[An autopsy case of amyotrophic lateral screlosis (ALS): magnetic resonance imaging and pathological findings of the pyramidal tract].
A 59-year-old woman was diagnosed as amyotrophic lateral screlosis (ALS) on the basis of neurological and electromyographical findings, and died after about 4 years course. Magnetic resonance imaging (MRI) on coronal planes through the internal capsule revealed high signal area almost limited to the pyramidal tract; the high signal area was more restricted in proton weighted imaging than in T2 weighted imaging. Histological lesion of the precentral gyrus was slight, while loss of myelinated fibers in the posterior limb of the internal capsule was remarkable. Extent of the pathological lesion in the posterior limb of the internal capsule well corresponded to the high signal area in proton weighted imaging. Comparison of the pyramidal tract pathology in the corona radiata and the internal capsule in Klüver-Barrera preparations with the MRI findings obtained 2 years and 8 months before the autopsy suggests us that the T2 weighted imaging of ALS brains may detect involvement of the pyramidal tract as early as or even earlier than histological changes become manifest.