Parasagittal Cortical Atrophy: a Cause of "primary Lateral Sclerosis".

Currently the problem of the existence of primary lateral sclerosis as a distinct clinical entity is not a mat te r of much controversy. I t seems generally accepted that what was once regarded as a disease process char­ acterized by selective degeneration of the pyramidal tracts is usually, if not always, but one manifestation of a number of we l l defined diseases, such as amyotrophic lateral sclerosis, mult iple sclerosis, subacute combined de­ generation of the cord, etc. However , it is not very long ago that such keen observers as Wechsler and Brody , and Stark and M o e r s c h 2 , having fol lowed a fairly large number of cases exhibiting no abnormalities other than bilateral pyramidal tract signs over periods of several years, were convinced that primary lateral sclerosis existed as a separate disease state. N o convincing pathological material has ye t been presented to support their conviction. Greenf ie ld 3 , and B r a i n 4 both ignore the problem. W a l s h e 5 expressed the opinion that " . . . m o s t cases so labeled ult imately prove to be amyotrophic lateral sclerosis or some other known affection of the nervous system, and the t i t le corresponds to no special recognized pathologic process and should be abandoned." M e r r i t t 6 has a very similar v iew. T h e unusual features of the fol lowing case illustrate the hazard involved in the liberal use of this diagnosis.