Intraspinal epidermoid and dermoid cysts-tumor resection with multimodal intraoperative neurophysiological monitoring and long-term outcome.

Abstract

Intraspinal epidermoid/dermoid cysts are very rare, benign tumors arising from pathological displacement of epidermal cells into the spinal canal. Literature data about the long-term outcome after microsurgical resection with multimodal intraoperative neurophysiological monitoring (IONM) are lacking. We analyzed one of the largest case series with special regard to intraoperative characteristics and long-term outcome after IONM-aided surgery. All 12 patients (m:f = 1.4:1) who underwent microsurgical tumor resection with multimodal IONM for intraspinal epidermoid/dermoid tumors between 1998 and 2019 in our university hospital were included. We retrospectively investigated the patients' characteristics, imaging/surgical parameters, and postoperative long-term outcomes. Symptomatic tumor manifestation was seen during adulthood in 4 patients (median age 33.0 years) and during childhood in 8 patients (median age 4.3 years). Spinal dysraphism was the most often comorbidity (75%). The most frequent symptoms at diagnosis were spastic pareses (75%), ataxia (58%), and vegetative disorders (42%). Tumors were most often lumbosacral (L1-L5 42%, L5-S3 50%) and intradural-extramedullary (92%). For microsurgical resection, IONM with EMG, SSEPs, and TcMEPs of the limbs and pudendal nerve/anal sphincter was always applied and feasible; intraoperative corrective actions were initiated in three cases due to transient IONM deterioration. None of the patients showed a postoperative deterioration of the neurological status with a gross total resection rate of 92%. Pain situation, McCormick grade, and mJOA Score were improved at long-term follow-up (median 4.8 years). IONM-aided resection of intraspinal epidermoid/dermoid tumors is feasible both in adult and pediatric cases and enables a satisfying clinical and surgical outcome.