Demyelination, segmental neuropathies

Dyck, P.J., O Brien, P.C., Ohnishi, A. (1977). Lead neuropathy 2. Random distribution of segmental demyelination among old intemodes of myelinated fibers. J. Neuropathol. Exp. Neurol. 36 570-5. 

Acute oral parenteral tellurium intoxication in animals results in restlessness, tremor, diminished reflexes, paralysis, convulsions, somnolence, coma, and death. Hematuria was prompt and occurred in all animals. Exposure of weanling rats to a diet containing elemental tellurium results in a peripheral neuropathy characterized by segmental demyelination and minimal axonal degeneration. It is noteworthy that functional recovery occurred despite... 

In diabetic patients, the incidence of clinically manifested deficits in peripheral nervous system function increases with duration of disease and is approx 50% after 25 yr of disease. The resulting diabetic neuropathies comprise a group of distinct disorders that can affect both somatic and autonomic nerves, the most common of which is symmetric sensory polyneuropathy. Clinical signs of overt human diabetic neuropathy include decreases in nerve conduction velocity and action potential amplitude and in resistance to ischemic conduction failure. These abnormalities may be accompanied by sensory deficits and, in some cases, severe pain. In diabetes of long standing, morphological deterioration is evident, and both nerve fiber loss and segmental demyelination may occur. 

While the peripheral neuropathies can occasionally be reversed with therapy, again such recovery is not assured particularly in the more severe neuropathies and often improvement is only partial. The lack of reversibility is felt to be due in part to segmental demyelination. 

Ohnishi, A., Schilling, K., Brimijoin, W.S., Lambert, E.H., Fairbanks, W.F. and Dyck, PJ. (1977) Lead neuropathy 1 morphometry, nerve conduction and choline acetyltransferase transport new finding of endoneurial edema associated with segmental demyelination, J. Neuropath. E cp. Neurol. 36, 499-518,... 

---