Other tardive syndromes include:
- tardive tics
- tardive parkinsonism
- tardive pain
- tardive myoclonus
- tardive akathisia
- tardive tremors.
The incidence of tardive syndromes increases 5% annually for the first 5 years of treatment. At 10 years of treatment, the annual incidence is thought to be 49%, and at 25 years of treatment, 68%.4 The predominant theory of the pathophysiology of tardive syndromes is that the chronic use of DRBAs causes a gradual hypersensitization of dopamine receptors.4 The diagnosis of a tardive syndrome is based on history of exposure to a DRBA as well as clinical observation of symptoms.
Compared with classic tardive dyskinesia, tardive dystonia is more common among younger patients. The mean age of onset of tardive dystonia is 40, and it typically affects young males.5 Typical posturing observed in cases of tardive dystonia include extension of the arms and flexion at the wrists.6 In contrast to cases of primary dystonia, tardive dystonia is typically associated with stereotypies, akathisia, or other movement disorders. Anticholinergic agents, such as benztropine or trihexyphenidyl, may or may not alleviate symptoms of tardive dystonia but can worsen tardive dyskinesia, so careful delineation between the 2 syndromes is important.6
The American Psychiatric Association has issued guidelines on screening for involuntary movement syndromes by using the Abnormal Involuntary Movement Scale (AIMS).7 The current recommendations include assessment every 6 months for patients receiving first-generation antipsychotics, and every 12 months for those receiving second-generation antipsychotics.7 Prescribers should also carefully assess for any pre-existing involuntary movements before prescribing a DRBA.7
The authors’ observations
In 2013, the American Academy of Neurology (AAN) published guidelines on the treatment of tardive dyskinesia. According to these guidelines, at that time, the treatments with the most evidence supporting their use were clonazepam, ginkgo biloba, amantadine, and tetrabenazine.8 Other medications, including bromocriptine, baclofen, botulinum toxin, and vitamin E, did not show sufficient evidence to be recommended or refuted as treatment options.8 Botulinum toxin has long been utilized to treat focal and cervical dystonias, although there is no clear consensus on its role in treating tardive syndromes because of the conflicting results of prior studies.8Table 28 outlines the AAN guidelines for treating tardive dyskinesia.
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