In most cases, the cerebellar syndrome evolves over a period of several weeks or months, after which it remains unchanged for many years. In others, it develops more rapidly or more slowly, but in these cases also the disease eventually stabilizes. Occasionally, the cerebellar disorder progresses in a saltatory manner, the symptoms worsening in relation to a severe infectious illness or an attack of delirium tremens.
The pathologic changes consist of a degeneration of all the neurocellular elements of the cerebellar cortex but particularly of the Purkinje cells in the anterior and superior aspects of the vermis. The cerebellar atrophy is readily visualized by CT (Fig. 40-4) and MRI.
Two particular forms of this syndrome have not been emphasized sufficiently. In one, the clinical abnormalities are limited to an instability of station and gait, individual movements of the limbs being unaffected. The pathologic changes in such cases are restricted to the anterosuperior portions of the vermis. A second type is strikingly acute but transient. Here, except for their reversibility, the cerebellar symptoms are identical to those that characterize the chronic, fixed form of the disease. In this transient type, the derangement is only one of function and has probably not progressed to the point of fixed structural changes. These forms of cerebellar disease, and particularly the restricted and reversible varieties, cannot be distinguished from the cerebellar manifestations of Wernicke disease either on pathologic or on clinical grounds. It is our opinion that the cerebellar ataxia of Wernicke disease and that referred to as alcoholic cerebellar degeneration are based on the same disease process, the former term being applicable when the cerebellar abnormalities are associated with ocular and mental signs and the latter when the cerebellar syndrome stands alone and becomes persistent. Alcoholic cerebellar degeneration is in all likelihood a result of nutritional deficiency and not of the toxic effects of alcohol, for reasons already indicated. Insofar as the cerebellar ataxia usually improves to some extent under the influence of thiamine alone (see earlier, under “Wernicke-Korsakoff Syndrome [Thiamine (B1) Deficiency]”), it is likely that a deficiency of this vitamin is in whole or part responsible for the cerebellar lesion, but this has not been proven.
Marchiafava-Bignami Disease (Degeneration of the Corpus Callosum)
In 1903, the pathologists Marchiafava and Bignami described a unique alteration of the corpus callosum in 3 alcoholic patients. In each case, coronal sectioning of the fixed brain disclosed a pink-gray discoloration of the central portion of the corpus callosum throughout the longitudinal extent of this structure. Microscopically, the lesion proved to be confined to the middle lamina (which makes up about two-thirds of the thickness of the corpus callosum), in which there was a loss of myelin and, to some degree, of the axis cylinders; macrophages were abundant in the altered zone, and astrocytic proliferation had followed. The clinical observations in these patients were few and incomplete. In 1907, Bignami described a case in which the corpus callosum lesion was accompanied by a similar lesion in the central portion of the anterior commissure.
These early reports were followed by a spate of articles that confirmed and amplified the original clinical and pathologic findings. By 1922, about 40 cases of this disorder had been described in the Italian literature (Mingazzini). With 1 exception, all the reported cases were in males, and all these men were insatiable drinkers. They drank red wine for the most part, but other forms of liquor as well. Beginning in 1936, with the report of King and Meehan, the disease came to be recognized throughout the world, and the notions that it had a predilection for drinkers of red wine and a special national predisposition or geographic locale were abandoned. The location of the white matter lesion was later appreciated by MRI to be variable with only a propensity for the corpus callosum.