Presentation of Neurolytic Effect of 10% Lidocaine after Perineural Ultrasound Guided Injection of a Canine Sciatic Nerve: A Pilot Study

BACKGROUND: Phenol and alcohol have been used to ablate nerves to treat pain but are not specific for nerves and can damage surrounding soft tissue. Lidocaine at concentrations > 8% injected intrathecal in the animal model has been shown to be neurotoxic. Tests the hypothesis that 10% lidocaine is neurolytic after a peri-neural blockade in an ex vivo experiment on the canine sciatic nerve. METHODS: Under ultrasound, one canine sciatic nerve was injected peri-neurally with 10 cc saline and another with 10 cc of 10% lidocaine. After 20 minutes, the sciatic nerve was dissected with gross inspection. A 3 cm segment was excised and preserved in 10% buffered formalin fixative solution. Both samples underwent progressive dehydration and infusion of paraffin after which they were placed on paraffin blocks. The sections were cut at 4 µm and stained with hemoxylin and eosin. Microscopic review was performed by a pathologist from Henry Ford Hospital who was blinded to which experimental group each sample was in. RESULTS: The lidocaine injected nerve demonstrated loss of gross architecture on visual inspection while the saline injected nerve did not. No gross changes were seen in the surrounding soft tissue seen in either group. The lidocaine injected sample showed basophilic degeneration with marked cytoplasmic vacuolation in the nerve fibers with separation of individual fibers and endoneurial edema. The saline injected sample showed normal neural tissue. CONCLUSIONS: Ten percent lidocaine causes rapid neurolytic changes with ultrasound guided peri-neural injection. The study was limited by only a single nerve being tested with acute exposure.

Mechanisms of acupuncture and herbal medicine in hypertension

Background: Acupuncture and herbal medicine have been of great benefit to Asian people for centuries. However, the discipline has not been subjected systematically and thoroughly to the rigors of scientific testing. Objective: This article reviews experimental evidence in regard to the vascular mechanisms of acupuncture and herbal medicine in hypertension. We focus on our hypothesis that acupuncture and herbal medicine reduce hypertension through activation of microvascular endothelial nitric oxide synthesis (eNOS). We also examine whether or not our results in experimental renovascular hypertension conform to the meridian theory. Results and conclusion: Acupuncture and herbal medicine 1) reduce experimental renovascular hypertension; 2) increase production of nitric oxide (NO), and contribute to vasodilation in the microvasculature and reduction of peripheral vascular resistance. We concluded that acupuncture and herbal medicine target eNOS and activate its signaling mechanisms, and that the benefits of acupuncture proceed along the meridian of the stimulated acupoint.