SEVERAL PUBLISHED REPORTS suggest that selective serotonin reuptake inhibitors (SSRI) might induce abnormal movement disorders.1 In that event, clinicians face difficult treatment decisions, especially in cases whereby SSRI cannot be discontinued or decreased. In the following, we report for the first time the case of a patient suffering from severe panic disorder with agoraphobia (PD-A) and severe paroxetine-induced orofacial and buccal dystonia, successfully treated with low-dose aripiprazole.

This is the case of a 39-year-old woman with a 1-year history of severe PD-A and concomitant depressive mood, resistant to her previous treatment with fluoxetine 60 mg/d for the last 6 months. On her first consultation at our department, paroxetine was incrementally substituted for fluoxetine, titrated up to 60 mg/d. At this dosage of paroxetine, along with sessions of cognitive behavior therapy, the patient's panic attacks subsided completely within the next 4 weeks with a marked improvement of her agoraphobia. However, on her next appointment the patient complained of severe orofacial movements. Her examination by means of the Abnormal Involuntary Movement Scale (AIMS) – section for rating facial and oral movements – yielded a score of 14 with moderate to severe orofacial and buccal dystonia (dystonic movements of the face, jaw, lips, tongue, perioral area and blinking). At that time, aripiprazole 10 mg/d was added to the patient's regimen and, on her re-examination 10 days later, her abnormal movements had improved markedly (AIMS facial and oral movements score: 4). The patient's improvement was fully preserved until her last follow-up visit 4 months later.

Orofacial and buccal motor activity is controlled by dopaminergic neurons of the mesocortical tract. Dopamine inhibits spontaneous movement whereas serotonin inhibits dopaminergic transmission in this tract and thus, releases the characteristic repetitive muscle contractions of orofacial and buccal dystonia. Activation of 5-HT1A auto- and hetero-receptors reduces serotoninergic inhibition of the dopaminergic mesocortical tract and thus, helps restore dopaminergic control of spontaneous orofacial and buccal movements. Extant case reports suggest that the 5-HT1A agonists buspirone and tandospirone are efficacious in the treatment of SSRI-induced abnormal movements, especially bruxism.2,3

Aripiprazole is a partial agonist/antagonist at dopamine D2 and D3 and serotonin 5-HT1A receptors and antagonist at the 5-HT2A receptors. We hypothesize that its beneficial effect on a patient's orofacial and buccal dystonia is attributable to its partial-agonist activity on dopamine receptors and above all to its partial-antagonist action on 5-HT1A receptors, jointly overwhelming its antagonism of the 5-HT2A receptors. Although anecdotal, our case suggests that low-dose aripiprazole might be a promising new treatment modality of sub-acute SSRI-induced abnormal movements.


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