As Korsakoff pointed out, signs of peripheral neuropathy are common, found in more than 80 percent of patients with the Wernicke-Korsakoff syndrome. In most, the neuropathic disease is mild and does not account for the disorder of gait, but in some it may be severe and particularly painful. In a small number, retrobulbar optic neuropathy is added. Despite the frequency of peripheral neuropathy, overt signs of beriberi heart disease are rare. However, indications of disordered cardiovascular function such as tachycardia, exertional dyspnea, postural hypotension, and minor electrocardiographic abnormalities are frequent; occasionally, the patient dies suddenly following only slight exertion. These patients may show an elevation of cardiac output associated with low peripheral vascular resistance, abnormalities that revert to normal after the administration of thiamine. Postural hypotension and syncope are common findings in Wernicke disease and are probably a result of impaired function of the autonomic nervous system, more specifically to a defect in the sympathetic outflow (Birchfield). There may be mild hypothermia, loss of libido, and erectile dysfunction.
Patients with the Korsakoff amnesic state may have demonstrably impaired olfactory discrimination. This deficit, like the notable apathy present in most Wernicke’s patients, is probably attributable to a lesion of the mediodorsal nucleus of the thalamus and its connections, and not to a lesion of the peripheral olfactory system (Mair et al). Vestibular function, as measured by the response to standard ice-water caloric tests, is universally impaired in the acute stage of Wernicke disease (Ghez), but vertigo is not a complaint. This vestibular paresis probably accounts for the severe disequilibrium in the initial stage of the illness.
The acute lesions of the Wernicke-Korsakoff syndrome in the mammillary bodies, and other medial thalamic and periaqueductal areas can be demonstrated in most cases by magnetic resonance imaging (MRI) (Donnal et al; Varnet et al). The changes are most apparent on the fluid-attenuated inversion recovery (FLAIR), T2, and diffusion-weighted sequences (if there is necrosis), but they may also enhance as shown in Fig. 40-2. It is not clear to what extent gradient-echo MRI images can be expected to consistently reveal the small hemorrhagic lesions of the diencephalon and periventricular areas. Imaging is particularly useful in patients in whom stupor or coma has supervened or in whom ocular and ataxic signs are otherwise inevident (Victor, 1990), but in milder cases a normal MRI does not preclude the diagnosis. The typical MRI changes are observed in only 58 percent of cases according to Weidauer and colleagues. In the chronic state, the mammillary bodies may be shrunken if measured by volumetric techniques (Charness and DeLaPaz).
The cerebrospinal fluid (CSF) in uncomplicated cases of the Wernicke-Korsakoff syndrome is normal or shows only a modest elevation of the protein content. Protein values greater than 100 mg/dL or a pleocytosis indicates the presence of a complicating illness such as subdural hematoma, meningeal infection, or encephalitis.
Measurements of serum thiamine and red blood cell transketolase have been explored as aids to diagnosis but are not sufficiently sensitive for clinical use and they are not readily available. Before treatment with thiamine, patients with Wernicke disease show a marked reduction in functional transketolase activity. Restoration of these values and of thiamine diand triphosphate toward normal occurs within a few hours of the administration of thiamine, and completely normal values are usually attained within 24 h.