Latency Of Somatosensory Evoked Potentials Research Articles

Facilitation of Early and Middle Latency SEP after tDCS of M1: No Evidence of Primary Somatosensory Homeostatic Plasticity

Homeostatic plasticity is a mechanism that stabilizes cortical excitability within a physiological range. Most homeostatic plasticity protocols have primed and tested the homeostatic response of the primary motor cortex (M1). This study investigated if a homeostatic response could be recorded from the primary sensory cortex (S1) after inducing homeostatic plasticity in M1. In 31 healthy participants, homeostatic plasticity was induced over M1 with a priming and testing block of transcranial direct current stimulation (tDCS) in two different sessions (anodal and cathodal). S1 excitability was assessed by early (N20, P25) and middle-latency (N33-P45) somatosensory evoked potentials (SEP) extracted from 4 electrodes (CP5, CP3, P5, P3). Baseline and post-measures (post-priming, 0-min, 10-min, and 20-min after homeostatic induction) were taken. Anodal M1 homeostatic plasticity induction significantly facilitated the N20-P25, P45 peak, and N33-P45 early SEP components up to 20-min post-induction, without any indication of a homeostatic response (i.e., reduced SEP). Cathodal homeostatic induction did not induce any significant effect on early or middle latency SEPs. M1 homeostatic plasticity induction by anodal stimulation protocol to the primary motor cortex did not induce a homeostatic response in SEPs.

A pig model of symptomatic spinal epidural hematoma.

The purpose of this study was to establish an animal model capable of simulating the development and decompression process of symptomatic spinal epidural hematoma (SSEH). A total of 16 male Bama miniature pigs were included in this study and randomly allocated into four groups: Group A (4h 20mmHg hematoma compression), Group B (4h 24mmHg hematoma compression), Group C (4h 28mmHg hematoma compression), and Group Sham (control). Real-time intra-wound hematoma compression values were obtained using the principle of connectors. Electrophysiological analyses, including the latency and amplitude of somatosensory evoked potentials (SSEP) and motor evoked potentials (MEP), along with behavioral observations (Tarlov score), were performed to assess this model. ANOVA tests demonstrated significant differences in the latency and relative amplitude of SSEP and MEP between Groups C and Sham after 4h of hematoma compression and one month after surgery (P < 0.01). Behavioral assessments 8h after surgery indicated that animals subjected to 28mmHg hematoma compression suffered the most severe spinal cord injury. Pearson correlation coefficient test suggested a negative correlation between the epidural pressure and Tarlov score (r = -0.700, p < 0.001). With the progression of compression and the escalation of epidural pressure, the latency of SSEP and MEP gradually increased, while the relative amplitude gradually decreased. When the epidural pressure reaches approximately 24mmHg, the spinal cord function occurs progressive dysfunction. Monitoring epidural pressure would be an effective approach to assist to identify the occurrence of postoperative SSEH.

Positive effect of microvascular proliferation on functional recovery in experimental cervical spondylotic myelopathy.

Cervical Spondylotic Myelopathy (CSM), the most common cause of spinal cord dysfunction globally, is a degenerative disease that results in non-violent, gradual, and long-lasting compression of the cervical spinal cord. The objective of this study was to investigate whether microvascular proliferation could positively affect neural function recovery in experimental cervical spondylotic myelopathy (CSM). A total of 60 male adult Sprague-Dawley (SD) were randomly divided into four groups: Control (CON), Compression (COM), Angiostasis (AS), and Angiogenesis (A G),with 15 rats in each group. Rats in the AS group received SU5416 to inhibit angiogenesis, while rats in the AG group received Deferoxamine (DFO) to promote angiogenesis. Motor and sensory functions were assessed using the Basso Beattie Bresnahan (BBB) scale and somatosensory evoked potential (SEP) examination. Neuropathological degeneration was evaluated by the number of neurons, Nissl bodies (NB), and the de-myelination of white matter detected by Hematoxylin & Eosin(HE), Toluidine Blue (TB), and Luxol Fast Blue (LFB) staining. Immunohistochemical (IHC) staining was used to observe the Neurovascular Unit (NVU). Rats in the CON group exhibited normal locomotor function with full BBB score, normal SEP latency and amplitude. Among the other three groups, the AG group had the highest BBB score and the shortest SEP latency, while the AS group had the lowest BBB score and the most prolonged SEP latency. The SEP amplitude showed an opposite performance to the latency. Compared to the COM and AS groups, the AG group demonstrated significant neuronal restoration in gray matter and axonal remyelination in white matter. DFO promoted microvascular proliferation, especially in gray matter, and improved the survival of neuroglial cells. In contrast, SU-5416 inhibited the viability of neuroglial cells by reducing micro vessels. The microvascular status was closely related to NVU remodeling an-d functional recovery. Therefore, proliferation of micro vessels contributed to function -al recovery in experimental CSM, which may be associated with NVU remodeling.

Neuromonitoring in pre-post and intraoperative total hip replacement surgery in type 4 high-riding developmental dysplasia of the hip.

The choice approach to treating congenital dislocation of the hip joint is total hip replacement (THR). One of the severe but uncommon complications of THR is nerve damage. The most common nerve injury associated with total hip arthroplasty (THA) is sciatic nerve palsy, and the second typical nerve damage with THA is femoral nerve paralysis. In this prospective cohort study, 35 patients with type 4 high riding developmental dysplasia of the hip (DDH) who were candidates for THA were enrolled. The somatosensory evoked potential (SSEP), motor evoked potential (MEP), and electromyography (EMG) were measured pre-post and intraoperatively to check the status of the sciatic and femoral nerves. After collecting the mentioned information, the data was analyzed by SPSS V. 26 software. Out of 35 patients with DDH type 4 who were candidates for THR, nine patients showed a 50 percent decrease in SSEP amplitude, and six patients showed a 10 percent decrease in SSEP latency. One patient during and two patients after the surgery showed more than an 80 percent decrease in MEP amplitude. Meanwhile, 14 patients showed abnormal spikes during and two patients after surgery regarding EMG. All patients with disturbed neurophysiological findings reverted to normal in the further investigation during follow-up. No correlation was found between increasing limb shortness and these modalities. Using neuromonitoring techniques during Total Hip Arthroplasty (THA) can help identify potential early nerve damage, prevent post-surgical complications, and improve high-riding DDH patient outcomes.

Sural nerve involvement in patients with acute inflammatory demyelinating polyneuropathy variant of Guillain-Barre syndrome with sural sparing at initial presentation

Introduction: Neurophysiological testing is a valuable tool in the diagnosis of Guillain-Barre syndrome (GBS). Sural sparing is a usual feature of acute inflammatory demyelinating polyneuropathy (AIDP) type GBS. However, sural involvement has been reported in later stages of GBS. It is important to identify patterns of sural nerve involvement to differentiate GBS from its mimickers and to stage the disease. This research aimed to detect the pattern of sural nerve involvement in AIDP-GBS cases with normal electrophysiological responses in the sural nerve at the beginning.Objectives: To determine the location and timing of sural nerve involvement in AIDP-GBS.Methods: This prospective follow up study included diagnosed cases of AIDP-GBS with preserved bilateral sural responses. Nerve conduction and somatosensory evoked potentials (SSEP) were done on admission and weekly thereafter for four consecutive weeks. The last evaluation was done four weeks after the fourth study.Results: All patients (100%) showed normal distal sural responses over the initial four weeks of follow up. They continued to remain normal up to eight weeks in eight patients (53.3%). Two patients had gradual prolongation of their sural SSEP on consecutive studies. One of them had gradual reduction of sural sensory nerve action potential and nerve conduction velocity along with the prolongation of sural SSEP latencies. The difference of SSEP latency increments in the left sural nerve of these two patients was statistically significant (p&lt;0.05). The right sural SSEP latency difference was not significant.Conclusion: Sparing of the distal sural sensory response was demonstrated in 100% of AIDP-GBS cases during the first four weeks of follow up. More than 50% of the cohort demonstrated preserved sural sensory responses for eight weeks from the initial presentation. Two out of fifteen patients showed statistically significant proximal sural sensory pathway involvement with increasing SSEP latencies. This finding suggests that in some patients, the sural sensory pathway may get affected at its proximal segments or at the central nervous system before the distal nerve is affected.

Intra-operative Neurophysiological Monitoring in Patients Undergoing Posterior Spinal Correction Surgery with Pre-operative Neurological Deficit: Its Feasibility and High-risk Factors for Failed Monitoring.

Considering spinal deformity patients with pre-operative neurological deficit were associated with more intra-operative iatrogenic neurological complications than those without, intra-operative neurophysiological monitoring (IONM) has been used for detecting possible iatrogenic injury timely. However, the IONM waveforms are often unreliable. To analyze the performance of intra-operative neurophysiological monitoring (IONM) including somatosensory evoked potentials (SEP) and motor evoked potentials (MEP) in patients with pre-operative neurological deficit undergoing posterior spinal correction surgery, and to identify the high-risk factors for failed IONM. Patients with pre-operative neurological deficit undergoing posterior spinal correction surgery between October 2017 and January 2022 were retrospectively reviewed. The presence or absence of SEP and MEP of target muscles were separately recorded. The P37/N50 latency and amplitude of SEP, and the MEP amplitude were measured. Any IONM alerts were also recorded. The IONM performance was compared among patients with different etiologies, levels responsible for neurological deficit, and strength of IONM-target muscles. Patients' demographics were analyzed using the descriptive statistics and were presented with mean ± standard deviation. Comparison analysis was performed using χ2 -test and statistically significant difference was defined as p < 0.05. A total of 270 patients (147 males, 123 females) with an average age of 48.4 ± 36.7 years were involved. The SEP records were available in 371 (68.7%) lower extremities while MEP records were available in 418 (77.4%). SEP alerts were reported in 31 lower extremities and MEP alerts in 22, and new neurological deficit at post-operation was observed in 11. The etiologies of neuromuscular and syndromic indicated relatively lower success rates of IONM, which were 44.1% and 40.5% for SEP, and 58.8% and 59.5% for MEP (p < 0.001). In addition, patients with pre-operative neurological deficit caused by cervical spine and muscle strength lower than grade 4 suffered from higher risk of failed IONM waveforms (p < 0.001). Patients with pre-operative neurological deficit suffered from a higher incidence of failed IONM results. The high-risk for failed IONM waveforms included the neuromuscular and syndromic etiologies, neurological deficit caused by cervical spine, muscle strength lower than grade 4 in patients with pre-operative neurological deficit undergoing posterior spinal correction surgery.

Non-invasive central nervous system assessment of a porcine model of neuropathic pain demonstrates increased latency of somatosensory-evoked potentials

BackgroundThe study of chronic pain and its treatments requires a robust animal model with objective and quantifiable metrics. Porcine neuropathic pain models have been assessed with peripheral pain recordings and behavioral responses, but thus far central nervous system electrophysiology has not been investigated. This work aimed to record non-invasive, somatosensory-evoked potentials (SEPs) via electroencephalography in order to quantitatively assess chronic neuropathic pain induced in a porcine model.New method: Peripheral neuritis trauma (PNT) was induced unilaterally in the common peroneal nerve of domestic farm pigs, with the contralateral leg serving as the control for each animal. SEPs were generated by stimulation of the peripheral nerves distal to the PNT and were recorded non-invasively using transcranial electroencephalography (EEG). The P30 wave of the SEP was analyzed for latency changes. ResultsP30 SEPs were successfully recorded with non-invasive EEG. PNT resulted in significantly longer P30 SEP latencies (p < 0.01 [n = 8]) with a median latency increase of 14.3 [IQR 5.0 – 17.5] ms. Histological results confirmed perineural inflammatory response and nerve damage around the PNT nerves.Comparison with existing method(s): Control P30 SEPs were similar in latency and amplitude to those previously recorded invasively in healthy pigs. Non-invasive recordings have numerous advantages over invasive measures. ConclusionsP30 SEP latency can serve as a quantifiable neurological measure that reflects central nervous system processing in a porcine model of chronic pain. Advancing the development of a porcine chronic pain model will facilitate the translation of experimental therapies into human clinical trials.

Skin type and nerve effects on cortical tactile processing: a somatosensory evoked potentials study.

Somatosensory evoked potentials (SEP) studies typically characterize short latency components following median nerve stimulations of the wrist. However, these studies rarely considered 1) skin type (glabrous/hairy) at the stimulation site, 2) nerve being stimulated, and 3) middle latency (>30 ms) components. Our aim was to investigate middle latency SEPs following simple mechanical stimulation of two skin types innervated by two different nerves. 18 adults received 400 mechanical stimulations over four territories of the right hand (two nerves: radial/median; two skin types: hairy/glabrous skin) while their EEG was recorded. Four middle latency components were identified: P50, N80, N130 and P200. As expected, significantly shorter latencies and larger amplitudes were found over the contralateral hemisphere for all components. A skin type effect was found for the N80: glabrous skin stimulations induced larger amplitude than hairy skin stimulations. Regarding nerve effects, median stimulations induced larger P50 and N80. Latency of the N80 was longer after median nerve stimulation compared to radial nerve stimulation. This study showed that skin type and stimulated nerve influence middle latency SEPs, highlighting the importance of considering these parameters in future studies. These modulations could reflect differences in cutaneous receptors and somatotopy. Middle latency SEPs can be used to evaluate the different steps of tactile information cortical processing. Modulation of SEPs components before 100 milliseconds possibly reflects somatotopy and differential processing in SI cortex.

Levcromakalim provokes an acute rapid-onset migraine-like phenotype without inducing cortical spreading depolarization

BackgroundMigraine headache attacks and accompanying sensory augmentation can be induced by several agents including levcromakalim (LVC), that is also capable of provoking aura-like symptoms in migraineurs. We investigated whether single LVC injection causes acute migraine-like phenotype in rats and induces/modulates cortical spreading depolarization (CSD), a rodent model of migraine aura.MethodsWistar rats were administered LVC (1 mg/kg, i.p.) and compared to control (CTRL, vehicle, i.p.) and nitroglycerin (NTG, 10 mg/kg, i.p.) groups. Von Frey filaments were used to examine the periorbital and hind paw mechanical allodynia. Dark–light box (DLB), elevated plus maze (EPM), and open field arena (OFA) were used to evaluate light sensitivity and anxiety-related behaviors. The effects of LVC on CSD parameters, somatosensory evoked potentials, and baseline dural EEG (electroencephalography) were investigated. Possible CSD-induced c-fos expression was studied with Western Blot. Blood–brain barrier integrity in cortex was examined with Evans blue assay.ResultsLVC and NTG administration robustly reduced periorbital mechanical thresholds in rats and induced anxiety-like behaviors and photophobia within 30 and 120 min, respectively. LVC induced migraine-like phenotype recovered in 2 h while NTG group did not fully recover before 4 h. Both LVC and NTG did not provoke DC (direct current) shift, EEG alterations or cortical c-fos expression characteristic to CSD. LVC did not induce de novo CSD and affect KCl (potassium chloride)-induced CSD parameters except for an increase in propagation failure. However, NTG significantly increased both CSD susceptibility and propagation failure. Somatosensory evoked potential (SSEP) configurations were not altered in both LVC and NTG groups, but SSEP latencies were prolonged after CSD. Acute LVC or NTG injection did not increase cortical BBB permeability.ConclusionsSingle LVC administration induced the fastest manifestation and recovery of acute migraine-like phenotype which was not mediated by CSD waves in the cerebral cortex. We suppose LVC triggered rapid-onset migraine-like symptoms are probably related to functional alterations in the trigeminal nociceptive system and K+ channel opening properties of LVC. Understanding the neurobiological mechanisms of this nociceptive window, may provide a novel target in migraine treatment.

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.

Hemodynamic Consideration in Intraoperative Neurophysiological Monitoring in Neuromuscular Scoliosis Surgery.

To prove the hypothesis that the parameters of intraoperative neurophysiological monitoring (IONM) during will be more deteriorated in neuromuscular scoliosis (NMS) than in adolescentidiopathic scoliosis (AIS). This retrospective study reviewed the data of 69 patients (NMS=32, AIS=37) who underwent scoliosis surgery under IONM. The amplitude of motor evoked potentials (MEPs), and the amplitude and the latency of somatosensory evoked potentials (SEPs) were examined. Demographic, preoperative, perioperative and postoperative data were analyzed to determine whether they affected the IONM parameters for each group. Of the items analyzed, the bleeding amount was the only significant risk factor for SEP latency deterioration in the NMS group only. The amplitude of SEP and MEP did not correlate with the hemodynamic parameters. The NMS/AIS ratios of the bleeding-related parameters were higher in the order of bleeding amount/weight (2.62, p<0.01), bleeding amount/body mass index (2.13, p<0.01), and bleeding amount (1.56, p<0.01). This study suggests that SEP latency is more vulnerable than SEP or MEP amplitude in ischemic conditions during scoliosis surgery. In NMS patients, it should be considered that the bleeding amount can have a critical effect on intraoperative electrophysiological deterioration.

Ultrastructural destruction of neurovascular unit in experimental cervical spondylotic myelopathy.

The pathogenesis of cervical spondylotic myelopathy (CSM) remains unclear. This study aimed to explore the ultrastructural pathology of neurovascular unit (NVU) during natural development of CSM. A total of 24 rats were randomly allocated to the control group and the CSM group. Basso-Beattie-Bresnahan (BBB) scoring and somatosensory evoked potentials (SEP) were used as functional assessments. Hematoxylin-eosin (HE), toluidine blue (TB), and Luxol fast blue (LFB) stains were used for general structure observation. Transmission electron microscopy (TEM) was applied for investigating ultrastructural characteristics. The evident compression caused significant neurological dysfunction, which was confirmed by the decrease in BBB score and SEP amplitude, as well as the prolongation of SEP latency (P < 0.05). The histopathological findings verified a significant decrease in the amount of Nissl body and myelin area and an increase in vacuolation compared with the control group (P < 0.05). The TEM results revealed ultrastructural destruction of NVU in several forms, including: neuronal degeneration and apoptosis; disruption of axonal cytoskeleton (neurofilaments) and myelin sheath and dystrophy of axonal terminal with dysfunction mitochondria; degenerative oligodendrocyte, astrocyte, and microglial cell inclusions with degenerating axon and dystrophic dendrite; swollen microvascular endothelium and loss of tight junction integrity; corroded basement membrane and collapsed microvascular wall; and proliferated pericyte and perivascular astrocytic endfeet. In the CSM group, reduction was observed in the amount of mitochondria with normal appearance and the number of cristae per mitochondria (P < 0.05), while no substantial drop of synaptic vesicle number was seen (P > 0.05). Significant narrowing of microvascular lumen size was also observed, accompanied by growth in the vascular wall area, endothelial area, basement membrane thickness, astrocytic endfeet area, and pericyte coverage area (rate) (P < 0.05). Altogether, the findings of this study demonstrated ultrastructural destruction of NVU in an experimental CSM model with dorsal-lateral compression, revealing one of the crucial pathophysiological mechanisms of CSM.

Intra-Operative Neurophysiological Monitoring in Patients with Intraspinal Abnormalities Undergoing Posterior Spinal Fusion.

ObjectiveTo analyze the intraoperative neurophysiological monitoring (IONM) data of patients with intraspinal abnormalities undergoing posterior spinal fusion and to determine how intraspinal abnormalities influence IONM results.MethodsPatients with severe kyphoscoliosis and intraspinal abnormalities who underwent posterior spinal correction and fusion between September 2015 and January 2019 were retrospectively reviewed. Candidate intraspinal abnormalities included Chiari malformation, syringomyelia, split cord malformation, and tethered cord syndrome. Total intravenous anesthesia was administered, and no muscle relaxant or inhalation anesthesia was used for maintenance. IONM data, including somatosensory evoked potentials (SSEP) and motor evoked potentials (MEP), were recorded. The P37 and N50 latencies and amplitude were recorded for SSEP, whereas only the amplitude was recorded for MEP. The possible high‐risk factors for abnormal IONM results were analyzed.ResultsThe current study included 87 patients (40 men, 47 women) with an average age of 20.2 ± 10.4 years. The etiologies were neuromuscular in 45 patients, idiopathic in four, and congenital in 38. A total of 136 intraspinal abnormalities were detected, including Chiari malformation in 33 patients, syringomyelia in 55, split‐cord malformation in 25, and tethered cord syndrome in 23. Forty patients had one intraspinal abnormality, whereas 47 patients had two or three intraspinal abnormalities. The monitorabilities were 87.4% and 97.7% for the SSEP and MEP, respectively. SSEP alerts were reported in five patients and MEP alerts in four patients, and new neurological deficits were observed in three patients postoperatively. The sensitivity and specificity were 100% and 97.3% for SSEP, and 100% and 98.8% for MEP, respectively. A significant difference in MEP amplitude between the concave and convex sides was observed, while significantly higher SSEP latency was observed on the concave side in patients with preoperative neurological deficits. There were 52 (59.8%) patients with abnormal IONM data. Preoperative neurological deficits (χ2 = 7.715, p = 0.005) and more than one intraspinal abnormality (χ2 = 9.186, p = 0.004) indicated a higher risk of abnormal IONM data.ConclusionsIONM can be effectively used in patients with intraspinal abnormalities who undergo posterior spinal fusion. Patients with preoperative neurological deficits and more than one intraspinal abnormality have a higher risk of abnormal IONM monitoring.

The Impact of Micro RNA-320a Serum Level on Severity of Symptoms and Cerebral Processing of Pain in Patients with Fibromyalgia.

The aim of this work was to explore the expression of miR-320a level in fibromyalgia patients in comparison to healthy controls, and to clarify its impact on the severity of symptoms and the cerebral processing of pain assessed by middle latency somatosensory evoked potentials (SSEPs). Case-control study. Rheumatology and Neurology outpatient clinics. Seventy-four fibromyalgia patients and seventy-four normal healthy controls. The included patients were subjected to detailed history taking, assessment of severity of fibromyalgia symptoms using the Fibromyalgia Impact Questionnaire Revised (FIQR), assessment of pain intensity using the Neuropathic Pain Symptom Inventory (NPSI), measurement of the serum level of miR-320a in addition to of measurement peak latencies and amplitudes of middle latency SSEPs. Fibromyalgia patients had significantly higher micro-RNA-320a levels (0.907 ± 0.022) in comparison to controls (0.874 ± 0.015) (P-value < .001). The mean values of micro-RNA-320a levels were significantly higher in fibromyalgia patients with insomnia, chronic fatigue syndrome, persistent depressive disorder, and primary headache disorder than those without (P-value = .024, <.001, .006, .036 respectively). There were statistically significant positive correlations between micro-RNA-320a levels, and disease duration, FIQR, and NPSI total scores (P-value <0.001, 0.003, 0.002 respectively). There were no statistically significant correlations between micro-RNA-320a levels and middle latency SSEPs. Micro-RNA-320a level is significantly upregulated in fibromyalgia patient. It has a crucial impact on the severity of symptoms but not related to the cerebral processing of pain.

Effects of berberine on neurological recovery after spinal cord injury in rats

ObjectiveSecondary inflammation after spinal cord injury is an important cause of neurological dysfunction. At present, there are relatively few effective drugs as an inflammatory inhibitor of spinal cord injury. Berberine is a common inflammatory inhibitor of traditional Chinese medicine extract, so we tried to explore the therapeutic significance of this drug for spinal cord injury.Materials and methodsThe SD rats were randomly divided into three groups: sham operation group(n=30), non‐intervention group(n=30), and Berberine intervention group(n=30). The T10 SCI model was established by Allen's percussion method. BBB score, SEP and MEP latency and amplitude were used to evaluate hind limb function. The water content of spinal cord was measured. The spinal cell structure was observed by HE and Nissl staining and electron microscopy. The motor function was detected by SEP(Somatosensory Evoked Potential) and MEP(motor evoked potential. BBB(Basso‐Beattie‐Bresnahan) score was used to evaluate the hind limb function of rats.ResultsThe BBB score of berberine in SCI model was significantly lower than that in sham operation group from postoperative day 1 to 31. Hindlimb function of Berberine intervention group began to recover faster than the non‐intervention group on day 10 (p &lt; 0.05). The latency of SEP and MEP after spinal cord injury was significantly longer than that of sham operation group (p &lt; 0.05), but there was no significant difference in the latency of SEP and MEP between the two groups (p &gt; 0.05). The amplitude of SEP and MEP in rats after spinal cord injury was significantly lower than that in the sham operation group (P &lt; 0.05). In addition, after berberine treatment, the degree of spinal cord edema in rats decreased to some extent (p &lt; 0.05).ConclusionBerberine can promote the recovery of injured spinal cord to some extent, which may be related to its inflammatory inhibition.

[Effects of eye acupuncture on motor evoked potential and somatosensory evoked potential in patients with incomplete spinal cord injury based on neuroelectrophysiological technology].

To observe the effects of eye acupuncture on motor evoked potential (MEP) and somatosensory evoked potential (SEP) in the patients with incomplete spinal cord injury so as to evaluate its clinical efficacy. According to the random number table, 90 patients were divided into exercise therapy group, eye acupuncture group and eye acupuncture combined exercise therapy group (combined treatment group), 30 cases in each. In the exercise therapy group, patients were treated with the routine exercise and occupational therapy. Patients of the eye acupuncture group were treated with eye acupuncture at upper jiao region, lower jiao region, liver region and kidney region bilaterally. Patients of the combined treatment group were given the routine exercise and occupational therapy combined with eye acupuncture. All the treatments were conducted once daily, 7 days as one treatment course for 4 treatment courses. Before treatment and 4 weeks after treatment, the motor function, light touch sensation and pinprick sensation, injury grade and clinical efficacy were assessed separately, using the criteria developed by the American Spinal Injury Association. The modified Barthel index(MBI) was adopted to evaluate the activities of daily livings. By monitoring SEP and MEP, the neurophysiological conditions were assessed for spinal cord injury. The total effective rate was 56.7% (17/30), 66.7% (20/30) and 90.0% (27/30) in the exercise therapy group, the eye acupuncture group and the combined treatment group, respectively. The total effective rate in the combined treatment group was higher than those in the other two groups (P<0.05). Compared with those before treatment, the scores of motor function, light tough sensation and pinprick sensation were all increased after treatment in three groups (P<0.05), MBI score was increased in both the exercise therapy group and the combined treatment group (P<0.05), and the latency of SEP (N11, N20, N23, P38) and the Cortical (hand region), Csp, Cortical (leg region) and Lsp of MEP were all shortened in the three groups separately (P<0.05). After treatment, compared with the exercise therapy group, the score of motor function was increased (P<0.05), MBI score decreased (P<0.05) and MEP latency shortened (P<0.05) in the eye acupuncture group. After treatment, compared with the exercise therapy group and the eye acupuncture group, the scores of motor function, light touch sensation and pinprick sensation, as well as MBI score were all increased (P<0.05), and the latency of SEP (N11,N20,N23,P38) and MEP shortened (P<0.05) in the combined treatment group. In treatment of incomplete spinal cord injury, eye acupuncture combined with exercise therapy can significantly increase the excitability of sensory and motor nerve conduction in the spinal cord and cerebral cortex of patients, effectively promote the recovery of patients' motor and sensory function and improve the activities of daily living.

Protective Effect of Extended Laminectomy on Spinal Cord Injury Induced by Spinal Shortening.

This study investigates the effect of extended laminectomy (EL) on spinal cord injury (SCI) caused by spinal shortening, and further, the timing and the optimal length of removal. Dogs received spinal column shortening at T13 segment, following which the control group underwent regular laminectomy while other groups underwent laminectomy with an additional 1-lamina length removed 6h after shortening ("1-lamina EL 6 h"), an extra 1.5-lamina length resected at 6 h or 12 h after shortening ("1.5-lamina EL 6 h" and "1.5-lamina EL 12 h"), and an extra 2-lamina length removed at 6 or 12 h after shortening ("2-lamina EL 6 h" and 2-lamina EL 12 h"), respectively. Somatosensory evoked potential (SSEP) and neurological function were recorded periodically; spinal cord blood flow (SCBF) and nerve cell apoptosis were detected. The results showed that resection of an additional 1-lamina length appeared inadequate to relieve the sharp kinking of the spinal cord, whereas the kinking disappeared with an additional 2-lamina length resection. The "1-lamina EL 6 h" and "1.5-lamina EL 12 h" groups showed no significant differences from the control in latency of SSEP, SCBF, hindlimb function and apoptosis. By contrast, significant recovery of SSEP, SCBF and hindlimb function as well as reduction of apoptosis were presented in other three groups. The "2-lamina EL 6 h" group, in particular, showed the most prominent recovery. In conclusion, an additional resection of two laminae at 6 h after shortening showed the best effect in alleviating SCI. Timely and adequately extended laminectomy could be a potential therapeutic strategy for SCI attributable to spinal shortening.

Brainstem Associated Somatosensory Evoked Potentials and Response to Vagus Nerve Stimulation: An Investigation of the Vagus Afferent Network.

Despite decades of clinical usage, selection of patients with drug resistant epilepsy who are most likely to benefit from vagus nerve stimulation (VNS) remains a challenge. The mechanism of action of VNS is dependent upon afferent brainstem circuitry, which comprises a critical component of the Vagus Afferent Network (VagAN). To evaluate the association between brainstem afferent circuitry and seizure response, we retrospectively collected intraoperative data from sub-cortical recordings of somatosensory evoked potentials (SSEP) in 7 children with focal drug resistant epilepsy who had failed epilepsy surgery and subsequently underwent VNS. Using multivariate linear regression, we demonstrate a robust negative association between SSEP amplitude (p < 0.01), and seizure reduction. There was no association between SSEP latency and seizure outcomes. Our findings provide novel insights into the mechanism of VNS and inform our understanding of the importance of brainstem afferent circuitry within the VagAN for seizure responsiveness following VNS.

Dexmedetomidine versus fentanyl in intraoperative neuromuscular monitoring using propofol based total intravenous anesthesia regimen in kyphoscoliosis correction surgery

BackgroundIntraoperative neuromuscular monitoring (IONM) is used to reduce the risk of postoperative neurological deficit in patients undergoing kyphoscoliosis correction surgery. Somatosensory evoked potentials (SSEPs) are among the several techniques developed by neurophysiologists to increase the sensitivity of intraoperative monitoring. We administered total intravenous anesthesia (TIVA) to 20 patients undergoing kyphoscoliosis deformity correction surgeries: group A: propofol and dexmedetomidine and group B: propofol and fentanyl. The primary objective of our study was to compare the effect of dexmedetomidine and fentanyl on intraoperative hemodynamic parameters and their interference with SSEP’s readings. The secondary objective was to assess the total intraoperative requirement of inhalational anesthetic agents, quality of surgical field, and the cost-effectiveness of either regimen.ResultsIntraoperative hemodynamic stability, analgesia, surgical field, and cost-effectiveness (due to reduced requirement of sevoflurane) were better with dexmedetomidine than fentanyl. SSEPs were successfully recorded with both the drugs while the requirement of inhalation anesthetic agents was significantly reduced in the dexmedetomidine group than in the fentanyl group. There were no injuries while recording SSEPs. The latency and amplitude of SSEPs were maintained throughout either group. No intraoperative awakening or awareness was noted (bispectral index was maintained in the range of 40 to 60). No postoperative neurological deficit was noted in any patient.ConclusionsBoth dexmedetomidine and fentanyl can be successfully used in propofol-based TIVA for SSEP monitoring in kyphoscoliosis correction surgeries, but the better analgesic profile, ease of maintaining stable hemodynamics with a significant reduction in inhalational agent requirement, and opioid-sparing effect by dexmedetomidine make it a more desirable agent to be used in propofol-based TIVA.