Asymmetric involvement of the spinal cord involving both large and small anterior horn cells in a case of familial amyotrophic lateral sclerosis.

A case of familial amyotrophic lateral sclerosis revealing neuronal loss in the anterior horns and Clarke's columns, Lewy body-like intracytoplasmic inclusions in some remaining cells, cord-like thickening of cell processes, mild perivascular infiltration of lymphocytes, and degeneration of the middle root zone in the posterior column and of the spinocerebellar tract is described. Two highly unusual features were noted. First, there was a marked asymmetry of the neuronal loss and tract degeneration in the spinal cord. The left side was much more severely affected than the right side. Second, both large and small neurons disappeared almost completely on the left side of the lumbar anterior horn.