Methylene-Blue–Associated Encephalopathy

Abstract

This article reviews the experience at our institution with infusion of methylene blue during parathyroidectomy and subsequent development of a rare encephalopathy. Use of methylene blue for localization of parathyroid adenomas is a well-described and time-proved technique. Its use aids identification and can decrease operative time. Few complications have ever been noted. There are only four case reports within the literature of neurologic sequelae after administration of methylene blue. Over the past 6 years, we have performed 132 parathyroidectomies aided by methylene-blue infusion, with unexplained encephalopathy developing in 5 patients. Interestingly, all the patients in whom encephalopathy developed had concurrent use of medications that altered the metabolism of serotonin. The same proved true for the patients in the four previous case reports, although no association had been made, as they appeared as isolated cases. In our series, encephalopathy did not develop in any patient without concurrent use of serotonin reuptake inhibitors. This proved significant when analyzed using Fisher’s exact test (two-sided p = 0.00002). We believe that use of methylene blue in patients currently taking drugs that alter the metabolism of serotonin should be reconsidered, as this can cause a profound and potentially life-threatening encephalopathy.