Methylene blue is a blue dye that was previously used for the intrathecal diagnostic application of cerebrospinal fluid fistulas. An intrathecal application of methylene blue is no longer recommended, as methylene blue probably has cytotoxic properties and fixes itself to the neural tissue.

Illustration

Image of a methylene blue solution. Image adapted from Wikimedia Commons.

Complications

In the literature, cases of paraparesis, hydrocephalus and cranial nerve deficits have been described after intrathecal injection of a 1% methylene blue solution[^1].