Glial outgrowth along spinal nerve roots in amyotrophic lateral sclerosis.

Formation of glial bundles in the proximal portion of the ventral nerve roots is described in a 51-year-old patient with the sporadic form of amyotrophic lateral sclerosis (ALS). Although the bundles were relatively fewer, they were identical in morphology and distribution to those consistently found in Werdnig-Hoffmann disease (WHD). The occurrence of glial bundles in ALS, albeit rare, indicates that this phenomenon is not a unique feature of WHD. Similar changes have been observed in several other unrelated conditions, always in association with degeneration of neurons or axons. Thus, outgrowth of astrocytes in the form of glial bundles should be considered a special type of astrocytic reaction at the interface of the central and peripheral nervous systems.