Abnormal Somatosensory Evoked Potentials Research Articles

Evaluation of the Relationship between Pain Exposure and Somatosensory Evoked Potentials in Preterm Infants: A Prospective Cohort Study.

First, to compare somatosensory evoked potentials (SEPs) in preterm newborns without major brain injury studied at term equivalent age (TEA) with a term historical control group. Second, to investigate the impact of pain exposure during the first 28 days after birth on SEPs. Third, to evaluate the association between SEPs and Bayley-III at 2 years corrected age (CA). Infants born at <32 weeks' gestational age (GA) were studied with continuous-SEPs. First, SEP differences between preterm and term infants were analyzed. Second, regression analyses were conducted to explore the association between SEPs and painful procedures, and then between SEPs and neurodevelopment. 86 preterm infants were prospectively enrolled. Preterm infants exhibited prolonged N1 latencies, central conduction times (CCTs), lower N1-P1 amplitudes, and more recurrently abnormal SEPs compared to term infants. Higher pain exposure predicted longer N1 latency and slower CCT (all p < 0.005), adjusting for clinical risk factors. Younger GA and postmenstrual age (PMA) at SEP recording were associated with longer N1 latency and lower N1-P1 amplitude (all p < 0.005). A normal SEP at TEA positively predicted cognitive outcome at 2 years CA (p < 0.005). Pain exposure and prematurity were risk factors for altered SEP parameters at TEA. SEPs predicted cognitive outcome.

From periphery to center, untold story of pure neuritic leprosy: an electrophysiological study.

Pure neuritic leprosy (PNL) is uncommon form of leprosy involving peripheral nerves. Some isolated case reports have shown imaging changes in the central nervous system (CNS) and also impairment in visual evoked potential (VEP), somatosensory evoked potential (SSEP) and brain stem auditory-evoked potentials (BAEPs) parameters in PNL, but there is lack of large study. This prospective observational study evaluates impairment in these central conduction studies among PNL patients. We screened patients with leprosy presenting with features of neuropathy and/or thickened nerves. Patients with bacilli-positive nerve biopsies were included in the study and subjected to routine tests along with nerve conduction study (NCS), VEP, tibial SSEP and BAEPs. Parameters of these studies were analyzed based on data from previous studies. Of 76 patients screened for PNL 49 had positive findings in biopsy. Most of patients were male and mean age group was 46.35 ± 15.35years. Mononeuritis multiplex was most common NCS pattern in 46.93% (23/49) patients. We found abnormal VEP in 13 out of 35 patients (37.14%). Similarly abnormal SSEP and BAEPs among 42.85% and 40% patients respectively. This study shows that in PNL significant number of patients have subclinical CNS involvement. Exact pathophysiology of CNS involvement is not known till now but study of VEP, SSEP and BAEPs parameter may help in early diagnosis of PNL.

Multimodal evoked potentials are useful for the diagnosis of pediatric acute disseminated encephalomyelitis.

The application of evoked potentials (EPs) to the diagnosis of acute disseminated encephalomyelitis (ADEM ) has not been investigated in detail. The aim of this study, therefore, was to analyze the value of multimodal EPs in the early diagnosis of pediatric ADEM. This was a retrospective study in which we enrolled pediatric ADEM patients and controls (Cs) from neurology units between 2017 and 2021. We measured indices in patients using brainstem auditory evoked potentials (BAEPs), visual evoked potentials (VEPs) and somatosensory evoked potentials (SEPs), and then we analyzed their early diagnostic value in ADEM patients. The mean age of the ADEM group was 6.15 ± 3.28 years (range,1-12 years) and the male/female ratio was 2.1:1 The mean age of the Cs was 5.97 ± 3.40 years (range,1-12 years) and the male/female ratio was 1.3:1. As we used magnetic resonance imaging (MRI) as the diagnostic criterion, the sensitivity, specificity, and accuracy (κ was 0.88) of multimodal EPs were highly consistent with those of MRI; and the validity could be ranked in the following order with respect to the diagnosis of ADEM: multimodal Eps > single SEP > single VEP > single BAEP. Of 34 patients with ADEM, abnormalities in multimodal EPs were 94.12%, while abnormalities in single VEPs, BAEPs and SEPs were 70.59%,64.71%and 85.3%, respectively. We noted significant differences between single VEP/BAEPs and multimodal EPs (χ2 = 6.476/8.995,P = 0.011/0.003). The combined application of multimodal EPs was superior to BAEPs, VEPs, or SEPs alone in detecting the existence of central nerve demyelination, and we hypothesize that these modalities will be applicable in the early diagnosis of ADEM.

Evaluating somatosensory evoked potentials in predicting treatment outcomes for thoracolumbar spinal compression fractures using closed reduction and over-extension techniques.

To evaluate the predictive value of somatosensory evoked potentials (SEPs) for the efficacy of closed reduction combined with over-extension reduction technique (PVP) in managing thoracolumbar spinal compression fractures. Data were collected from 125 patients who underwent closed reduction with PVP and SEP monitoring from February 2021 to July 2023. We evaluated surgery success rates, incidence of bone cement leakage, and patient recovery outcomes including vertebral anterior height, Oswestry Disability Index (ODI), and Cobb angle restoration. SEP results were analyzed to categorize patients into effective and ineffective treatment groups. Differences in SEP waveforms between these groups were examined, and ROC analysis was used to assess the predictive value of these differences. Multivariate logistic regression was employed to identify risk factors affecting treatment efficacy. Post-treatment assessments showed significant improvements in vertebral anterior height, ODI, and Cobb angle. SEP monitoring correlated well with intraoperative findings and physical examinations. During reduction, changes in SEP latency and amplitude were noted in 37 patients, with 7 patients meeting SEP amplitude alarm criteria, which normalized after adjustments. During PVP, 28 patients exhibited SEP amplitude fluctuations and 5 experienced a 30% reduction in amplitude following initial cement injection, with no significant latency changes. Treatment was deemed effective in 93 patients and ineffective in 32. SEP amplitudes during vertebral compression and PVP were significantly lower in the effective group (P<0.05). The AUC for predicting treatment efficacy was 0.819 and 0.859, respectively. Multivariate analysis revealed low preoperative vertebral compression ratio, number of fractures, and abnormal SEP amplitudes as independent risk factors for treatment outcomes. SEP monitoring provides an accurate reflection of spinal cord function during closed reduction with PVP, aiding in predicting treatment safety and efficacy. The use of SEP monitoring is thus recommended for clinical application in this context.

Somatosensory evoked potentials in spinocerebellar ataxias type 3 and 10: Preliminary data (P8-11.012)

<h3>Objective:</h3> To report the electrophysiological findings presented in somatosensory evoked potentials in a cohort of patients with spinocerebellar ataxias type 3 and 10, comparing them. <h3>Background:</h3> Although spinocerebellar ataxias (SCA) are heterogeneous diseases, the Brazilian patients with SCA 10 tend to have a low incidence of peripheral neuropathy. Electrophysiological testing might uncover subclinical abnormalities, and somatosensory evoked potentials (SSEPs) can provide further insights by evaluating the dorsal column-medial lemniscus pathway. <h3>Design/Methods:</h3> This is a cross-sectional study evaluating the somatosensory evoked potentials in a cohort of patients with SCA 3 (n = 15) and SCA 10 (n = 8). The patients underwent a clinical evaluation in which demographic and clinical data, such as sex, age, duration of disease, and SARA scores, were registered. After the clinical evaluation, all patients were submitted to somatosensory evoked potentials following the American College of Neurophysiology guidelines. We evaluated amplitudes, latencies, and interpeak latencies for the N9, N20, N21, and P40 potentials. <h3>Results:</h3> The groups did not differ regarding demographic and clinical data. In the cohort of patients with SCA 3, 86% of the sample (n = 13) presented SSEP abnormalities, while only 12.5% (n = 1) of the SCA 10 sample presented abnormalities, and this difference was statistically significant (<i>p</i> = 0.001). Correlations of SSEP abnormalities to SARA scores (SCA 3: Rho = 0.11, <i>p</i> = 0.6866; SCA 10: Rho = − 0.41, <i>p</i> = 0.31) and duration of disease (SCA 3: Rho = − 0.13, <i>p</i> = 0.626; SCA 10: Rho = − 0.58, <i>p</i> = 0.136) did not present statistical significance. <h3>Conclusions:</h3> Our preliminary data indicate that the Brazilian patients with SCA 10 present a low incidence of SSEP abnormalities, suggesting that the dorsal column-medial lemniscus pathway. Our findings are following most of the descriptions of clinical phenotypes for Brazilian patients with SCA 10. <b>Disclosure:</b> Dr. Coutinho has nothing to disclose. Dr. Hernandez Fustes has nothing to disclose. Miss Nunes has nothing to disclose. Patricia Bonilha has nothing to disclose. Miss Cassarotti has nothing to disclose. Dr. Bayer has nothing to disclose. Dr. Filpo has nothing to disclose. Dr. Cassou has nothing to disclose. Dr. Teive has nothing to disclose.

Intra-Operative Neurophysiological Monitoring in Patients with Thoracic Spinal Stenosis: Its Feasibility and High-Risk Factors for New Neurological Deficit.

Considering the high risk of postoperative neurological complications for patients with thoracic spinal stenosis (TSS), intra-operative neurophysiological monitoring (IONM) has been used for detecting possible iatrogenic injury timely. However, the IONM waveforms are often unreliable. This article is designed to determine the test performance of somatosensory evoked potentials (SEP) and motor evoked potentials (MEP) during surgical thoracic decompression in patients with TSS, and to investigate the risk factors associated with deteriorated neurologic function at immediate postoperation. Patients undergoing posterior spinal fusion from February 2009 to December 2020 were retrospectively reviewed. Patients were divided into the deteriorated neurologic function (DNF) group and the improved/intact neurological function (INF) group based on the postoperative neurological status. Demographic parameters such as gender, age, height, weight, etiology and IONM data were compared between groups. Demographics and IONM data between DNF and INF groups were compared by independent t or nonparametric tests. The incidence of abnormal SEP was analyzed by Chi-square test. A total of 108 patients (63 males, 45 females) with an average age of 53.5 ± 14.0 years were included. The SEP and MEP records were available in 94 and 98 patients, with the overall success rates being 87.0% and 90.7%, respectively. The sensibilities and specificities were 100% and 88.2% for SEP, 100% and 98.8% for MEP, respectively. There were 17 patients in DNF group and 91 patients in INF group. High weight (79.1 ± 14.6 vs 69.7 ± 15.7 kg, P = 0.024), high inter-side difference of MEP amplitude (899.1 ± 997.5 vs 492.3 ± 512.4 μV, P = 0.013) and high incidence of abnormal SEP (94.1% vs 64.8%, P = 0.024) were observed in the DNF group. Fourteen (82.4%) patients in the DNF group showed improvement in neurological status during follow-up. The overall success rates were 87.0% for SEP and 90.7% for MEP in patients with TSS.

Role of Intraoperative Neurophysiological Monitoring in Preventing Stroke After Cardiac Surgery

BackgroundPerioperative stroke after cardiac surgical procedures carries significant morbidity. Dual intraoperative neurophysiological monitoring with electroencephalography (EEG) and somatosensory-evoked potentials detects cerebral hypoperfusion and predicts postoperative stroke in noncardiac procedures. We further evaluated preoperative risk factors and intraoperative neuromonitoring ability to predict postoperative stroke after cardiac operations. MethodsAll patients who underwent cardiac operations with intraoperative neurophysiological monitoring from 2009 to 2020 at a single academic medical center were retrospectively analyzed. Patients with circulatory arrest were excluded. Risks factors analyzed were sex, age, tobacco use, hypertension, diabetes mellitus, dyslipidemia, atrial fibrillation, prior cerebrovascular accident, cerebrovascular disease, antiplatelet/anticoagulant use, abnormal somatosensory-evoked potentials and EEG baselines, and significant somatosensory-evoked potentials and EEG change as well as their permanence. Patients were divided into 2 groups by 30-day postoperative stroke occurrence. Univariate and multivariate logistical regressions were used for postoperative stroke significant predictors, and Kaplan-Meier curves estimated survival. ResultsThe study included 620 patients (67.6% men), mean age 65.1 ± 14.1 years, with stroke in 5.32%. In univariate analysis, diabetes (odds ratio [OR], 2.62) and permanence of EEG change (OR, 5.35) were each associated with increased postoperative stroke odds. In multivariate analysis, diabetes (OR, 2.64) and permanent EEG change (OR, 4.22) were independently significantly associated with postoperative stroke. Overall survival was significantly better for patients with no intraoperative neurophysiological monitoring changes (P < .005). ConclusionsPermanent EEG change and diabetes were significant postoperative stroke predictors in cardiac operations. Furthermore, overall survival out to 10 years postoperatively was significantly higher in the group without intraoperative neurophysiological monitoring changes, emphasizing its important predictive role.

Tibial nerve SEPs in diagnosing lumbar spinal stenosis: The utility of segmental evaluation using P15 and N21

ObjectiveTo establish the utility of the additional evaluation of the P15 potential generated at the greater sciatic foramen in the tibial nerve somatosensory evoked potentials (SEPs) in diagnosing lumbar spinal stenosis (LSS). MethodsWe retrospectively reviewed tibial nerve SEP findings in patients having MRI-confirmed LSS at the cauda equina or conus/epiconus region. P15 and N21 potentials were recorded and the following findings were defined as localizing abnormalities: 1) normal P15 latency either with prolonged P15-N21 interval or with absent N21; 2) decreased ratio of the N21 amplitude to P15 amplitude. As non-localizing abnormalities, N21 and P38 latencies were also evaluated. Tibial nerve F-wave findings were also investigated. ResultsAccording to the entry criteria, 18 patients were included, 15 with cauda equina lesions and 3 with conus/epiconus lesions. Localizing abnormalities in SEPs were found in 67% of patients, achieving significantly higher sensitivity than delayed P38 latency (28%), and higher sensitivity than N21 abnormalities (39%), though this was not significant. Localizing abnormalities were observed even in 6 out of 11 patients lacking both sensory symptoms and signs. Tibial nerve F-wave was abnormal in 36% of 14 patients with F-wave examinations, whereas the localizing abnormalities in SEPs were found in 64% of the same patient population. P15 amplitude was depressed in 4 patients (22%), which may indicate the involvement of the dorsal root ganglion in LSS, although its latency was normal even for these patients. ConclusionsTibial nerve SEPs with the recording of P15 and N21 potentials achieved sufficiently high sensitivity in diagnosing LSS. They have the advantage over F-wave in that they can localize the lesion at the cauda equina or conus/epiconus level. SignificanceTibial nerve SEPs are promising in evaluating LSS, especially in documenting sensory tract involvement in cases lacking sensory symptoms/signs.

Correlation of urodynamic studies and somatosensory evoked potential and their prognostic value in children with closed spinal dysraphism

Somatosensory evoked potential (SSEP) and urodynamic studies (UD) are valuable tools for assessing patients with closed spinal dysraphism (CSD) before neurosurgical intervention. No studies have correlated their findings in this cohort and our aim is to study their correlation and prognostic value in pediatric patients with closed spinal dysraphism. Retrospective review of all patients referred to a multidisciplinary clinic in a tertiary pediatric surgical center over a 17 years period between April 2004 to September 2021 was performed. Inclusion criteria were <18 years old, diagnosed with CSD, with SSEP and UD done within 1 year of each other. Demographics data collected include age at presentation/at referral/at neurosurgical operation, gender, symptoms at presentation and intra-operative diagnoses. Pre-operative SSEP and UD findings were documented. Primary outcome was UD results in the group with normal and abnormal SSEP. Secondary outcome was urological and bowel function outcome in 4 groups of patients (Group A-both normal SSEP and UD, Group B- abnormal SSEP only, Group C - abnormal UD only and Group D-both abnormal SSEP and UD). A total of 45 patients were included for analysis. Mean follow up time was 118.9 months (24-216 months, SD 55.8 months). SSEP was normal in 20 patients and abnormal in 25 patients. Baseline demographics, preoperative symptoms and imaging were similar between 2 groups. Primary outcome Patients with abnormal SSEP were more likely to have abnormal UD results with a statistically significant difference (84% vs 40%, p<0.05). They have a significantly higher end-fill detrusor pressure (12% vs 0%, p<0.05), abnormal bladder compliance (20% vs 0%, p<0.05), abnormal cystometric capacity (48% vs 10%, p<0.05), poor emptying efficiency (24% vs 5%, p<0.05) and sphincter incompetence (8% vs 0%, p<0.05). Secondary outcome When compared to Groups A to C, patients in group D were more likely to be on anti-cholinergic (33.3% vs 4.3%, p<0.05), required clean intermittent catheterization (42.9% vs 4.3%, p<0.05) and had intravesical botulinum injection (19% vs 0%, p<0.05). All the patients who had augmentation cystoplasty were in this group as well. Bowel function in terms of regular enema use was also statistically significantly higher in this group (33.4% p<0.05). Pre-operative SSEP and UD results correlate well in patients with closed spinal dysraphism. Patients with abnormal SSEP and UD preoperatively have higher risk of urological deterioration over time. Close monitoring in this group is warranted.

Dermatomal somatosensory evoked potentials and cortical somatosensory evoked potentials assessment in congenital scoliosis

BackgroundThe aim of this study was to assess the value of dermatomal somatosensory evoked potentials (DSEPs) and cortical somatosensory evoked potentials (SSEPs) in monitoring spinal cord function for patients with congenital scoliosis (CS).MethodsThis retrospective study reviewed the medical records of patients (n = 102) who underwent DSEP (T2-S1 dermatome), of whom 60 were normal subjects and 62 with congenital scoliosis. The study analyzed the latencies and peaks of N1-L, N1-R, P1-L and P1-R recorded by DSEPs of patients’ thoracolumbar dermatomes. To observe the incidence of abnormal DSEPs and SSEPs in CS patients and to analyze the difference in sensitivity and reliability between the two in the examination of scoliosis patients. SPSS 22.0 statistical software package was used to analyze the data, and χ2 test and correlation analysis were used to indicate that the difference was statistically significant, p < 0.05.ResultsSixty two patients with CS were evaluated with total spine magnetic resonance imaging (MRI). Only 23 patients (37.09%) showed spinal cord malformations in the MRI findings. The DSEP recordings showed a relatively high sensitivity (97.8%) compared to the abnormality rate of SSEPs recordings, and the rates of waveform, latency and amplitude abnormalities were much higher in DSEPs recordings (36.6, 36.3, 24.8%) than in SSEPs recordings (3.2, 22.5, 14.5%). The abnormality rate of DSEP records with and without neurological symptoms was higher than the abnormality rate of SSEP records (100% vs 20, 96.2% vs 44.2%, p<0.05). And in 62 patients with CS, the rate of positive MRI (37.1%) was lower than that recorded by DSEP (79.6% / 57.9%). p < 0.05.ConclusionDSEPs are more sensitive to microscopic posterior column dysfunction in patients with CS that cannot be detected by either radiology or routine clinical examination. Preoperative DSEPs assessment is recommended as a baseline examination for intraoperative monitoring and comparison with the postoperative situation. DSEPs recording complements the information obtained from routine clinical and radiological evaluation.

Application of multimodal neuroelectrophysiological monitoring technology in surgical treatment of thoracic tuberculosis

To explore the value of multimodal neuroelectrophysiological monitoring technology in the evaluation of spinal cord and nerve root function for the treatment of thoracic tuberculosis with debridement and bone grafting and posterior internal fixation by transcostal transverse process approach. The clinical data of 25 patients with thoracic tuberculosis underwent debridement and bone grafting and posterior vertebral arch internal fixation by transcostal transverse process approach from December 2018 to September 2019 was retrospectively analyzed. Among these 25 patients, including 14 males and 11 females;aged from 20 to 83 years old, with a mean of (63.45±9.65) years;there were 3 cases of single vertebral body destruction, 13 cases of 2 vertebral bodies destruction, and 9 cases of 3 or more vertebral bodies destruction. All surgical patients underwent intraoperative detection of somatosensory evoked potential(SEP) and transcranial electric stimulation-motor evoked potential(TES-MEP);and electromyography (EMG) was used to monitor the pedicle screw placement and lesion removal. The erythrocyte sedimentation rate(ESR) was used to evaluate the decline of inflammatory indexes, the visual analogue scale (VAS) was used to evaluate the thoracic spine pain, and the Cobb angle and Oswestry Disability Index(ODI) were used to evaluate the improvement of function. All 25 patients were successfully monitored. Five patients had abnormal SEP waveforms during operation, 3 cases were caused by intraoperative clearing of lesions and spinal cord compression during irrigation, timely replacement of instruments and gestures, and adjustment of irrigation water flow rate returned the waveform to normal; one case was caused by a decrease in systolic blood pressure, and the waveform returned to normal after timely treatment of increased blood pressure;after 1 case of SEP waveform abnormality, the operation was suspended for 10 minutes and recovered spontaneously, and the waveform abnormality did not reappear until the end of the operation. Seven patients had abnormal TES-MEP waveforms, 5 cases occurred when the pedicle screw was inserted, the nail path was adjusted in time, and the waveform recovered after nail repositioning;one case was caused by tilting the operation bed during operation, and the waveform gradually recovered after adjusting the tilt angle of operation bed; one case occurred during the correction of the pedicle screw and rod system, and the waveform gradually returned to normal after the contralateral screw and rod correction were completed during operation. In 5 cases, the EMG burst potential was detected at the same time when the TES-MEP waveform was abnormal. After adjustment, the EMG burst potential disappeared. There was no abnormality in the TES-MEP and SEP waveforms at the same time. Postoperative VAS, ESR, Cobb angle, and ODI were improved compared with preoperatively (P<0.05). In patients with thoracic tuberculosis, the use of debridement and bone grafting and posterior internal fixation by transcostal transverse process approach combined with intraoperative SEP, TES-MEP and EMG monitoring can timely reflect the spinal cord and nerve root function, avoid intraoperative injuries while achieving good fixation and lesion removal.

Study of Short Latency Somatosensory and Brain Stem Auditory Evoked Potentials Patients with Acute Ischemic Stroke Involving Middle Cerebral Artery Territory.

Background The precise timings of evoked potentials in evaluating the functional outcome of stroke have remained indistinct. Few studies in the Indian context have studied the outcome of early prognosis of stroke utilizing evoked potentials. Objective The aim of this study was to determine somatosensory evoked potentials (SSEPs) and brain stem auditory evoked potentials (BAEPs), their timing and abnormalities in acute ischemic stroke involving the middle cerebral artery (MCA) territory and to correlate SSEP and BAEP with the functional outcome (National Institutes of Health Stroke Scale (NIHSS), modified Rankin scale (mRS) and Barthel’s index) at 3 months. Methods MCA territory involved acute ischemic stroke patients ( n = 30) presenting consecutively to the hospital within 3 days of symptoms onset were included. Details about clinical symptoms, neurological examination, treatment, NIHSS score, mRS scores were collected at the time of admission. All patients underwent imaging of the brain and were subjected to SSEP and BAEP on two occasions, first at 1 to 3 days and second at 4 to 7 days from the onset of stroke. At 3 months of follow-up, NIHSS, mRS, and Barthel’s index were recorded. Results P37 and N20 amplitude had a strong negative correlation (at 1–3 and 4–7 days) with NIHSS at admission, NIHSS at 3 months, mRS at admission, and mRS at 3 months and a significant positive correlation with Barthel’s index ( p < 0.0001). BAEP wave V had a negative correlation (at 1–3 and 4–7 days) with NIHSS at admission, NIHSS at 3 months, mRS at admission, and mRS at 3 months and a positive correlation with Barthel’s index ( p < 0.0001). Conclusion SSEP abnormalities recorded on days 4 to 7 from onset of stroke are more significant than those recorded within 1 to 3 days of onset of stroke; hence, the timing of 4 to 7 days after stroke onset can be considered as better for predicting functional outcome.

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.

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

A Hybrid Strategy for Patients With Complex Cerebral Aneurysm: STA-MCA Bypass in Combination With Endovascular Embolization.

Objective: This work aims to present our experience of patients with complex cerebral aneurysm treated with a hybrid approach: superficial temporal artery–middle cerebral artery (STA–MCA) bypass in combination with endovascular exclusion of the aneurysm.Method: Patients with aneurysms deemed unclippable and uncoilable were included. All patients were treated with a hybrid approach. After STA–MCA bypass, the parent artery was temporarily occluded. If the intraoperative motor evoked potential (MEP) and somatosensory evoked potential (SEP) waveforms remain normal and last for 30 min, the aneurysm and te parent artery will be embolized permanently with detachable balloons or coils.Results: A total of 20 patients with 22 aneurysms were included in this study. There were 13 women and 7 men, with an average age of 42.5 years. Intraoperative angiography showed the good patency of all the STA grafts, and neither SEP nor MEP abnormalities were detected. After the parent artery and the aneurysm were occluded, the intraoperative angiography showed an immediately successful exclusion of the aneurysm in 20 aneurysms and immediate contrast stasis in two. All patients recovered uneventfully without ischemic or hemorrhagic complication. Angiography at 6-month follow-up showed the total obliteration in 20 aneurysms. Two aneurysms showed residuals and were recoiled. All STA grafts showed a good patency, and the mean graft flow was 124.2 ml/min.Conclusion: STA–MCA bypass in combination with endovascular exclusion is an appropriate option for patients with complex cerebral aneurysms that are not amenable to direct surgical clipping or endovascular embolization.

Chronic immune polyradiculopathies: Three clinical variants of one disease?

Chronic immune polyradiculopathies (sensory, motor, and mixed) are uncommon. In this single-center, retrospective study, the inclusion criteria for participants were progressive sensory ataxia and/or areflexic limb weakness; tibial somatosensory evoked potential (SSEP) abnormalities of the N22 and P40 potentials with normal sensory and motor nerve conduction studies or root involvement, according to magnetic resonance imaging (MRI); and albuminocytological dissociation. Eight patients were included in our study. Two had weakness, two had sensory ataxia, and four had both weakness and ataxia. Patients with weakness had abnormal SSEPs and patients with sensory ataxia also had absent F waves. Electromyography showed chronic denervation. MRI scans confirmed thickening and enhancement of roots. The patients responded to corticosteroid treatment. The overlapping clinicoelectrophysiological findings and similarities in radiological and therapeutic responses suggest that these entities are clinical variants of the same disease. The terms CIS(m)P, CI(s)MP, and CISMP (for chronic immune sensory motor polyradiculopathy) could be used to denote the predominant clinical involvement.

Utility of Motor and Somatosensory Evoked Potentials for Neural Thermoprotection in Ablations of Musculoskeletal Tumors

PurposeTo characterize the utility of monitoring transcranial electrical motor evoked potentials (TCeMEPs) and somatosensory evoked potentials (SSEPs) for neural thermoprotection during musculoskeletal tumor ablations. Materials and MethodsRetrospective review of 29 patients (16 male; median age, 46 y; range, 7–77 y) who underwent musculoskeletal tumor radiofrequency ablation (n = 8) or cryoablation (n = 22) with intraprocedural TCeMEP and SSEP monitoring was performed. The most common tumor histologies were osteoid osteoma (n = 6), venous malformation (n = 5), sarcoma (n = 5), renal cell carcinoma (n = 4), and non–small-cell lung cancer (n = 3). The most common tumor sites were spine (n = 22) and lower extremities (n = 4). Abnormal TCeMEP change was defined by 100-V increase above baseline threshold activation for a given myotome; abnormal SSEP change was defined by 60% reduction in baseline amplitude and/or 10% increase in latency. ResultsAbnormal changes in TCeMEP (n = 9; 30%) and/or SSEP (n = 5; 17%) occurred in 12 procedures (40%) and did not recover in 5 patients. Patients with unchanged TCeMEP/SSEP activities throughout the procedure (n = 18) did not have motor or sensory symptoms after the procedure; 3 (60%) with unrecovered activity changes and 2 (29%) with transient activity changes had new motor (n = 1) or sensory (n = 4) symptoms. Relative risk for neurologic sequelae for patients with unrecovered TCeMEP/SSEP changes vs those with transient or no changes was 7.50 (95% confidence interval, 1.66–33.9; P = .009). ConclusionsAbnormal activity changes of TCeMEP or SSEP during percutaneous ablative procedures correlate with postprocedural neurologic sequelae.

Electrophysiological features of patients with subacute combined degeneration

Objective: To investigate the electrophysiological features of patients with subacute combined degeneration (SCD). Methods: The electrophysiological data of 85 hospitalized patients in Department of Neurology, First Medical Centre, Chinese PLA General Hospital from January 2014 to September 2018 were retrospectively analyzed. Results: Abnormality rate of motor nerve conduction (27.4%(93/339)) was lower than that of sensory nerve conduction (45.9%(107/233)) (P<0.001). Abnormality of sensory nerve action potential amplitude was more frequent than conduction velocity abnormality (22.7%(53/233) vs 4.7%(11/233), P=0.001). Abnormality rate of needle electromyogram (EMG) was higher in lower limbs than upper limbs (31.9%(59/185) vs 5.7%(5/87), P<0.001). Spontaneous potentials were unrelated to disease duration or severity. Abnormal somatosensory evoked potential (SEP) results appeared more frequent in lower limbs (80.8%(118/146)) than upper limbs (61.1%(77/126)) (P<0.001). SEP abnormalities (71.7%(195/272)) were more common than nerve conduction abnormalities (35.0%(200/572)). Abnormal findings presented in 15/16 of visual evoked potential (VEP) studies. Neurological severity score were correlated with electrophysiological findings. Conclusions: Posterior funiculus is more likely to be affected than peripheral nerves in SCD patients. The sensory nerves rather than motor nerves, lower limbs rather than upper limbs, axons of sensory nerves rather than myelin, are more severely affected. Electrophysiological tests can provide evidence in early diagnosis, lesions location, and disease severity evaluation for SCD.

Somatosensory and motor evoked potentials during correction surgery of scoliosis in neurologically asymptomatic Chiari malformation-associated scoliosis: A comparison with idiopathic scoliosis

ObjectivesTo analyze the somatosensory evoked potentials (SEPs) and motor evoked potentials (MEPs) in neurologically asymptomatic Chiari malformation-associated scoliosis (CMS) patients with and without syringomyelia as compared with those in idiopathic scoliosis (IS) ones, and to identify whether the deformities have impacts on the neurophysiological monitoring. Patients and methodsThis study included neurologically asymptomatic CMS patients undergoing posterior correction surgery between January 2010 and January 2016. IS patients were involved as control group and a subgroup of age- and height-matched IS patients were selected. The age, standing height and Cobb angles of main curve were measured. The SEPs latency and amplitude, MEPs amplitude, and the rate of abnormal SEPs pathologic change were compared between CMS and IS patients using independent-sample t-test and Chi-square test. ResultsSixty CMS patients and 210 IS patients were included. There was no difference between CMS patients and IS or matched IS patients in SEPs latency and amplitude, MEPs amplitude or rate of abnormal SEPs (p > 0.05). Forty-eight CMS patients concurrent with syringomyelia were associated with higher Cobb angle of main curve and lower SEPs amplitude than those without syringomyelia (p < 0.05). No significant difference was found between CMS patients with and without syringomyelia in age, height, SEPs latency, MEPs amplitude or rate of abnormal SEPs (p > 0.05). ConclusionNeurologically asymptomatic CMS patients showed similar absolute values of neurophysiological monitoring with IS patients. The syringomyelia in CMS indicated more severe curvature and lower SEPs amplitude even after posterior fossa decompression.

Safe range of shortening the middle thoracic spine, an experimental study in canine.

To determine the safe range of shortening the spinal column at middle thoracic spine and to observe the changes in blood-spinal cord barrier (BSCB), microglia/macrophage activation and inducible nitric oxide synthase (iNOS) activity after shortening-induced spinal cord injury. Dogs were allocated to four groups. Group A (control) underwent laminectomy of T7 without shortening the spinal column. Groups B, C and D had 1/3, 1/2, and 2/3 of T7 resected, respectively, followed by spinal shortening. Somatosensory evoked potential (SSEP) and hind-limb function were recorded periodically for 14days after operation. Spinal cord blood flow (SCBF) and BSCB were detected at the acute phase of shortening. Microglia/macrophage reactions and iNOS activity were observed by immunohistochemistry. Shortening of 1/3 of a vertebral height caused no significant changes in SSEP and hind-limb function after operation, whereas shortening of 1/2 of the height caused SSEP abnormality and paraparesis, and severe neurologic deficit of hind-limb was observed when the shortening reached 2/3 of the height. SCBF increased temporarily and showed a trend of recovery when the shortening was within 1/2 of a vertebral segment height. When it reached 1/2 or 2/3 of the height, SCBF at 6h post-operation was 86.33% or 74.95% of the baseline, and an increasing BSCB permeability was observed. In the subsequent 7days, obvious activation of macrophage and increased number of iNOS-positive cells were observed. It is safe to shorten the spinal cord within 1/3 of a vertebral height in middle thoracic spine under two-segment laminectomy in canine. The BSCB disruption, macrophage activation, and increased iNOS activity were observed in the acute phase of the injury. These slides can be retrieved under Electronic Supplementary Material.

Assesment of Functional Results for the Lesions Located in Eloquent Areas with Using Intraoperative Cortical-Subcortical Stimulation and Cortical Mapping.

To assess the classical and functional imaging features of patients with pathology located in the eloquent areas of the brain who were admitted to our centre between October 2012 and February 2018. We also studied intraoperative somatosensory evoked potential (SEP), motor evoked potentials (MEP), phase reversal, cortical mapping, the extent of resection and the calculation of postoperative morbidity. We compared our results with previous studies in which this technique was not used. The patient records of 163 patients were reviewed retrospectively after approval by the institutional ethics committee and comparisons were made with reports in the literature. The lesion was localised in the visual cortex in eight of the 163 patients. We did not encounter any abnormality in the VEP recordings, so the surgeries were continued. The remaining 155 cases were followed by intraoperative SEP and MEP monitoring. We observed a greater than 50% decrease in the amplitude and an increase in latencies that was greater than 10% in intraoperative MEP and SEP monitoring in 24 patients of 155. Although 8 of 24 patients with abnormal SEP and MEP values were corrected with manuveurs, 6 patients developed increased neurological deficits postoperatively. In conclusion, all of these methods should not be seen as competitive with each other; they could be considered as complementary. All of these methods are helpful for a surgical team regarding loss of neurological function. The rate of loss might be up to 100% and irreversible despite corrective maneveurs.