MENINGITIS occurred in 19% of 84 cases of post-traumatic cerebrospinal fluid (CSF) rhinorrhea in one series.1 In the less common "spontaneous" CSF leaks, the incidence of meningitis is uncertain, since only a few isolated cases have been reported.2,3 Consequently, the prevention of meningitis may be one of the prime reasons for stopping the leak.
To help find the exact point of leakage, an easily identifiable substance is introduced into the subarachnoid space. Determination of the specific site of appearance of this substance then guides the surgeon to a precise localization for his reparative efforts. For this purpose, several dyes,4 radioactive isotopes,5-7 fluorescein,8 and iophendylate injection (Pantopaque)9,10 have been used.
Of the dye substances available for intrathecal instillation, methylene blue has been demonstrated to be noxious to the central nervous system.11 Apparently, the neural toxicity of methylene blue has not been sufficiently emphasized.