Vitamin B12 in the pathogenesis of subacute combined degeneration of the spinal cord.

T h e etiopathogenesis of subacute combined degeneration of the spinal cord ( S C D S C ) is still a mat ter of controversy. In spite of the numerous investigations made in the last years, concerning particularly the metabolism of vi tamin B 1 2 , some fundamental aspects of the disease process are still unknown. I t is granted that the finding of deficient absorption of vitamin B 1 2 and/or the absence of chlorhydropeptic secretion lead to the diagnosis of S C D S C in the face of a characteristic clinical picture. Nevertheless, recent researches on this subject evidence that it can not be stated, as some authors pretend 18, 2 4 , that the funicular myelosis results exclusively from vi tamin B 1 2 deficiency. Typica l clinical pictures of the disease have been reported in patients wi th normal absorption of c y a n o c o b a l a m i n 6 . 3 1 . Even achlorhydria is not a constant feature of the affection 2, 8, 18, 26, 31, 3 4 .