Autosomal dominant sensory ataxia: a neuroaxonal dystrophy

Autosomal dominant sensory ataxia (ADSA), a rare hereditary ataxia, is characterized by progressive dysfunction of central sensory pathways. Its pathological features have not been previously documented. We report a case of a 61-year-old man with ADSA who died of congestive heart failure. Autopsy specimens of brain, thoracolumbar spinal cord, peripheral nerve and skeletal muscle were examined. There was no abnormality on gross examination. Microscopically, there were occasional swollen axons within the cerebral cortex and deep nuclei, particularly the subthalamic nucleus, with no neuronal loss, gliosis or microglial activation. There were many axonal spheroids within the medulla, particularly in the dorsal column nuclei. Axonal spheroids were also seen in the dorsal columns and ventral horns in the thoracolumbar spinal cord, but there was no Wallerian degeneration or demyelination. Amyloid precursor protein (APP) immunostaining of some of the spheroids suggested continuing dysfunction of axoplasmic flow in some regions. There was mild inflammation of peripheral nerve roots but no spheroid, and patchy chronic inflammation of skeletal muscle. In summary, the major pathological process in ADSA is a neuroaxonal dystrophy most prominent in the dorsal columns and dorsal column nuclei, consistent with the clinical pattern of central sensory pathway degeneration.