[Neuropathology of longstanding subacute myelo-optico-neuropathy (SMON): an autopsy case of SMON with duration of 28 years].

The present case, 78-years-old female, had been troubled with SMON during 28 years, and was suddenly died from cerebral hemorrhage. The neuropathology characteristic for SMON could not be revealed in the spinal cord on routine histological preparations. There were decreasing number of immunopositive granules in the nucleus gracilis of medulla oblongata for synaptophysin, and in the marginal zone of the lumbar dorsal horn for substance P. These findings showed the presence of tractus gracilis degeneration and the disappearance of nociceptive fibers from the dorsal roots, respectively. To elucidate the histopathological changes of the spinal cord in long standing cases with SMON, the 11 cases reported were reviewed. The mean duration from the onset to death was 22.8 years(16 to 33 years). The mean age was 76.3 years old(54 to 92), and the 10 cases were female. All cases showed sensory impairment of the lower extremities, while deep tendon reflex exaggerated was seen in 7 cases. There were nine cases involving dorsal funiculi degeneration of the spinal cord, in contrast the lateral funiculi alternation were noticed in only two cases. It was considered that the corticospinal tract alteration becomes undiscernible during the long course, although the dorsal funiculi degeneration remained.