[Experimental study on the repair of peripheral nerve lesions--subacute compression neuropathy and neurolysis]

Neurolysis has been a widely accepted treatment for entrapment neuropathy and other nerve injuries in continuity. The purpose of this experimental study is to clarify the effects of neurolysis on the recovery from subacute compression neuropathy. The sciatic nerves of 49 mongrel dogs were used. In order to make the model of subacute compression neuropathy, the apparatus designed by Horiuchi to compress the nerve with constant force was applied to each nerve for three weeks. The pressure of compression was 55 mmHg when the thickness of the nerve was 2 mm. According to the degree of injury of the motor nerve in the peroneal funiculus of the sciatic nerve, 18 nerves were classified as first-degree injury ( Sunderland ) and 31 as second-degree injury. After removing the compressing apparatus, either external neurolysis (E.N.) or internal neurolysis (I.N.) was performed on these neuropathies under magnification. After the operation, each nerve was electrophysiologically followed up to 24 weeks; at one-week interval in the early stage and at four-week interval in the late stage. The macroscopic and histological observations were made on the fifth, eighth and 24th week. Electrophysiological findings: In the first-degree injuries, conduction block at the compressed site had already disappeared at the first week and motor nerve conduction velocity (M.N.C.V.) recovered rapidly with no apparent difference among the removal group (removal of apparatus only) and the neurolysis groups. In the second-degree injuries, evoked muscle action potential in the anterior tibial muscle appeared at the sixth week, about one week earlier in the I.N. group than in the removal group. M.N.C.V. of the removal group recovered gradually without exception, but that of the neurolysis groups inconstantly in the early stage. In the late stage, M.N.C.V. of all groups reached about 60 m/sec gradually and exponentially and never exceeded the average value (75.3 m/sec) of normal M.N.C.V. Macroscopic findings: The swelling of the portion adjacent to the compressed site ( pseudoneuroma ), which had been observed until the eighth week, disappeared at the 24th week. A scar around the nerve existed even at 24 weeks post-operatively, but it became loose and appeared like a mesoneurium and its vessels communicated with epineurial nerve vessels.(ABSTRACT TRUNCATED AT 400 WORDS)