Motor-evoked potential monitoring for intramedullary spinal cord tumor surgery: correlation of clinical and neurophysiological data in a series of 100 consecutive procedures

Abstract

<jats:p>Resection of intramedullary spinal cord tumors carries a high risk for surgical damage to the motor pathways. This surgery is therefore optimal for testing the performance of intraoperative motor evoked potential (MEP) monitoring. This report attempts to provide evidence for the accurate representation of patients' pre- and postoperative motor status by combined epidural and muscle MEP monitoring during intramedullary surgery.</jats:p> <jats:p>The authors used transcranial electrical motor cortex stimulation to elicit MEPs, which were recorded from the spinal cord (with an epidural electrode) and from limb target muscles (thenar, anterior tibial) with needle electrodes. The amplitude of the epidural MEPs and the presence or absence of muscle MEPs were the parameters for MEP interpretation. A retrospective analysis was performed on data from the resection of 100 consecutive intramedullary tumors and MEP data were compared with the pre- and postoperative motor status.</jats:p> <jats:p>Intraoperative monitoring was feasible in all patients without severe preoperative motor deficits. Preoperatively paraplegic patients had no recordable MEPs. The sensitivity of muscle MEPs to detect postoperative motor deficits was 100% and its specificity was 91%. There was no instance in which a patient with stable MEPs developed a motor deficit postoperatively. Intraoperative MEPs adequately represented the motor status of patients undergoing surgery for intramedullary tumors. Because deterioration of the motor status was transient in all cases, it can be considered that impairment of the functional integrity of the motor pathways was detected before permanent deficits occurred.</jats:p>

Relevance of intraoperative D wave in spine and spinal cord surgeries

“…[7] for a comprehensive review). Although there is general agreement as to the methodology to elicit both e-MEPs and m-MEPs, controversies do persist as to the indications for IOM with both e-MEPs and m-MEPs [6,[10][11][12][13][14][15][16]. Numerous studies have proposed that a combined recording of epidural and muscle MEPs be carried out during IMSCT surgery [6,[10][11][12][13] to predict motor outcome in the presence of deterioration/disappearance of LLm-MEPs, however, not all agree [14][15][16].…”

“…The introduction of transcranially motor evoked potentials (MEPs) represented a significant step forward for intraoperative assessment of motor pathway function in spine surgery [1][2][3][4][5][6][7]. Two methodologies have been developed to elicit MEPs by transcranial electrical stimulation [7]:…”

“…Numerous studies have proposed the combined use of D wave recordings and m-MEPs in intramedullary spinal cord surgery [6,[10][11][12][13], however, not all literature is in agreement [14][15][16].…”

The diagnostic value of multimodal intraoperative monitoring (MIOM) during spine surgery: a prospective study of 1,017 patients

“…After basic physiological research since the 1950s [14], MEPs were introduced to regular monitoring of spinal cord function [17]. A major advancement in the multimodal intraoperative monitoring has been achieved Completely by the group of Epstein [8] as well as Tamaki [7] by applying the different modalities to monitor motor pathways during spine surgeries. Luk then presented the major advantages of multimodal evaluation of the spinal cord [10]; however, with their small patient population of just 30 cases, the sensitivity and specificity could not be determined.…”

Multimodal intraoperative monitoring during surgery of spinal deformities in 217 patients

“…The concept of monitoring guiding surgery in spinal disorders, particularly in intramedullary tumour was introduced by the group of Epstein in the 1980s and 1990s [8,3] which was introduced in our institution in the late 1990s by personal communication from both pioneering groups (Tamaki, Epstein). The close collaboration between neurologist specially trained in the monitoring techniques and the spine surgeon already during the preoperative planning stage facilitated the communication during the surgical procedure.…”