The neuropathy resulting from muscle-nerve translocation

The biceps femoris muscle was cut close to its distal tendon in seventeen rats, inserted under the partially freed sciatic nerve and the muscle then resutured leaving the nerve in a translocated position. The rats were killed at intervals from 4 to 22 weeks later and the sciatic nerve above, around, and below the muscle reflection site examined by light and electron microscopy and teased fibre preparations. In all cases, the sciatic nerve was affected to varying degrees at its reflected site ranging from focal sub-perineurial demyelination and remyelination to widespread myelin sheath abnormalities. Teased fibre studies confirmed that the myelin sheath was predominantly affected with little evidence of active axonal degeneration. There was no proximal and minimal distal sciatic nerve damage. The most likely cause of these changes was thought to be focal compression but the possible role of other factors is also discussed.