Multimodality Intraoperative Monitoring Research Articles

Expandable Lateral Lumbar Cages With Integrated Fixation: A Viable Option for Rostral Adjacent Segment Disease.

Adjacent segment disease (ASD) above a previous posterior lumbar instrumented fusion can be managed with minimally invasive lateral lumbar interbody fusion. Earlier procedures with stand-alone lateral cages risked nonunion, and lateral cages with separate lateral plates risked lumbar plexus injury and vertebral fracture. We investigated clinical and radiographic outcomes of an expandable lateral titanium interbody cage with an integrated lateral fixation (eLLIFp) device as a stand-alone treatment for symptomatic ASD above a previous posterior lumbar fusion and performed a comparative cost analysis of eLLIFp to alternative operations for ASD. In this prospective, observational study, patients with ASD above 1-, 2-, 3-, or 4-level instrumented posterior fusions underwent surgery with lateral expandable titanium cage(s) with an integrated lateral plate with single screws into each adjacent vertebra from August 2017 to August 2019. Multimodality intraoperative neural monitoring was performed. Patient-reported outcomes, computed tomography outcomes, and total costs were analyzed. A total of 33 patients received 35 eLLIFp cages. All clinical outcomes improved significantly. The eLLIFp cages added 2.2° segmental lordosis and 2.7 mm posterior disc height. Interbody fusion rate was 94% at 12 months. There were 2 neurologic complications (6%): 1 patient reported transient anterior thigh numbness and 1 had mild persistent L4 radiculopathy. No cage subsidence, cage migration, screw loosening, or vertebral fracture occurred. No revision lateral surgery, posterior decompression, or supplemental posterior fixation was required. The total eLLIFp cost (AU$19,715) was lower than the cost for all other procedures. eLLIFp provided a minimally invasive, low morbidity, cost-effective, and robust alternative to traditional posterior construct extension surgery for rostral lumbar ASD in selected patients with 1- to 2-level stenosis and minimal deformity. Traditional ASD treatment involves substantial risks and expense. eLLIFp should be considered a safe, effective, and lower cost alternative to posterior construct extension surgery.

The Significance of Motor Evoked Potential Changes and Utility of Multimodality Intraoperative Monitoring in Spinal Surgery: A Retrospective Analysis of Consecutive Cases at a Single Institution.

ObjectiveThe objective of the study is to identify specific population groups that may benefit from intraoperative motor evoked potentials (MEP) and to assess positive predictive value (PPV) and negative predictive value (NPV) changes during operation by correlating these with postoperative motor outcomes.MethodsWe retrospectively reviewed 1,043 consecutive patient cases undergoing spine surgery with and without intraoperative monitoring (IOM) at a single institution from January 1, 2016 to December 31, 2017. Demographic and clinical outcome data were collected at multiple time points. An MEP amplitude decrease of 50% or greater was correlated with a motor deficit for this study.ResultsOn multivariate analysis, patients with coronary artery disease and who received IOM were more likely to experience no new deficit (p=0.047) than those who did not receive IOM. Additionally, patients with hyperlipidemia and coronary artery disease (CAD) were less likely than those without to experience no new deficit (p=0.001 and p=0.02, respectively). MEP accounted for 244 cases, of which 15 had alert MEP criteria but no deficit for a PPV of 21.05% at day 1 post-operation. Day 7-30 PPV declined to 14.29%, and by day 90, there was no association.ConclusionAmong patients in our study with CAD, IOM use was associated with significantly better outcomes. Patients with higher intraoperative blood loss, hyperlipidemia, and those with CAD were at increased risk of new neurological deficit. The use of motor evoked potentials was associated with low sensitivity and low PPV.

42. Multimodality intraoperative neurophysiologic monitoring in spondilotic myelopathy

Cervico/dorsal spondilotyc myelopathy (CDSM) is the most frequent spinal disorder encountered in people aged >55 years. Although CDSM is frequently scheduled for multimodal intraoperative monitoring (MIOM), it is not completely clarified the rate of monitorability and intraoperative modification. We retrospectively reviewed the data from 361 consecutive spinal surgeries (213 CDSM, 35 intramedullary spinal cort tumors – IMSCT – and 113 extranedullary spinal cord tumors – EMSCT) in whom 4 lower limbs Motor Evoked Potentials (ll-MEPs) and posterior tibial nerve somatosensory evoked potential (ptn-SEPs) were studied. Patients were clinically classified according the MacKormick scale. The overall monitorability was 96.4% (IMSCT = 97.1%, EMSCT = 99.1%, CDSM = 94.8%). ptn-SEPs were absent or unilaterally present in 16.9% of the whole casistic (20% of IMSCT, 9.7% of EMSCT and 20.2% of CDSM); globally, ll-MEPs were absent or unilaterally recordable in 15.2% (11.4% of IMSCT, 4.4% of EMSCT and 21.6% of CDSM). The rate of postoperative worsening was higher in patients with T2 signal abnormality on preoperative MR images. Spondilotic myelopathy is the worst “scenario” for the intraoperative neurophysiologist.

Transient neurological deficit following midthoracic decompression for severe stenosis: a series of three cases

To report three cases of transient perioperative neurological deficit in the absence of direct cord insult following decompression of the severely stenotic thoracic spine. The clinical and radiographic electronic medical records of three patients who underwent decompression for severe midthoracic stenosis with transient neurological deficits perioperatively were reviewed. The cases are presented with consideration of possible underlying mechanisms and multimodality intraoperative monitoring (IOM) findings. Two patients had neurologic changes on IOM and Stagnara wake-up test, the remaining patient had absent motor and sensory potentials at baseline and throughout the case. IOM changes were observed immediately following decompression in the absence of direct cord insult or displacement. Postoperatively all patients experienced neurological motor deficits which presented as complete paralysis of the right lower extremity in two of the patients and the left lower extremity in one patient. The deficit was transient-improvement of motor strength occurred between 1 and 13 months of follow-up in all patients. Decompression of a severely stenotic region of the thoracic spinal cord may lead to a complete yet transient motor deficit in the perioperative period in the absence of direct mechanical cord insult. Potential etiologies include ischemia-reperfusion injury, microthrombi, and altered perfusion due to internal recoil of spinal cord architecture following decompression. IOM may show conspicuous findings in such events, however, may not be relied upon when baseline potentials are sub-optimal. Recognition of this short-lived neurological deficit following decompression of the severely stenotic thoracic spine will improve preoperative patient counseling and merits further study for determination of the precise pathophysiology.

Significant Change or Loss of Intraoperative Monitoring Data

Retrospective. The purpose of this study was to report the spectrum of intraoperative events responsible for a loss or significant change in intraoperative monitoring (IOM) data. The efficacy of spinal cord/nerve root monitoring is demonstrated in a large, single institution series of patients, involving all levels of the spinal column (occiput to sacrum) and all spinal surgical procedures. Multimodality IOM included somatosensory-evoked potentials, descending neurogenic-evoked potentials, neurogenic motor-evoked potentials, and spontaneous and triggered electromyography. A total of 12,375 patients who underwent surgery for spinal pathology between January 1985 and December 2010 were reviewed. There were 59.3% female patients (7178) and 40.7% male patients (5197). Procedures by spinal level were as follows: cervical 29.7% (3671), thoracic/thoracolumbar 45.4% (5624), and lumbosacral 24.9% (3080). Age at the time of surgery was as follows: older than 18 years, 72.7% (242/8993) and younger than 18 years, 27.3% (144/3382). A total of 77.8% (9633) patients underwent primary surgical procedures and 22.2% (2742) patients underwent revision surgical procedures. A total of 406 instances of IOM data change/loss occurred in 386 of 12,375 (3.1%) patients. Causes for data degradation/loss included the following: instrumentation (n = 131), positioning (n = 85), correction (n = 56), systemic (n = 49), unknown (n = 24), and focal spinal cord compression (n = 15). Data loss/change was seen in revision (6.1%/167 patients) surgical procedures more commonly than in primary procedures (2.3%/219 patients; P < 0.0001). Data improvement was demonstrated by 88.7% (n = 360) after intervention versus 11.3% (n = 46) with no improvement in IOM data. One patient with improved data after intervention versus 14 with no improvement despite intervention had a permanent neurological deficit (P < 0.0001). IOM data identified 386 (3.1%) patients with loss/degradation of data in 12,375 spinal surgical procedures. Fortunately, in 93.3% of patients, intervention led to data recovery and no neurological deficits. Reduction from a potential (worst-case scenario) 3.1% (386) of patients with significant change/loss of IOM data to a permanent neurological deficit rate of 0.12% (15) patients was achieved (P < 0.0001), thus confirming efficacy of IOM.

Use of Multi-Modality Intraoperative Monitoring during Carotid Endarterectomy Surgery: A Case Study

ABSTRACT.Carotid artery stenosis is a major risk factor leading to cerebral infarct, transient ischemic attack (TIA), and ischemic stroke in the United States. While carotid endarterectomy (CEA) surgery has been established as an effective treatment option for severe carotid artery stenosis, many risks remain inherent in performing this procedure. Surgeons will often utilize various intraoperative monitoring techniques in an effort to reduce surgical complications and morbidity. The usefulness of continuous EEG and somatosensory evoked potential (SSEP) monitoring during CEA surgery has been examined by many groups over the last couple decades. The following case review clearly proves that such monitoring is an effective tool in the detection of cerebral ischemic changes and is therefore feasible in CEA surgery.

Multi-modality neurophysiological monitoring during surgery for adult tethered cord syndrome

During complex microneurosurgery performed in patients with tethered cord syndrome, the conus medullaris and the roots that innervate the lower limbs, bladder and bowel are potentially exposed to damage. The aim of multimodality intraoperative monitoring (IOM) is to reduce the risk of inadvertent injury of neural tissue. We simultaneously record tibial nerve somatosensory evoked potentials (SSEPs) from the scalp and free run electromyography (EMG) of limb muscles supplied by L2 to S2 roots, anal and urethral sphincters. We also identify critical neural structures in the operative field, including the conus and exiting nerve roots, with a nerve stimulator to evoke EMG. SSEPs assess the sensory pathways mainly mediated by the S1 roots. Continuous EMG provides the surgeon with immediate auditory feedback resulting from irritative discharges triggered by manipulation of nerve fibres. Microstimulation can distinguish the filum terminale, scar tissue and invasive tumors from functional neural tissue, thus minimizing the risk of iatrogenic injury. Overall multimodality IOM proves a valuable adjunct to microneurosurgery of the lumbosacral spine.

Multimodality intraoperative monitoring during complex lumbosacral procedures: indications, techniques, and long-term follow-up review of 61 consecutive cases.

The purpose of this study was to examine the neurological outcomes after complex lumbosacral surgery in patients undergoing multimodality neurophysiological monitoring. Sixty-one patients were consecutively enrolled in this study. These patients underwent complex intra- and extradural lumbosacral procedures with concomitant intraoperative electromyography (EMG) monitoring of the lower-limb muscles, external anal and urethral sphincters (EAS and EUS), and lower-limb somatosensory evoked potentials (SSEPs). Long-term (minimum 2-year) clinical follow-up data were obtained in all cases. Most patients were treated for spinal/spinal cord tumors (61%) or adult tethered cord syndrome (25%). Recordable lower-extremity SSEPs were reported in 54 patients (89%). New postoperative neurological deficits occurred in only three patients (4.9%), and remained persistent in only one patient (1.6%) at long-term follow-up examination. In only one of these cases was a significant decrease in SSEP amplitude detected. Spontaneous EMG activity was observed in the lower-extremity muscles and/or EAS and EUS in 51 cases (84%). Intraoperatively, EMG demonstrated activity only in the EUS in 5% of patients and only in the EAS in 28%. In seven patients (11%) spontaneous intraoperative EMG activity was observed in both the EAS and the EUS; however, in only three of these cases was EMG activity recorded in both sphincters simultaneously. In addition to spontaneously recorded EMG activity, electrically evoked EMG activity was also used as an intraoperative adjunct. A bipolar stimulating electrode was used to identify functional neural tissue before undertaking microsurgical dissection in 58 individuals (95%). In the majority of these patients, evoked EMG activity occurred either in one (33%) or in two muscles (9%) simultaneously. The presence of electrically evoked EMG activity in structures encountered during microdissection altered the plan of treatment in 24 cases (42%). The authors conclude that the combined SSEP and EMG monitoring of lower-limb muscles, EAS, and EUS is a practical and reliable method for obtaining optimal electrophysiological feedback during complex neurosurgical procedures involving the conus medullaris and cauda equina. Analysis of the results indicates that these intraoperative adjunctive modalities positively influence decision making with regard to microsurgery and reduce the risk of perioperative neurological complications. Validation of the clinical value of these approaches, however, will require further assessment in a larger prospective cohort of patients.

形態的モニターと機能的モニターを統合した術中multi-modalityモニタリング : テクニカルノート

各種形態的モニターと機能的モニターを用い, さらにそれらを統合した形で術者に提示できる術中multi-modalityモニターシステムを作製した.機能的モニターは, 誘発電位を中心とする各種電気生理学的モニターを行った.形態的モニターは, 神経ナビゲーション, 神経内視鏡を行った.これら各種モニターの結果を顕微鏡画像とともに, 同時かつ効率的に表示するための方法として, multi-viewer systemを用いた.本システムを用い, 各種モニター, 特に形態モニターと機能モニターを同時に行うことにより互いに補い, それぞれの有用性がさらに増すものと考えられた.