Polyneuropathies may be classified in different ways , such as by cause , by speed of progression , or by classes of polyneuropathy , in terms of which part of the nerve cell is affected mainly : the axon , the myelin sheath , or the cell body .
Polyneuropathies may be classified in different ways , such as by cause , by speed of progression , or by the parts of the body involved . 
 Classes of polyneuropathy also are distinguished by which part of the nerve cell is affected mainly : the axon , the myelin sheath , or the cell body .