Short-latency afferent inhibition is reduced in people with multiple sclerosis during fatiguing muscle contractions.

Understanding how inhibitory pathways influence motor cortical activity during fatiguing contractions may provide valuable insight into mechanisms associated with multiple sclerosis (MS) muscle activation. Short-latency afferent inhibition (SAI) reflects inhibitory interactions between the somatosensory cortex and the motor cortex, and although SAI is typically reduced with MS, it is unknown how SAI is regulated during exercise-induced fatigue. The current study examined how SAI modulates motor evoked potentials (MEPs) during fatiguing contractions. Fourteen people with relapsing-remitting MS (39 ± 6 years, nine female) and 10 healthy individuals (36 ± 6 years, six female) participated. SAI was induced by stimulation of the median nerve that was paired with TMS over the motor representation of the abductor pollicis brevis. A contraction protocol was employed that depressed force generating capacity using a sustained 3-min 15% MVC, immediately followed by a low-intensity (15% MVC) intermittent contraction protocol so that MEP and SAI could be measured during the rest phases of each duty cycle. Similar force, electromyography and MEP responses were observed between groups. However, the MS group had significantly reduced SAI during the contraction protocol compared to the healthy control group (p < .001). Despite the MS group reporting greater scores on the Fatigue Severity Scale and Modified Fatigue Impact Scale, these scales did not correlate with inhibitory measures. As there were no between-group differences in SSEPs, MS-related SAI differences during the fatiguing contractions were most likely associated with disease-related changes in central integration.

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 .

Diagnostic efficacy of tract-specific diffusion tensor imaging in cervical spondylotic myelopathy with electrophysiological examination validation.

PURPOSE: This study aimed to investigate the effectiveness of tract-specific diffusion tensor imaging (DTI) metrics in identifying the responsible segments for neurological dysfunction in cervical spondylotic myelopathy (CSM). METHODS: The study encompassed nineteen participants diagnosed with CSM, including 10 males and 9 females. Additionally, a control group consisting of ten healthy caregivers (5 males and 5 females) were recruited with no symptoms and no compressions on magnetic resonance imaging (MRI). All participants underwent a comprehensive physical examination, MRI assessment, and DTI examination conducted by a senior chief physician. Several parameters were collected from the MR images, including the aspect ratio (defined as the anteroposterior diameter / the transverse diameter of the corresponding segment's spinal cord), transverse ratio (defined as the transverse diameter of the corresponding segment's spinal cord / the transverse diameter of the spinal cord at C2/3), and T2 high signal of the spinal cord. Furthermore, quantitative DTI metrics, such as axial diffusivity (AD), mean diffusivity (MD), radial diffusivity (RD), and fractional anisotropy (FA), were calculated using automatic region-of-interest (ROI) analysis for both whole spinal cord column and dorsal column. Receiver operating characteristic (ROC) curves were constructed to evaluate the diagnostic efficacy of the aspect ratio, transverse ratio, and DTI parameters. The area under the curve (AUC), sensitivity, and specificity were calculated. Intraoperative spinal cord electrophysiological examination was performed as the objective measure of spinal cord function during surgery. RESULTS: As determined by electrophysiological examination, neurological dysfunction was found in 2 patients due to C3/4 compression, in 10 patients due to C4/5 compression, in 6 patients due to C5/6 compression, and in 1 patient due to C6/7 compression. The modified Japanese Orthopedic Association scale (mJOA) was 12.71 ± 1.55 in the CSM group, with 4.87 ± 0.72 for sensory nerve function and 5.05 ± 1.35 for motor nerve function. For the control group, none of the volunteers had neurological dysfunction. T2 high signal was found at the most stenotic segment in 13 patients of the CSM group. Considering all the cervical segments, the aspect ratio (AUC = 0.823, P = 0.001, Sensitivity = 68.42%, Specificity = 82.47%) was more capable of determining the responsible segment than transverse ratio (AUC = 0.661, P = 0.027, Sensitivity = 68.42%, Specificity = 67.01%). AD, MD, and RD were significantly higher while FA was significantly lower in the responsible segment than in the irresponsible segment (P < 0.05). The AUC of DTI-Dorsal column parameters (AD, MD, RD, FA) was larger than the corresponding parameters of the DTI (Whole spinal cord). AD of DTI-Dorsal Column possessed the greatest efficacy (AUC = 0.823, sensitivity = 84.21%, specificity = 77.32%) to determine the responsible segment, larger than AD of DTI-Whole spinal cord (AUC = 0.822, P = 0.001, Sensitivity = 89.47%, Specificity = 77.32%), aspect ratio (AUC = 0.823, P = 0.001, Sensitivity = 68.42%, Specificity = 82.47%) and transverse ratio (AUC = 0.661, P = 0.027, Sensitivity = 68.42%, Specificity = 67.01%). Subgroup analysis revealed that the diagnostic efficacy of DTI and MRI parameters was influenced by cervical spine segment. CONCLUSIONS: When considering all cervical segments, AD from the DTI-Dorsal Column exhibited the most significant potential in identifying responsible segments. This potential was found to be superior to that of DTI-Whole spinal cord, aspect ratio, the most stenotic segment, T2 high signals, transverse ratio, motor nerve dysfunction, and sensory nerve dysfunction. The diagnostic effectiveness of both DTI and MRI parameters was notably influenced by the specific cervical spine segment.

Lightning strike­induced cauda equina syndrome: a case report.

Peripheral nerve injuries after being struck by lightning have been documented. Here, we report a case of cauda equina syndrome induced by lightning. A 27-year-old man presented with numbness, a burning sensation in the saddle region, and increased urinary urgency after being struck by lightning. He had absent Achilles reflexes and paresthesia in the saddle region upon neurological examination, and magnetic resonance imaging of the spine was normal. Electrophysiological studies indicated involvement of bilateral L5, S1, and S2 myotomes and revealed cauda equina lesions. 
Peripheral nerve injury induced by lightning is rare, and the evaluation of people with neurological complaints using electromyography will help determine the true incidence.

Electrical Source Imaging of Somatosensory Evoked Potentials from Intracranial EEG Signals.

Stereoelectroencephalography (SEEG) records electrical brain activity with intracerebral electrodes. However, it has an inherently limited spatial coverage. Electrical source imaging (ESI) infers the position of the neural generators from the recorded electric potentials, and thus, could overcome this spatial undersampling problem. Here, we aimed to quantify the accuracy of SEEG ESI under clinical conditions. We measured the somatosensory evoked potential (SEP) in SEEG and in high-density EEG (HD-EEG) in 20 epilepsy surgery patients. To localize the source of the SEP, we employed standardized low resolution brain electromagnetic tomography (sLORETA) and equivalent current dipole (ECD) algorithms. Both sLORETA and ECD converged to similar solutions. Reflecting the large differences in the SEEG implantations, the localization error also varied in a wide range from 0.4 to 10 cm. The SEEG ESI localization error was linearly correlated with the distance from the putative neural source to the most activated contact. We show that it is possible to obtain reliable source reconstructions from SEEG under realistic clinical conditions, provided that the high signal fidelity recording contacts are sufficiently close to the source of the brain activity.

Feasibility of non-invasive neuro-monitoring during extracorporeal membrane oxygenation in children.

INTRODUCTION: Detection of neurological complications during extracorporeal membrane oxygenation (ECMO) may be enhanced with non-invasive neuro-monitoring. We investigated the feasibility of non-invasive neuro-monitoring in a paediatric intensive care (PIC) setting. METHODS: In a single centre, prospective cohort study we assessed feasibility of recruitment, and neuro-monitoring via somatosensory evoked potentials (SSEP), electroencephalography (EEG) and near infrared spectroscopy (NIRS) during venoarterial (VA) ECMO in paediatric patients (0-15 years). Measures were obtained within 24h of cannulation, during an intermediate period, and finally at decannulation or echo stress testing. SSEP/EEG/NIRS measures were correlated with neuro-radiology findings, and clinical outcome assessed via the Pediatric cerebral performance category (PCPC) scale 30 days post ECMO cannulation. RESULTS: We recruited 14/20 (70%) eligible patients (median age: 9 months; IQR:4-54, 57% male) over an 18-month period, resulting in a total of 42 possible SSEP/EEG/NIRS measurements. Of these, 32/42 (76%) were completed. Missed recordings were due to lack of access/consent within 24 h of cannulation (5/42, 12%) or PIC death/discharge (5/42, 12%). In each patient, the majority of SSEP (8/14, 57%), EEG (8/14, 57%) and NIRS (11/14, 79%) test results were within normal limits. All patients with abnormal neuroradiology (4/10, 40%), and 6/7 (86%) with poor outcome (PCPC ≥4) developed indirect SSEP, EEG or NIRS measures of neurological complications prior to decannulation. No study-related adverse events or neuro-monitoring data interpreting issues were experienced. CONCLUSION: Non-invasive neuro-monitoring (SSEP/EEG/NIRS) during ECMO is feasible and may provide early indication of neurological complications in this high-risk population.

The value of somatosensory evoked potentials in intraoperative evaluation of indirect decompression effect of oblique lumbar interbody fusion for lumbar spinal stenosis.

PURPOSE: The aim of this study was to explore the relationship between intraoperative somatosensory evoked potential (SEP) amplitude changes and clinical outcomes of OLIF indirect decompression for degenerative lumbar spinal stenosis (DLSS). METHODS: A prospective study was performed on 201 patients who received oblique lumbar interbody fusion (OLIF) in our hospital from July 2017 to May 2021 due to single segmental DLSS. The patients were divided into three groups: group A (mild DLSS), group B (moderate DLSS), and group C (severe DLSS). The P40 amplitude during operation were recorded, and the clinical efficacy was evaluated by JOA score 1 year postoperative. ROC curves for satisfactory efficacy of P40 amplitude improvement rate and CSA improvement rate were established. Pearson correlation was used to analyze the relationship between P40 improvement rate and JOA improvement rate. RESULTS: In group A and group B, the improvement rate of JOA in P40 significantly improved group was significantly greater that in improved group and unimproved group (Pa = 0.009; Pb < 0.000). No significant among-subgroup differences in group C (all P > 0.05). In both groups A and B, there was a significant difference in the improvement rate of P40 amplitude between the satisfactory group and the ineffective group (Pa = 0.013; Pb = 0.001), while in group C, there was no statistical significance (Pc = 0.107). By variable Person correlation analysis, a significant positive correlation was obtained between JOA improvement rate and P40 amplitude improvement rate in groups A and B (r1 = 0.27, P1 = 0.02; r2 = 0.508, P2 = 0.001), no correlation between the two in group C (r3 = 0.243, P3 = 0.056). The area under the ROC for assessing surgical efficacy in terms of CSA improvement rate was 0.813 (95% CI: 0.737-0.889, P < 0.001) and 0.767 (95% CI: 0.677-0.856, P < 0.001) in group A and group B, respectively, with satisfactory efficacy cutoff points of 50.18% and 67.89%. CONCLUSION: For mild and moderate DLSS, the intraoperative P40 amplitude improvement rate can predict the improvement of clinical symptoms after surgery and can be used as a reference index to assess the effect of indirect decompression. For severe DLSS, the P40 amplitude improvement rate has limited significance in guiding indirect decompression, and OLIF indirect decompression is not the right treatment for this type of patients.

Patients with degenerative cervical myelopathy exhibit neurophysiological improvement upon extension and flexion: a retrospective cohort study with a minimum 1-year follow-up.

BACKGROUND: Cervical extension and flexion are presumably harmful to patients with degenerative cervical myelopathy (DCM) because they worsen medullary compression visible on dynamic magnetic resonance imaging (MRI). Dynamic somatosensory evoked potentials (SSEPs) are an objective tool to measure the electrophysiological function of the spinal cord at different neck positions. In contrast to previous hypotheses, a considerable proportion of patients with DCM present improved SSEPs upon extension and flexion compared to a neutral position. METHODS: Patients with DCM who underwent preoperative dynamic SSEP examinations and subsequent decompression surgeries between 2015 and 2019 were retrospectively evaluated. We compared extension and flexion SSEPs with neutral SSEPs in each patient and classified them into extension-improved (EI) or extension-nonimproved (EN) and flexion-improved (FI) or flexion-nonimproved (FN) groups. Preoperative clinical evaluations, decompression surgical methods and one-year follow-up clinical data were recorded. Cervical spondylolisthesis and cervical alignment types were evaluated on plain cervical lateral radiographs. The number of stenotic segments, Mühle stenosis grade and disc degeneration stage of the most severe segment, and presence of ligamentum flavum hypertrophy and intramedullary T2 weighted imaging (T2WI) hyperintensity were evaluated on lateral and axial MRI. Data were compared between the EN and EN groups or FI and FN groups with T-tests, chi-square tests or Kruskal-Wallis tests. Prediction criteria were determined with logistic regression analyses. RESULTS: Forty-nine patients were included, and 9 (18.4%) and 11 (22.4%) showed improved extension and flexion SSEPs compared to their own neutral SSEPs, respectively. Interestingly, EI or FI patients had significantly better one-year postoperative mJOA recoveries than EN or FN patients (T-test, P < 0.001). Moreover, the disease duration (T-test, P = 0.024), involved segment number (Kruskal-Wallis test, P < 0.001), and cervical alignment type (chi-square test, P = 0.005) varied significantly between the EI and EN groups. The FI group presented a significantly higher Mühle stenosis grade than the FN group (Kruskal-Wallis test, P = 0.038). Furthermore, ≤ 2 involved segments and straight or sigmoid cervical alignment were significant criteria predicting improved extension SSEPs (probability: 85.7%), while Mühle stenosis Grade 3 and disease duration ≤6 months were significant criteria predicting improved flexion SSEPs (probability: 85.7%). CONCLUSIONS: Our findings provide evidence for neurophysiological improvement in patients with DCM at extension and flexion and its significance in predicting prognoses. Moreover, certain clinical and radiographic criteria may help predict neurophysiological improvement upon extension or flexion. TRIAL REGISTRATION: " [2020]151 ". Retrospectively registered on April 30, 2020.

Magnetic resonance imaging negative myelopathy in Leber's hereditary optic neuropathy: a case report.

BACKGROUND: Leber's hereditary optic neuropathy (LHON) is a common form of mitochondrial disease. The typical clinical presentation of LHON is subacute, painless loss of vision resulting from bilateral optic nerve atrophy. Moreover, extra-ocular manifestations such as cardiac conduction abnormalities and neurological manifestations such as multiple sclerosis (MS) like disease or parkinsonism are encountered in some patients. Abnormal findings in spinal cord MR imaging or in the cerebrospinal fluid (CSF) have been observed in previous cases of LHON-associated myelopathy. CASE PRESENTATION: We report a male patient with LHON who developed symptoms of myelopathy including gait unsteadiness, enhanced deep tendon reflexes and sensory loss of the lower extremities. Imaging of the brain and spinal cord, CSF analysis, as well as neurography and electromyography did not disclose any abnormalities. The somatosensory evoked potential (SEP) findings were suggestive of dorsal column dysfunction. CONCLUSIONS: The patient case demonstrates that myelopathy associated with LHON can present without abnormal findings in central nervous system MR imaging or in the CSF, and without evidence suggestive of multiple sclerosis or MS-like disease. The dorsal column seems to be particularly vulnerable to myelopathy changes in LHON. Evoked potential investigations may assist in confirming the diagnosis, when clinical features are in line with myelopathy but findings in CSF analysis and central nervous system imaging are normal.

Overpressure on fingertips prevents state estimation of the pen grip force and movement accuracy.

We tested the hypothesis that the inability to move a pen accurately in a graphic task is partly due to a decrease of afferent somatosensory information resulting from overpressure on the tactile receptors of the fingers holding the pen. To disentangle the depressed somatosensory origin from an altered motor command, we compared a condition in which the participant actively produces pressure on the pen (active grip) with a condition in which pressure is passively applied (passive grip, no grip-related motor command). We expected that the response of the somatosensory cortex to electric stimulation of the wrist's tactile nerve (i.e., SEP) would be greater in the natural pen grip (baseline condition) than in the two overpressure conditions (actively or passively induced). Fifteen adults were required to trace a geometrical shape in the three grip conditions. The SEP amplitude was not significantly different between the baseline and both overpressure conditions. However, behavioral results showed that drawing accuracy is impaired when the pressure on the pen is increased (passively or actively). Cortical source analyses revealed that the activity of the superior parietal areas (SPL) increased in both overpressure conditions. Our findings suggest that the SPL is critical for sensorimotor integration, by maintaining an internal representation of pen holding. These cortical changes might witness the impaired updating of the finger-pen interaction force for such drawing actions under visual guidance.

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

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

Selective Calpain Inhibition Improves Functional and Histopathological Outcomes in a Canine Spinal Cord Injury Model.

Calpain activation has been implicated in various pathologies, including neurodegeneration. Thus, calpain inhibition could effectively prevent spinal cord injury (SCI) associated with neurodegeneration. In the current study, a dog SCI model was used to evaluate the therapeutic potential of a selective calpain inhibitor (PD150606) in combination with methylprednisolone sodium succinate (MPSS) as an anti-inflammatory drug. SCI was experimentally induced in sixteen mongrel dogs through an epidural balloon compression technique. The dogs were allocated randomly into four groups: control, MPSS, PD150606, and MPSS+PD150606. Clinical evaluation, serum biochemical, somatosensory evoked potentials, histopathological, and immunoblotting analyses were performed to assess treated dogs during the study. The current findings revealed that the combined administration of MPSS+PD150606 demonstrated considerably lower neuronal loss and microglial cell infiltration than the other groups, with a significant improvement in the locomotor score. The increased levels of inflammatory markers (GFAP and CD11) and calcium-binding proteins (Iba1 and S100) were significantly reduced in the combination group and to a lesser extent in MPSS or PD150606 treatment alone. Interestingly, the combined treatment effectively inhibited the calpain-induced cleavage of p35, limited cdk5 activation, and inhibited tau phosphorylation. These results suggest that early MPSS+PD150606 therapy after acute SCI may prevent subsequent neurodegeneration via calpain inhibition.

[Research Progress in Clinical Electrophysiological Assessment of Patients with Sepsis-Associated Encephalopathy].

Sepsis-associated encephalopathy(SAE) caused by infections outside the central nervous system always presents extensive brain damage.It is common in clinical practice and associated with a poor prognosis.There are problems in the assessing and diagnosing of SAE.Many factors,such as sedation and mechanical ventilation,make it difficult to assess SAE,while electrophysiological examination may play a role in the assessment.We reviewed the studies of electrophysiological techniques such as electroencephalography and somatosensory evoked potentials for monitoring SAE,hoping to provide certain evidence for the clinical evaluation and diagnosis of SAE.

Reconstructing subcortical and cortical somatosensory activity via the RAMUS inverse source analysis technique using median nerve SEP data.

This study concerns reconstructing brain activity at various depths based on non-invasive EEG (electroencephalography) scalp measurements. We aimed at demonstrating the potential of the RAMUS (randomized multiresolution scanning) technique in localizing weakly distinguishable far-field sources in combination with coinciding cortical activity. As we have shown earlier theoretically and through simulations, RAMUS is a novel mathematical method that by employing the multigrid concept, allows marginalizing noise and depth bias effects and thus enables the recovery of both cortical and subcortical brain activity. To show this capability with experimental data, we examined the 14-30 ms post-stimulus somatosensory evoked potential (SEP) responses of human median nerve stimulation in three healthy adult subjects. We aim at reconstructing the different response components by evaluating a RAMUS-based estimate for the primary current density in the nervous tissue. We present source reconstructions obtained with RAMUS and compare them with the literature knowledge of the SEP components and the outcome of the unit-noise gain beamformer (UGNB) and standardized low-resolution brain electromagnetic tomography (sLORETA). We also analyzed the effect of the iterative alternating sequential technique, the optimization technique of RAMUS, compared to the classical minimum norm estimation (MNE) technique. Matching with our previous numerical studies, the current results suggest that RAMUS could have the potential to enhance the detection of simultaneous deep and cortical components and the distinction between the evoked sulcal and gyral activity.

A Study of Differences in Penile Dorsal Nerve Somatosensory Evoked Potential Testing Among Healthy Controls and Patients With Primary and Secondary Premature Ejaculation.

BACKGROUND: Penile dorsal nerve somatosensory evoked potential (DNSEP) is a scientific and objective technique that provides effective and objective data to establish the diagnosis of premature ejaculation (PE). AIM: To explore differences in DNSEP between patients with primary premature ejaculation (PPE) and those with secondary premature ejaculation (SPE), in order to investigate the clinical value of DNSEP in the diagnosis of PE. METHODS: The participants were divided into a PPE group (34 cases), an SPE group (25 cases) and a healthy control group (18 cases). All participants underwent DNSEP testing, and the latencies and amplitudes of DNSEP were recorded. OUTCOMES: Differences in the latencies and amplitudes of DNSEP were compared among the PPE, SPE, and healthy control groups. RESULTS: The latencies of DNSEP in the PPE and SPE groups were shorter than those in the healthy control group, and these differences were statistically significant (P < 0.01). However, there was no statistically significant difference between the PPE and SPE groups (P > 0.05). The amplitudes of DNSEP in the PPE group were significantly higher than those in the healthy control group (P < 0.01). However, the amplitudes of DNSEP in the SPE group were significantly lower than those in the healthy control group (P < 0.05). CLINICAL IMPLICATIONS: PPE and SPE can be differentiated based on differences in the amplitudes of DNSEP, providing an objective basis for treatments and follow-up examinations. STRENGTHS AND LIMITATIONS: We evaluated differences in the amplitudes of DNSEP between PPE and SPE patients, which were rare in the published literature. However, specific causes of these differences are still unclear. SEP only reflects afferent pathways in the ejaculatory reflex arc, and role of the brain as a higher center should not be ignored. CONCLUSION: Both PPE and SPE patients are characterized by an increased excitability of the penile sensory nerves. Sun Z, Liao Z, Zheng Q, et al. A Study of Differences in Penile Dorsal Nerve Somatosensory Evoked Potential Testing Among Healthy Controls and Patients With Primary and Secondary Premature Ejaculation. J Sex Med Rev 2021;18:732-736.

Impaired pain processing and its association with attention disturbance in patients with amyotrophic lateral sclerosis.

BACKGROUND: Cognitive dysfunction characterized by executive dysfunction and persistent attention function has been reported in patients with amyotrophic lateral sclerosis (ALS); however, it is unclear if this contributes to the pain processing deficits associated with the disease. OBJECTIVE: We clarified the relationship between pain processing and both cognitive function and sensory symptoms in patients with ALS. METHODS: We enrolled 23 patients with ALS and 14 healthy control subjects. We examined pain-related somatosensory evoked potentials (SEPs) using an intra-epidermal needle electrode. We evaluated cognitive function and the clinical characteristics of sensation and analyzed their relationships with pain-related SEPs. RESULTS: Pain-related SEP amplitudes were significantly lower, while the rate of amplitude attenuation due to habituation or change in attention was significantly greater in patients with ALS than in control subjects. There were no significant differences in pain-related SEP parameters between patients with or without sensory symptoms. Instead, pain-related SEP amplitude and its rate of attenuation were correlated with cognitive dysfunction, particularly with attention domains. CONCLUSIONS: Our results suggest that attention deficit, but not sensory nerve involvement, is a major cause of the alterations in pain-related SEP in patients with ALS.

Focused ultrasound enhances the anesthetic effects of topical lidocaine in rats.

BACKGROUND: High-intensity ultrasound has been used to induce acoustic cavitation in the skin and subsequently enhances skin permeability to deliver hydrophobic topical medications including lidocaine. In contrast, instead of changing skin permeability, pulsed application of low-intensity focused ultrasound (FUS) has shown to non-invasively and temporarily disrupt drug-plasma protein binding, thus has potential to enhance the anesthetic effects of hydrophilic lidocaine hydrochloride through unbinding it from serum/interstitial α1-acid glycoprotein (AAG). METHODS: FUS, operating at fundamental frequency of 500 kHz, was applied pulse-mode (55-ms pulse duration, 4-Hz pulse repetition frequency) at a spatial-peak pulse-average intensity of 5 W/cm2. In vitro equilibrium dialysis was performed to measure the unbound concentration of lidocaine (lidocaine hydrochloride) from dialysis cassettes, one located at the sonication focus and the other outside the sonication path, all immersed in phosphate-buffered saline solution containing both lidocaine (10 µg/mL) and human AAG (5 mg/mL). In subsequent animal experiments (Sprague-Dawley rats, n = 10), somatosensory evoked potential (SSEP), elicited by electrical stimulations to the unilateral hind leg, was measured under three experimental conditions-applications of FUS to the unilateral thigh area at the site of administered topical lidocaine, FUS only, and lidocaine only. Skin temperature was measured before and after sonication. Passive cavitation detection was also performed during sonication to evaluate the presence of FUS-induced cavitation. RESULTS: Sonication increased the unbound lidocaine concentration (8.7 ± 3.3 %) from the dialysis cassette, compared to that measured outside the sonication path (P < 0.001). Application of FUS alone did not alter the SSEP while administration of lidocaine reduced its P23 component (i.e., a positive peak at 23 ms latency). The FUS combined with lidocaine resulted in a further reduction of the P23 component (in a range of 21.8 - 23.4 ms after the electrical stimulations; F(2,27) = 3.2 - 4.0, P < 0.05), indicative of the enhanced anesthetic effect of the lidocaine. Administration of FUS neither induced cavitation nor altered skin conductance or temperature, suggesting that skin permeability was unaffected. CONCLUSIONS: Unbinding lidocaine from the plasma proteins by exposure to non-thermal low-intensity ultrasound is attributed as the main mechanism behind the observation.

Electrical Thalamic Stimulation in the Anterior Part of the Ventral Posterolateral Nucleus for the Treatment of Patients With Central Poststroke Pain.

OBJECTIVES: The effects of thalamic stimulation of the anterior part of the ventral posterolateral nucleus (VPLa) for central poststroke pain (CPSP) and the pain-related electrophysiological characteristics of this structure were investigated. MATERIALS AND METHODS: Nine patients with CPSP manifesting as hemibody pain were enrolled. Stereotactic thalamic VPLa stimulation was implemented, and intraoperative electrophysiological studies on hyperactive and unstable discharges (HUDs) and responses to sensory and electrical stimulation were performed in the sensory thalamus. A preoperative somatosensory-evoked potential (SEP) study was carried out in all nine patients and in eight other patients with localized pain. RESULTS: The patients were classified into two groups: a HUD-dominant group (group H, n = 5) and a sensory response-dominant group (group R, n = 4). HUDs were frequently encountered in the thalamic VPLa in the former group. The total number of HUDs and the number along the trajectory to the VPLa in group H were significantly larger than those in group R. The improvements on the pain numeric rating scale in group H were significantly higher than those in group R two years after surgery. The amplitude ratio of the SEP N20s in the ipsilateral to the contralateral side of CVD lesion in the study group was significantly lower than in the localized pain group. CONCLUSIONS: Adequate and stable pain relief with thalamic VPLa stimulation is obtainable in patients with CPSP who exhibit hyperactivity and electrical instability along the trajectory to this nucleus. Both responders and nonresponders were found to have severe dysfunction of the lemniscal system.

Efficacy of Carotid Artery Stenting Performed under General Anesthesia with Somatosensory Evoked Potential Monitoring.

OBJECTIVES: During carotid artery stenting (CAS), hemodynamics may be affected by the carotid sinus reflex in some cases. Although general anesthesia has been reported to stabilize intraoperative hemodynamics, the patient's neurological condition must be assessed indirectly. Therefore, we investigated the changes in intraoperative hemodynamics and perioperative complications of CAS under general anesthesia and evaluated the efficacy of somatosensory evoked potential (SEP) monitoring in detecting a reduction in perfusion during CAS. MATERIALS AND METHODS: From April 2011 to August 2016,57 consecutive patients who underwent CAS under general anesthesia were evaluated. The follow-up period ranged from 3 to 8 years. During CAS, anesthesiologists monitored and managed the hemodynamics. SEP monitoring was performed during the CAS procedure in all patients. RESULTS: Intraoperative hypotension (systolic blood pressure ≤ 100 mmHg) was evident in 16 patients (28.1%), and 13 patients (22.8%) experienced intraoperative bradycardia; however, all of these cases were promptly managed under general anesthesia. None of the patients showed systolic blood pressure < 50 mmHg from baseline. Regarding perioperative complications, none of the patients exhibited myocardial infarction or postoperative hyperperfusion symptoms, and there was no mortality. Among 21 patients (36.8%) with a decrease in the intraoperative SEP, 3 (5.3%) exhibited transient ischemic symptoms and 1 (1.8%) had postoperative infarction. CONCLUSIONS: CAS under general anesthesia is a safe and effective management option in terms of intraoperative hemodynamic stability. In addition, our findings indicate that SEP monitoring could be helpful in evaluating transient postoperative cerebral ischemia or cerebral infarction after CAS.