fluvoxamine and Spinal-Cord-Injuries

There have been only a few reports of serotonin syndrome developing after mono-therapy with a selective serotonin reuptake inhibitor (SSRI). We report a case of serotonin syndrome caused by long-term therapy with fluvoxamine prior to treatment with paroxetine. An 18-year-old man with spinal cord injury (SCI) at thoracic level 2-3 presented with onset of serotonin syndrome after taking fluvoxamine (50 mg per day) for 8 weeks prior to treatment with paroxetine (10 mg per day) for 6 days. He had confusion, agitation, severe headache, tachycardia (124 beats/minute), hypertension (165/118 mmHg), high fever (39.1 degrees C), and myoclonus. All of the symptoms disappeared within 24 hours after discontinuation of administration of paroxetine. This is an interesting case of serotonin syndrome that developed after minimum doses of single therapy with an SSRI in a patient with SCI.

Topics: Adolescent; Antidepressive Agents, Second-Generation; Fluvoxamine; Humans; Male; Paroxetine; Selective Serotonin Reuptake Inhibitors; Serotonin Syndrome; Spinal Cord Injuries

Although dysesthesia is one of the most serious problems in patients with spinal cord injury, most of them being unresponsive to conventional treatments. In this study, we established a rat thoracic spinal cord mild-compression model that revealed thermal hyperalgesia in the hind limb. The thoracic spinal cord was compressed gently, using a 20 g weight for 20 min. The withdrawal latency of the thermal stimulation of the bilateral hind-limb was monitored using Hargreaves' Plantar test apparatus. In this model, thermal-hyperalgesia was observed for 1 week after the injury. The spinal cord injury-induced thermal-hyperalgesia was mimicked by the intrathecal application of metergoline, a non-selective 5-HT antagonist, 1-(2-methoxyphenyl)-4-[4-(2-phthalimido) butyl]-piperazine hydrobromide (NAN190), a selective 5-HT1 antagonist, and 3-tropanyl-3,5-dichlorobenzoate (MDL72222), a selective 5-HT3 antagonist. Intraperitoneal application of fluvoxamine maleate, a selective serotonin reuptake inhibitor, reduced the intensity of hyperalgesia induced by spinal cord injury. The inhibitory effect of fluvoxamine maleate on thermal hyperalgesia was prevented by the application of the aforementioned nonselective or selective 5-HT receptor antagonists. Intrathecal application of fluvoxamine maleate and selective 5-HT receptor agonists, i.e., 8-hydroxy-2-(di-n-proplyamino)-tetralin hydrobromide (8-OH-DPAT: 5HT-1 selective) and 2-methyl-5-hydroxytryptamine maleate (2-m-5-HT: 5HT-3 selective), inhibited the spinal cord injury-induced hyperalgesia. These results suggest that the change in the descending serotonergic signal plays an important role in hyperalgesia after the spinal cord injury, and that the application of selective serotonin reuptake inhibitors will be one of the candidates for new therapeutic methods against post-spinal cord injury dysesthesia.

Topics: Animals; Brain Stem; Female; Fluvoxamine; Hot Temperature; Hyperalgesia; Metergoline; Nociceptors; Pain Measurement; Physical Stimulation; Rats; Rats, Wistar; Receptors, Serotonin; Selective Serotonin Reuptake Inhibitors; Serotonin; Serotonin Antagonists; Signal Transduction; Spinal Cord; Spinal Cord Compression; Spinal Cord Injuries

Spinal cord injury (SCI) results in abnormal locomotor and pain syndromes in humans. In a rodent SCI model, T13 unilateral spinal hemisection results in bilateral mechanical allodynia and thermal hyperalgesia, partly by interruption of tonic descending serotonin (5-HT) inhibition. In the current study, we examined changes in density and distribution of 5-HT and 5-HT(T) in cervical (C8) and lumbar (L5) enlargements after T13 spinal hemisection and studied the effects of intrathecally delivered 5-HT (10, 21, and 63 microg), 5-HT antagonist methysergide (125 microg/kg), and 5-HT reuptake inhibitor fluvoxamine (75 microg/kg) on pain-related behaviors. Thirty-day-old male Sprague-Dawley rats were spinally hemisected and sacrificed at 3 (n = 20) and 28 (n = 20) days postsurgery for immunohistochemistry, Western blot, and ELISA analysis and compared against sham-operated animals (n = 10). At day 3, C8 5-HT levels were not significantly changed but at L5 there was a significant decrease in ipsilateral 5-HT in laminae I-II followed by incomplete recovery at 28 days postinjury. At both 3 and 28 days postinjury, C8 5-HT(T) levels were not significantly changed, but at L5 there was significant ipsilateral up-regulation of 5-HT(T) in laminae I-II. A second group of animals (n = 30) was hemisected and, starting at 28 days postinjury, behaviorally tested with intrathecal compounds. Increasing doses of 5-HT attenuated both fore- and hindlimb mechanical allodynia and thermal hyperalgesia, and effects of endogenous 5-HT were attenuated by methysergide and enhanced with fluvoxamine, all without locomotor alterations. Sham controls (n = 10) were unaffected. Thus, permanent changes occur in 5-HT and 5-HT(T) after SCI, denervation 5-HT supersensitivity develops, and modulation of 5-HT attenuates pain-related behaviors. Insight gained by these studies may aid in the understanding of dynamic 5-HT systems which will be useful in treating chronic central pain after SCI.

Topics: Animals; Blotting, Western; Carrier Proteins; Denervation; Enzyme-Linked Immunosorbent Assay; Fluvoxamine; Hot Temperature; Hyperalgesia; Immunohistochemistry; Injections, Spinal; Male; Membrane Glycoproteins; Membrane Transport Proteins; Methysergide; Motor Activity; Nerve Tissue Proteins; Pain; Physical Stimulation; Rats; Rats, Sprague-Dawley; Selective Serotonin Reuptake Inhibitors; Serotonin; Serotonin Antagonists; Serotonin Plasma Membrane Transport Proteins; Spinal Cord; Spinal Cord Injuries