Additional family history is gathered from B’s parents for possible hereditary movement disorders such as Wilson’s disease. They report that no family members have developed involuntary movements or other neurologic syndromes. Additional considerations on the differential diagnosis for B include juvenile ALS or mononeuropathy involving the C5 and C6 nerve roots. B’s parents deny any recent shoulder trauma, and radiographic studies did not demonstrate any involvement of the nerve roots.
TREATMENT A trial of bromocriptine
At this point, B’s neurologic workup is essentially normal, and he is given a provisional diagnosis of antipsychotic-induced tardive dystonia vs tardive parkinsonism. Risperidone continues to be held, and B is monitored for clinical improvement. B is administered a one-time dose of diphenhydramine, 25 mg, for dystonia with no improvement in symptoms. He is then started on bromocriptine, 1.25 mg twice daily with meals, for parkinsonian symptoms secondary to antipsychotic medication use. After 1 day of treatment, B shows less sustained flexion of his left wrist. He is able to relax his left arm, shows improvements in ambulation, and requires less assistance. B continues to be observed closely and continues to improve toward his baseline.
At Day 4, he is discharged. B is able to walk mostly without assistance and demonstrates improvement in left wrist flexion. He is scheduled to see a movement disorders specialist a week after discharge. The initial diagnosis given by the movement disorder specialist is tardive dystonia.
The authors’ observations
Tardive dyskinesia is a well-known iatrogenic effect of antipsychotic medications that are commonly used to manage conditions such as schizophrenia or behavioral agitation associated with autism spectrum disorder. Symptoms of tardive dyskinesia typically emerge after 1 to 2 years of continuous exposure to dopamine receptor blocking agents (DRBAs). Tardive dyskinesia symptoms include involuntary, repetitive, purposeless movements of the tongue, jaw, lips, face, trunk, and upper and lower extremities, with significant functional impairment.1
Tardive syndromes refer to a diverse array of hyperkinetic, hypokinetic, and sensory movement disorders resulting from at least 3 months of continuous DRBA therapy.2 Tardive dyskinesia is perhaps the most well-known of the tardive syndromes, but is not the only one to consider when assessing for antipsychotic-induced movement disorders. A key feature differentiating a tardive syndrome is the persistence of the movement disorder after the DRBA is discontinued. In this case, B had been receiving a stable dose of risperidone for >1 year. He developed dystonic posturing of his left wrist and elbow that was both unresponsive to anticholinergic medication and persisted after risperidone was discontinued. The term “tardive” emphasizes the delay in development of abnormal involuntary movement symptoms after initiating antipsychotic medications.3 Table 12 shows a comparison of tardive dystonia vs an acute dystonic reaction.
Continue to: Other tardive syndromes include...