[A case of anti-GM1 antibody positive HTLV-I associated myelopathy (HAM) with polyneuropathy]

We report a case of HTLV-I associated myelopathy (HAM) with polyneuropathy. A 59-year old man suffering from progressive paraparesis associated with subclinical polyneuropathy was admitted to our hospital. HTLV-I antibodies in the serum and CSF were positive, and a diagnosis of HAM was made. His laboratory investigation revealed elevated serum IgG and IgM anti GM-1 antibodies. The nerve conduction study showed a mild reduction in motor and sensory conduction velocity in all extremities. A sural nerve biopsy revealed active demyelination and globule-like changes, which are specific for HAM neuropathy. Anti-GM1 antibodies are frequently present in autoimmune motor neuropathy. They are thought to inflict a damage on both the myelin and axons of the peripheral nerves. Ours is believed to be the first case of HAM associated with anti-GM1 antibodies, although polyneuropathy is often associated with HAM. While it is not clear whether the lesion observed in HAM neuropathy results from the direct cytopathic effect of the virus or from the immune response, some immune-mediated reactions are thought to play an important role. This case suggests that a case of HAM with polyneuropathy should be examined for the presence of the anti-ganglioside antibodies. More investigations are needed to fully understand the mechanism of the HAM neuropathy.