 (53%) patients. Other etiologies included tardive dystonia (n = 2), dystonia secondary to cavernous hemangioma in the basal ganglia (n = 1), dystonia due to hypoxic encephalopathy (n = 1), and 4 with idiopathic dystonia. Identifying the underlying etiology of opisthotonus is important to guide therapeutic strategies. Benzodiazepines, baclofen, anticholinergics, and botulinum toxin are common pharmacological options, whereas deep brain stimulation and surgical correction of the underlying cause should be considered in selected cases.