Endotracheal tube (ETT) surface electrodes are used to monitor the vagus nerve (VN), recurrent laryngeal nerve (RLN), and external branch of the superior laryngeal nerve (EBSLN) during thyroid and parathyroid surgery. Alternative nerve monitoring methods are desirable when intubation under general anesthesia is not desirable or possible. In this pilot study, we compared the performance of standard ETT electrodes to four different noninvasive cutaneous recording electrode types (two adhesive electrodes and two needle electrodes) in three different orientations.
The VN was stimulated directly during thyroid and parathyroid surgery using a Prass stimulator probe. Electromyographic (EMG) responses for each patient were recorded using an ETT plus one of the following four cutaneous electrode types: large-foot adhesive, small-foot adhesive, long-needle and short-needle. Each of the four electrode types was placed in three orientations: (1) bilateral, (2) ipsilateral mediolateral, and (3) ipsilateral craniocaudal.
Four surgical cases were utilized for data collection with the repetitive measures obtained in each subject. Bilateral electrode orientation was superior to ipsilateral craniocaudal and ipsilateral mediolateral orientations. Regardless of electrodes type, all amplitudes in the bilateral orientation were >100 μV. When placed bilaterally, the small-foot adhesive and the long-needle electrodes obtained the highest EMG amplitudes as a percentage of ETT amplitudes.
Cutaneous electrodes could potentially be used to monitor the VN during thyroid and parathyroid procedures. Different electrode types vary in their ability to record amplitudes and latencies. Bilateral orientation improves EMG responses in all electrode types. Additional validation of cutaneous electrodes as an alternative noninvasive method to monitor the VN is needed.

BACKGROUND: Combined somatosensory- and motor-evoked potential (SSEP and MEP) changes for predicting prognosis in thoracic spinal surgery have been variably reported.
OBJECTIVE: We aimed to explore the validity of combined SSEP and MEP for predicting postoperative motor deficits (PMDs) in thoracic spinal decompression surgery (TSDS) and identify a relatively optimal neurophysiological predictor of PMDs in patients based on preoperative motor status.
METHODS: Retrospective study.
METHODS: A total of 475 patients were analyzed.
METHODS: A reduction in muscle strength by more than or equal to one manual muscle testing (MMT) grade postoperatively compared with the preoperative MMT grade was identified as PMDs. Postoperative motor deficits were detected by comparing the preoperative and postoperative physical examination findings in short- and long-term follow-up visits.
METHODS: All patients were divided into two subgroups according to preoperative motor status. The following data were collected: (1) demographic data; (2) IONM (intraoperative neuromonitoring) data; and (3) postoperative motor outcomes. Binary logistic regression analysis was performed to assess the efficacy of IONM change to predict PMDs. A receiver operating characteristic curve (ROC) was used to establish optimal IONM warning criteria.
RESULTS: Ninety-eight patients had severe preoperative motor deficits (Group S), and 377 patients did not (Group N). MEP and SSEP change was effective for predicting PMDs in the short term (p<.01) and long term (p<.01) for TSDS patients. In Group N, the cutoff values for predicting PMDs in the short term were a decrease of 65% in SSEP amplitude and 89.5% in MEP amplitude of the baseline value. Furthermore, the cutoff values for predicting PMDs in the short term were durations of change of 24.5 minutes for SSEP and 32.5 minutes for MEP. In Group S, however, the cutoff values for predicting PMDs in the short term were a decrease of 36.5% in SSEP amplitude and 59.5% in MEP amplitude of the baseline value. Moreover, the critical values for predicting short-term PMDs were durations of change of 16.5 minutes for SSEP and 17.5 minutes for MEP.
CONCLUSIONS: The optimal IONM changes for prediction vary depending on preoperative motor status. Combined SSEP and MEP are excellent for predicting PMDs in TSDS.

UNASSIGNED: Brachial plexus schwannoma (BPS) is a rare clinical entity that poses a significant challenge for head and neck surgeons due to its neuroanatomical complexity and potential severe complications, such as major motor or sensory neurological deficits or pain of the corresponding upper extremity. This article summarizes our experience in its diagnosis and intracapsular enucleation with intraoperative neuromonitoring (INM).
UNASSIGNED: A retrospective review of BPS cases treated at our tertiary medical institution was conducted between April 2020 and May 2023. The clinical and demographic data were retrieved from case notes.
UNASSIGNED: Totally, 3 cases were included. All 3 patients were male, aged 43 to 54 years (median age = 52). The presenting symptom was a palpable supraclavicular mass in all these cases (2 on the left side and 1 on the right side). Neuromonitoring was performed with a 4-channel nerve integrity monitor, with the electrodes placed in the upper arm and forearm muscles, as demonstrated in the literature. After exposing the mass and identifying its origin from the brachial plexus, a unipolar stimulating probe was used to stimulate the tumor surface or the nerves with a 1.0-mA current, and a longitudinal incision into the tumor capsule was made along a carefully mapped line with no INM response. Then the mass was carefully exposed and meticulously dissected from its capsule to achieve an intact enucleation. Immediate postoperative neurological deficit was documented in Case 1 as a mild grasping weakness. The recovery of the other 2 patients was uneventful. The follow-up duration was 7 to 38 months (median = 8 months). The minor motor deficit of Case 1 recovered completely 1 month after surgery. No recurrence of BPS was observed.
UNASSIGNED: Intracapsular enucleation with INM could result in complete removal of BPS and minimal postoperative neurological deficit, whose recovery was quick and satisfactory.

This study evaluated the feasibility, stability, safety, and economy of cricothyroid membrane (CM)-inserted needle electrodes for recurrent laryngeal nerve monitoring.
Parallel and controlled study.
Clinical research center for thyroid diseases of Shaanxi province.
A total of 64 patients in the needle electrodes group (104 recurrent laryngeal nerves [RLNs]) and 44 patients in the endotracheal tube (ETT)-based electrodes group (80 RLNs) underwent monitored thyroidectomy. The evoked electromyography (EMG) signals detected by the 2 electrodes were recorded and analyzed. The changes in EMG during Berry\'s ligament traction and tracheal displacement were compared. All patients underwent preoperative and postoperative laryngoscopy within 1 week.
Both electrodes successfully recorded typical evoked laryngeal EMG waveforms from RLNs. The needle electrodes recorded relatively higher amplitudes and similar latencies compared to ETT-based electrodes. The evoked EMG signals attributed to needle electrodes could accurately predict the function of RLNs with 100% sensitivity and specificity. The reduction in the recorded amplitudes attributed to needle electrodes was higher than that observed with ETT-based electrodes during Berry\'s ligament traction or trachea displacement, whereas a similar increase in the latencies was recorded in the 2 groups. Particularly, Berry\'s ligament traction was more likely to lead to EMG amplitude reduction and latency prolongation. The needle electrodes group recorded 2 cases of minor bleeding on the CM. The needle electrodes were more cost-effective than ETT-based electrodes.
The CM-inserted needle electrodes are feasible, stable, safe, and economical for RLN monitoring, and they provide an alternative novel intraoperative neural monitoring format for thyroid surgeons.

BACKGROUND: Monitoring the depth of anesthesia by electroencephalogram (EEG) based on the prefrontal cortex is an important means to achieve accurate regulation of anesthesia for subthalamic nucleus (STN) deep brain stimulation (DBS) under general anesthesia in patients with Parkinson\'s disease (PD). However, no previous study has conducted an in-depth investigation into this monitoring data. Here, we aimed to analyze the characteristics of prefrontal cortex EEG during DBS with propofol general anesthesia in patients with PD and determine the reference range of parameters derived from the depth of anesthesia monitoring. Additionally, we attempted to explore whether the use of benzodiazepines in the 3 days during hospitalization before surgery impacted the interpretation of the EEG parameters.
METHODS: We included the data of 43 patients with PD who received STN DBS treatment and SedLine monitoring during the entire course of general anesthesia with propofol in a single center. Eighteen patients (41.86%) took benzodiazepines during hospitalization. We divided the anesthesia process into three stages: awake state before anesthesia, propofol anesthesia state, and shallow anesthesia state during microelectrode recording (MER). We analyzed the power spectral density (PSD) and derived parameters of the patients\' prefrontal EEG, including the patient state index (PSI), spectral edge frequency (SEF) of the left and right sides, and the suppression ratio. The baseline characteristics, preoperative medication, preoperative frontal lobe image characteristics, preoperative motor and non-motor evaluation, intraoperative vital signs, internal environment and anesthetic information, and postoperative complications are listed. We also compared the groups according to whether they took benzodiazepines before surgery during hospitalization.
RESULTS: The average PSI of the awake state, propofol anesthesia state, and MER state were 89.86 ± 6.89, 48.68 ± 12.65, and 62.46 ± 13.08, respectively. The preoperative administration of benzodiazepines did not significantly affect the PSI or SEF, but did reduce the total time of suppression, maximum suppression ratio, and the PSD of beta and gamma during MER. Regarding the occurrence of postoperative delirium and mini-mental state examination (MMSE) scores, there was no significant difference between the two groups (chi-square test, p = 0.48; Mann-Whitney U test, p = 0.30).
CONCLUSIONS: For the first time, we demonstrate the reference range of the derived parameters of the depth of anesthesia monitoring and the characteristics of the prefrontal EEG of patients with PD in the awake state, propofol anesthesia state, and shallow anesthesia during MER. Taking benzodiazepines in the 3 days during hospitalization before surgery reduces suppression and the PSD of beta and gamma during MER, but does not significantly affect the observation of anesthesiologists on the depth of anesthesia, nor affect the postoperative delirium and MMSE scores.

UNASSIGNED: This meta-analysis evaluated the diagnostic value of intraoperative brainstem auditory evoked potential (BAEP) for predicting post-operative hearing loss.
UNASSIGNED: Research articles in MEDLINE, Embase, and Cochrane Library databases were searched and selected up to 20 January 2022, and data were extracted following a standard procedure. A diagnostic accuracy test meta-analysis was performed using a mixed-effect binary regression model.
UNASSIGNED: A total of 693 patients from 15 studies were extracted. The change in intraoperative BAEP showed high sensitivity (0.95) but low specificity (0.37), with an area under the curve of 0.83. Diagnostic accuracy of the loss of potentials showed high sensitivity (0.82) and specificity (0.79). The area under the curve was 0.88. No factor was found to account for the heterogeneity of the results according to the meta-regression and subgroup analyses (all P-values > 0.05).
UNASSIGNED: Our results showed that the loss of BAEP has meaningful value for predicting hearing loss after vestibular schwannoma surgery. The change in BAEP is also important for its high sensitivity during hearing preservation surgery.

UNASSIGNED: Complete endoscopic radical resection of thyroid cancer, especially through the areolar approach, can achieve curative and acceptable cosmetic effects in patients with differentiated thyroid carcinoma. However, some inherent characteristics of endoscopic procedures hamper functional protection of the recurrent laryngeal nerve (RLN). Intraoperative neuromonitoring (IONM) is considered the most important accessory to protect the nerves during conventional radical thyroidectomy. This study aimed to evaluate the feasibility and necessity of IONM during complete endoscopic radical resection of thyroid cancer.
UNASSIGNED: A total of 106 patients with differentiated thyroid carcinoma were enrolled in the study between February 2013 and April 2018. Based on the use of the IONM technique, all patients were divided into the IONM (n = 54) and non-IONM groups (n = 52). Overall, 66 RLNs were involved in the IONM group, and 61 RLNs were involved in the non-IONM group. The time and ratio of RLN identification and the number of transient and permanent RLN injuries between both groups were compared.
UNASSIGNED: Compared to the non-IONM group, the IONM group required less time for RLN identification (3.05 ± 1.58 vs. 9.36 ± 4.82 min, p < .01). The ratio of RLN identification in the IONM group was much higher than that in the non-IONM group (100.00% vs. 88.52%, p = .01). A significant difference was observed in RLN transient injury between the two groups (one case accounting for 1.51% in the IONM group vs. eight cases accounting for 13.11% in the non-IONM group; p = .03).
UNASSIGNED: IONM significantly improved RLN identification and reduced transient RLN injuries during complete endoscopic radical resection.
UNASSIGNED: 3b.

UNASSIGNED: Intraoperative neuromonitoring (IONM) has become an increasingly essential technique in spinal surgery. However, data on the diagnostic value of IONM in predicting impending postoperative neurological deficits (PONDs) for patients who underwent posterior decompression surgery for thoracic spinal stenosis (TSS) are limited. Furthermore, patients who are at the highest risk of waveform changes during the surgery remain unknown. Our purpose was to (1) assess the diagnostic accuracy of IONM by combining somatosensory-evoked potential (SSEP) with motor-evoked potential (MEP) in predicting PONDs for patients who underwent the surgery and (2) identify the independent risk factors correlated with IONM changes in our study population.
UNASSIGNED: A total of 326 consecutive patients who underwent the surgery were identified and analyzed. We collected the following data: (1) demographic and clinical data; (2) IONM data; and (3) outcome data such as details of PONDs, and recovery status (complete, partial, or no recovery) at the 12-month follow-up visit.
UNASSIGNED: In total, 27 patients developed PONDs. However, 15, 6, and 6 patients achieved complete recovery, partial recovery, and no recovery, respectively, at the 12-month follow-up. SSEP or MEP change monitoring yielded better diagnostic efficacy in predicting PONDs as indicated by the increased sensitivity (96.30%) and area under the receiver operating characteristic (ROC) curve (AUC) value (0.91). Only one neurological deficit occurred without waveform changes. On multiple logistic regression analysis, the independent risk factors associated with waveform changes were as follows: preoperative moderate or severe neurological deficits (p = 0.002), operating in the upper- or middle-thoracic spinal level (p = 0.003), estimated blood loss (EBL) ≥ 400 ml (p < 0.001), duration of symptoms ≥ 3 months (p < 0.001), and impairment of gait (p = 0.001).
UNASSIGNED: Somatosensory-evoked potential or MEP change is a highly sensitive and moderately specific indicator for predicting PONDs in posterior decompression surgery for TSS. The independent risks for IONM change were as follows: operated in upper- or middle-thoracic spinal level, presented with gait impairment, had massive blood loss, moderate or severe neurological deficits preoperatively, and had a longer duration of symptoms.
UNASSIGNED: [http://www.chictr.org.cn]; identifier [ChiCTR 200003 2155].

Background: The effect of a bolus dose of dexmedetomidine on intraoperative neuromonitoring (IONM) parameters during spinal surgeries has been variably reported and remains a debated topic. Methods: A randomized, double-blinded, placebo-controlled study was performed to assess the effect of dexmedetomidine (1 μg/kg in 10 min) followed by a constant infusion rate on IONM during thoracic spinal decompression surgery (TSDS). A total of 165 patients were enrolled and randomized into three groups. One group received propofol- and remifentanil-based total intravenous anesthesia (TIVA) (T group), one group received TIVA combined with dexmedetomidine at a constant infusion rate (0.5 μg kg-1 h-1) (D1 group), and one group received TIVA combined with dexmedetomidine delivered in a loading dose (1 μg kg-1 in 10 min) followed by a constant infusion rate (0.5 μg kg-1 h-1) (D2 group). The IONM data recorded before test drug administration was defined as the baseline value. We aimed at comparing the parameters of IONM. Results: In the D2 group, within-group analysis showed suppressive effects on IONM parameters compared with baseline value after a bolus dose of dexmedetomidine. Furthermore, the D2 group also showed inhibitory effects on IONM recordings compared with both the D1 group and the T group, including a statistically significant decrease in SSEP amplitude and MEP amplitude, and an increase in SSEP latency. No significance was found in IONM parameters between the T group and the D1 group. Conclusion: Dexmedetomidine delivered in a loading dose can significantly inhibit IONM parameters in TSDS. Special attention should be paid to the timing of a bolus dose of dexmedetomidine under IONM. However, dexmedetomidine delivered at a constant speed does not exert inhibitory effects on IONM data.

BACKGROUND: Brachial plexus injury (BPI) leading to palsy of the upper extremities is the most serious complication of the Woodward procedure for treatment of Sprengel deformity. Intraoperative neuromonitoring (IONM) is widely used for detecting emerging spinal cord or peripheral nerve injury during spinal and shoulder surgery. However, to date, its utilization in pediatric patients with Sprengel deformity is limited. Furthermore, it remains unclear whether IONM can help prevent BPI during surgery. The purpose of the current study was to assess the feasibility and effectiveness of IONM for early identification and prevention of nerve injury during the Woodward procedure.
METHODS: We retrospectively reviewed the records of patients who underwent the Woodward procedure for Sprengel deformity at our institution between January 2017 and January 2020. IONM, including somatosensory evoked potentials (SEP) and motor evoked potentials (MEPs), was performed in all patients. Detailed IONM data were collected and analyzed. Preoperative and postoperative cosmetic appearance (according to the Cavendish classification), shoulder joint abduction function, and radiologic evaluation of the scapula were reviewed. Surgical complications were recorded.
RESULTS: Forty-six patients (19 girls, 27 boys) were included (mean age, 5.1 ± 2.1 years). Both SEP and MEP (amplitude of the abductor pollicis) were successfully performed (100%). MEP alerts occurred in 3 patients (6.5%). After scapula position adjustment, signals recovered in 2 patients and remained unchanged in 1 patient-this patient exhibited postoperative motor deficits that resolved completely by 4 months recovery. The SEP amplitudes decreased in all 3 patients but did not reach the warning criteria. Forty patients were classified as grade III and 6 as grade IV in the Cavendish classification, whereas 35 patients were classified as grade II and 11 as grade III in the Rigault scale. The preoperative Cavendish grade was III (III, IV) and the postoperative Cavendish grade was I (I, II) (χ2 = 88.098, P < .001). The preoperative Rigault grade was II (II, III) and the postoperative Rigault grade was I (I, II) (χ2 = 62.133, P < .001). The mean arc of shoulder joint abduction improved from 99° ± 8° to 167° ± 7° (t = -45.871, P < .001) after surgery. Except for temporary motor deficits detected in 1 patient, no other postoperative complications were observed through the time of final follow-up.
CONCLUSIONS: IONM during the Woodward procedure for Sprengel deformity is feasible and effective in detecting intraoperative neurologic changes and may be effective in preventing BPI associated with surgery.