The effects of pressure on conduction in peripheral nerve

The effects of compression upon conduction in myelinated axons of the isolated frog sciatic nerve.

“…Bentley & Schlapp (1943) applied 130-200 mmHg over a 20-40 mm length of cat sciatic nerve and observed conduction failure after 2-5-3 h. Recovery was not apparent after a further 3 h, and the block was located at the edges of the compressed region. Gelfan & Tarlov (1956) compressed 5 mm of dog sural nerve such that complete block of the compound potential was achieved in 41-62 min.…”

“…The mechanisms underlying this conduction failure are not fully understood. Experiments using in vivo techniques have highlighted two important factors, namely: (i) the direct mechanical deformation of nerve fibres and (ii) the effects of ischaemia following occlusion of the nerve's blood supply (Bentley & Schlapp, 1943;Ochoa, Fowler & Gilliatt, 1972;Lundborg, Gelberman, Minteer-Convery, Lee & Hargens, 1982;Powell & Myers, 1986). However, these studies have been unable to investigate these two aetiological factors separately and a coherent account of the cause of conduction block has thus not been forthcoming.…”

The Straight-Leg-Raising Test: A Review

“…SprangfortB4 in a study of 2,157 cases with confirmed lumbar disc herniation found that: 1 ) positive straight-leg raising test was seen in 98.6% nf the patients; 2) t h e p c e of the sign cor r el -e level of herniation as one moved cranially; and 3 ) thesign when correlated with age decreased constantly.…”

Spinal nerve root compression

“…It has been observed that compression-induced effects on peripheral nerves are most pronounced at the edges of the compression zone (Bentley & Schlapp 1943, Edwards & Cattell 1928, Ochoa et al 1972, Rydevik & Lundborg 1977. It has been suggested that this so called "edge-effect" is due to a displacement of the compressed nerve tissue towards the uncompressed parts of the nerve.…”

“…However, at comparatively low pressure levels, local compression can block impulse conduction (Bentley & Schlapp 1943, Rydevik & Nordborg 1980. These data have stressed the importance of the pressure gradient between compressed and uncompressed nerve tissue.…”