Pathology of inflammatory demyelinating neuropathies.

GBS and CIDP are multifocal demyelinating diseases with lesions widely disseminated throughout the peripheral nervous system including cranial nerves, terminal intramuscular nerves and autonomic nerves. In both conditions myelin destruction is mediated by macrophages that attack myelin without disturbing the integrity of Schwann cells. The same pattern of myelin breakdown occurs in EAN, providing additional evidence that these disorders are immune-mediated. Recent autopsy and biopsy studies have challenged the view that lymphocytes are always present in newly forming lesions, an observation supporting a role for humoral immunity in the pathogenesis of some cases of GBS and CIDP. In both conditions neurological dysfunction is related to both myelin destruction and axonal loss. In some cases of CIDP there is the additional factor of impaired remyelination. Other chronic demyelinating neuropathies that may be immune-mediated differ from CIDP in presenting as solitary or multiple mononeuropathies. These can be classified into cases with and without evidence of widespread demyelination, cases with and without focal nerve enlargements, and a pure motor variant, multiple motor neuropathy associated with elevated anti-GM1 ganglioside antibody titres.