Vitamin B12 levels of cerebrospinal fluid in patients with a variety of neurological disorders.

Abstract

The vitamin B₁₂ levels of cerebrospinal fluid were assayed microbiologically (Lactobacillus leichmannii method) using samples from 44 patients with various neurological disorders, 4 patients with megalo-blastic anemia and 34 controls. Twenty-seven controls that did not receive vitamin B₁₂ showed a mean cerebrospinal fluid vitamin B₁₂ level of 21.5 pg/ml (range: 0-60). No decrease in cerebrospinal fluid vitamin B₁₂ level was seen in patients with subacute myelo-optico-neuropathy (SMON). High levels of cerebrospinal fluid vitamin B₁₂ were observed only in the patients receiving long term administration of the vitamin. Intrathecal administration of vitamin B₁₂ caused only a slight increase in serum vitamin B₁₂ level after four hours. The existence of a blood brain barrier for vitamin B₁₂ was suggested.