Hyun Sook Cho

Relationship between neuronal nitric oxide synthase and NADPH-diaphorase in the dorsal root ganglia during neuropathic pain

BACKGROUND Changes in nitric oxide (NO) production in the dorsal root ganglia (DRG) may contribute to allodynia after nerve injury. It is known that the histochemistry of NADPH-diaphorase (NADPH-d) is known to be not always coincident with NOS. This study was conducted to investigate the relationship between nNOS and NADPH-d expression in the DRG in a spinal nerve injury model of neuropathic pain, and to elucidate role that NO plays in neuropathic pain. METHODS nNOS immunohistochemistry and/or NADHP-d histochemistry were conducted in the DRG of a spinal nerve transection model of neuropathic pain, and the pain behavior was then measured by a von Frey filament test of the hindpaws of wild type and nNOS knock-out mice. RESULTS nNOS immunoreactive neurons and NADPH-d stained neurons were not always identical. Additionally NADPH-d increased, but nNOS did not increase significantly in the DRG after spinal nerve transection. Neuropathic pain behavior increased in the hindpaw of nNOS(-/-) mice after spinal nerve transection, but was lower than that of wild type mice after spinal nerve transection. CONCLUSIONS nNOS immunoreactive neurons and NADPH-d stained neurons were not always identical in the DRG, and a novel NADPH-d positive source may be involved in neuropathic pain after spinal nerve transection. Changes in nNOS expression in the DRG were not the primary cause of neuropathic pain behavior in a spinal nerve transection model of neuropathic pain.

Cauda equina syndrome after spinal anesthesia in a patient with severe spinal stenosis - A case report -

Cauda equina syndrome is a well-known but rare complication of spinal anesthesia. An 80-year-old man was scheduled for both herniorrhaphy. Spinal anesthesia was performed at the L3-4 interspinous space with 0.5% hyperbaric bupivacaine 12 mg. Eight hours after anesthesia, the patient complained bilateral sensorimotor deficits of the lower extremities and peroneal region. Urinary and fecal incontinence were also observed. MRI and myelography showed severe central spinal stenosis at L3-4 and L4-5. EMG showed cauda equina syndrome. Seven weeks after the procedure, left decompressive subtotal laminectomy L2-L5 was done. The patient still complains the neuropathic pain in the both lower extremities and ambulates using a walker. The local anesthetic was injected into thecal sac between maximum stenoses, and it is likely that there was poor upward spread leading to maldistribution of local anesthetic and resultant local anesthetic toxicity.