Somatosensory Evoked Potentials Research Articles

The Role of Magnetic Transcranial Stimulation in the Diagnosis and Post-Surgical Follow-Up of Cervical Spondylotic Myelopathy.

Degenerative cervical myelopathy (DCM) consists of spinal cord damage due to its compression through the cervical spine. The leading cause is degenerative. The diagnosis is clinical, and the therapeutic approach is usually surgical. Confirmation of the diagnostic suspicion is done by magnetic resonance imaging (MRI); however, this test lacks functional information of the spinal cord, the abnormality of which may precede involvement in neuroimaging. Neurophysiological examination using somatosensory evoked potentials (SSEPs) and transcranial magnetic stimulation (TMS) allows for an evaluation of spinal cord function, and provides information in the diagnostic process. Its role in the post-surgical follow-up of patients undergoing decompressive surgery is being studied. We present a retrospective study of 24 patients with DCM and surgical decompression who underwent neurophysiological tests (TMS and SSEP) before, 6, and 12 months after surgery. The result of the TMS and the SSEP in the post-operative follow-up did not correlate with the clinical outcome, either subjective or measured by clinical scales at six months. We only found post-surgical improvement of central conduction times (CMCTs) in patients with severe pre-surgical motor impairment on TMS. In patients with normal pre-surgical CMCT, we found a transient worsening with return to baseline at the one-year follow-up. Most patients presented pre-surgical increased P40 latency at diagnosis. CMCT and SSEP were more related to clinical outcomes one year after the surgical procedure and were very useful in diagnosing.

Neurovascular Unit Compensation from Adjacent Level May Contribute to Spontaneous Functional Recovery in Experimental Cervical Spondylotic Myelopathy.

The progression and remission of cervical spondylotic myelopathy (CSM) are quite unpredictable due to the ambiguous pathomechanisms. Spontaneous functional recovery (SFR) has been commonly implicated in the natural course of incomplete acute spinal cord injury (SCI), while the evidence and underlying pathomechanisms of neurovascular unit (NVU) compensation involved in SFR remains poorly understood in CSM. In this study, we investigate whether compensatory change of NVU, in particular in the adjacent level of the compressive epicenter, is involved in the natural course of SFR, using an established experimental CSM model. Chronic compression was created by an expandable water-absorbing polyurethane polymer at C5 level. Neurological function was dynamically assessed by BBB scoring and somatosensory evoked potential (SEP) up to 2 months. (Ultra)pathological features of NVUs were presented by histopathological and TEM examination. Quantitative analysis of regional vascular profile area/number (RVPA/RVPN) and neuroglial cells numbers were based on the specific EBA immunoreactivity and neuroglial biomarkers, respectively. Functional integrity of blood spinal cord barrier (BSCB) was detected by Evan blue extravasation test. Although destruction of the NVU, including disruption of the BSCB, neuronal degeneration and axon demyelination, as well as dramatic neuroglia reaction, were found in the compressive epicenter and spontaneous locomotor and sensory function recovery were verified in the modeling rats. In particular, restoration of BSCB permeability and an evident increase in RVPA with wrapping proliferated astrocytic endfeet in gray matter and neuron survival and synaptic plasticity were confirmed in the adjacent level. TEM findings also proved ultrastructural restoration of the NVU. Thus, NVU compensation changes in the adjacent level may be one of the essential pathomechanisms of SFR in CSM, which could be a promising endogenous target for neurorestoration.

Efficacy and Safety of a Novel Plum Blossom Needling with Mild Moxibustion Device for Upper Limb Pain Disorder and Motor Dysfunction in Patients with Stage 1 Post-Stroke Shoulder-Hand Syndrome: Study Protocol for a Multi-Center, Single-Blind, Randomized Sham-Controlled Trial.

Post-stroke shoulder-hand syndrome (PS-SHS), a common neurological comorbidity after stroke episodes, poses a grave threat on patients' functional recovery. Preliminary trials have demonstrated that the acupuncture and moxibustion treatment, including a dermal acupuncture tapping method known as plum blossom needling (PBN) can improve pain and motor dysfunctions in patients with PS-SHS. However, there are few reports describing simultaneous moxibustion treatment in combination with PBN. Hence, a novel plum blossom needle device with mild moxibustion (PBNMM) was developed to evaluate its potential efficacy and safety in patients with stage 1 PS-SHS. This multicenter, sham-controlled, randomized controlled trial (RCT) will recruit 102 eligible patients with stage 1 PS-SHS from three clinical centers, randomly allocated in a ratio of 1:1:1 to the PBNMM group, PBNMM with no moxa smoke (PBNMM-NMS) group and sham control group. Patients in each group will receive a 30-minute treatment once per day for 4 weeks, with 5 consecutive sessions per week, for a total of 20 sessions. The primary outcome measure will be defined as the decreased scores from baseline in the visual analog scale (VAS) assessment at week 4. Secondary outcome measures will include scores on the Fugl-Meyer Assessment of the Upper Extremity Scale (FMA-UE), the Modified Barthel Index (MBI), and the somatosensory evoked potential (SEP) records. All outcomes will be evaluated at baseline and weeks 4, 5, 6 and 10, and the intention-to-treat analysis will be applied. This study aims to provide robust evidence for the efficacy and safety of the PBNMM for PS-SHS treatment, as well as the specific impact of moxibustion smoke itself in dealing with PS-SHS. Chinese Clinical Trial Registry No. ChiCTR2200062441. Registered on 7 August 2022.

Utility of the tibial nerve somatosensory evoked potentials in differentiating between neuromyelitis optica spectrum disorders and multiple sclerosis.

Somatosensory evoked potentials (SEPs) are widely used for the diagnosis and evaluation of neuromyelitis optica spectrum disorder (NMOSD) and multiple sclerosis (MS). However, whether the parameters of tibial nerve SEPs can help to distinguish NMOSD from MS remains unclear. Thus, the aim of this study was to investigate the utility of tibial nerve SEP parameters in differentiating patients with NMOSD and MS. The clinical data of patients with NMOSD or MS treated in our institution between 2005 and 2021 were retrospectively extracted from our electronic database. Additional inclusion criteria were presentation with sensory symptoms in the lower extremities with corresponding lesions in the magnetic resonance images as well as available data on anti-aquaporin-4 antibodies and tibial nerve SEPs. The Z-scores of the N21-P38 interval (central sensory conduction time), P38 latency, and P38 amplitude were compared between the patients with NMOSD and MS. The relationship of disease severity with the parameters of the tibial nerve SEPs was also evaluated. Twenty patients with NMOSD and 13 patients with MS were enrolled. The Z-scores of the N21-P38 interval and P38 latency were significantly higher in the MS group than in the NMOSD group (p < 0.05 and p < 0.01, respectively), whereas there was no difference in the Z-scores of the P38 amplitude between the two groups. In the MS group, only the N21-P38 interval and P38 latency were significantly correlated with disease severity (p < 0.05 and p < 0.01, respectively). In contrast, none of the tibial nerve SEP parameters were significantly correlated with disease severity in the NMOSD group. Evaluation of the N21-P38 interval and P38 latency in tibial nerve SEPs potentially helps in differentiating between NMOSD and MS.

Effects of dexmedetomidine on evoked potentials in spinal surgery under combined intravenous inhalation anesthesia: a randomized controlled trial

ObjectiveWe aimed to investigate the effects of different doses of dexmedetomidine (Dex) on evoked potentials in adult patients undergoing spinal surgery under intravenous anesthesia with low-concentration desflurane.MethodsNinety patients were divided into three groups at random. To maintain anesthesia in the control group (group C), desflurane 0.3 MAC (minimal alveolar concentration), propofol, and remifentanil were administered. Dex (0.5 μg·kg−1) was injected for 10 min as a loading dose in the low-dose Dex group (group DL), then adjusted to 0.2 μg·kg−1·h−1 until the operation was completed. Dex (1 μg·kg−1) was injected for 10 min as a loading dose in the high-dose Dex group (group DH), then adjusted to 0.7 μg·kg−1·h−1 until the operation was completed. The additional medications were similar to those given to group C. The perioperative hemodynamics, body temperature, intraoperative drug dosages, fluid volume, urine volume, blood loss, the latency and amplitude of somatosensory evoked potentials (SEPs) at four different time points, the incidence of positive cases of SEPs and transcranial motor evoked potentials (tcMEPs), and perioperative adverse reactions were all recorded.ResultsData from 79 patients were analyzed. The MAP measured at points T2-T4 in group DH was higher than at corresponding points in group C (P < 0.05). The MAP at point T4 in group DL was higher than at corresponding points in group C (P < 0.05). The remifentanil dosage in group DH was significantly lower than in group C (P = 0.015). The fluid volume in group DL was significantly lower than in group C (P = 0.009). There were no significant differences among the three groups in the amplitude and latency of SEP at different time points, nor in the incidence of warning SEP signals. The incidence of positive tcMEP signals did not differ significantly between groups C and DL (P > 0.05), but was significantly higher in group DH than in groups DL (P < 0.05) or C (P < 0.05). The incidence of intraoperative hypertension was significantly higher in group DH than in group C (P = 0.017).ConclusionsLow-dose Dex has no effect on the SEPs and tcMEPs monitoring during spinal surgery. High-dose Dex has no effect on SEPs monitoring, but it may increase the rate of false positive tcMEPs signals and the incidence of intraoperative hypertension.Trial registrationThis study has completed the registration of the Chinese Clinical Trial Center at 11/09/2020 with the registration number ChiCTR2000038154.

Sensory and motor cortical excitability changes induced by rTMS and sensory stimulation in stroke: A randomized clinical trial.

The ability to produce coordinated movement is dependent on dynamic interactions through transcallosal fibers between the two cerebral hemispheres of the brain. Although typically unilateral, stroke induces changes in functional and effective connectivity across hemispheres, which are related to sensorimotor impairment and stroke recovery. Previous studies have focused almost exclusively on interhemispheric interactions in the primary motor cortex (M1). To identify the presence of interhemispheric asymmetry (ASY) of somatosensory cortex (S1) excitability and to investigate whether S1 repetitive transcranial magnetic stimulation (rTMS) combined with sensory stimulation (SS) changes excitability in S1 and M1, as well as S1 ASY, in individuals with subacute stroke. A randomized clinical trial. Participants with a single episode of stroke, in the subacute phase, between 35 and 75 years old, were allocated, randomly and equally balanced, to four groups: rTMS/sham SS, sham rTMS/SS, rTMS/SS, and sham rTMS/Sham SS. Participants underwent 10 sessions of S1 rTMS of the lesioned hemisphere (10 Hz, 1,500 pulses) followed by SS. SS was applied to the paretic upper limb (UL) (active SS) or non-paretic UL (sham SS). TMS-induced motor evoked potentials (MEPs) of the paretic UL and somatosensory evoked potential (SSEP) of both ULs assessed M1 and S1 cortical excitability, respectively. The S1 ASY index was measured before and after intervention. Evaluator, participants and the statistician were blinded. Thirty-six participants divided equally into groups (nine participants per group). Seven patients were excluded from MEP analysis because of failure to produce consistent MEP. One participant was excluded in the SSEP analysis because no SSEP was detected. All somatosensory stimulation groups had decreased S1 ASY except for the sham rTMS/Sham SS group. When compared with baseline, M1 excitability increased only in the rTMS/SS group. S1 rTMS and SS alone or in combination changed S1 excitability and decreased ASY, but it was only their combination that increased M1 excitability. clinicaltrials.gov, identifier (NCT03329807).

Assessment of intraoperative neurophysiological monitoring techniques in intramedullary spinal cord tumor removal surgery

ObjectiveIntraoperative neurophysiological monitoring in intramedullary spinal cord tumor removal surgery helps surgeons detect early warning signs of postoperative nerve damage, in order to reduce or prevent permanent neuron injury. We performed a study to evaluate the value of intraoperative neurophysiological monitoring techniques in intramedullary spinal cord tumor resection surgery. MethodsWe performed a retrospective study of 29 patients undergoing surgery for intramedullary spinal cord tumors and intraoperative neurophysiological monitoring from 2017 to 2021 at the University Medical Center, Ho Chi Minh City. Clinical assessment before and after surgery, intraoperative neurophysiological monitoring to find out the sensitivity, specificity, positive predictive value, and negative predictive value of intraoperative neurophysiological monitoring techniques were performed. ResultsOf the 29 patients, 4 patients had worse postoperative neurological symptoms (13.8%) at 1 day after surgery. The rate of postoperative worsening neurological symptoms decreased to 10.3% at the 1-month follow-up. SSEP (somatosensory evoked potential) had 75% sensitivity and 72% specificity in detecting postoperative nerve damage, while the sensitivity and specificity of MEP (motor evoked potential) were 100% and 80%, respectively. ConclusionBoth SSEP and MEP have a high sensitivity in detecting postoperative nerve damage, meanwhile, MEP is more sensitive than SSEP. These techniques help predict and possibly prevent timely neurological damage during intramedullary spinal cord resection surgery.

Effects of Botulinum Toxin Type A on the Nociceptive and Lemniscal Somatosensory Systems in Chronic Migraine: An Electrophysiological Study.

(1) Background: OnabotulinumtoxinA (BoNT-A) is a commonly used prophylactic treatment for chronic migraine (CM). Although randomized placebo studies have shown its clinical efficacy, the mechanisms by which it exerts its therapeutic effect are still incompletely understood and debated. (2) Methods: We studied in 15 CM patients the cephalic and extracephalic nociceptive and lemniscal sensory systems using electrophysiological techniques before and 1 and 3 months after one session of pericranial BoNT-A injections according to the PREEMPT protocol. We recorded the nociceptive blink reflex (nBR), the trigemino-cervical reflex (nTCR), the pain-related cortical evoked potential (PREP), and the upper limb somatosensory evoked potential (SSEP). (3) Results: Three months after a single session of prophylactic therapy with BoNT-A in CM patients, we found (a) an increase in the homolateral and contralateral nBR AUC, (b) an enhancement of the contralateral nBR AUC habituation slope and the nTCR habituation slope, (c) a decrease in PREP N-P 1st and 2nd amplitude block, and (d) no effect on SSEPs. (4) Conclusions: Our study provides electrophysiological evidence for the ability of a single session of BoNT-A injections to exert a neuromodulatory effect at the level of trigeminal system through a reduction in input from meningeal and other trigeminovascular nociceptors. Moreover, by reducing activity in cortical pain processing areas, BoNT-A restores normal functioning of the descending pain modulation systems.

Combined neuromuscular electrical stimulation and transcutaneous spinal direct current stimulation increases motor cortical plasticity in healthy humans.

Neuromuscular electrical stimulation (NMES) induces neural plasticity of the central nervous system (CNS) and improves motor function in patients with CNS lesions. However, the extended stimulus duration of NMES reduces its clinical applicability. Transcutaneous spinal direct current stimulation (tsDCS), which increases afferent input, may enhance the effects and reduce the stimulus duration of NMES. This study investigated the excitability of the motor cortex, somatosensory cortex, and spinal motor neurons after the combined stimulation of NMES and tsDCS. Among the 55 participants in this study, 24 were allocated to experiment 1, 15 to experiment 2, and 16 to experiment 3. They received intervention for 20 min on different days: (1) NMES combined with tsDCS (NMES + tsDCS), (2) NMES combined with sham tsDCS (NMES + sham tsDCS), and (3) sham NMES combined with tsDCS (sham NMES + tsDCS). NMES was delivered to the right common peroneal nerve at 25 Hz with the intensity at 120% of the motor threshold. For tsDCS, the cathodal electrode was positioned on the thoracic 10th-12th vertebral levels, and the anodal electrode was located on the right shoulder. The stimulus intensity was 2.5 mA. In experiment 1, motor evoked potentials (MEPs) and short-latency intracortical inhibition (SICI) were measured by transcranial magnetic stimulation up to 60 min after stimulation. The spinal motor neurons' excitability was assessed by recording the posterior root muscle reflex (PRMR) induced via transcutaneous spinal cord stimulation in experiment 2, and the primary somatosensory cortex excitability was evaluated by recording the somatosensory evoked potentials (SEPs) in experiment 3 up to 15 min after stimulation. Compared to before the stimulation, NMES + tsDCS significantly increased MEP for 60 min or more, and significantly decreased SICI immediately after. Conversely contrast, the PRMR significantly decreased immediately after, and SEPs were unchanged. These results suggest that simultaneous afferent inputs from different stimulus positions critically induce primary motor cortex plasticity. The combined stimulation of NMES with tsDCS may facilitate the development of a new neurorehabilitation technique.

Which sites better represent the sensory function of hands in convalescent stroke patients? A study based on electrophysiological examination.

Assessing hand sensation in stroke patients is necessary; however, current clinical assessments are time-consuming and inaccurate. This study aimed to explore the nature of light touch sensation and two-point discrimination (2-PD) of different hand sites in convalescent stroke patients based on somatosensory evoked potentials (SEP). Light touch sensation and 2-PD of the thumb, the index finger, the little finger, thenar, and hypothenar were measured (n = 112) using sensory measurement tools. Sensory differences among the hand sites were then compared. The correlation analysis between SEP and the hemiplegic hand function was made. Sensory functions were divided into three levels: sensory intactness, sensory impairment, and sensory loss. Light touch sensations were mainly associated with sensory impairment in the finger and palm region. The 2-PD of the finger region was mainly sensory loss and that of the palm region was mainly sensory impairment. There was no statistical difference in the light touch sensation among the sites of the hand. The correlation coefficients between the 2-PD and SEP N20 amplitudes differed. The correlation coefficients of the thenar and hypothenar were the smallest, and that of the finger was the largest. Light touch sensation and 2-PD in patients with stroke were related to the hemiplegic hand function. Any site on the hand could be selected as the measurement site for light touch sensation. The little finger and hypothenar may be appropriate sites when screening for 2-PD. To improve the patient's recovery they could receive more sensory stimulation of the hand.

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.

Diagnostic performance of preoperative ultrasound for traumatic brachial plexus root injury: A comparison study with an electrophysiology study.

Accurate preoperative assessment for traumatic brachial plexus injury (BPI) is critical for clinicians to establish a treatment plan. The objective of this study was to investigate the diagnostic performance of preoperative ultrasound (US) through comparison with an electrophysiology study (EPS) in the assessment of traumatic brachial plexus (BP) root injury. We performed a retrospective study in patients with traumatic BPI who had preoperative US and EPS, excluding obstetric palsy and other nontraumatic neuropathies. US examination was performed on an EPIQ 5 color Doppler equipment. EPS was performed on a Keypoint 9033A07 Electromyograph/Evoked Potentials Equipment, testing electromyography (EMG), nerve conduction studies (NCS), and somatosensory evoked potentials (SEP). Each BP root of all patients was assessed by US and EPS as completely injured or incompletely injured, respectively. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were calculated based on the correlation with intraoperative findings. The accuracy of US and EPS were compared using the McNemar test. The added benefit of US was evaluated by comparing the sensitivity and specificity between the combined tests with EPS using the McNemar test. This study included 49 patients with traumatic BPI who underwent BP surgeries from October 2018 to September 2022. Surgical exploration confirmed 89 completely injured BP roots in 28 patients. US correctly detected 80 completely injured BP roots (sensitivity, 0.899; specificity, 0.981; PPV, 0.964; NPV, 0.944; accuracy, 0.951). EPS correctly detected 75 completely injured BP roots (sensitivity, 0.843; specificity, 0.929; PPV, 0.872; NPV, 0.912; accuracy, 0.898). US showed significantly higher accuracy than EPS (p = 0.03). When combining US and EPS for completely injured BP root detection, the sensitivity of the inclusive combination (0.966) was significantly higher than EPS alone (p = 0.000977), and the specificity of the exclusive combination (1.000) was significantly higher than EPS alone (p = 0.000977). Preoperative US is an effective diagnostic tool in the assessment of traumatic BP root injury. US had higher accuracy than EPS in this study. Sensitivity and specificity were significantly higher than EPS when US was combined with EPS.

Sensorimotor integration and motor learning during a novel force-matching task in young adults with attention-deficit/hyperactivity disorder.

Attention-Deficit/Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder that exhibits unique neurological and behavioral characteristics. Those with ADHD often have noted impairments in motor performance and coordination, including during tasks that require force modulation. The present study provides insight into the role of altered neural processing and SMI in response to a motor learning paradigm requiring force modulation and proprioception, that previous literature has suggested to be altered in those with ADHD, which can also inform our understanding of the neurophysiology underlying sensorimotor integration (SMI) in the general population. Adults with ADHD (n = 15) and neurotypical controls (n = 15) performed a novel force-matching task, where participants used their right-thumb to match a trace template that varied from 2-12% of their Abductor Pollicis Brevis maximum voluntary contraction. This motor task was completed in pre, acquisition, and post blocks. Participants also completed a retention test 24 h later. Median nerve somatosensory-evoked potentials (SEPs) were collected pre and post motor acquisition. SEPs were stimulated at two frequencies, 2.47 Hz and 4.98 Hz, and 1,000 sweeps were recorded using 64-electrode electroencephalography (EEG) at 2,048 Hz. SEP amplitude changes were normalized to each participant's baseline values for that peak. Both groups improved at post measures (ADHD: 0.85 ± 0.09; Controls: 0.85 ± 0.10), with improvements maintained at retention (ADHD: 0.82 ± 0.11; Controls: 0.82 ± 0.11). The ADHD group had a decreased N18 post-acquisition (0.87 ± 0.48), while the control N18 increased (1.91 ± 1.43). The N30 increased in both groups, with a small increase in the ADHD group (1.03 ± 0.21) and a more pronounced increase in controls (1.15 ± 0.27). Unique neural differences between groups were found after the acquisition of a novel force-matching motor paradigm, particularly relating to the N18 peak. The N18 differences suggest that those with ADHD have reduced olivary-cerebellar-M1 inhibition when learning a novel motor task dependent on force-modulation, potentially due to difficulties integrating the afferent feedback necessary to perform the task. The results of this work provide evidence that young adults with ADHD have altered proprioceptive processing when learning a novel motor task when compared to neurotypical controls.

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.

Intraoperative Neuromonitoring in Spine Surgery

The objectives were to review the evidence on whether intraoperative neurophysiological monitoring (IONM) sensitively and specifically detects intraoperative neurologic injury during spine surgery and whether it reduces neurological complications in spine surgery. A systematic literature review and meta-analysis were conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and studies spanning 1990–2022 were searched. The diagnostic accuracy of somatosensory evoked potentials (SSEPs) and motor-evoked potential (MEP) in predicting postoperative neurologic outcomes in spine surgery was assessed. We also analyzed clinical comparative studies that compared patients who underwent spine surgery with and without IONM to determine the rate of new neurologic events. Fifty studies that provided exact SSEP or MEP changes and postoperative neurological outcomes were analyzed. The features of SSEP changes included low sensitivity (67.7%), high specificity (94.1%), and strong negative predictive value (NPV) (92.1%). For the assessed alarm criteria of a 50% reduction, a 65% reduction, an 80% reduction in amplitude, and a total signal loss, the sensitivity and specificity values for MEP were 87.4%, 100%, 100%, and 100%, and 94.8%, 97%, 94.5%, and 90.5%, respectively. A random effects model was used to assess six research that compared neurological events with and without the use of IONM. The pooled Odds ratio was 0.5746 (confidence interval = 0.48; 0.67), z = 6.637, and the P value was 0.0001. The usefulness of IONM in detecting neurological events during spine surgery is well demonstrated by a growing body of research. However, prospective trials with high-level data are lacking to establish its efficacy in preventing new neurological deficits.

Histological and electroencephalographic demonstration of probiotic effect for reduce of oxidative stress and apoptosis in experimental traumatic brain injury.

The gut microbiota modulates nervous system function. In the literature, it has been shown that this modula-tion is used in many nervous system injuries through oxidative stress (OS) and apoptosis mechanisms. In this study, it was aimed to investigate the neuroprotective effects of probiotic (PB) treatment in a rat traumatic brain injury (TBI) model with histological and electroencephalographic (EEG) data. Forty male Wistar albino rats were divided into four groups. Group 1 was the control group (CONTROL, n=10) and no trauma was applied. Group 2 was the trauma group with the weight-drop technique (TBH, n=10). Group 3 was the sham group (SHAM), (TBH+sterile saline [SS], n=10) rats were given 500 µL of SS per day by oral gavage. Group 4 was the PB treatment group, (TBH+PB, n=10) rats were treated daily for 7 days with 500 µL of PB oral gavage. Brain samples were collected 7 days after trauma. Histopathological evaluation of brain samples was done with HE. OS with Endothelial nitric oxide synthase, vascularization with Vas-cular Endothelial Growth Factor, gliosis with S100, and apoptosis with caspase 3 were evaluated immunohistochemically. Apoptotic index was determined with TUNEL. In addition, EEG and somatosensory evoked potential (SEP) recording findings were compared. It was determined by HE staining that there was a significant (P<0.001) damage in the TBI and sham groups compared to the control group. It was found that PB treatment provided a significant (P<0.01) improvement in the damage created. While OS (P<0.01), gliosis (P<0.01), and apoptosis (P<0.05) decreased with PB treatment, angiogenesis (P<0.01) increased. In support of these findings, in the software-mediated EEG and SUP examination; Delta wave power and theta/alpha ratio increased with TBI and de-creased with PB treatment. The results showed that PB treatment provided a significant improvement in rats by reducing OS, apoptosis, and gliosis and increasing vascularity. To the best of our knowledge in the literature, it was shown for the 1st time that histological results for the treatment of PB were supported by software-mediated EEG and SEP analysis.

Comparative analysis of neurophysiological studies in the diagnosis of bulbar syndrome in patients with Chiari malformation Type 1

The incidence of bulbar syndrome in craniovertebral junction anomalies is between 12% and 35%. Although the use of evoked potentials intraoperatively and preoperatively has advanced in recent years, their use in predicting the development of neurological deficits remains a challenge. This research explores the predictive significance of evoked potentials in the diagnosis of bulbar syndrome in Chiari 1 anomaly. Data from 39 patients and 30 controls were reviewed. Standard multimodal neurophysiological investigations including Brainstem auditory evoked potentials (BAEPs), somatosensory evoked potentials (SSEPs), Nerve Conduction Studies (NCS), and Electromyogram (EMG) were performed. All studies were conducted on the 4-channel complex “Synapsis” (Neurotech, Russia) with computer data processing. The threshold Nerve conduction velocity (NCV) value was 21.5 m/s. The sensitivity and specificity were 75.5% and 71.2% respectively. The area under the ROC curve (AUC) was 0.96±0.36 (95% CI: 0.89-1.00) and p-value 0.004. The M-response amplitude threshold dividing the study group into high and low-risk groups was 1.01 microV. The sensitivity and specificity were 78.0 and 71.2%, respectively. The BAEPs interpeak intervals III-V and I-V were significantly prolonged (P˂ 0.05). SSEPs showed a decreased amplitude and reduced NCV (P ˂ 0.01). Glossopharyngeal nerve electroneuromyography is the most informative test. A decrease in M-response amplitude of bulbar muscles and NCV on efferent fibers is highly predictive of the development of bulbar disorders in patients with Chiari 1, even in subclinical cases.

Perspective: Triple intraoperative neurophysiological monitoring (IONM) should be considered the standard of care (SOC) for performing cervical surgery for ossification of the posterior longitudinal ligament (OPLL).

Triple Intraoperative Neurophysiological Monitoring (IONM) should be considered the standard of care (SOC) for performing cervical surgery for Ossification of the Posterior Longitudinal Ligament (OPLL). IONM's three modalities and their alerts include; Somatosensory Evoked Potentials (SEP: =/> 50% amplitude loss; =/>10% latency loss), Motor Evoked Potentials (MEP: =/> 70% amplitude loss; =/>10-15% latency loss), and Electromyography (loss of EMG, including active triggered EMG (t-EMG)). During cervical OPLL operations, the 3 IONM alerts together better detect intraoperative surgical errors, enabling spine surgeons to immediately institute appropriate resuscitative measures and minimize/avoid permanent neurological deficits/injuries. This focused review of the literature regarding cervical OPLL surgery showed that SEP, MEP, and EMG monitoring used together better reduced the incidence of new nerve root (e.g., mostly C5 but including other root palsies), brachial plexus injuries (i.e., usually occurring during operative positioning), and/or spinal cord injuries (i.e., one study of OPLL patients documented a reduced 3.79% incidence of cord deficits utilizing triple IONM vs. a higher 14.06% frequency of neurological injuries occurring without IONM). Triple IONM (i.e., SEP, MEP, and EMG) should be considered the standard of care (SOC) for performing cervical OPLL surgery. However, the positive impact of IONM on OPLL surgical outcomes critically relies on spinal surgeons' immediate response to SEP, MEP, and/or EMG alerts/significant deterioration with appropriate resuscitative measures to limit/avert permanent neurological deficits.

Methods and Principles of the Intraoperative Neurophysiologic Monitoring in Neurosurgery.

Intraoperative neurophysiologic monitoring (IONM) is an innovation introduced in neurosurgery in the past decades. It aims to support and guide the neurosurgeon to obtain the best surgical result possible, preventing the occurrence of neurological deficits. The somatosensory evoked potentials (SSEP) assess the integrity of the sensory pathways monitoring the dorsal column-medial lemniscus pathway during spine and cerebral surgery. Motor evoked potentials (MEPs) provide information on the integrity of the motor pathway monitoring the efferent motor pathways from the motor cortex to the muscle through corticospinal (or corticobulbar) tracts. Free-running EMG is the standard technique to monitor peripheral nerves, roots, or cranial motor nerves during surgery. Intraoperative EMG signals are activated during cranial motor nerves damaging or after an irritative stimulus. The duration, morphology, and persistence of EMG reflects the severity of neural injury. Nerve mapping consists of recording muscle activations given by direct nerve stimulation. This technique makes use of a stimulation probe available to the neurosurgeon which allows administering current directly to the nervous tissue (nerves, roots, etc.). Intraoperative neurophysiological monitoring (IONM) represents the standard of care during many procedures, including spinal, intracranial, and vascular surgeries, where there is a risk of neurological damage. Close communication and collaboration between the surgical team, neurophysiologist, and anesthesiologist is mandatory to obtain high-quality neuromonitoring, thus preventing neurologic injuries and gaining the best surgical "safe" results.

The sensitivity difference between the glans penis and penile shaft in primary premature ejaculation.

The penis is a vital organ of perception that transmits perceived signals to ejaculation-related centers. The penis consists of the glans penis and penile shaft, which differ considerably in both histology and innervation. This paper aims to investigate whether the glans penis or the penile shaft is the main source of sensory signals from the penis and whether penile hypersensitivity affects the whole organ or only part of it. The thresholds, latencies, and amplitudes of somatosensory evoked potentials (SSEPs) were recorded in 290 individuals with primary premature ejaculation using the glans penis and penile shaft as the sensory areas. The thresholds, latencies, and amplitudes of SSEPs from the glans penis and penile shaft in patients were significantly different (all P < 0.0001). The latency of the glans penis or penile shaft was shorter than average (indicating hypersensitivity) in 141 (48.6%) cases, of which 50 (35.5%) cases were sensitive in both the glans penis and penile shaft, 14 (9.9%) cases were sensitive in the glans penis only, and 77 (54.6%) cases were sensitive in the penile shaft only (P < 0.0001). There are statistical differences in the signals perceived through the glans penis and the penile shaft. Penile hypersensitivity does not necessarily mean that the whole penis is hypersensitive. We classify penile hypersensitivity into three categories, namely, glans penis, penile shaft, and whole-penis hypersensitivity, and we propose the new concept of penile hypersensitive zone.