Serotonin reuptake inhibitor induced sensory disturbances

Abstract

Serotonin reuptake inhibitor induced sensory disturbances are reported rarely in the literature. This case report describes numbness and dysmorphic symptoms in the upper facial area associated with fluoxetine. There is no previous report of such an adverse reaction with any serotonin reuptake inhibitor in the literature and this report is intended to draw attention towards these unusual adverse effects.

Case report

Mr HC, a 26 year old Indian male, weighing 62 kg, presented with 6 months of low mood, decreased interest in activities, decreased concentration, difficulty falling asleep and mild headache and was diagnosed as having major depressive disorder. He had no past history of major medical or psychiatric disorder, substance abuse or history of allergy. He was started on fluoxetine 20 mg daily after breakfast and zolpidem 10 mg at bedtime for insomnia. He reported feeling better during follow up at 2 weeks, but complained of numbness and a strange sensation around the eyes and upper face which occurred throughout the day. His medication was continued but at the second follow up at 4 weeks he reported worsening of the numbness and felt that his nose had increased in size and was obstructing his vision. The dysmorphic symptoms were not to a delusional extent but were distressing to the patient. Fluoxetine was stopped and substituted with mirtazapine 15 mg at bedtime, following which all symptoms disappeared within a week, and the patient continued to show improvement in his depressive symptoms. Rechallenge could not be done as the patient did not agree to another trial.

Discussion

Sensory disturbances reported for the selective serotonin reuptake inhibitors (SSRIs) include: fluoxetine, anaesthesia of the penis [1, 2], vagina [3, 4, 9] and nipples [4], and paresthesias [5]; sertraline, anaesthesia of the penis [6]; paroxetine, vaginal anaesthesia [7], and limb anaesthesia [8]. In Michael & Andrews’[7] case, vaginal anaesthesia occurred with paroxetine, recurred with citalopram and sertraline, but did not recur with reboxetine. Most of these cases responded to discontinuation of medications, or with substitution of another drug like trazodone [4]. Ellison & DeLuca [9] reported a case of fluoxetine-induced vaginal anaesthesia that did not improve with the addition of cyproheptadine or yohimbine but responded to Ginkgo biloba, but only minimal improvement was noticed in another case of paroxetine-induced vaginal anaesthesia with Ginkgo biloba[7].

Paresthesias are described by many patients during withdrawal of serotonin reuptake inhibitors (including clomipramine) and usually present as numbness, tingling, burning, and occasionally ‘electricity-like’ feelings, predominantly in the upper legs and orofacial regions [10]. These symptoms, which may be exacerbated by movement [10], occurred within 5 days of stopping the drug and lasted for up to weeks [11]. Paresthesia during withdrawal from serotonin reuptake inhibitors could be due to serotonin receptor supersensitivity [10].

Body dysmorphic disorder is characterized by preoccupation with an imagined defect in appearance in a normal-appearing person, or markedly excessive concern about a slight imperfection, which often causes significant and repetitive behaviours such as frequent mirror checking, excessive grooming, and skin picking [12]. Body dysmorphic symptoms as described in this case do not appear to have been reported with the SSRIs. Indeed SSRIs have been shown to have modest benefit in body dysmorphic disorder [13]. It may be possible that the sensory disturbances associated with both SSRI use and withdrawal could be due to the hyperserotonergic state. SSRI therapy increases serotonin concentrations in the brain acutely (though the therapeutic effect is delayed by several weeks), which could account for the early appearance of sensory symptoms, and the disappearance by 2–3 weeks may relate to homeostasic compensation. This could be analogous to the appearance or increase in anxiety symptoms early in SSRI therapy, which decrease with continued treatment. The inconsistency observed, i.e. both the occurrence and relief of body dysmorphic symptoms by serotonin reuptake inhibitors could be due to possible involvement of different receptor subtypes, the nature of which need to be explored further. Patients on serotonin reuptake inhibitors should be asked about these transient but distressing side-effects as they may contribute towards noncompliance.