Spinal cord stimulation does not change peripheral skin blood flow in patients with neuropathic pain.

BACKGROUND AND OBJECTIVE: Spinal cord stimulation has been used successfully for many years in the management of neuropathic pain. Nociceptive pathways are closely integrated into many autonomic reflexes. The aim was to test the hypothesis that pain relief caused by spinal cord stimulation is related to changes in peripheral skin blood flow. METHODS: Twelve patients with spinal cord stimulators implanted as a treatment for neuropathic pain were entered into the study. Laser Doppler perfusion scanning was used as a direct method for selective measurement of changes in skin (peripheral) blood flow. Measurements were taken before and after the onset of spinal cord stimulation over the site of its sensory projection. The degree of pain relief due to spinal cord stimulation and the skin temperature of each patient were also recorded. RESULTS: Apart from one patient, spinal cord stimulation did not change skin blood flow in a statistically significant manner. CONCLUSIONS: Pain relief due to spinal cord stimulation is not related to changes of skin blood flow.

Efficacy of intravenous magnesium in neuropathic pain.

BACKGROUND: Postherpetic neuralgia is a complication of acute herpes zoster characterized by severe pain and paraesthesia in the skin area affected by the initial infection. There is evidence that the N-methyl-D-aspartate receptor is involved in the development of hypersensitivity states and it is known that magnesium blocks the N-methyl-D-aspartate receptor. METHOD: A double-blind, placebo-controlled, cross-over study was conducted in which magnesium sulphate was administered as an i.v. infusion. Spontaneous pain was recorded and qualitative sensory testing with cotton wool was performed in seven patients with postherpetic neuralgia before and after the i.v. administration of either magnesium sulphate 30 mg kg(-1) or saline. RESULTS: During the administration, pain scores were significantly lower for magnesium compared with placebo at 20 and 30 min (P=0.016) but not at 10 min. I.V. magnesium sulphate was safe, well-tolerated and effective in patients with postherpetic neuralgia. CONCLUSION: The present study supports the concept that the N-methyl-D-aspartate receptor is involved in the control of postherpetic neuralgia.

The use of lamotrigine in neuropathic pain.

Sodium channel antagonists have been used in the management of neuropathic pain for several years. Recent evidence suggests that lamotrigine, which is active at glutaminergic excitatory synapses, is very effective in producing pain relief. We have successfully used lamotrigine in two patients suffering from neuropathic pain. Our results suggest that this novel channel antagonist can be used to treat neuropathic pain. Double blind placebo control studies are therefore needed to substantiate these findings.

Continuous lumbar sympathetic block.

A 74-year-old woman with peripheral vascular disease suffered from rest pain in the right big toe and intermittent claudication. Because of concomitant venous congestion, a chemical lumbar sympathectomy was considered to carry an increased risk of leg edema. A continuous lumbar sympathetic block with local anesthetic abolished the pain in the toe without side effects. After this reversible block, a chemical lumbar sympathectomy was performed producing pain relief for 4 weeks when the patient was last seen.