Vitamin A levels were measured in the cerebrospinal fluid of a total of 78 patients having idiopathic intracranial hypertension (IIH;n=20), elevated pressure of other causes (E-ICP;n=19), and normal pressure (N-ICP;n=39), in a study at the University of Utah, Salt Lake City, UT. Higher CSF vitamin A levels found in some patients with IIH were significantly correlated (p=0.036) when compared with control E-ICP and IIH patients. Higher levels were marginally significantly associated with female gender (p=0.094) and younger age (p=0.069). Multivitamin use was not associated with the levels of vitamin A. High vitamin A levels in patients with IIH and high average vitamin A levels in patients with breakdown of the blood-brain barrier are suggestive of a toxic effect of CSF retinol on the arachnoid granulation resorption mechanism in IIH. [1]

COMMENT. Some patients with idiopathic intracranial hypertension have significantly higher levels of vitamin A in the CSF than patients with normal pressure or those with increased pressure due to other causes. Serum retinol-binding protein (RBP) and retinol are also elevated in some patients with IIH [2]. Vitamin A may have a specific transport mechanism into the CSF, and it becomes toxic when the level exceeds the RBP binding capacity. Study of patients with breakdown of the blood-brain barrier may elucidate the transport mechanism of CSF vitamin A and pathogenesis of IIH.

The role of vitamin A intoxication in the pathogenesis of IIH is discussed in an editorial by Fishman RA. [3]. It is speculated that vitamin A increases CSF volume and pressure by an effect on aquaporins present in membranes of the choroid plexus that control CSF secretion.