Evoked Compound Muscle Action Potentials Research Articles

Krause approach to pineal tumour with intraoperative oculomotor nerve monitoring

BackgroundThe supra-cerebellar infratentorial approach to pineal region tumours is versatile and safe corridor to lesions located below the deep veins. Monitoring of the extra-ocular muscle pathways using the evoked compound muscle action potential can lead to safer resections. Technical noteTo describe the use of electrooculography and a three handed retractor less method for pineal region tumour surgeries. Material and methodsIntraoperative electrooculography uses recording done from two channels (horizontal and vertical)by inserting disposable subdermal needle electrodes along the periorbital area. The oculomotor nerve is being monitored as it exits the midbrain. Retractor-less three-handed-technique allows for minimal handling of the cerebellum while maximizing the operative corridor. ResultThe oculomotor nerve was stimulated post resection and correspondingly led to improved symptoms post-operatively. Discussion and conclusionWe demonstrate a method for the intraoperative monitoring of the continuity of the oculomotor tracts and a three handed retractor-less method of resection of pineal region tumours. The placement of electrodes and area of stimulation need sound knowledge of anatomy of the region. Haemostasis at every step is absolutely essential to be able to visualize in the narrow corridor.

Electromyographic predictors of abducens nerve palsy after endoscopic skull base surgery.

Recovery of abducens nerve palsy (ANP) after endoscopic endonasal skull base surgery (ESBS) has been shown to be potentially predicted by postoperative ophthalmological examination. Triggered electromyography (t-EMG) and free-run electromyography (f-EMG) activity provide an intraoperative assessment of abducens nerve function, but associations with long-term ANP outcomes have not been explored. The objective of this study was to describe intraoperative abducens EMG characteristics and determine whether these electrophysiological profiles are associated with immediately postoperative and long-term ANP outcomes after ESBS. The authors conducted a 5-year (2011-2016) retrospective case-control study of patients who underwent ESBS in whom the abducens nerve was stimulated (t-EMG). Electrophysiological metrics were compared between patients with a new postoperative ANP (cases) and those without ANP (controls). Pathologies included chordoma, pituitary adenoma, meningioma, cholesterol granuloma, and chondrosarcoma. Electrophysiological data included the presence of abnormal f-EMG activity, t-EMG stimulation voltage, stimulation threshold, evoked compound muscle action potential (CMAP) amplitude, onset latency, peak latency, and CMAP duration at various stages of the dissection. Controls were selected such that pathologies were similarly distributed between cases and controls. Fifty-six patients were included, 26 with new postoperative ANP and 30 controls without ANP. Abnormal f-EMG activity (28.0% vs 3.3%, p = 0.02) and lack of response to stimulation (27% vs 0%, p = 0.006) were more frequent in patients with immediately postoperative ANP than in controls. Patients with immediately postoperative ANP also had a lower median CMAP amplitude (35.0 vs 71.2 μV, p = 0.02) and longer onset latency (5.2 vs 2.8 msec, p = 0.04). Comparing patients with transient versus persistent ANP on follow-up, those with persistent ANP tended to have a lower CMAP amplitude (12.8 vs 57 μV, p = 0.07) and higher likelihood of not responding to stimulation at the end of the case (45.5% vs 7.1%, p = 0.06). Abnormal f-EMG was not associated with long-term ANP outcomes. The presence of f-EMG activity, lack of CMAP response to stimulation, decreased CMAP amplitude, and increased CMAP onset latency were associated with immediately postoperative ANP. Long-term ANP outcomes may be associated with t-EMG parameters, including whether the nerve is able to be stimulated once identified and CMAP amplitude. Future prospective studies may be designed to standardize abducens nerve electrophysiological monitoring protocols to further refine operative and prognostic utility.

ID: 203988 Spinal ECAP Thresholds Relative to Evoked Muscle Activation in Rats With Clinically Translatable Paradigms

Rats are commonly used as a translational model of pain and spinal cord stimulation (SCS), with stimulation amplitudes often programmed relative to visual motor threshold (vMT). Recent work1 explored both vMTs and spinal evoked compound action potentials (ECAPs)—a sensed measured of neural activation—in rats using SCS with a 2 Hz rate and a 20 μs pulse width (PW). However, this rate and PW are slower and narrower, respectively, than those typically used clinically. In this study2, we used clinically relevant SCS traditional parameters to characterize the relationship between ECAP thresholds (ECAPTs) and evoked muscle activity as measured both by evoked compound muscle action potential thresholds (ECMAPTs) and vMTs.

Spinal Evoked Compound Action Potentials in Rats With Clinically Relevant Stimulation Modalities

ObjectivesRats are commonly used for translational pain and spinal cord stimulation (SCS) research. Although many SCS parameters are configured identically between rats and humans, stimulation amplitudes in rats are often programmed relative to visual motor threshold (vMT). Alternatively, amplitudes may be programmed relative to evoked compound action potential (ECAP) thresholds (ECAPTs), a sensed measure of neural activation. The objective of this study was to characterize ECAPTs, evoked compound muscle action potential thresholds (ECMAPTs), and vMTs with clinically relevant SCS modalities. Materials and MethodsWe implanted ten anesthetized rats with two quadripolar epidural SCS leads: one for stimulating in the lumbar spine, and another for sensing ECAPs in the thoracic spine. We then delivered two SCS paradigms to the rats. The first used 50-Hz SCS with 50-, 100-, 150-, and 200-μs pulse widths (PWs), whereas the second used a 50-Hz, 150-μs PW low-rate program (LRP) multiplexed to a 1200-Hz, 50-μs PW high-rate program (HRP). We increased SCS amplitudes up to the vMT in the first paradigm, and in the second, we increased HRP amplitudes up to the HRP ECAPT with a fixed amplitude (70% of the vMT) LRP. For each test case, we captured ECAPTs, ECMAPTs, and vMTs from each rat. ResultsvMTs were 3.0 ± 0.7 times greater than ECAPTs, with vMTs marginally (3.0 ± 3.6%) greater than ECMAPTs (mean ± SD) across all PWs with the first paradigm. With the second paradigm, we noted a negligible increase (3.6 ± 6.2%) on the LRP ECAP as HRP amplitudes were increased. ConclusionsOur results demonstrate reasonable levels of neural activation in anesthetized rats with SCS amplitudes appropriately programmed relative to vMT or ECMAPT when using clinically relevant SCS modalities. Furthermore, we demonstrate the feasibility of ECAP recording in rats with multiplexed HRP SCS.

The effect of a gap concept on peripheral nerve recovery in modified epineurial neurorrhaphy: An experimental study in rats.

Several factors such as surgical approach that only consider topographic anatomy; inadequate fascicular alignment, extraepineurial sprouting in the repair zone; contact of axons with the suture area are the disadvantages of epineurial neurorrhaphy. Accordingly, axonal mismatch, neuroma, and unfavorable nerve recovery become inevitable. Neurotropism is the theory clarifying appropriate matching of the nerve fibers independently without needing surgical approach. The studies comparing the primary nerve repair with the nerve defects bridged in different ways demonstrated better outcomes of nerve recovery in the groups with a nerve gap. In this study, we aimed to demonstrate the effects of the gap concept in primary nerve repair bridged by own epineurium. We hypothesized that this technique will provide better results in terms of peripheral nerve recovery and will significantly eliminate the occurrence of a neuroma, which is quite possible in epineurial neurorrhaphy. A total of 35 Wistar female rats weighing 200 ~ 250 g were randomly divided into five groups each with seven rats. Sham controls constituted Group 1, while the rats with epineural neurorrhaphy were included in Group 2. The remaining three groups were the study groups. In Group 3, after the sciatic nerve transection, epineurium of the distal segment was sleeved and preserved. A 2-mm axonal segment was removed from the epineurium free distal ending and no any procedure was applied to the proximal ending of the transected sciatic nerve. Epineuriums of the both sides were approximated and repaired. In Group 4, a 2-mm axonal segment was removed from the proximal ending of the sciatic nerve after preservation of epineurium and no any procedure was applied to the distal part of sciatic nerve. Epineuriums of the both sides were approximated and repaired. In addition, in Group 5, after epineuriums were sleeved in the both distal and proximal stumps, a 1-mm nerve segment was removed from both endings and epineuriums were repaired in the middle bridging a 2-mm axonal gap again. After a 3months follow-up period Sciatic Functional Index (SFI) was measured by walking track analysis; the area under the evoked compound muscle action potential (CMAP) and latency periods were calculated via electromyographic (EMG) analysis; and histopathological evaluation were performed to compare the parameters of edema, fibrosis, inflammation, vascularization, axonal degeneration, axonal density, myelination, disorganization, and neuroma occurrence. Vascular structures and nerve fibers were counted at ×200 magnification: +1, +2, and +3 indicated the presence of 0-15, 16-30, and >30 structures, respectively. For uncountable parameters (edema, disorganization, myelination, fibrosis, and inflammation): +1 indicated mild, +2 indicated moderate, and +3 indicated severe. The differences between the groups with axonal gap repair and epineural neurorrhaphy were not significant regarding to SFI. The areas under CMAP were as follows: 27.9 ± 5.9 (Δ=12.1%) in Group 1; 16.5 ± 5.5 (Δ=6.3%) in Group 2; 14.1 ± 6.2 (Δ=4.8%) in group 3; 13.8 ± 2.3 (Δ=9.2%) in Group 4, and 22.5 ± 18.3 (Δ=2.2%) in Group 5. Group 5 (1 mm gap in the distal +1 mm gap in the proximal segments) had a significantly better result in terms of the area under CMAP with the value of 22.5 ± 18.3m/Mv (p=.031). Axonal density was 0.9 ± 0.6 (Δ=2.2%) in Group 2, 2.4 ± 0.3 (Δ=5.1%) in Group 3, 2.8 ± 0.1 (Δ=7.7%) in Group 4, and 2.8 ± 0.2 (Δ=4.8%) in Group 5. Myelination was 1.1 ± 0.5 (Δ=3.4%) in group 2, 2.2 ± 0.2 (Δ=6.7%) in group 3, 2.4 ± 0.4 (Δ=6.0%) in Group 4, and 2.7 ± 0.3 (Δ=4.6%) in Group 5. Disorganization was 2.3 ± 0.4 (Δ=4.1%) in Group 2, 1.2 ± 0.2 (Δ=7.7%) in Group 3, 1.3 ± 0.2 (Δ=6.5%) in Group 4, and 1 ± 0.3 (Δ=5.9%) in Group 5. And, neuroma occurrence was found 2.2 ± 0.6 (Δ=2.8%) in Group 2 and 0.3 ± 0.2 (Δ=0.1%) in Group 4 while neuroma was not encountered in Group 3 and Group 5. Comparison between the epineurial neurorrhaphy group and the groups with axonal defect revealed the statistically significant results in the factors of axonal density (p=.001), myelination (p=.028), disorganization (p=.016) and neuroma (p=.001). Creating axonal gap bridged by own epineurium showed favorable results comparing with epineurial neurorrhaphy. Resection of a 1 mm axonal segment from the proximal and distal stumps following the epineurial sleeve procedure and performing the epineurium- only repair can facilitate the nerve regeneration. The feasibility of the described technique has been demonstrated in a small rat model and must be further validated in larger animals before clinical testing.

Electroneurography abnormality in Parkinson’s disease: a potential biomarker to help diagnosis

Parkinson’s disease (PD) is a common neurodegenerative disease, pathologically characterized by the progressive degeneration of dopaminergic neurons in the substantia nigra. Although various biomarkers and imaging criteria for PD have been established, objective and reliable evaluation methods are still lacking. Electroneurography, as an objective measurement of evoked compound muscle action potentials, is used to assess the integrity of the peripheral nerve and is important in the diagnosis and differential diagnosis of PD with neuromuscular injury. Moreover, it provides references for the evaluation and quantification of the motor function in PD. Here, we summarize recent advances in clinical research of electroneurography in PD, including the peripheral nerve conduction velocity, needle electromyography, surface electromyography, and motion unit number estimation. The potential values of electroneurography in PD diagnosis are also involved.

An electrophysiological evaluation method for the ovine facial nerve.

IntroductionLarge-animal models such as sheep for facial nerve regeneration research have not yet been established because of the lack of methods for assessing the electrophysiological function of regenerated nerves. In this study, we developed a percutaneous measurement method for the evoked compound muscle action potential (CMAP) of the facial nerve in sheep.MethodsSix 3-year-old castrated male Corriedale sheep were used in this study. Under general anesthesia, an anatomical exploration was performed to identify the course of the buccal branch of the facial nerve and its innervating muscles on one side, followed by the application of surface stimulating electrodes to the contralateral side of the face along the course of the buccal branch of the facial nerve to obtain CMAP measurements of the nasolabial levator muscle.ResultsPercutaneous CMAP measurements of the nasolabial levator muscle could be obtained in all animals by placing stimulating electrodes 1 cm apart on the line coinciding with the course of the buccal branch of the facial nerve revealed by the preceding anatomical exploration. Mean values for electrophysiological parameters were amplitude 4.7 ± 0.7 mV, duration 2.1 ± 0.6 ms, and latency 3.6 ± 0.4 ms.ConclusionWe have established a percutaneous measurement method for CMAP of the buccal branch of the facial nerve in sheep. This method is expected to be very useful in future studies of facial nerve regeneration for long nerve defects in sheep.

Electrodiagnostic data-driven clustering identifies a prognostically different subgroup of patients with chronic inflammatory demyelinating polyneuropathy

ObjectiveThis study aimed to explore the correlations between electrodiagnostic (EDX) features in patients with chronic inflammatory demyelinating polyneuropathy (CIDP) and to investigate whether EDX data-driven clustering can identify a distinct...

The anti-stress effects of therapy dogs on college students

The relationship between dysmyelination and the progression of neuropathy in Charcot–Marie–Tooth (CMT) hereditary polyneuropathy is unclear. Mice heterozygously deficient for the myelin protein P0 gene (P0+/−) are indistinguishable from wild-type (WT) at birth and then develop a slowly progressing demyelinating neuropathy reminiscent of CMT Type 1b. Accumulating evidence suggests that impulse conduction can become lethal to acutely demyelinated central and peripheral axons. Here we investigated the vulnerability of motor axons to long-lasting, high-frequency repetitive stimulation (RS) in P0+/− mice as compared to WT littermates at 7, 12, and 20 months of age. RS was carried out in interrupted trains of 200 Hz trains for 3 h. Tibial nerves were stimulated at the ankle while the evoked compound muscle action potentials (CMAPs) and the ascending compound nerve action potentials (CNAPs) were recorded from plantar muscles and the sciatic nerve, respectively. In 7-month old mice, there was recovery of CMAP and CNAP following RS. When mice were about one year old, electrophysiological recovery following RS was incomplete and in P0+/− also associated with morphological signs of partial Wallerian degeneration. The effect of RS was larger in P0+/− as compared to age-matched WT. When mice were about 2 years old, the effect was stronger and became similar between WT and P0+/−. RS was followed by a transient hyperpolarization, which decreased with age and was smaller in P0+/− than in WT. Our data suggest that both aging and the dysmyelinating disease process may contribute to the susceptibility to activity-induced axonal degeneration. It is possible that in aging mice and in P0+/− there is inadequate energy-dependent Na+/K+ pumping, as indicated by the reduced post-stimulation hyperpolarization, which may lead to a lethal Na+ overload in some axons.

MIPO of proximal humerus fractures through an anterolateral acromial approach. Is the axillary nerve at risk?

PurposeIt is known that shoulder surgery may cause iatrogenic injury to the axillary nerve as a serious complication, but there is little evidence to indicate whether the axillary nerve is at risk of injury during an anterolateral acromial approach for minimally-invasive plate osteosynthesis (MIPO) of proximal humerus fractures. We hypothesised that this surgical method is safe for the axillary nerve and would preserve it from iatrogenic injury. Materials and methodsWe conducted a prospective follow-up cohort study on 49 consecutive patients with proximal humerus fractures who were managed with MIPO through an anterolateral approach. All patients underwent standardised electroneurographic testing, with assessment of amplitudes of evoked compound muscle action potentials (CMAP) and distal motor latencies (DML) of the axillary nerves, pre- and post-operatively. Six weeks after injury, all patients underwent needle electromyographic (EMG) testing of anterior, middle, posterior deltoid, teres minor and paraspinal muscles for detecting abnormal muscle activity as a sign of acute denervation. After six months of physical rehabilitation, patients with axillary nerve injury underwent control electroneurographic testing to check the recovery of neurographic features (CMAP, DML). All nerve measurements were compared to reference values, and between right and left side. ResultsFive patients had a mild-to-moderate traumatic axillary nerve injury before surgery. There were no significant differences between amplitudes of CMAP (p = 0.575) and DML (p = 0.857) pre- and post-surgical procedure. ConclusionsThese results confirmed safety of this surgical method in the preservation of axillary nerve from iatrogenic injury, but the course of the axillary nerve must be kept in mind.

S54 Motor axon excitability changes during anti-epileptic voltage-gated NA+ channel blocker therapy

Objectives Anti-epileptic drugs targeting voltage-gated Na channels (VGSC) are not selective for the brain. The aim of this study was to investigate the excitability of myelinated median nerve motor axons in epileptic patients treated with carbamazepine and other anti-VGSC drugs. Methods Stimulation was carried out at wrist and evoked compound muscle action potential (CMAP) was recorded from the abductor pollicis brevis muscle. Multiple measures of motor excitability using the TRONDNF protocol were carried out using an automatic threshold-tracking setup. In addition, the current required to evoke threshold responses targeting 40–50% of maximal CMAP amplitude was also determined by manual trial-and-error, for cathodic pulses of 0.2, 0.5 and 1 ms duration to measure the strength-duration time constant (SDTC). Results Across the anti-VGSC treated group there was an impairment in motor axon excitability with a 30% reduction in SDTC as compared to age-matched normal controls. A similar reduction in SDTC could be detected by manual threshold tracking in 3 different laboratories, using conventional nerve conduction equipment. The time for manual SDTC measurements was comparable to the full automatic multiple excitability measures protocol. Discussion The excitability impairment by partial VGSC block did not affect conduction of normal motor axons. Conclusions Our data suggest that, at the therapeutic doses of anti-VGSC drugs, there is an impairment in motor axon excitability that can be measured with conventional neurophysiological equipment. Significance Nerve excitability measurements could prove useful for monitoring the functional consequences of the anti-VGSC therapy in epilepsy.

The electrophysiological response to immunoglobulin therapy in chronic inflammatory demyelinating polyneuropathy.

To characterize changes in motor nerve conduction studies (MNCS) and motor unit number index (MUNIX) following treatment with subcutaneous immunoglobulin and to assess whether these changes are related to muscle strength. Data from 23 patients participating in a randomized, controlled trial were analyzed. MNCS and MUNIX were performed before and after 12weeks of treatment. Isokinetic strength (IMS) was measured in various muscles together with grip strength (GS). Proximally evoked compound muscle action potential (CMAP) amplitudes and MUNIX tended to be better preserved in treated patients (P=.049 and .045). Changes in other parameters did not differ between groups. There was no correlation between changes in electrophysiological parameters and IMS. Changes in GS were related to median nerve motor conduction velocity, distal motor latency, CMAP amplitudes, and distally evoked CMAP duration (P=.013-.035). Proximally evoked CMAP amplitudes appear to be the best MNCS parameter to assess treatment outcome in chronic inflammatory demyelinating polyneuropathy.

Facial-Hypoglossal End-To-Side Neurorrhaphy: Exploration of the Source of Axonal Sprouting.

Background The clinical application of end-to-side (ETS) neurorrhaphy is under debate partly due to a lack of consensus on the source of axonal sprouting. Methods In this study, 24 rats were divided into three groups: sham operation, facial-hypoglossal ETS neurorrhaphy, and end-to-end (ETE) neurorrhaphy. Electrophysiological tests were employed to detect the evoked compound muscle action potentials (CMAPs) in different situations, and the latencies and maximal amplitudes of the CMAPs recorded were compared. Fluorescence retrograde tracing studies, hematoxylin and eosin (HE) staining, and immunohistochemical staining of growth-associated protein 43 (GAP-43) were performed. The number and the diameter of myelinated axons proximal and distal to the coaptation sites were measured. Results Twelve weeks after the surgeries, reinnervation of whisker pad muscles by hypoglossal nerves in both the ETS and ETE groups were confirmed via electrophysiological study. The maximal amplitudes of the CMAPs recorded in different situations and the quantification of myelinated axons supported the coexistence spontaneous collateral sprouting and regenerative sprouting of axons. Double-labeled neurons were found within the hypoglossal nuclear areas in the ETS neurorrhaphy group and HE staining illustrated the axons crossed the coaptation site into the facial acceptor nerve. Although immunohistochemical staining of GAP-43 revealed different timeframes between ETS and ETE neurorrhaphy groups, no significant difference on latency or diameters of the myelinated axons distal to the coaptation sites was noted between ETE and ETS groups. Conclusion Both spontaneous collateral sprouting and regenerative sprouting of axons coexisted following ETS neurorrhaphy, which represents an alternative approach to peripheral nerve reconstruction.

Reduced evoked motor and sensory potential amplitudes in obstructive sleep apnea patients.

It is unknown to what extent chronic intermittent hypoxaemia in obstructive sleep apnea causes damage to the motor and sensory peripheral nerves. It was hypothesized that patients with obstructive sleep apnea would have bilaterally significantly impaired amplitudes of both motor and sensory peripheral nerve-evoked potentials of both lower and upper limbs. An observational study was conducted on 43 patients with obstructive sleep apnea confirmed by the whole-night polysomnography, and 40 controls to assess the relationship between obstructive sleep apnea and peripheral neuropathy. All obstructive sleep apnea subjects underwent standardized electroneurographic testing, with full assessment of amplitudes of evoked compound muscle action potentials, sensory neural action potentials, motor and sensory nerve conduction velocities, and distal motor and sensory latencies of the median, ulnar, peroneal and sural nerves, bilaterally. All nerve measurements were compared with reference values, as well as between the untreated patients with obstructive sleep apnea and control subjects. Averaged compound muscle action potential and sensory nerve action potential amplitudes were significantly reduced in the nerves of both upper and lower limbs in patients with obstructive sleep apnea compared with controls (P<0.001). These results confirmed that patients with obstructive sleep apnea had significantly lower amplitudes of evoked action potentials of both motor and sensory peripheral nerves. Clinical/subclinical axonal damage exists in patients with obstructive sleep apnea to a greater extent than previously thought.

Remodeling of motor units after nerve regeneration studied by quantitative electromyography

ObjectivePeripheral nerve has the capacity to regenerate after nerve lesions; during reinnervation of muscle motor units are gradually reestablished. The aim of this study was to follow the time course of reestablishing and remodeling of motor units in relation to recovery of force after different types of nerve repair. MethodsReinnervation of muscle was compared clinically and electrophysiologically in complete median or ulnar nerve lesions with short gap lengths in the distal forearm repaired with a collagen nerve conduit (11 nerves) or nerve suture (10 nerves). Reestablishment of motor units was studied by quantitative EMG and recording of evoked compound muscle action potential (CMAP) during a 24-month observation period after nerve repair. ResultsForce recovered partially to about 80% of normal. Denervation activity gradually decreased during reinnervation though it was still increased at 24months. Nascent motor unit potentials (MUPs) at early reinnervation were prolonged and polyphasic. During longitudinal studies, MUPs remained prolonged and their amplitudes gradually increased markedly. Firing of MUPs was unstable throughout the study. CMAPs gradually increased and the number of motor units recovered to approximately 20% of normal. There was weak evidence of CMAP amplitude recovery after suture ahead of conduit repair but without treatment related differences at 2years. ConclusionsSurgical repair of nerve lesions with a nerve conduit or suture supported recovery of force and of motor unit reinnervation to the same extent. Changes occurred at a higher rate during early regeneration and slower after 12months but should be followed for at least 2years to assess outcome. EMG changes reflected extensive remodeling of motor units from early nascent units to a mature state with greatly enlarged units due to axonal regeneration and collateral sprouting and maturation of regenerated nerve and reinnervated muscle fibers after both types of repair. SignificanceRemodeling of motor units after peripheral nerve lesions provides the basis for better recovery of force than the number of motor axons and units. There were no differences after repair with a collagen nerve conduit and nerve suture at short nerve gap lengths. The reduced number of motor units indicates that further improvement of repair procedures and nerve environment is needed.

Plasma exchange for chronic inflammatory demyelinating polyradiculoneuropathy.

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an uncommon progressive or relapsing paralysing disease caused by inflammation of the peripheral nerves. If the hypothesis that it is due to autoimmunity is correct, removal of autoantibodies in the blood by plasma exchange should be beneficial. To assess the effects of plasma exchange for treating CIDP. On 30 June 2015, we searched the Cochrane Neuromuscular Disease Group Specialized Register, the Cochrane Central Register for Controlled Trials (CENTRAL), MEDLINE, EMBASE, CINAHL Plus, and LILACS. We also scrutinised the bibliographies of the trials, contacted the trial authors and other disease experts, and searched trials registries for ongoing studies. Randomised controlled trials (RCTs) or quasi-RCTs in participants of any age comparing plasma exchange with sham treatment or no treatment. Two review authors independently selected the trials, extracted the data, and assessed risk of bias. Where possible the review authors combined data according to the methods of the Cochrane Neuromuscular Disease Review Group. one cross-over trial including 18 participants showed after four weeks, 2 (95% confidence interval (CI) 0.8 to 3.0) points more improvement on an 11-point disability scale with plasma exchange (10 exchanges over four weeks) than with sham exchange. Rapid deterioration after plasma exchange occurred in eight of 12 who had improved. when we combined the results of this cross-over trial and a trial with 29 participants treated in a parallel-group design, there were 31 points (95% CI 16 to 45) more improvement on an impairment scale (maximum score 280) after plasma exchange (six exchanges over three weeks) than after sham exchange. There were significant improvements in both trials in an electrophysiological measure, the proximally evoked compound muscle action potential, after three or four weeks. Nonrandomised evidence indicates that plasma exchange induces adverse events in 3% to 17% of procedures. These events are sometimes serious. Both trials had a low risk of bias. A trial that showed no significant difference in the benefit between plasma exchange and intravenous immunoglobulin is included in the Cochrane review of intravenous immunoglobulin for this condition. Moderate- to high-quality evidence from two small trials shows that plasma exchange provides significant short-term improvement in disability, clinical impairment, and motor nerve conduction velocity in CIDP but rapid deterioration may occur afterwards. Adverse events related to difficulty with venous access, use of citrate, and haemodynamic changes are not uncommon. We need more research to identify agents that will prolong the beneficial action of plasma exchange.

Human iPS cell-derived astrocyte transplants preserve respiratory function after spinal cord injury

Transplantation-based replacement of lost and/or dysfunctional astrocytes is a promising therapy for spinal cord injury (SCI) that has not been extensively explored, despite the integral roles played by astrocytes in the central nervous system (CNS). Induced pluripotent stem (iPS) cells are a clinically-relevant source of pluripotent cells that both avoid ethical issues of embryonic stem cells and allow for homogeneous derivation of mature cell types in large quantities, potentially in an autologous fashion. Despite their promise, the iPS cell field is in its infancy with respect to evaluating in vivo graft integration and therapeutic efficacy in SCI models. Astrocytes express the major glutamate transporter, GLT1, which is responsible for the vast majority of glutamate uptake in spinal cord. Following SCI, compromised GLT1 expression/function can increase susceptibility to excitotoxicity. We therefore evaluated intraspinal transplantation of human iPS cell-derived astrocytes (hIPSAs) following cervical contusion SCI as a novel strategy for reconstituting GLT1 expression and for protecting diaphragmatic respiratory neural circuitry. Transplant-derived cells showed robust long-term survival post-injection and efficiently differentiated into astrocytes in injured spinal cord of both immunesuppressed mice and rats. However, the majority of transplant-derived astrocytes did not express high levels of GLT1, particularly at early times post-injection. To enhance their ability to modulate extracellular glutamate levels, we engineered hIPSAs with lentivirus to constitutively express GLT1. Overexpression significantly increased GLT1 protein and functional GLT1-mediated glutamate uptake levels in hIPSAs both in vitro and in vivo post-transplantation. Compared to human fibroblast control and unmodified hIPSA transplantation, GLT1-overexpressing hIPSAs reduced (1) lesion size within the injured cervical spinal cord, (2) morphological denervation by respiratory phrenic motor neurons at the diaphragm neuromuscular junction, and (3) functional diaphragm denervation as measured by recording of spontaneous EMGs and evoked compound muscle action potentials. Our findings demonstrate that hiPSA transplantation is a therapeutically-powerful approach for SCI.

Usefulness of cervical root magnetic stimulation in assessing proximal motor nerve conduction

Objectives: To evaluate the reliability and utility of cervical root magnetic stimulation in exploring proximal motor conduction. Methods: In 20 patients with demyelinating polyneuropathy (DPN), 20 patients with amyotrophic lateral sclerosis (ALS) and 25 healthy subjects, evoked compound muscle action potentials (CMAPs) were recorded from abductor digiti minimi muscle in response to electrical stimulation up to Erb’s point and magnetic stimulation up to the cervical roots. Results: In all healthy and ALS subjects, magnetic root stimulation confirmed the absence of conduction abnormalities, including those in whom supramaximal responses at Erb’s point were not achieved. In the DPN group, conduction block and/or temporal dispersion was revealed by magnetic root stimulation in 9 out of 20 patients (45%), 3 more than those detected at Erb’s point. Conclusions: Cervical root stimulation allowed clear distinction between motor neuronopathy and DPN. It is recommended as part of the routine evaluation of patients suspected of having DPN, especially when distal nerve studies are inconclusive.

Electrically stimulated signals from a long-term Regenerative Peripheral Nerve Interface.

Despite modern technological advances, the most widely available prostheses provide little functional recovery beyond basic grasping. Although sophisticated upper extremity prostheses are available, optimal prosthetic interfaces which give patients high-fidelity control of these artificial limbs are limited. We have developed a novel Regenerative Peripheral Nerve Interface (RPNI), which consists of a unit of free muscle that has been neurotized by a transected peripheral nerve. In conjunction with a biocompatible electrode on the muscle surface, the RPNI facilitates signal transduction from a residual peripheral nerve to a neuroprosthetic limb. The purpose of this study was to explore signal quality and reliability in an RPNI following an extended period of implantation. Following a 14-month maturation period, electromyographic signal generation was evaluated via electrical stimulation of the innervating nerve. The long-term RPNI was viable and healthy, as demonstrated by evoked compound muscle action potentials as well as histological tissue analysis. Signals exceeding 4 mV were successfully acquired and amplitudes were consistent across multiple repetitions of applied stimuli. There were no evident signs of muscle denervation, significant scar tissue, or muscle necrosis. This study provides further evidence that after a maturation period exceeding 1 year, reliable and consistent signals can still be acquired from an RPNI.

Cranial Nerve Monitoring and Intraoperative Cranial Computer Tomography for Safe Resection of Intra- and Periorbital Tumors

Background: During surgery for intra- or periorbital tumors, we recorded evoked compound muscle action potentials (ECMAPs) from the extraocular and intraocular muscles. Intraoperative cranial computer tomography (iCCT) allows on the one hand resection control during surgery and on the other hand location control of intraocular needles. Methods: We analyzed patients with sphenoorbital and orbital tumors for safe and complete resection from January, 2012 to October, 2013. The ECMAPs were recorded through a surface electrode and/or intraorbital needle electrodes. For further neuromonitoring control and resection control, we performed iCCT. Results: We analyzed 15 patients with sphenoorbital tumors: 11 meningiomas, 3 fibrous dysplasias, 1 metastasis. For 15 patients, ECMAPs were successfully recorded from the intraocular muscles. Five patients were recorded by extraocular surface muscle monitoring. Ten patients did not exhibit any postoperative deterioration of oculomotor nerve function. Three patients exhibited a temporary deterioration of oculomotor nerve function immediately after surgery. Two patients had a preoperative permanent functional deficit. In 12 patients tumor were completely resected and in 3 patients small tumor rest was revealed by iCCT. Conclusion: ECMAP recordings from the intraocular muscles precisely indicated the locations of cranial nerves better than surface electrodes. The iCCT enable tumor resection control and neuromonitoring control for intraorbital neuromonitoring.