Amyotrophic Lateral Sclerosis

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Amyotrophic Lateral Sclerosis

Amyotrophic Lateral Sclerosis is an insidiously developing, adult-onset, progressive anterior horn cell degeneration with associated degeneration of descending motor pathways. Despite increasing clinical and research interest, its cause remains obscure. Although many theories as to its cause have been proposed, no intervention has yet been shown to modify biologically determined motor system degeneration.

There is no clear cut neuropathological diagnosis for Amyotrophic Lateral Sclerosis (ALS). Instead, clinicians must rely on both the topographic distribution of the neuronal loss and the finding of some characteristic cytological changes. The precise pattern of these changes, however, varies to some extent, depending on whether the disease is of the classical sporadic type, one of the less common familial types, or the Chamorro form in Guam (1).

The primary feature of ALS is anterior horn neuronal cell degeneration and loss. The pathologic features of this process include shrinkage and pyknosis of the large spinal motor neurons (with consequent prominence of lipofuscin), the presence of ghost cells, neuronophagia, and gliosis (2). There is a massive loss of Betz cells and other pyramidal cells from the precentral cortex. Along with the loss of cortical cells, the corticospinal tracts are preferentially depleted of large myelinated fibers (3). Corticospinal tract involvement is most readily observed in the anterior and lateral columns of the spinal cord, particularly caudally. Degeneration of the spinocerebellar tracts may be seen. The posterior columns are affected (but not always) as well (4).

Cell loss can be difficult to judge in the brainstem nuclei. Associated findings such as i...

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...lerosis. Neurology, 1987; 37:529-532.

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6. Hirano, A., et. al. Fine structural observations of neurofilamentous changes in amyotrophic lateral sclerosis. J. Neuropathol. Exp. Neurol., 1984; 43:461-470.

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