Sensory symptoms such as paresthesias and anesthesia are uncommon side effects of selective serotonin reuptake inhibitors (SSRIs) and are known to occur both during the initiation and withdrawal of these medications [1], [2]. While the bulk of literature on these sensory adverse effects focuses on sensory symptoms such as tingling, numbness and ‘electric’ shock like sensations on SSRI discontinuation, only anecdotal reports of such symptoms during the initiation of SSRIs exist [3]. A PubMed search revealed that most of the latter reports are of paresthesias with only a handful of cases of SSRI-induced anesthesia, mostly due to fluoxetine but none due to paroxetine. These sensory side effects can often be uncomfortable to the patient and are likely to be misinterpreted as worsening or recurrence of an existent neurological illness. Moreover, it is known that some of the adverse effects of SSRIs on initiation may be mistaken for an ensuing panic attack in patients with panic disorder. However, there are no reports of SSRI-induced anesthesia precipitating a panic attack.
The patient was a 74-year-old female with hypertension, hypothyroidism and an incidentally discovered right carotid artery occlusion (less than 70%) but had no prior history of stroke or transient ischemic attacks. She was started on aspirin about two years earlier after being told about her risk for a cerebrovascular event, which was communicated to her as: “if you stop your aspirin, you would have a stroke.” In addition, she had panic disorder for the past fifteen years and was on 0.25 mg of alprazolam thrice daily. Her panic attacks had become infrequent occurring once in two months.
The patient presented to the emergency room of a community hospital with numbness in her left leg, which had lasted for 15 min. This was not accompanied by weakness, other paresthesias or neurological symptoms. She felt her left leg below the knee ‘dead as wood’. Fearing that this was an impending stroke, she became anxious and had a full blown panic attack characterized by hyperventilation, dryness of mouth, dizziness, perspiration, palpitations and tremulousness along with the sense of impending doom. Her neurological examination at the time of presentation was unremarkable as was her cranial CT scan. Blood chemistry, including thyroid profile, was normal. On further interviewing, it became evident that she had been depressed for the past two months and had been started on 5 mg of paroxetine four days ago. The treating physician, though not aware of paroxetine-induced anesthesia, knew about the reported association of sensory symptoms such as numbness with SSRI initiation [4]. Thus based on the physician’s clinical suspicion, the presentation, (an isolated sensory symptom that appeared less likely secondary to a localizable cerebrovascular event), a negative neurological work up, and the fact that her other medications—aspirin and alprazolam, had been not been associated with such a side effect (as per Physician’s Desk Reference and PubMed search), paroxetine-initiation was implicated in the patient’s presentation. The patient was advised to continue with paroxetine and report if further sensory symptoms occurred. Fortunately, the patient had an uneventful follow up with no recurrence of the numbness.
SSRIs rarely cause sensory symptoms, including paresthesias and anesthesia, the latter, curiously, limited to mostly genital anesthesia with no reports of limb anesthesia [4], [5], [6], [7]. Of the SSRIs, fluoxetine has been most commonly implicated in sensory side effects and a patient may develop these with one SSRI but not with another [8]. No reports of paroxetine-induced anesthesia exist but, interestingly, one report cites facial numbness on its discontinuation [2], while another reports transient, paroxysmal shock like paresthesias on initiation [1]. Though sensory symptoms may be more common than previously thought as a study on the adverse effects of SSRIs showed paresthesias to be the fourth most reported side effect after nausea, rash and anxiety [9], no systematic study has assessed SSRI-induced anesthesia per se. However, there have been increasing number of case reports of SSRI-induced anesthesia in recent literature. Thus as the use of SSRIs becomes more frequent, the awareness that these sensory symptoms may be a side effect with an SSRI should be high, particularly amongst primary care and emergency room physicians and also neurologists. While it would still be prudent to ask the patient to report any unusual or rare side effect and to thoroughly investigate it, the knowledge of such side effects, especially the neurological ones which do not fit into any localizable disease pattern as in this patient, may obviate the need of an extensive neurological work up. Moreover, proper communication of these side effects to patients with existent neurological disorder would prevent these patients from catastrophizing about their condition. Regarding managing these symptoms, in most cases they either disappeared on discontinuing the medication or were transient. In addition, some authors have advocated using Ginkgo biloba [6] or pyridoxine [10].
The other notable feature of this presentation was the SSRI-induced anesthesia triggering a panic attack. Patients with panic disorder are known to misinterpret bodily sensations, which can then precipitate a panic attack. In case of SSRIs, this is usually associated with initial side effects such as nervousness, anxiety, dry mouth and tremor. Interestingly, this patient never had any sensory symptoms during her previous panic attacks. Her index episode of panic attack could be explained by the cognitive theory of panic disorder as she misinterpreted bodily sensations not only because of previous experiences but also because of informational transmission from physicians about her physical health, which was the vulnerability for stroke in her case [11]. Hence, besides informing patients with panic disorder about these sensory adverse effects of SSRIs, a clinician should provide information about the risk and nature of a physical illness in a considerate and nonthreatening manner. While patients with panic disorder characterized by sensory symptoms may find it difficult to distinguish between drug-induced and panic-related sensory symptoms, as gleaned from the available literature and this report, isolated, transient or paroxysmal sensory symptoms in the absence of other panic symptoms may be more indicative of the former.
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