A morphological study of experimental mononeuropathy in the rat: early ischemic changes.

This paper describes early morphological changes following the placement of four loose ligatures round the rat sciatic nerve, a method used to produce altered pain-related behaviour. The ligatures were tied so as not to constrict the nerve, but there was compression of some epineurial blood vessels. This mild lesion caused behavioural changes and nerve fiber abnormalities within 8.5 h. The distribution of nerve fiber changes was patchy, and initially due to stagnant ischemia, with necrosis of Schwann cells and evidence of axonal stasis. By 48 h, endoneurial oedema increased leading to a compressive lesion and eventually to severe nerve fiber degeneration.