Hypothermia effects on neuronal plasticity post spinal cord injury.

BACKGROUND: SCI is a time-sensitive debilitating neurological condition without treatment options. Although the central nervous system is not programmed for effective endogenous repairs or regeneration, neuroplasticity partially compensates for the dysfunction consequences of SCI. OBJECTIVE AND HYPOTHESIS: The purpose of our study is to investigate whether early induction of hypothermia impacts neuronal tissue compensatory mechanisms. Our hypothesis is that although neuroplasticity happens within the neuropathways, both above (forelimbs) and below (hindlimbs) the site of spinal cord injury (SCI), hypothermia further influences the upper limbs' SSEP signals, even when the SCI is mid-thoracic. STUDY DESIGN: A total of 30 male and female adult rats are randomly assigned to four groups (n = 7): sham group, control group undergoing only laminectomy, injury group with normothermia (37°C), and injury group with hypothermia (32°C +/-0.5°C). METHODS: The NYU-Impactor is used to induce mid-thoracic (T8) moderate (12.5 mm) midline contusive injury in rats. Somatosensory evoked potential (SSEP) is an objective and non-invasive procedure to assess the functionality of selective neuropathways. SSEP monitoring of baseline, and on days 4 and 7 post-SCI are performed. RESULTS: Statistical analysis shows that there are significant differences between the SSEP signal amplitudes recorded when stimulating either forelimb in the group of rats with normothermia compared to the rats treated with 2h of hypothermia on day 4 (left forelimb, p = 0.0417 and right forelimb, p = 0.0012) and on day 7 (left forelimb, p = 0.0332 and right forelimb, p = 0.0133) post-SCI. CONCLUSION: Our results show that the forelimbs SSEP signals from the two groups of injuries with and without hypothermia have statistically significant differences on days 4 and 7. This indicates the neuroprotective effect of early hypothermia and its influences on stimulating further the neuroplasticity within the upper limbs neural network post-SCI. Timely detection of neuroplasticity and identifying the endogenous and exogenous factors have clinical applications in planning a more effective rehabilitation and functional electrical stimulation (FES) interventions in SCI patients.

Local contribution to the somatosensory evoked potentials in rat's thalamus.

Local Field Potential (LFP), despite its name, often reflects remote activity. Depending on the orientation and synchrony of their sources, both oscillations and more complex waves may passively spread in brain tissue over long distances and be falsely interpreted as local activity at such distant recording sites. Here we show that the whisker-evoked potentials in the thalamic nuclei are of local origin up to around 6 ms post stimulus, but the later (7-15 ms) wave is overshadowed by a negative component reaching from cortex. This component can be analytically removed and local thalamic LFP can be recovered reliably using Current Source Density analysis. We used model-based kernel CSD (kCSD) method which allowed us to study the contribution of local and distant currents to LFP from rat thalamic nuclei and barrel cortex recorded with multiple, non-linear and non-regular multichannel probes. Importantly, we verified that concurrent recordings from the cortex are not essential for reliable thalamic CSD estimation. The proposed framework can be used to analyze LFP from other brain areas and has consequences for general LFP interpretation and analysis.

Somatosensory evoked potentials recorded from DBS electrodes: the origin of subcortical N18.

The different peaks of somatosensory-evoked potentials (SEP) originate from a variety of anatomical sites in the central nervous system. The origin of the median nerve subcortical N18 SEP has been studied under various conditions, but the exact site of its generation is still unclear. While it has been claimed to be located in the thalamic region, other studies indicated its possible origin below the pontomedullary junction. Here, we scrutinized and compared SEP recordings from median nerve stimulation through deep brain stimulation (DBS) electrodes implanted in various subcortical targets. We studied 24 patients with dystonia, Parkinson's disease, and chronic pain who underwent quadripolar electrode implantation for chronic DBS and recorded median nerve SEPs from globus pallidus internus (GPi), subthalamic nucleus (STN), thalamic ventral intermediate nucleus (Vim), and ventral posterolateral nucleus (VPL) and the centromedian-parafascicular complex (CM-Pf). The largest amplitude of the triphasic potential of the N18 complex was recorded in Vim. Bipolar recordings confirmed the origin to be close to Vim electrodes (and VPL/CM-Pf) and less close to STN electrodes. GPi recorded only far-field potentials in unipolar derivation. Recordings from DBS electrodes located in different subcortical areas allow determining the origin of certain subcortical SEP waves more precisely. The subcortical N18 of the median nerve SEP-to its largest extent-is generated ventral to the Vim in the region of the prelemniscal radiation/ zona incerta.

Intraoperative Neurophysiological Monitoring in Corrective Surgery of Scoliosis - Experience at a Tertiary Care Hospital.

OBJECTIVE: To evaluate the role of intraoperative neurophysiological monitoring (IONM) in reducing the postoperative neurologic deficit following corrective surgery of scoliosis. STUDY DESIGN: Observational Study. Place and Duration of the Study: Spine Surgery Department, Combined Military Hospital, Rawalpindi, from December 2022 to May 2023. METHODOLOGY: The study included 170 cases of scoliosis operated under multimodal IONM. Decreased amplitude of ≥50% in SSEP or 70-80% in MEPs were considered warning signs. Cases were divided into two groups: Group 1 (signal drop) and Group 2 (no signal drop). Group 1 was subdivided into Group 1a (true positive), Group 1b (false positive) and Group 1c (intermediate positive). Group 2 was subdivided into Group 2a (true negative) and Group 2b (false negative). RESULTS: Evoked potential changes were observed in 27 (15.9%) cases. This includes transient drop of signals in 16 (9.4%) and sustained drop of signals in 11 (6.5%) cases. Among sustained signal drop, 9 (5.29%) cases had exhibited postoperative neurological deficit whereas 2 (1.17%) cases did not show postoperative neurological deficit (false positive). Multimodal IONM in the current study shows sensitivity of 100%, specificity of 98.6%, positive predictive value of 92.6%, and negative predictive value of 100%. CONCLUSION: Multimodal IONM reduces the incidence of postoperative neurological deficit in corrective surgery of scoliosis by effectively detecting neurologic injury during surgery. Monitoring events alert surgical team to exercise immediate corrective measures which likely results in recovery of lost signals and predict the favorable outcome. KEY WORDS: Intraoperative monitoring, Motor evoked potentials, Neurological deficit, Scoliosis, Somatosensory evoked potentials.

Intraoperative High-Resolution Color-Coded Ultrasound to Identify the Posterior Median Sulcus for Midline Myelotomy in Intramedullary Spinal Cord Surgery.

A 14-year-old boy presented with a 2-year history of slowly increasing weakness and atrophy in the right forearm and leg. Magnetic resonance imaging (MRI) revealed an intramedullary diffusely infiltrating lateralized tumor at C3-7. An extended biopsy was planned. After laminotomy and durotomy, the swollen spinal cord was noted to be rotated by 45° with the right dorsal root entry zone being in the midline. A 15 MHz linear ultrasound probe was used to identify the midline by visualizing the dorsal median sulcal vein within the midline raphe. A myelotomy was made in that zone without deterioration of somatosensory evoked potentials (SEPs) and an extended biopsy was performed. Histological examination revealed a pilocytic astrocytoma. Modern intraoperative high-resolution color-coded ultrasound enables the identification of the midline in intramedullary spinal cord lesions even when the spinal cord anatomy is distorted.

Intraoperative Neurophysiologic Monitoring and Mapping During Surgery on Intramedullary Spinal Cord Tumors in Children and Adolescents.

SUMMARY: Surgical resection of intramedullary spinal cord tumors carries significant risks of neurologic deficits, especially in cases of infiltrative tumors. In pediatric patients, this type of surgery may be associated with a high risk of poor neurologic outcome. Intraoperative neurophysiologic monitoring has been adopted as part of the clinical routine by many centers as a useful adjunct for intraoperative assessment of neurologic integrity. To what extent intraoperative neurophysiologic mapping strategies may further support intraoperative decision-making is still a matter of debate. Here, we report on a small cohort of five pediatric patients in whom mapping with the double-train paradigm was used to identify the dorsal column and corticospinal tract and to guide the surgical resection. We also discuss the possible benefits and challenges regarding the available literature.

Intraoperative Monitoring of Scoliosis Surgery in Young Patients.

SUMMARY: Intraoperative neurophysiologic monitoring has added substantially to the safety of spinal deformity surgery correction since its introduction over four decades ago. Monitoring routinely includes both somatosensory evoked potentials and motor evoked potentials. Either modality alone will detect almost all instances of spinal cord injury during deformity correction. The combined use of the two modalities provides complementary information, can permit more rapidly identification of problems, and enhances safety though parallel redundancy should one modality fail. Both techniques are well established and continue to be refined. Although there is room for provider preference, proper monitoring requires attention to technical detail, understanding of the underlying physiology, and familiarity with effects of commonly used anesthetic agents.

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

BACKGROUND: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.

Diagnostic utility of different types of somatosensory evoked potential changes in pediatric idiopathic scoliosis correction surgery.

PURPOSE: To evaluate the diagnostic accuracy of intraoperative somatosensory evoked potential (SSEP) monitoring and types of SSEP changes in predicting the risk of postoperative neurological outcomes during correction surgery for idiopathic scoliosis (IS) in the pediatric age group (≤ 21 years). METHODS: Database review was performed to identify literature on pediatric patients with IS who underwent correction with intraoperative neuromonitoring. The sensitivity, specificity, and diagnostic odds ratio (DOR) of transient and persistent SSEP changes and complete SSEP loss in predicting postoperative neurological deficits were calculated. RESULTS: Final analysis included 3778 patients. SSEP changes had a sensitivity of 72.9%, specificity of 96.8%, and DOR of 102.3, while SSEP loss had a sensitivity of 41.8%, specificity of 99.3%, and DOR of 133.2 for predicting new neurologic deficits. Transient and persistent SSEP changes had specificities of 96.8% and 99.1%, and DORs of 16.6 and 59, respectively. CONCLUSION: Intraoperative SSEP monitoring can predict perioperative neurological injury and improve surgical outcomes in pediatric scoliosis fusion surgery. LEVEL OF EVIDENCE: Level 2. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Subclinical Neck Pain Leads to Differential Changes in Early Somatosensory Evoked Potentials in Response to a Novel Force Matching Tracking Task.

BACKGROUND: Neural adaptions in response to sensorimotor tasks are impaired in those with untreated, recurrent mild-to-moderate neck pain (subclinical neck pain (SCNP)), due to disordered central processing of afferent information (e.g., proprioception). Neural adaption to force modulation, a sensorimotor skill reliant on accurate proprioception, is likely to be impaired in those with SCNP. This study examined changes in somatosensory evoked potential (SEP) peak amplitudes following the acquisition of a novel force matching tracking task (FMTT) in those with SCNP compared to non-SCNP. METHODS: 40 (20 female (F) & 20 male (M); average age (standard deviation, SD): 21.6 (3.01)) right-handed participants received controlled electrical stimulation at 2.47 Hz and 4.98 Hz (averaged 1000 sweeps/frequency) over the right-median nerve, to elicit SEPs before and after FMTT acquisition. Participants used their right thumb to match a series of force profiles that were calibrated to their right thumb (abductor pollicis brevis muscle) strength. To determine if motor learning was impacted, retention was assessed 24 to 48 hours later. Outliers were removed before running independent t-tests on normalized SEP peak amplitudes, and repeated measures analysis of variance (ANOVA) with planned contrasts on absolute and normalized motor performance accuracy. Benjamini-hochberg test was used to correct for multiple independent SEP comparisons. RESULTS: SEP peaks: N18 (t(29.058) = 2.031, p = 0.026), N20 (t(35) = -5.460, p < 0.001), and P25 (t(33) = -2.857, p = 0.004) had group differences. Motor performance: Absolute error (n = 38) had a main effect of time, and significant pre-and post-acquisition contrast for time (both p < 0.001). CONCLUSIONS: Group differences in the olivary-cerebellar pathway (N18), and cortical processing at the somatosensory cortex (N20 and P25), suggests that SCNP alters cortical and cerebellar processing compared to non-SCNP in response to FMTT acquisition. The sensory-motor integration differences in the SCNP group suggests that those with SCNP may rely more on feedback loops for discrete sensorimotor tasks dependent on proprioception. Early SEP changes may be used as a marker for altered neuroplasticity in the context of motor skill acquisition of a novel discrete FMTT in those with SCNP.

Cost-benefit analysis of intraoperative neuromonitoring for cardiac surgery.

BACKGROUND: Intraoperative neuromonitoring (IONM) can detect large vessel occlusion (LVO) in real-time during surgery. The aim of this study was to conduct a cost-benefit analysis of utilizing IONM among patients undergoing cardiac surgery. METHODS: A decision-analysis tree with terminal Markov nodes was constructed to model functional outcome, as measured via the modified Rankin Scale (mRS), among 65-year-old patients undergoing cardiac surgery. Our cost-benefit analysis compares the use of IONM (electroencephalography and somatosensory evoked potential) against no IONM in preventing neurological complications from perioperative LVO during cardiac surgery. The study was performed over a lifetime horizon from a societal perspective in the United States. Base case and one-way probabilistic sensitivity analyses were performed. RESULTS: At a baseline LVO rate of 0.31%, the mean attributable lifetime expenditure for IONM-monitored cardiac surgeries relative to unmonitored cardiac surgeries was $1047.41 (95% CI, $742.12 - $1445.10). At a critical LVO rate of approximately 3.67%, the costs of both monitored and unmonitored cardiac surgeries were the same. Above this critical rate, implementing IONM became cost-saving. On one-way sensitivity analysis, variation in LVO rate from 0% - 10% caused lifetime costs attributable to receiving IONM to range from $1150.47 - $29404.61; variations in IONM cost, percentage of intervenable LVOs, IONM sensitivity, and mechanical thrombectomy cost exerted comparably minimal influence over lifetime costs. DISCUSSION: We find considerable cost savings favoring the use of IONM under certain parameters corresponding to high-risk patients. This study will provide financial perspective to policymakers, clinicians, and patients alike on the appropriate use of IONM during cardiac surgery.

A Novel Approach to Screen for Somatosensory Evoked Potentials in Critical Care.

BACKGROUND: Somatosensory evoked potentials (SSEPs) help prognostication, particularly in patients with diffuse brain injury. However, use of SSEP is limited in critical care. We propose a novel, low-cost approach allowing acquisition of screening SSEP using widely available intensive care unit (ICU) equipment, specifically a peripheral "train-of-four" stimulator and standard electroencephalograph. METHODS: The median nerve was stimulated using a train-of-four stimulator, and a standard 21-channel electroencephalograph was recorded to generate the screening SSEP. Generation of the SSEP was supported by visual inspection, univariate event-related potentials statistics, and a multivariate support vector machine (SVM) decoding algorithm. This approach was validated in 15 healthy volunteers and validated against standard SSEPs in 10 ICU patients. The ability of this approach to predict poor neurological outcome, defined as death, vegetative state, or severe disability at 6 months, was tested in an additional set of 39 ICU patients. RESULTS: In each of the healthy volunteers, both the univariate and the SVM methods reliably detected SSEP responses. In patients, when compared against the standard SSEP method, the univariate event-related potentials method matched in nine of ten patients (sensitivity = 94%, specificity = 100%), and the SVM had 100% sensitivity and specificity when compared with the standard method. For the 49 ICU patients, we performed both the univariate and the SVM methods: a bilateral absence of short latency responses (n = 8) predicted poor neurological outcome with 0% FPR (sensitivity = 21%, specificity = 100%). CONCLUSIONS: Somatosensory evoked potentials can reliably be recorded using the proposed approach. Given the very good but slightly lower sensitivity of absent SSEPs in the proposed screening approach, confirmation of absent SSEP responses using standard SSEP recordings is advised.

Intraoperative Neurophysiological Monitoring During Lead Placement for Dorsal Root Ganglion Stimulation: A Literature Review and Case Series.

INTRODUCTION: Dorsal root ganglion stimulation (DRG-S) is a viable interventional option for intractable pain management. Although systematic data are lacking regarding the immediate neurologic complications of this procedure, intraoperative neurophysiological monitoring (IONM) can be a valuable tool to detect real-time neurologic changes and prompt intervention(s) during DRG-S performed under general anesthesia and deep sedation. MATERIALS AND METHODS: In our single-center case series, we performed multimodal IONM, including peripheral nerve somatosensory evoked potentials (pnSSEPs) and dermatomal somatosensory evoked potentials (dSSEPs), spontaneous electromyography (EMG), transcranial motor evoked potentials (MEPs), and electroencephalogram (EEG) for some trials and all permanent DRG-S lead placement per surgeon preference. Alert criteria for each IONM modality were established before data acquisition and collection. An IONM alert was used to implement an immediate repositioning of the lead to reduce any possible postoperative neurologic deficits. We reviewed the literature and summarized the current IONM modalities commonly applied during DRG-S, including somatosensory evoked potentials and EMG. Because DRG-S targets the dorsal roots, we hypothesized that including dSSEP would allow more sensitivity as a proxy for potential sensory changes under generalized anesthesia than would including standard pnSSEPs. RESULTS: From our case series of 22 consecutive procedures with 45 lead placements, one case had an alert immediately after DRG-S lead positioning. In this case, dSSEP attenuation was seen, indicating changes in the S1 dermatome, which occurred despite ipsilateral pnSSEP from the posterior tibial nerve remaining at baselines. The dSSEP alert prompted the surgeon to reposition the S1 lead, resulting in immediate recovery of the dSSEP to baseline status. The rate of IONM alerts reported intraoperatively was 4.55% per procedure and 2.22% per lead (n = 1). No neurologic deficits were reported after the procedure, resulting in no postoperative neurologic complications or deficits. No other IONM changes or alerts were observed from pnSSEP, spontaneous EMG, MEPs, or EEG modalities. Reviewing the literature, we noted challenges and potential deficiencies when using current IONM modalities for DRG-S procedures. CONCLUSIONS: Our case series suggests dSSEPs offer greater reliability than do pnSSEPs in quickly detecting neurologic changes, and subsequent neural injury, during DRG-S cases. We encourage future studies to focus on adding dSSEP to standard pnSSEP to provide a comprehensive, real-time neurophysiological assessment during lead placement for DRG-S. More investigation, collaboration, and evidence are required to evaluate, compare, and standardize comprehensive IONM protocols for DRG-S.

Diagnostic and prognostic significance of preoperative evoked potential tests in degenerative cervical myelopathy.

BACKGROUND CONTEXT: Decompression surgery is a treatment option for patients with degenerative cervical myelopathy (DCM). Surgical decisions primarily depend on clinical symptoms and radiological examinations. The diagnostic and prognostic significance of evoked potential tests for surgical outcomes in patients with DCM has not been thoroughly examined. PURPOSE: To identify the diagnostic and prognostic significance of preoperative evoked potential tests in patients with DCM who underwent decompression surgery. STUDY DESIGN: This was a retrospective observational study. PATIENT SAMPLE: One hundred two consecutive patients who underwent evoked potential tests and surgical treatment between January 2016 and December 2020 in a single spine center and had a minimum follow-up of 6 months. OUTCOME MEASURES: Japanese Orthopedic Association (JOA) scores obtained preoperatively and 6 months after surgery. METHODS: This study evaluated the preoperative central motor conduction time (CMCT), somatosensory evoked potentials, and Japanese Orthopedic Association (JOA) scores obtained preoperatively and 6 months after surgery. RESULTS: Abnormal CMCT findings were observed in 94 patients (92.2%). Abnormal somatosensory evoked potentials were observed in 77 patients (75.5%). There was a statistically significant correlation between preoperative JOA score and abductor pollicis brevis (APB)-CMCT (r=-0.546, p=.001), tibialis anterior (TA)-CMCT (r=-0.517, p<.001), median nerve (MN)-SSEP (r=-0.353, p=.001), and tibial nerve (TN)-SSEP (r=-0.349, p=.003). There were significant differences in recovery rates associated with diabetes mellitus (DM), preoperative severity of myelopathy, TA-CMCT, MN-SSEP, and TN-SSEP. Stepwise multiple regression analysis showed that the major factors affecting the clinical outcomes were TN-SSEP (ß=0.327, p=.004), preoperative JOA score (ß=0.278, p=.012), and DM (ß=0.241, p=.025). CONCLUSIONS: Evoked potential testing is a functional diagnostic tool that can indicate the severity of myelopathic symptoms in patients with DCM. Additionally, preoperative TN-SSEP may have significant prognostic value in predicting postoperative clinical outcomes. Thus, preoperative evoked potential tests could be helpful for determining suitable surgical treatment candidates and forecasting postoperative prognosis.

Effectiveness of MEP and SSEP Monitoring in the Diagnosis of Neurological Dysfunction Immediately After Craniotomy Aneurysm Clipping.

OBJECTIVE: To explore the diagnostic accuracy of motor-evoked potential (MEP) and somatosensory-evoked potential (SSEP) monitoring in predicting immediate neurological dysfunction after craniotomy aneurysm clipping. METHODS: A total of 184 patients with neurosurgery aneurysms in the Affiliated Hospital of Qingdao University from April 2019 to December 2021 were retrospectively included. All patients underwent craniotomy aneurysm clipping, and MEP and SSEP were used to monitor during the operation. Receiver operating characteristic (ROC) curve analysis was used to determine the optimal cutoff value for early warning of MEP and SSEP amplitude decline and to evaluate the effectiveness of MEP and SSEP changes in predicting immediate postoperative neurological dysfunction. RESULTS: Among the 184 patients with intracranial aneurysms, the incidences of immediate postoperative neurological dysfunction were 44.4% (12/27) and 3.2% (5/157) in patients with intraoperative MEP changes and without changes, respectively. For SSEP, The incidence rates were 52.6% (10/19) and 4.2% (7/165), respectively, and the differences were statistically significant ( P <0.001). Significant changes in intraoperative MEP and SSEP were significantly associated with the development of immediate postoperative neurological deficits ( P <0.05). The critical values for early warning of MEP and SSEP amplitude decrease were: 61.6% ( P < 0.001, area under the curve 0.803) for MEP amplitude decrease and 54.6% ( P <0.001, area under the curve 0.770) for SSEP amplitude decrease. The sensitivity and specificity of MEP amplitude change in predicting immediate postoperative neurological dysfunction were 70.6% and 91.0%, respectively. For SSEP amplitude changes, the sensitivity and specificity were 58.8% and 95.8%, respectively. CONCLUSIONS: Motor-evoked potential and SSEP monitoring have moderate sensitivity and high specificity for immediate postoperative neurological dysfunction after craniotomy aneurysm clipping. Motor-evoked potential is more accurate than SSEP. Patients with changes in MEP and SSEP are at greatly increased risk of immediate postoperative neurologic deficits.

Somatosensory evoked potentials amplitude is enhanced after non-invasive brain stimulation in chronic ischemic stroke: Preliminary results from a randomised control trial.

OBJECTIVE: To investigate the effects of transcranial electrical and magnetic non-invasive brain stimulation (NIBS) protocols on somatosensory evoked potential (SEP) in chronic ischemic stroke. METHODS: 33 patients were randomly assigned to one of the four treatment groups of the transcranial direct current stimulation (tDCS) and/or repetitive transcranial magnetic stimulation (rTMS) protocol. SEP parameters were recorded before and after ten days of the treatment session. All the statistical analyses were carried out using SPSS version 19. RESULTS: It was found that there is a statistically significant improvement in the N20-P22 mean amplitude after treatment sessions in all groups except the group where tDCS and rTMS groups were sham. On paired t-tests, the difference betweeen post and pre-stimulation SEP amplitudes for the real tDCS and real rTMS coupled group was 1.045 ± 0.732 (p value = 0.005). For sham tDCS+real rTMS group, 1.05 ± 0.96 (P = 0.04); for real tDCS+sham rTMS 0.543 ± 0.332 (P = 0.01) and for double sham stimulation, 0.204 ± 0.648 (P =  0.4) respectively CONCLUSION: In ischemic stroke patients, either or coupled true transcranial tDCS and rTMS was found to be safe and significantly enhanced the amplitude of cortical somatosensory potentials when combined with standard physiotherapy, in the interim analysis of an ongoing randomised controlled trial. CLINICAL TRIAL REGISTRY OF INDIA: CTRI/2019/11/022009 SIGNIFICANCE: The results of this research indicates the importance of RCTs in developing robust improved NIBS protocols coupled to physiotherapy to enhance the sensory-motor functional recovery following ischemic stroke.

Lower Extremity Somatosensory Evoked Potentials Predict Functional Outcomes in Complete Traumatic Cervical Spinal Cord Injury.

BACKGROUND: Traumatic cervical spinal cord injury (tCSCI) is often a debilitating injury, making early prognosis important for medical and surgical planning. Currently, the best early predictors of prognosis are physical examination, imaging studies, and patient demographics. Despite these factors, patient outcomes continue to vary significantly. The purpose of this study was to evaluate the prognostic value of somatosensory evoked potentials (SSEPs) with functional outcomes in tCSCI patients. METHODS: A retrospective study was conducted on prospectively collected data from 2 academic institutions. Patients 18 years and older who had tCSCI and underwent posterior cervical decompression and stabilization with intraoperative neuromonitoring were reviewed. The outcomes of interest were the American Spinal Injury Association (ASIA) Impairment Scale (AIS) grade and ASIA motor score at follow-up. Outcomes measures were assessed via student t-tests, chi-squared tests, and multivariable regression analysis. RESULTS: A total of 79 patients were included. In complete injuries, detectable lower extremity SSEPs were associated with higher ASIA motor scores at follow-up (P = 0.002), greater increases in ASIA motor scores at follow-up (P = 0.009), and a greater likelihood of clinically important improvement in ASIA motor score (P = 0.024). Incomplete, AIS grade C injuries has higher rates of grade conversion (P = 0.019) and clinically important improvement in ASIA motor score (P = 0.010), compared to AIS grade A or B injuries. CONCLUSIONS: The detection of lower extremity SSEP signals during initial surgical treatment of tCSCI is associated with greater improvement in ASIA motor scores postoperatively. The association is most applicable to patients with complete injury.

Variability of somatosensory evoked potential and motor evoked potential change criteria in thoracic spinal decompression surgery based on preoperative motor status.

BACKGROUND CONTEXT: Combined somatosensory- and motor-evoked potential (SSEP and MEP) changes for predicting prognosis in thoracic spinal surgery have been variably reported. PURPOSE: 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. STUDY SETTING: Retrospective study. PATIENT SAMPLE: A total of 475 patients were analyzed. OUTCOME MEASURES: 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.