Toxic Myelitis and Arachnoiditis After Intrathecal Delivery of Bupivacaine via an Implanted Drug Delivery System: Case Report and Review of the Literature.

The off-label usage of amino-amide anesthetics in intrathecal drug delivery systems (IDDS) for the treatment of chronic non-malignant and malignant pain is supported in the polyanalgesic consensus guidelines as a second-line adjunctive therapy. Although strong evidence for its clinical efficacy is lacking, its clinical safety profile has been well established within established dosing parameters. Despite the rarity of neurological adverse reactions to intrathecal bupivacaine, whether given as regional anesthesia or intrathecal therapy, neurologic morbidity associated with its administration is well documented. The etiology of adverse reactions is often difficult to definitively identify, especially given the variabilities associated with compounding errors in the formulation, solvent contamination, and mechanical factors. We present a rare case of toxic myelitis and arachnoiditis resulting in paraplegia two months after the addition of bupivacaine to the intrathecal analgesic regimen and discuss possible etiological factors with a review of the literature.