DISCUSSION

1. A Case Of Bruxism Induced By Fluoxetine And Treated By Gabapentin Ahmet Zihni Soyata1 , Serap Oflaz11I.U. Istanbul Medical Faculty Psychiatry Department INTRODUCTION Bruxism is an umbrella term grouping together different motor activities of the jaw muscles, characterised by clenching or grinding of the teeth and/or by bracing or thrusting of the mandible(1). A prevalence ranging from 8% to 31.4% was reported for sleep bruxism, decreasing with age and unrelated to sex(2). Although several medications, psyhotherapeutic and other interventions have been tried so far, there is not any gold standard therapy for clinically relevant bruxism(3). Bruxism can also be caused by several psychotropic drugs such as antidepressant drugs, cocaine, amphetamines and antipyschotics. There are two reports of bruxism induced by fluoxetine so far(4,5,7) which were treated with buspirone or aripiprazole. There is also a case report of bruxism due to venlafaxine which responded to treatment with gabapentin(6). We report here a case report of bruxism induced by fluoxetine and treated by gabapentin. CASE DESCRIPTION A 43 year old woman admitted to our consultation liaison psychiatry clinic with severe bruxism symptoms such as jaw pain, teeth grinding, clenching. Her symptoms had been present for the previous four months. Her psychosocial stressors were related with her parents and her children. She thought she had high responsibility towards her parents as their single child. Her mother had severe Parkinson disease and uterine carcinoma. Her father had heart failure and a previous episode of myocardial infarction. Her two children were diagnosed with ADHD hyperactive/impulsive type.  She was diagnosed with major depressive disorder and generalized anxiety disorder, thus, she was initiated 20 mg fluoxetine four months ago by her previous psychiatrist. Despite reporting clear improvement of her anxiety and depressive symptoms,  she reported severe bruxism symptoms during sleep as informed by her spouse. She had severe teeth grinding, clenching, jaw pain and temporal headache.  She was experiencing difficulties opening her mouth in the mornings.  Restless Legs Syndrome symptoms including paresthesia and pain also emerged after initiation of fluoxetine. Sleep quality of her spouse was also disrupted. She disagreed to change her medication because she had been administered citalopram and escitalopram previously and best treatment response was achieved with fluoxetine. Diagnosis of RLS was made according to International RLS Study Group Criteria(4 criteria met). Since DSM-V does not have a distinct category, diagnosis of bruxism was made according to International Classification Of Sleep Disorders-2(2005) criteria.  Unfortunately, polysomnography data were not available to diagnose or exclude comorbid periodic leg movements and confirm bruxism in sleep. Obstructive sleep apnea was excluded due to an interview with the patient and her spouse. In her psychiatric history, she also had childhood ADHD and a previous major depressive episode 5 years ago. She had used citalopram and escitalopram for the treatment of the previous episode but no treatment response was achieved. Her previous major depressive episode remitted spontaneously in 8 months. She was also diagnosed with Obsessive Compulsive Personality Disorder due to DSM-IV criteria. Her Rohrschach and MMPI tests revealed high somatization,anxiety and meticulosity levels. Neurological examination and radiological diagnostic tests did not reveal a pathological finding and her blood tests including serum ferritine and iron levels were within the normal range. In her medical history, she had Hashimoto thyroiditis and was taking levothyroxine 100 mg. Her thyroid hormone levels were within the normal range. She also had  a previous history of painful Restless Legs Syndrome(RLS)  four years ago and had used gabapentin for a year. There was not any other medical condition and medication in her history. Regarding to the prior reports, buspirone 10 mg bid had been administered for 2 weeks, however no improvement was reported. Considering previous RLS treatment response of the patient, gabapentin was initiated and titrated up to 300 mg. Beginning from the fifth day,  jaw ache, teeth grinding and clenching completely disappeared. Restless Legs Syndrome symptoms also subsided. Only minimal dizziness was reported as a side effect and the patient was very satisfied with the treatment regimen.  She was also referred to the group treatment for bruxism and cognitive behavioral treatment for major depression and generalized anxiety disorder. Further assessments at the 16th, 20th and 24th weeks of the treatment revealed that the treatment gains had been maintained without relapses. DISCUSSION Bruxism is characterized by nonfunctional teeth locking, and grinding leads to temporomandibulary articular dysfunction, weakening of teeth, periodontal diseases, hypertrophy of masseter, and headache(29). Bruxism was reported as a side effect of SSRIs including escitalopram(7,8), citalopram(9,15), fluoxetine(4,5,7,14), fluvoxamine(16), sertraline(5,13,14), paroxetine(10-12,14,15), as well as SNRIs such as venlafaxine(6,17-21), duloxetine(22) and atomoxetine(23,24). Although not common, bruxism due to drugs may result in severe consequences to health that include destruction of tooth structure, irreversible harm to the temporomandibular joint, severe myofascial pain, and muscle contraction headache(30).  Majority of the cases were reported to subside after addition of buspirone/tandospirone or reduction of dosage(4,5,8-15,17-19,22-24), a case was reported to subside after addition of aripiprazole(7), a case was reported to remit after electroconsulvie therapy(16) and a case which was due to venlafaxine was reported to respond to gabapentin(6). Notably, cases with no response to buspirone were also reported(14,16). In our patient bruxism and RLS symptoms emerge after initiation of fluoxetine which was previously associated with bruxism(4,5,7,14). Notably,our patient, her father and her both children had ADHD and ADHD was associated with an increased risk of bruxism(25) which may be due to increased motor activity in sleep(26). Although our patient had a previous history of RLS four years ago, it was aggrevated by fluoxetine. Emergence of RLS and bruxism symptoms at the same time suggests that there may be a relationship between two conditions as both conditions were found to be concomitant in a previous study(27). The mechanism of SSRI-induced bruxism is not clear. Bruxism has been discerned as a special form of akathisia and it has been hypothesized that serotonergic drugs mediate excessive serotonergic action on mesocortical neurons arising from the ventral tegmental area leading to dopaminergic deficit which in turn causes akathisia-like movement of jaw muscles leading to bruxism and buspirone-mediated dopaminergic activity in the mesocortical pathway is responsible for an improvement in bruxism(13). However, our patient had no relief after addition of buspirone. Contribution of psychosocial factors are possible in the ethiology of sleep bruxism in our patient. However,  no evidence was found to relate psychosocial factors with sleep bruxism in a recent review(28). To our knowledge, this is the first case of bruxism induced by fluoxetine and treated by gabapentin. This case is considered to represent evidence of a role of gabapentin in relieving symptoms of drug-induced bruxism, as reported previously(6). Moreover, gabapentin was found to have significant ameliorating effects in sleep bruxism generally and it was also reported to improve sleep efficiency (31). The efficacy of gabapentin showed in our case is promising, but it should be confirmed in placebo-controlled studies using larger samples. . Bruxism Assessment Are you aware, or has anyone heard you, grindingyour teeth frequently during sleep? (yes⁄no) 2 Are you aware that your dentition is worn downmore than it should be? (yes⁄no) 3 Are you aware of any of the following symptomsupon awakening? (yes⁄no): (i) Sensation of fatigue, tightness or soreness ofyour jaw upon awakening? 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