Neuropathological studies of the spinal cord in early stage HTLV-I-associated myelopathy (HAM).

Necropsy findings for a patient with HTLV-I-associated myelopathy (HAM) of 9 months clinical duration are reported. Loss of myelin sheaths and axons together with perivascular lymphocytic infiltration was seen in the lateral and posterior columns of the spinal cord from the cervical to the lumbar region where vacuolar changes caused by the splitting of myelin sheaths were prominent. Immunohistochemical analyses revealed CD8+ cytotoxic T cell infiltration predominated in the absence of HTLV-I core protein antigen bearing-cells in the brain and spinal cord. Myelin sheath damage and predominant CD8+ cytotoxic T cell infiltration are thought to be the main neuropathological findings in the spinal cord in early stage HAM.