Temporomandibular dislocation due to aripiprazole induced dystonia

Abstract

We wish to report the case of a patient who developed temporomandibular joint dislocation due to dystonia following a single dose of aripiprazole. Our patient was a 23-year-old woman presenting with persistent low mood, fatiguability, insomnia and suicidal ideation. There was no past history of psychiatric morbidity. There was family history of depressive episode and deliberate self harm in her husband who was her paternal cousin. She was given 10 mg escitalopram and 0.5 mg clonazepam for insomnia on a diagnosis of a moderate depressive episode and improved over the next 3 weeks. However she developed irritability and agitation while on the above medications for which she was given a single dose of aripiprazole 10 mg at night by another psychiatrist not attached to our institution, which was not appropriate for her condition. The patient had taken 10 mg escitalopram in the morning. There was no history of intake of any over the counter drugs or herbal preparations. Twelve hours after the first dose she developed sedation and salivation and her care givers withheld subsequent doses of aripiprazole, escitalopram and clonazepam. Twenty hours after the first dose, she developed painful spasms of the muscles of her neck on the right side. She also had forced opening and deviation of jaw, both to the left and right. This was followed by persistent deviation of the jaw to the left and pain in the left temporomandibular joint. She was unable to close her mouth, swallow or talk for which she was brought to the emergency department of our hospital. A left-sided temporomandibular dislocation was diagnosed and a manual reduction was performed, after which the pain subsided. The next morning she was examined by us and seen to have forced mouth opening, excessive salivation and bilateral hand tremors. There were no other dystonic reactions. The dystonia and temporomandibular joint dislocation could not be part of the somatic symptoms of depression. We gave her 50 mg promethazine intramuscularly on suspicion of an aripiprazole induced dystonia. Two hours later, the dystonic movements subsided and the patient was sent home on oral promethazine. She did not have dystonic movements on follow-up the next morning. A rechallenge with aripiprazole could not be done for ethical reasons. The dystonia was rated as possibly due to aripiprozole according to the Naranjo adverse drug reaction probability scale [1]. She was restarted on escitalopram and clonazepam. A 1 month follow-up did not reveal any dystonic reactions. The adverse drug reaction was reported to the regional pharmacovigilance reporting centre. Aripiprazole is a second generation anti-psychotic which has a low propensity to cause extra-pyramidal side effects [2]. There are reports of acute dystonia induced by aripiprazole in drug-naive [3], and cocaine dependent patients [4] and in a patient on sertraline [5]. It has been proposed that aripiprazole caused dystonia because it lacked a protective anti-cholinergic action unlike other second generation anti-psychotics like clozapine [3]. Temporomandibular joint dislocations have been reported with conventional neuroleptics [6, 7] but no case has been reported with aripiprazole. Aripiprazole has been found to have no meaningful effect on the pharmacokinetics of escitalopram [8].We propose that our patient developed temporomandibular dislocation due to a dystonic reaction to aripiprazole possibly mediated through a pharmacodynamic synergism with escitalopram as selective serotonin re-uptake inhibitors can cause extrapyramidal side effects including dystonias through serotonergically mediated inhibition of the dopaminergic system [9]. From our case report we recommend a lower starting dose of aripiprazole especially in drug naive non psychotic patients and close monitoring of such patients.