In the early 1900s, pellagra attained epidemic proportions in the southern United States and in the alcoholic population of large urban centers. Since 1940, it has diminished greatly because of the general practice of enriching bread with niacin. Nevertheless, among the vegetarian, maize-eating people of underdeveloped countries, and among the black population of South Africa, pellagra is still a common disease (Bomb et al; Shah et al; Ronthal and Adler). In developed countries, pellagra is practically confined to malnourished alcoholic patients (Ishii and Nishihara;
Spivak and Jackson; Serdaru et al).
In its fully developed form, pellagra affects the skin, alimentary tract, and hematopoietic and nervous systems. The early symptoms may be mistaken for those of a psychiatric disorder. Insomnia, fatigue, nervousness, irritability, and feelings of depression are common complaints; taken together they have the character of neurasthenia. Examination discloses mental dullness, apathy, and a mild impairment of memory. Sometimes an acute confusional psychosis dominates the clinical picture. Untreated, these symptoms may progress to a dementia. Pellagra may not only produce mental impairment but occasionally result from it, by virtue of anorexia and refusal of food. The dermatologic feature, often the aspect that permits one to make a confident diagnosis, is a scaly dermatitis in sun-exposed areas, followed by hyperpigmentation of these areas. Diarrhea and glossitis or other forms of mucous membrane disorder may be accompaniments (hence the alliterative triad dementia-dermatitis-diarrhea). The spinal cord manifestations have not been clearly delineated, but in general, the signs are referable to both posterior and lateral columns, predominantly the former, and thereby simulating SCD. Signs of peripheral neuropathy are relatively less common and are indistinguishable from those of neuropathic beriberi.
These are most readily discerned in the large cells of the motor cortex (Betz cells), and to a lesser extent in the smaller pyramidal cells of the cortex, the large cells of the basal ganglia, the cranial motor and cerebellar dentate nuclei, and the anterior horn cells of the spinal cord. The affected neurons are swollen and rounded, with eccentric nuclei and loss of the Nissl bodies that have the appearance of a secondary axonal reaction. However, in the pathologic material presented by Hauw and associates, these chromatolytic changes were most pronounced in the brainstem nuclei (upper reticular and pontine) and not in the Betz cells. They concluded that the neuronal changes were not caused by a retrograde axonal lesion but did not comment on the status of the spinal cord or nerves. The few studies of the peripheral nerves in pellagra have disclosed changes like those in alcoholics and other patients with nutritional deficiency.
The spinal cord lesions in pellagra take the form of a symmetrical degeneration of the dorsal columns, especially of Goll, and to a lesser extent of the corticospinal tracts. The posterior column degeneration is likely to be secondary to degeneration of the dorsal root ganglion cells or posterior roots. The exact mechanisms underlying the corticospinal tract degeneration have not been elucidated.
It has been known since 1937, when Elvehjem and coworkers showed that nicotinic acid cured black tongue, a pellagra-like disease in dogs, that this vitamin is effective in the treatment of pellagra. Many years before,