An investigation of the pathophysiology of ischaemic neuropathy.

This study assesses the changes in the microvasculature of peripheral nerves in acute large vessel ischaemic neuropathy. An animal model of large vessel ligation, producing an ischaemic neuropathy was used: the presence and extent of the neuropathy was documented by clinical examination and nerve conduction studies. The nerve microcirculation, the "vasa nervorum" was examined using casting materials, methyl methacrylate and silicone rubber, which were in turn examined by light microscopy and scanning electron microscopy. In all, ten animals were used, all of whom showed clinical evidence of an ischaemic neuropathy 1 week post-ligation. This ischaemic neuropathy was confirmed by nerve conduction studies. Corrosion casts were produced in five of the ten animals. Examination of these casts showed that all five had an area of underfilling of the microcirculation in the region of the proximal tibial nerve with good filling of vessels proximal and distal to this, indicating that in generalised hypoperfusion states such as large vessel ligation, the area of poorest perfusion (and thus maximal damage) is not the distal vascular field, but a probable "watershed zone" between two adjacent nutrient vessels to the nerve.