Case Report: A rare phenomenon of venlafaxine induced vocal tics

Venlafaxine is a serotonin norepinephrine reuptake inhibitor, an effective medication widely used in many psychiatric conditions, including major depressive disorder and generalized anxiety disorder. It is a relatively safe and tolerated medication. Despite that, it has some side effects affecting many systems, including nausea, insomnia, and tremors. Also, it has some neuropsychiatric side effects, such as akathisia. Venlafaxine induced akathisia has been reported in some studies. Several antidepressants have been associated with some neuropsychiatric manifestations, including tics, usually motor, but not vocal. In our study, we reported a rare side effect of venlafaxine, which is venlafaxine-induced vocal tics.

A 57-year-old women was diagnosed with anxiety and started on venlafaxine with a good response for three months. Then she stopped it. Her anxiety symptoms started to appear again. Then she re-initiated venlafaxine again. A few days afterwards she started to develop vocal tics that are frequent and distressing to the patient. The Yale Global Tic Severity Scale (YGTSS) score at presentation was 22 (Total Tic Score), indicating moderate severity, with an impairment score of 20. Causality assessment using the Naranjo Adverse Drug Reaction Probability Scale yielded a score of 7, indicating a probable relationship between and the vocal tics.

To our knowledge, this appears to be the first reported case of venlafaxine induced vocal tics. On the other hand, there were previous reports on Sertraline and Mirtazapine. Previous studies reported associations of tics with SSRIs and atypical antidepressants but not SNRIs. Also, our study is the first study that reported "vocal" tics in association with antidepressant. The proposed mechanism involves a complex interaction between serotonergic augmentation and dopaminergic dysregulation in fronto-striatal circuits, in which increased serotonin levels may indirectly modulate dopamine concentrations to express tics in susceptible individuals.

Our findings suggest that venlafaxine may induce vocal tics. Physicians should consider venlafaxine as a potential cause when patients develop vocal tics while on treatment. Early detection and discontinuation of the medication can prevent complications and lead to symptom resolution.