Detection of evolving injury to the brachial plexus during transaxillary robotic thyroidectomy.

OBJECTIVES/HYPOTHESIS: Continuous intraoperative neuromonitoring (IONM) of transcranial electric motor evoked potentials (tceMEPs) and somatosensory evoked potentials (SSEPs) has gained universal acceptance as an efficacious method for detecting emerging positional brachial plexopathy or peripheral nerve compression during spinal and shoulder surgery. This has implications for transaxillary thyroid surgery. STUDY DESIGN: Case report with literature review. METHODS: The patient underwent robotic transaxillary thyroid surgery with continuous tceMEP and SSEP monitoring of brachial plexus function. We present detailed IONM data depicting the emergence of positional brachial plexopathy. RESULTS: Significant amplitude loss of both IONM modalities were identified during an evolving positional plexopathy, which resolved upon upper extremity repositioning and conversion to an open procedure. No permanent nerve injury or deficit was noted following surgery. CONCLUSIONS: Given the potential for brachial plexus injury during robotic transaxillary thyroid surgery secondary to arm positioning, we recommend that continuous tceMEP and SSEP monitoring be considered during such procedures

Impact of inhalational anesthetic agents on the baseline monitorability of motor evoked potentials during spine surgery: a review of 22,755 cervical and lumbar procedures.

BACKGROUND CONTEXT: During spine surgery, motor evoked potentials (MEPs) are often utilized to monitor both spinal cord function and spinal nerve root or plexus function. While there are reports evaluating the impact of anesthesia on the ability of MEPs to monitor spinal cord function, less is known about the impact of anesthesia on the ability of MEPs to monitor spinal nerve root and plexus function. PURPOSE: To compare the baseline monitorability and amplitude of MEPs during cervical and lumbar procedures between two cohorts based on the maintenance anesthetic regimen: a total intravenous anesthesia (TIVA) versus a regimen balanced with volatile inhalational and intravenous agents. STUDY DESIGN: Baseline MEP data from a total of 16,559 cervical and 6,196 lumbar extradural spine procedures utilizing multimodality intraoperative neuromonitoring (IONM) including MEPs between January 2017 and March 2020 were obtained from a multi-institutional database. Two cohorts for each region of spine surgery were delineated based on the anesthetic regimen: a TIVA cohort and a Balanced anesthesia cohort. PATIENT SAMPLE: Age 18 and older. Fellowship support for 65,000 for year 2021. OUTCOME MEASURES: Percent monitorability and amplitudes of baseline MEPs. METHODS: The baseline monitorability of each muscle MEP was evaluated by the IONM team in real-time and recorded in the patient\u27s electronic medical record. The relation between anesthetic regimen and baseline monitorability was estimated using mixed effects logistic regression, with distinct models for cervical and lumbar procedures. Subsets of cervical and lumbar procedures from each anesthesia cohort in which all MEPs were deemed monitorable were randomly selected and the average peak-to-trough amplitude of each muscle MEP was retrospectively measured. Mixed-effects linear regression models were estimated (one each for cervical and lumbar procedures) to assess possible differences in average amplitude associated with anesthesia regimen. RESULTS: At the time of surgery, baseline MEPs were reported monitorable from all targeted muscles in 86.8% and 83.0% of cervical and lumbar procedures, respectively, for the TIVA cohort, but were reported monitorable in just 59.3% and 61.0% of cervical and lumbar procedures, respectively, in the Balanced cohort, yielding disparities of 27.5% and 22.0%, respectively. The model-adjusted monitorability disparity between cohorts for a given muscle MEP ranged from 0.2% to 16.6% but was smallest for distal intrinsic hand and foot muscle MEPs (0.2%-1.1%) and was largest for proximal muscle MEPs (deltoid: 10.8%, biceps brachii: 8.8%, triceps: 13.0%, quadriceps: 16.6%, gastrocnemius: 7.8%, and tibialis anterior: 3.7%) where the monitorability was significantly decreased in the Balanced cohort relative to the TIVA cohort (p CONCLUSIONS: TIVA is the preferred anesthetic regimen for optimizing MEP monitoring during spine surgery. Inhalational agents significantly decrease MEP monitorability and amplitudes for most muscles, and this effect is especially pronounced for proximal limb muscles such as the deltoid, biceps, triceps, and quadriceps

Awake vs. Asleep Placement of Spinal Cord Stimulators: A Cohort Analysis of Complications Associated With Placement

Introduction: Patients will typically undergo awake surgery for permanent implantation of SCS in an attempt to optimize electrode placement using patient feedback about the distribution of stimulation-induced paresthesia. The present study compared efficacy of first-time electrode placement under awake conditions with that of neurophysiologically-guided placement under general anesthesia. Methods: A retrospective review was performed of 387 SCS surgeries among 259 patients which included 167 new stimulator implantation to determine whether first time awake surgery for placement of spinal cord stimulators is preferable to non-awake placement. Results: The incidence of device failure for patients implanted using neurophysiologically-guided placement under general anesthesia was one-half that for patients implanted awake (14.94% vs 29.7%). Conclusion: Non-awake surgery is associated with fewer failure rates and therefore fewer re-operations, making it a viable alternative. Any benefits of awake implantation should carefully be considered in the future

Transcranial electric motor evoked potential monitoring during spine surgery: is it safe?

STUDY DESIGN: Retrospective review. OBJECTIVE: To report on the safety of repetitive transcranial electric stimulation (RTES) for eliciting motor-evoked potentials during spine surgery. SUMMARY OF BACKGROUND DATA: Theoretical concerns over the safety of RTES have hindered broader acceptance of transcranial electric motor-evoked potentials (tceMEP), despite successful implementation of spinal cord monitoring with tceMEPs in many large spine centers, as well as their apparent superiority over mixed-nerve somatosensory-evoked potentials (SSEP) for detection of spinal cord injury. METHODS: The records of 18,862 consecutive patients who met inclusion criteria and underwent spine surgery with tceMEP monitoring were reviewed for RTES-related complications. RESULTS: This large retrospective review identified only 26 (0.14%) cases with RTES-related complications; all but one of these were tongue lacerations, most of which were self-limiting. CONCLUSIONS: The results demonstrate that RTES is a highly safe modality for monitoring spinal cord motor tract function intraoperatively

Intraoperative neurophysiology in tethered cord surgery:Techniques and results

©AANS, 2017. OBJECTIVE The aim of this study was to establish optimal electric stimulation parameters for intraoperatively monitoring the bulbocavernosus reflexes (BCRs) in infants. METHODS The authors retrospectively reviewed the medical records of all infants (age < 24 months) who had undergone an untethering operation for tethered cord syndrome between May 2013 and February 2014 at a single institution and whose baseline BCR had been elicited during surgery. Using different combinati ons of stimulation parameters-number of stimulation pulses: 4 or 8 pulses, interpulse interval: 1, 2, or 5 msec, and polarity of stimulation: biphasic or monophasic-the authors compared the relative mean amplitude of 10 BCR responses (rmaBCRs) to each combination of parameters. RESULTS The rmaBCRs were larger with the 8-pulse stimulations than with the 4-pulse stimulations (p < 0.0001). There was a tendency, though not statistically significant, for larger rmaBCRs to be obtained with the longer interpulse interval in the 8-pulse stimulation (p = 0.1289). The biphasic stimulation produced larger rmaBCRs than the monophasic stimulation (p = 0.0005). CONCLUSIONS Biphasic 8-pulse stimulations with 5-msec or 2-msec intervals yield the largest BCR responses. Considering that an 8-pulse stimulation with 5-msec intervals may overlap the onset of the BCR, a biphasic 8-pulse stimulation with 2-msec intervals is recommended as the optimal stimulation paradigm to monitor intraoperative BCRs in infants