Alterations in lumbar cerebrospinal fluid protein during air encephalography.

A significant fall occurred in the protein content of successive specimens of lumbar cerebrospinal fluid (C.S.F.) withdrawn during the course of air encephalography in 57% of cases. No correlation was found between the fall in the protein concentration and the total volume of air injected or the total volume of C.S.F. withdrawn, but the size of the fall was greater when the initial lumbar C.S.F. protein concentration was raised. The importance of taking specimens for routine laboratory analysis before the injection of any air is emphasized.