Intraoperative neurophysiological monitoring during resection of intradural extramedullary spinal cord tumors: experience with 100 cases

Continuous mapping of the corticospinal tracts in intramedullary spinal cord tumor surgery using an electrified ultrasonic aspirator

Intramedullary spinal cord tumors (IMSCTs) represent a rare entity, accounting for 4%–10% of all central nervous system tumors. Microsurgical resection of IMSCTs is currently considered the primary treatment modality. Intraoperative neurophysiological monitoring (IONM) has been shown to aid in maximizing tumor resection and minimizing neurological morbidity, consequently improving patient outcome. The gold standard for IONM to date is multimodality monitoring, consisting of both somatosensory evoked potentials, as well as muscle-based transcranial electric motor evoked potentials (tcMEPs). Monitoring of tcMEPs is optimal when combining transcranial electrically stimulated muscle tcMEPs with D-wave monitoring. Despite continuous monitoring of these modalities, when classic monitoring techniques are used, there can be an inherent delay in time between actual structural or vascular-based injury to the corticospinal tracts (CSTs) and its revelation. Often, tcMEP stimulation is precluded by the surgeon’s preference that the patient not twitch, especially at the most crucial times during resection. In addition, D-wave monitoring may require a few seconds of averaging until updating, and can be somewhat indiscriminate to laterality. Therefore, a method that will provide immediate information regarding the vulnerability of the CSTs is still needed.

The authors performed a retrospective series review of resection of IMSCTs using the tip of an ultrasonic aspirator for continuous proximity mapping of the motor fibers within the spinal cord, along with classic muscle-based tcMEP and D-wave monitoring.

The authors present their preliminary experience with 6 patients who underwent resection of an IMSCT using the tip of an ultrasonic aspirator for continuous proximity mapping of the motor fibers within the spinal cord, together with classic muscle-based tcMEP and D-wave monitoring. This fusion of technologies can potentially assist in optimizing resection while preserving neurological function in these challenging surgeries.

Diagnostic Accuracy of Somatosensory Evoked Potential Monitoring in Evaluating Neurological Complications During Endovascular Aneurysm Treatment

BACKGROUND

Somatosensory evoked potential (SSEP) monitoring is used extensively for early detection and prevention of neurological complications in patients undergoing many different neurosurgical procedures. However, the predictive ability of SSEP monitoring during endovascular treatment of cerebral aneurysms is not well detailed.

OBJECTIVE

To evaluate the performance of intraoperative SSEP in the prediction postprocedural neurological deficits (PPNDs) after coil embolization of intracranial aneurysms.

METHODS

This population-based cohort study included patients ≥18 years of age undergoing intracranial aneurysm embolization with concurrent SSEP monitoring between January 2006 and August 2012. The ability of SSEP to predict PPNDs was analyzed by multiple regression analyses and assessed by the area under the receiver operating characteristic curve.

RESULTS

In a population of 888 patients, SSEP changes occurred in 8.6% (n = 77). Twenty-eight patients (3.1%) suffered PPNDs. A 50% to 99% loss in SSEP waveform was associated with a 20-fold increase in risk of PPND; a total loss of SSEP waveform, regardless of permanence, was associated with a greater than 200-fold risk of PPND. SSEPs displayed very good predictive ability for PPND, with an area under the receiver operating characteristic curve of 0.84 (95% CI 0.76-0.92).

CONCLUSION

This study supports the predictive ability of SSEPs for the detection of PPNDs. The magnitude and persistence of SSEP changes is clearly associated with the development of PPNDs. The utility of SSEP monitoring in detecting ischemia may provide an opportunity for neurointerventionalists to respond to changes intraoperatively to mitigate the potential for PPNDs.

Intraoperative neurophysiological mapping and monitoring in spinal tumor surgery: sirens or indispensable tools?

Spinal tumor (ST) surgery carries the risk of new neurological deficits in the postoperative period. Intraoperative neurophysiological monitoring and mapping (IONM) represents an effective method of identifying and monitoring in real time the functional integrity of both the spinal cord (SC) and the nerve roots (NRs). Despite consensus favoring the use of IONM in ST surgery, in this era of evidence-based medicine, there is still a need to demonstrate the effective role of IONM in ST surgery in achieving an oncological cure, optimizing patient safety, and considering medicolegal aspects. Thus, neurosurgeons are asked to establish which techniques are considered indispensable. In the present study, the authors focused on the rationale for and the accuracy (sensitivity, specificity, and positive and negative predictive values) of IONM in ST surgery in light of more recent evidence in the literature, with specific emphasis on the role of IONM in reducing the incidence of postoperative neurological deficits. This review confirms the role of IONM as a useful tool in the workup for ST surgery. Individual monitoring and mapping techniques are clearly not sufficient to account for the complex function of the SC and NRs. Conversely, multimodal IONM is highly sensitive and specific for anticipating neurological injury during ST surgery and represents an important tool for preserving neuronal structures and achieving an optimal postoperative functional outcome.

Surgical Resection of Intradural Extramedullary Spinal Tumors: Patient Reported Outcomes and Minimum Clinically Important Difference

STUDY DESIGN

Analysis of prospectively collected longitudinal web-based registry data.

OBJECTIVE

To determine relative validity, responsiveness, and minimum clinically important difference (MCID) thresholds in patients undergoing surgery for intradural extramedullary (IDEM) spinal tumors.

SUMMARY OF BACKGROUND DATA

Patient-reported outcomes (PROs) are vital in establishing the value of care in spinal pathology. There is limited availability of prospective, quality studies reporting PROs for IDEM spine tumors.

METHODS

. A total of 40 patients were analyzed. Baseline, postoperative 3-month, and 12-month PROs were recorded: Oswestry Disability Index or Neck disability Index (ODI/NDI), Quality of life EuroQol-5D (EQ-5D), Short Form-12 (SF-12), Numeric Rating Scale (NRS)-pain scores. Responders were defined as those who achieved a level of improvement one or two, after surgery, on health transition index (HTI) of SF-36. Receiver-operating characteristic curves were generated to assess the validity of PROs, and the difference between standardized response means (SRMs) in responders versus nonresponders was utilized to determine the relative responsiveness of each PRO measure. MCID thresholds were derived using previously reported minimal detectable change approach.

RESULTS

A significant improvement across all PROs at 3-months and 12-months follow up was noted. The derived MCID thresholds were 13.9 points: ODI/NDI, 0.14 quality adjusted life years: EQ-5D, 2.8 points: SF-12PCS and 10.7 points: SF-12MCS, 1.9 points: NRS-back/neck pain, and 1.8 points: NRS-leg/arm pain. SF-12PCS was most accurate discriminator of meaningful improvement (area under the curve, AUC-0.83) and most responsive (SRM-1.36) to postoperative improvement. EQ-5D, ODI/NDI, NRS-pain scores were all accurate discriminator (AUC-0.7-0.8) and responsive measures (0.97-0.67) of meaningful postoperative improvement. SF-12MCS was neither a valid discriminator (AUC-0.48) nor a responsive measure (SRM: -1.5) of outcome.

CONCLUSION

Surgical resection of IDEM spinal tumors provides significant and sustained improvement in quality of life, general health, disability, and pain at 12-month after surgery. The surgically resected IDEM-specific clinically meaningful thresholds are reported. All the PROs reported in this study can accurately discriminate responders and nonresponder based on SF-36 HTI index except for SF-12 MCS.

LEVEL OF EVIDENCE

3.

The value of multimodality intraoperative neurophysiological monitoring in treating pediatric Chiari malformation type I

INTRODUCTION

Chiari malformation type I is defined as a descent of cerebellar tonsils below the level of the foramen magnum. The traditional treatment for symptomatic patients is foramen magnum decompression (FMD) surgery. Intraoperative neurophysiological monitoring (INM) is an established surgical adjunct, which is proposed to reduce the potential risk of various surgical procedures. Though INM has been suggested as being helpful in patient positioning and in determining the optimal surgical extent of FMD (i.e., duroplasty, laminectomy, tonsillectomy), its shortcomings include prolongation of anesthesia and surgery as well as monetary costs. Multimodality INM including transcranial-electric motor evoked potential (TcMEP) is not routinely employed in most practices. This study evaluates efficacy of multimodality INM during FMD.

METHODS

This work is a retrospective analysis of prospectively collected data. Twenty-two FMD surgeries in 21 pediatric patients (aged 1-18 years) were performed at our center utilizing multimodality INM. All patients presented Chiari malformation type I, 18 of which had presented with syringomyelia, underwent posterior fossa decompression (FMD + C1 laminectomy), accompanied in some with additional cervical laminectomies, duroplasty, and partial tonsillectomies. TcMEP and somatosensory evoked potentials (SSEP) were monitored throughout the procedure including before and after positioning. INM alarms were correlated with perioperative and long-term patient outcomes.

RESULTS

INM data remained stable during 19 operations. Three cases displayed significant attenuation in the monitoring signals, all concomitant with patient positioning on the surgical table. One case showed attenuation in SSEP data only, which remained attenuated following repositioning. Another displayed altered TcMEP concomitant with positioning which partially stabilized following repositioning and resolved following bony decompression. The third case showed unilateral attenuation of both TcMEP and SSEP data, which did not rectify until closure. In each of these three cases, no new neurological deficits were observed post operatively.

CONCLUSIONS

Multimodality INM can be useful in FMD surgery, particularly during patient positioning. TcMEP attenuations may occur independent of SSEPs. The clinical implications of these monitoring alerts have yet to be defined. There is a need to establish an optimal, cost-effective monitoring protocol for FMD.