In 2017, valbenazine and deutetrabenazine became the first FDA-approved treatments for tardive dyskinesia in adults. Both medications block the vesicular monoamine transporter 2 (VMAT2) system, which results in decreased synaptic dopamine and dopamine receptor stimulation. Both VMAT2 inhibitor medications have a category level A supporting their use for treating tardive dyskinesia.8-10
Currently, there are no published treatment guidelines on pharmacologic management of tardive dystonia. In B’s case, bromocriptine, a dopamine agonist, was used to counter the dopamine-blocking effects of risperidone on the nigrostriatal pathway and improve parkinsonian features of B’s presentation, including bradykinesia, stooped forward posture, and masked facies. Bromocriptine was found to be effective in alleviating parkinsonian features; however, to date there is no evidence demonstrating its effectiveness in countering delayed dystonic effects of DRBAs.
OUTCOME Improvement of dystonia symptoms
One week after discharge, B is seen for a follow-up visit. He continues taking bromocriptine, 1.25 mg twice daily, with meals after discharge. On examination, he has some evidence of tardive dystonia, including flexion of left wrist and posturing while ambulating. B’s parkinsonian features, including stooped forward posture, masked facies, and cogwheel rigidity of the left wrist muscle, have resolved. B is now able to walk on his own without unsteadiness. Bromocriptine is discontinued after 1 month, and his symptoms of dystonia continue to improve.
Two months after hospitalization, B is started on quetiapine, 25 mg twice daily, for behavioral aggression. Quetiapine is chosen because it has a lower dopamine receptor affinity compared with risperidone, and theoretically, quetiapine is associated with a lower risk of developing tardive symptoms. During the next 6 months, B is monitored closely for recurrence of tardive symptoms. Quetiapine is slowly titrated to 25 mg in the morning, and 50 mg at bedtime. His behavioral agitation improves significantly and he does not have a recurrence of tardive symptoms.
Bottom Line
Tardive dystonia is a possible iatrogenic adverse effect for patients receiving long-term dopamine receptor blocking agent (DRBA) therapy. Tardive syndromes encompass delayed-onset movement disorders caused by long-term blockade of the dopamine receptor by antipsychotic agents. Tardive dystonia can be contrasted from acute dystonic reaction based on the time course of development as well as by the persistence of symptoms after DRBAs are withheld.
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