Blood flow in a chronic entrapment neuropathy model in the rabbit sciatic nerve

A model of chronic entrapment neuropathy in the rabbit sciatic nerve was de veloped to try to elucidate the pathogenesis of chronic nerve entrapment. A non-compressive Silastic cuff was wrapped around the nerve at the mid-thig h level in eight rabbits. A sham operation that only elevated the sciatic n erve was performed in seven control rabbits. Six months later, the blood fl ow in the cuffed and the control sciatic nerves was determined with intra-a rterially injected microspheres. Blood flow was significantly reduced in th e entrapped nerve, compared to control nerves, but only in the segment prox imal to the cuff. After surgical release of the cuff, the blood flow signif icantly increased in the proximal segment. This suggested that decreased bl ood flow may occur, but not necessarily at the site of nerve entrapment. Ne rve conduction velocity changes were also consistent with an entrapment neu ropathy. However, there were no significant quantitative morphometric chang es at the nerve entrapment site, that is, in myelin thickness/nerve diamete r ratio, distribution of axon sizes, and mean nerve Fiber diameter. This in dicates that only a mild entrapment was created.