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Distal neuropathy in experimental diabetes mellitus
Author(s) -
Brown Mark J.,
Sumner Austin J.,
Greene Douglas A.,
Diamond Susan M.,
Asbury Arthur K.
Publication year - 1980
Publication title -
annals of neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.764
H-Index - 296
eISSN - 1531-8249
pISSN - 0364-5134
DOI - 10.1002/ana.410080207
Subject(s) - tibial nerve , medicine , diabetes mellitus , lesion , nerve conduction velocity , anatomy , atrophy , pathological , diabetic neuropathy , peripheral , electrophysiology , peripheral neuropathy , abnormality , pathology , endocrinology , stimulation , psychiatry
Although nerve conduction slowing is a well‐accepted abnormality in rats with acute experimental diabetes, reports of neuropathological changes in diabetic rat nerves have been inconsistent. To examine this further, we studied electrophysiological and morphological features of posterior tibial nerves and their distal branches from four‐week streptozotocin‐induced diabetic rats and matched controls. Diabetic rat posterior tibial motor conduction was slowed (mean ± 1 SD, 34.8 ± 3.1 m/sec; controls, 41.2 ± 2.5 m/sec), and evoked muscle response amplitudes were only half of control values. Using quantitative techniques, we documented a diminution in number of the largest myelinated fibers in otherwise normal mid posterior tibial nerves, with an increase in the smaller sizes, indicating either a degree of axonal atrophy or impaired fiber growth during development. The principal pathological finding was active breakdown of myelinated fibers in the most distal motor twigs of hind foot muscles supplied by posterior tibial branches, with preservation of fibers in more proximal segments of these nerves. This anatomical lesion in diabetic nerves could account for both observed conduction slowing and lowered muscle response amplitudes. A consistent feature in both diabetic and control mid lateral plantar nerves was a zone of demyelination that apparently occurs at this natural site of nerve entrapment in rats. Taken together, the pathological abnormalities of peripheral nerve in acute experimental diabetes are best explained as resulting from a distal axonopathy.