A Pilot Study of a Novel Automated Somatosensory Evoked Potential (SSEP) Monitoring Device for Detection and Prevention of Intraoperative Peripheral Nerve Injury in Total Shoulder Arthroplasty Surgery

Increasing Awareness of Complications of Nerve Injury Following Shoulder Surgery: Preventing Delays in Referral and Treatment

BACKGROUND

Nerve injuries remain a challenging complication after shoulder surgery. While most resolve spontaneously, some require surgical intervention. This study describes the characteristics of patients sustaining nerve injuries following shoulder surgery, evaluates referral patterns to nerve surgeons, and characterizes nerve surgeries performed and their outcomes. Increased awareness of these injuries allows patients and providers to be better informed regarding the appropriate management when these complications occur.

METHODS

A retrospective review of referrals with nerve injuries following shoulder surgery between 2007 and 2015 was performed. The final analysis included 65 patients. Data reviewed included demographics, procedure and anesthesia type, and diagnosis of nerve injury. Time to referral to nerve surgeon and proportional changes in the Disabilities of the Arm, Shoulder, and Hand (DASH) scores were determined. Outcomes were categorized as failed, partially successful, and successful based on final follow-up.

RESULTS

Patients were referred following arthroscopic shoulder surgeries (35.4%), shoulder arthroplasties (24.6%), open shoulder procedures (21.5%), and combined open and arthroscopic procedures (18.5%). The mean time to referral was 7.6 months. Nerve injuries involved brachial plexus (33) and individual and multiple peripheral nerve branches (23 and 7, respectively). Twenty-five (38%) nerve injuries demonstrated spontaneous recovery. Thirty-five patients underwent surgical intervention, of which 27 were successful, 3 were partially successful, and 3 failed.

CONCLUSIONS

This is the largest series of patients with iatrogenic nerve injury following shoulder surgeries to date. Our data demonstrate a lack of timely referral to nerve surgeons, especially after arthroscopy. There continues to be a variable injury pattern even among similar surgeries. Despite this, timely surgical intervention, when indicated, can lead to favorable outcomes.

Postoperative ulnar neuropathy: a systematic review of evidence with narrative synthesis

BACKGROUND

Postoperative ulnar neuropathy (PUN) is an injury manifesting in the sensory or motor distribution of the ulnar nerve after anaesthesia or surgery. The condition frequently features in cases of alleged clinical negligence by anaesthetists. We performed a systematic review and applied narrative synthesis with the aim of summarising current understanding of the condition and deriving implications for practice and research.

METHODS

Electronic databases were searched up to October 2022 for primary research, secondary research, or opinion pieces defining PUN and describing its incidence, predisposing factors, mechanism of injury, clinical presentation, diagnosis, management, and prevention.

RESULTS

We included 83 articles in the thematic analysis. PUN occurs after approximately 1 in 14 733 anaesthetics. Men aged 50-75 yr with pre-existing ulnar neuropathy are at highest risk. Preventative measures, based on consensus and expert opinion, are summarised, and an algorithm of suspected PUN management is proposed, based upon the identified literature.

CONCLUSIONS

Postoperative ulnar neuropathy is rare and the incidence is probably decreasing over time with general improvements in perioperative care. Recommendations to reduce the risk of postoperative ulnar neuropathy are based on low-quality evidence but include anatomically neutral arm positioning and padding intraoperatively. In selected high-risk patients, further documentation of repositioning, intermittent checks, and neurological examination in the recovery room can be helpful.

Utilization of intraoperative neuromonitoring during the Woodward procedure for treatment of Sprengel deformity

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.

CONCLUSION

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.

Saphenous somatosensory-evoked potentials monitoring of femoral nerve health during prone transpsoas lateral lumbar interbody fusion

PURPOSE

To assess whether saphenous somatosensory-evoked potentials (saphSSEP) monitoring may provide predictive information of femoral nerve health during prone lateral interbody fusion (LIF) procedures.

METHODS

Intraoperative details were captured prospectively in consecutive prone LIF surgeries at a single institution. Triggered electromyography was used during the approach; saphSSEP was monitored throughout using a novel system that enables acquisition of difficult signals and real-time actionable feedback facilitating intraoperative intervention. Postoperative neural function was correlated with intraoperative findings.

RESULTS

Fifty-nine patients (58% female, mean age 64, mean BMI 32) underwent LIF at 95 total levels, inclusive of L4-5 in 76%, fixated via percutaneous pedicle screws (81%) or lateral plate, with direct decompression in 39%. Total operative time averaged 149 min. Psoas retraction time averaged 16 min/level. Baseline SSEPs were unreliable in 3 due to comorbidities in 2 and anesthesia in 1; one of those resulted in transient quadriceps weakness, fully recovered at 6 weeks. In 25/56, no saphSSEP changes occurred, and none had postoperative femoral nerve deficits. In 24/31 with saphSSEP changes, responses recovered intraoperatively following intervention, with normal postoperative function in all but one with delayed quadriceps weakness, improved at 4 months and recovered at 9 months, and a second with transient isolated anterior thigh numbness. In the remaining 7/31, saphSSEP changes persisted to close, and resulted in 2 transient isolated anterior thigh numbness and 2 combined sensory and motor femoral nerve deficits, both resolved at between 4 and 8 months.

CONCLUSIONS

SaphSSEP was reliably monitored in most cases and provided actionable feedback that was highly predictive of neurological events during LIF.

LEVEL OF EVIDENCE

Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding.

Risk Factors, Management, and Prognosis of Brachial Plexopathy Following Reverse Total Shoulder Arthroplasty

Brachial plexus injuries can have a significant impact on patient outcomes following RTSA by slowing the overall recovery and return of function. Risk factors for brachial plexopathy include traction injury related to arm positioning and exposure during the procedure, direct nerve injury from surgical dissection, and compression injury from retractor placement. Risk of nerve injury can be minimized by limiting the time spent with the arm extended and externally rotated and avoiding excessive traction on the arm during humeral preparation and implant insertion. Prompt identification of postoperative brachial plexopathy is important to optimize the recovery of function.

Concomitant Total Shoulder Arthroplasty and Ipsilateral Carpal Tunnel Release: Is it Safe?

PURPOSE

Symptomatic carpal tunnel syndrome in patients with advanced ipsilateral glenohumeral arthritis requiring total shoulder arthroplasty (TSA) may be easily overlooked. Even when diagnosed beforehand, most upper extremity surgeons have historically chosen to perform TSA and carpal tunnel release (CTR) separately. We hypothesized that combined single-stage TSA and CTR is feasible and yields results comparable with those when the 2 procedures are performed separately, while avoiding 2 surgeries.

METHODS

This was a retrospective review of patients who underwent single-stage primary TSA and ipsilateral CTR between 2015 and 2019. The shoulder outcomes included pain, range of motion, and validated quality of life (QoL) questionnaires: Veterans RAND 12-Item Health Survey (VR-12) and Penn Shoulder Score. The CTR outcomes included pain, grip, pinch, VR-12, shortened Disabilities of the Arm, Shoulder, and Hand Questionnaire (QuickDASH), and Boston Carpal Tunnel Questionnaire. The time to the initiation of rehabilitation and complications were also analyzed. The comparison group consisted of patients who underwent independent TSA or CTR during the same period.

RESULTS

Forty-one patients underwent concomitant TSA and CTR, 248 underwent isolated TSA, and 154 underwent isolated CTR. The shoulder outcomes of patients who underwent the combined procedure were similar to those of patients who underwent isolated TSA in terms of pain, range of motion, general QoL (VR-12), and shoulder-specific QoL (Penn Shoulder Score). The outcomes of patients who underwent the combined procedure were similar to those of patients who underwent isolated CTR in terms of pain, grip and pinch, general QoL (VR-12), QuickDASH, and Boston Carpal Tunnel Questionnaire. The time to the initiation of rehabilitation was also comparable.

CONCLUSIONS

Concomitant CTR and TSA are feasible. The functional outcomes and QoL of patients who underwent the concomitant treatment were comparable with those of patients who underwent the 2 procedures separately.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Automated Nerve Monitoring in Shoulder Arthroplasty: A Prospective Randomized Controlled Study

BACKGROUND

Evoked potential monitoring is believed to prevent neurologic injury in various surgical settings; however, its clinical effect has not been scrutinized. It was hypothesized that an automated nerve monitor can minimize intraoperative nerve injury and thereby improve clinical outcomes in patients undergoing shoulder arthroplasty.

METHODS

A prospective, blinded, parallel group, superiority design, single-center, randomized controlled study was conducted. Study participants were equally randomized into either the automated nerve-monitored or the blinded monitored groups. The primary outcome was intraoperative nerve injury burden as assessed by the cumulative duration of nerve alerts. Secondary outcomes were neurologic deficits and functional scores of the operative arm, and the quality of life index (Euro Quality of life-5 domain-5 level score) at postoperative weeks 2, 6, and 12.

RESULTS

From September 2018 to July 2019, 213 patients were screened, of whom 200 were randomized. There was no statistically significant difference in the duration of nerve alerts between the automated nerve-monitored and control groups (median [25th, 75th interquartile range]: 1 [0, 18] and 5 [0, 26.5]; Hodges-Lehman difference [95% CI]: 0 [0 to 1] min; P = 0.526). There were no statistically significant differences in secondary outcomes between groups. However, in the ancillary analysis, there were reductions in neurologic deficits and improvements in quality of life index occurring in both groups over the course of the study period.

CONCLUSIONS

Protection from nerve injury is a shared responsibility between surgeons and anesthesiologists. Although a progressive improvement of clinical outcomes were observed over the course of the study in both groups as a consequence of the real-time feedback provided by the automated nerve monitor, this trial did not demonstrate that automated nerve monitoring by itself changes important clinical outcomes compared with no monitoring.

EDITOR’S PERSPECTIVE

Incidence of peripheral nerve injury in revision total shoulder arthroplasty: an intraoperative nerve monitoring study

BACKGROUND

The incidence of nerve injuries in revision total shoulder arthroplasty (TSA) is not well defined in the literature and may be higher than that in primary procedures, with 1 study reporting a complication rate of 50% for shoulder revisions. Given that continuous intraoperative nerve monitoring (IONM) can be an effective tool in diagnosing evolving neurologic dysfunction and preventing postoperative injuries, the purpose of this study was to report on IONM data and nerve injury rates in a series of revision TSAs.

METHODS

A retrospective cohort review of consecutive patients who underwent revision TSA was performed from January 2016 to March 2020. Indications for revision included infection (n = 7); failed total arthroplasty and hemiarthroplasty secondary to pain, dysfunction, and/or loose components (n = 36); and periprosthetic fracture (n = 1). Of the shoulders, 32 underwent revision to a reverse TSA, 6 underwent revision to an anatomic TSA, and 6 underwent spacer placement. IONM data included transcranial electrical motor evoked potentials (MEPs), somatosensory evoked potentials, and free-run electromyography. The motor alert threshold was set at ≥80% signal attenuation in any peripheral nerve. Patients were screened for neurologic deficits immediately following surgery, prior to administration of an interscalene nerve block, and during the first 2 postoperative visits. Additional data collection included surgical indication, sex, laterality, age at surgery, procedure performed, body mass index, history of tobacco use, Charlson Comorbidity Index, medical history, and preoperative range of motion.

RESULTS

A total of 44 shoulders in 38 patients were included, with a mean age of 63.2 years (standard deviation, 13.0 years). Of the procedures, 22.4% (n = 10) had an MEP alert, with 8 isolated to a single nerve (7 axillary and 1 radial) and 1 isolated to the axillary and musculocutaneous nerves. Only 1 patient experienced a major brachial plexus alert involving axillary, musculocutaneous, radial, ulnar, and median nerve MEP alerts, as well as ulnar and median nerve somatosensory evoked potential alerts. Age, sex, body mass index, Charlson Comorbidity Index, and preoperative range of motion were not found to be significantly different between cases in which an MEP alert occurred and cases with no MEP alerts. In the postoperative period, no minor or major nerve injuries were found whereas distal peripheral neuropathy developed in 4 patients (9.1%).

CONCLUSION

Among 44 surgical procedures, no patients (0%) had a major or minor nerve injury postoperatively and 4 patients (9.1%) complained of distal peripheral neuropathy postoperatively. In this study, we have shown that through the use of IONM, the rate of minor and major nerve injuries can be minimized in revision shoulder arthroplasty.

Neurologic complications in primary anatomic and reverse total shoulder arthroplasty: A review

Neurologic injury during shoulder replacement is one of the less common complications of the procedure, however the clinical implications can be significant. The purpose of this paper is to review the current literature on neurologic complications in various types of shoulder replacement and provide recommendations regarding avoidance, evaluation, and management of these complications.

A novel approach of using brachial plexus blockade as an experimental model for diagnosis of intraoperative nerve dysfunction with somatosensory evoked potentials: a blinded proof-of-concept study

PURPOSE

Intraoperative nerve dysfunction has been difficult to investigate because of its rarity and unpredictable occurrence. The diagnostic test attributes of nerve function monitors have not been clearly defined. This proof-of-concept study aimed to assess the feasibility of using brachial plexus blockade (BPB) in awake patients as an experimental model for nerve dysfunction to characterize the diagnostic test attributes of somatosensory evoked potentials (SSEPs).

METHODS

We obtained baseline SSEPs and neurologic function in patients and subsequently placed BPBs (experimental model) to generate progressive states of nerve dysfunction. We monitored SSEP changes (index test) and neurologic symptoms (reference standard) simultaneously during the onset of BPB to determine the temporal relationships and diagnostic test attributes of SSEPs.

RESULTS

Brachial plexus blockade produced differential motor and sensory dysfunction that allowed simultaneous clinical and neurophysiologic assessment. One hundred and fifty-seven pairs of multiple data points from 14 patients were included for final analysis. The onset of abnormal SSEP signals almost always preceded the onset of neurologic symptoms. The sensitivities and specificities of SSEP to detect the impairment of power (motor rating score ≤ 4/5), cold sensation, and two-point discrimination were 100% and 67%, 99% and 55%, and 100% and 46%, respectively.

CONCLUSION

This study found that BPB can produce sufficient differential nerve dysfunction to allow adequate evaluation of the diagnostic test attributes of SSEPs as a nerve monitor. The results of this study may stimulate further work on refining intraoperative nerve dysfunction models and diagnostic nerve function monitors.

TRIAL REGISTRATION

www.clinicaltrials.gov (NCT03409536); registered 24 January 2018.

Neuropraxia: An Underappreciated Morbidity of Liver Transplantation

BACKGROUND

Peripheral nerve injuries can be devastating complications of surgery, potentially resulting in severe functional disability and decreased quality of life. Long surgeries with considerable tissue manipulation, for example, liver transplantation, may present increased risk; however, neuropraxia in transplantation has not been well investigated.

MATERIALS AND METHODS

This is a retrospective study of all adult patients undergoing liver transplantation at a large academic center between January 2013 and December 2015. Descriptive analyses, logistic regressions, and forward selection procedures were used to determine the odds of developing neuropraxia and associated factors.

RESULTS

Of the 283 liver recipients, the mean age was 55.8 y, 35.1% were female, 65.6% were Caucasian, 8.9% were African American, 16.7% were Hispanic, and mean model for end-stage liver disease sodium score at transplant was 24.2 ± 10.9. The underlying etiology was alcohol (26.2%), hepatitis C (34.8%), nonalcoholic steatohepatitis (13.1%), and other (14.2%). The incidence of neuropraxia after liver transplantation was 8.3% (n = 25), with 60% (n = 16) upper extremities, 82% left sided, and 84% male. There was no difference in age, race, body mass index, hypertension, diabetes, hyperlipidemia, or smoking in those with neuropraxia versus those without. In multivariate analysis, neuropraxia was significantly associated with male gender, lower model for end-stage liver disease score, and longer duration of surgery (P < 0.05). Symptoms lasted median 5 d, with a wide range up to 187 d. Neuropraxia-specific treatment (physical therapy or medications) was required in 32% (n = 9).

CONCLUSIONS

Peripheral nerve injuries are an unexplored complication of liver transplantation. Although transient, a high number (8.2%) of patients developed neuropraxia, negatively affecting their ability for recovery. Exploration of mechanisms for minimizing risk and intraoperative detection and prevention should be considered to mitigate this complication.

Peripheral Nerve Injury in Thoracic Surgery Detected by Automated Somatosensory Evoked Potential Monitoring

Study Objective. Our objectives were to estimate the incidence of symptoms of peripheral nerve injury (sPNI) in thoracic surgical patients undergoing video-assisted thoracic surgery or open thoracotomy and to determine whether intraoperative somatosensory evoked potentials (SSEPs) waveform changes correlate with postoperative peripheral neuropathic symptoms. Methods. We conducted a prospective observational study in the operating room of a tertiary hospital. We measured SSEPs intraoperatively and assessed patients for sPNI postoperatively. Results. Forty-four patients consented. Six were excluded from analysis. We found that 42% (95% confidence interval [CI] = 26% to 57%) of patients undergoing thoracic surgery had significant changes in SSEP amplitude and latency. Furthermore, 16% (95% CI = 4% to 28%) of patients had new postoperative symptoms of sensory or motor deficits in an upper extremity. We calculated a sensitivity of 66.7% (95% CI = 29.0% to 100%) and a specificity of 50% (95% CI = 33% to 67.3%) for the identification of sPNI based on automated intraoperative SSEP changes. Conclusions. We identified the incidence of SSEP changes in thoracic surgery (42%) and the incidence of postoperative sPNI after thoracic surgery (16%). We identified a positive correlation between intraoperative SSEP changes and postoperative sPNI, which after multivariate analysis was not significant given the small sample size of the study. By the time sensory and/or motor changes are detected postoperatively, it may be too late to reverse the nerve damage. Future versions of the EPAD device could provide anesthesiologists a way to monitor for the development of sPNI, and make changes before a potential injury becomes permanent.

Neuroanesthesiology Update

This review is intended to provide a summary of the literature pertaining to the perioperative care of neurosurgical patients and patients with neurological diseases. General topics addressed in this review include general neurosurgical considerations, stroke, neurological monitoring, and perioperative disorders of cognitive function.