Involvement of the brain stem reticular formation in familial amyotrophic lateral sclerosis.

The reticular formation of the brain stem of three cases of familial amyotrophic lateral sclerosis (ALS) with posterior column and spinocerebellar tract involvement showed a paucity of large neurons, chromatolytic neurons and Lewy body-like intracytoplasmic inclusions. Some of the remaining neurons were stained focally by antibodies to phosphorylated neurofilaments and ubiquitin; the staining patterns were similar to those seen in anterior horn cells. Within the reticular formation, the medial part of the medulla oblongata was most pronouncedly affected. The reticular formation should be among the systems other than motor neurons that may be involved in this type of familial ALS.