Segmental demyelination and

Figure 20.1. Hypotlietical scheme of tlie immune response in acute inflammatory demyelinadng polyiadiculoneuiopatliy (AIDP) Inflammatory cells migrate from die systemic immune compartment dnough die damaged blood-nei ve banier into die endoneuiium. Inflammatory infiltrates, which contain T-lymphocytes and macrophages cause marked segmental demyelination and secondary axonal degeneradon (B B-cell T T-cell M0 Macrophage).

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... 

Bilateral, symmetrical ascending r>europatoy with lesions d segmental demyelination and axonopathy, eventually resulting in paralysis... 

Windebank AJ, McCall JT, Hunder HG, et al. 1980. The endoneurial content of lead related to the onset and severity of segmental demyelination. J Neuropathol Exp Neurol 39 692-699. 

Pale coat color, axonal degeneration -motor and sensory, limited segmental demyelination pit (71-73)... 

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. 

The toxic principle is rK)t known, but is speculated to be a pofyphenollc compound. The mechanism of action is unknown, but the plant appears to Induce segmental demyelination of the peripheral nerves and degeneration of the ventral horn cells c4 the spinal cord. 

In adult animals the most consistent effect of Pb is segmental demyelination. " This effect is found in rats and guinea pigs, but not in humans and several other animals. It is characterized by progressive demyelination and remyelination, but precedes the development of endoneurial edema. ... 

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