The effects of long-term bed rest on H-reflex and motor evoked potential in the human soleus muscle during standing

Abstract Muscle motor-evoked potentials are commonly monitored during brain tumour surgery in motor areas, as these are assumed to reflect the integrity of descending motor pathways, including the corticospinal tract. However, while the loss of muscle motor-evoked potentials at the end of surgery is associated with long-term motor deficits (muscle motor-evoked potential-related deficits), there is increasing evidence that motor deficit can occur despite no change in muscle motor-evoked potentials (muscle motor-evoked potential-unrelated deficits), particularly after surgery of non-primary regions involved in motor control. In this study, we aimed to investigate the incidence of muscle motor-evoked potential-unrelated deficits and to identify the associated brain regions. We retrospectively reviewed 125 consecutive patients who underwent surgery for peri-Rolandic lesions using intra-operative neurophysiological monitoring. Intraoperative changes in muscle motor-evoked potentials were correlated with motor outcome, assessed by the Medical Research Council scale. We performed voxel–lesion–symptom mapping to identify which resected regions were associated with short- and long-term muscle motor-evoked potential-associated motor deficits. Muscle motor-evoked potentials reductions significantly predicted long-term motor deficits. However, in more than half of the patients who experienced long-term deficits (12/22 patients), no muscle motor-evoked potential reduction was reported during surgery. Lesion analysis showed that muscle motor-evoked potential-related long-term motor deficits were associated with direct or ischaemic damage to the corticospinal tract, whereas muscle motor-evoked potential-unrelated deficits occurred when supplementary motor areas were resected in conjunction with dorsal premotor regions and the anterior cingulate. Our results indicate that long-term motor deficits unrelated to the corticospinal tract can occur more often than currently reported. As these deficits cannot be predicted by muscle motor-evoked potentials, a combination of awake and/or novel asleep techniques other than muscle motor-evoked potentials monitoring should be implemented.

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Intraoperative motor and somatosensory evoked potential monitoring during surgical clipping of ruptured and unruptured intracranial aneurysms: a comparative study

Journal of Neurosurgery ◽

10.3171/2021.8.jns21479 ◽

2021 ◽

pp. 1-8

Author(s):

Hao You ◽

Xing Fan ◽

Jiajia Liu ◽

Dongze Guo ◽

Zhibao Li ◽

...

Keyword(s):

Evoked Potential ◽

Motor Evoked Potential ◽

Critical Values ◽

Somatosensory Evoked Potential ◽

Short Term ◽

Surgical Clipping ◽

Unruptured Aneurysms ◽

Ruptured Aneurysms ◽

Unruptured Intracranial Aneurysms

OBJECTIVE The current study investigated the correlation between intraoperative motor evoked potential (MEP) and somatosensory evoked potential (SSEP) monitoring and both short-term and long-term motor outcomes in aneurysm patients treated with surgical clipping. Moreover, the authors provide a relatively optimal neurophysiological predictor of postoperative motor deficits (PMDs) in patients with ruptured and unruptured aneurysms. METHODS A total of 1017 patients (216 with ruptured aneurysms and 801 with unruptured aneurysms) were included. Patient demographic characteristics, clinical features, intraoperative monitoring data, and follow-up data were retrospectively reviewed. The efficacy of using changes in MEP/SSEP to predict PMDs was assessed using binary logistic regression analysis. Subsequently, receiver operating characteristic curve analysis was performed to determine the optimal critical value for duration of MEP/SSEP deterioration. RESULTS Both intraoperative MEP and SSEP monitoring were significantly effective for predicting short-term (p < 0.001 for both) and long-term (p < 0.001 for both) PMDs in aneurysm patients. The critical values for predicting short-term PMDs were amplitude decrease rates of 57.30% for MEP (p < 0.001 and area under the curve [AUC] 0.732) and 64.10% for SSEP (p < 0.001 and AUC 0.653). In patients with an unruptured aneurysm, the optimal critical values for predicting short-term PMDs were durations of deterioration of 17 minutes for MEP (p < 0.001 and AUC 0.768) and 21 minutes for SSEP (p < 0.001 and AUC 0.843). In patients with a ruptured aneurysm, the optimal critical values for predicting short-term PMDs were durations of deterioration of 12.5 minutes for MEP (p = 0.028 and AUC 0.706) and 11 minutes for SSEP (p = 0.043 and AUC 0.813). CONCLUSIONS The authors found that both intraoperative MEP and SSEP monitoring are useful for predicting short-term and long-term PMDs in patients with unruptured and ruptured aneurysms. The optimal intraoperative neuromonitoring method for predicting PMDs varies depending on whether the aneurysm has ruptured or not.

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Impact of Motor-Evoked Potential Monitoring on Facial Nerve Outcomes after Vestibular Schwannoma Resection

Annals of Otology Rhinology & Laryngology ◽

10.1177/0003489418803969 ◽

2018 ◽

Vol 128 (1) ◽

pp. 56-61 ◽

Cited By ~ 2

Author(s):

Kareem O. Tawfik ◽

Zoe A. Walters ◽

Gavriel D. Kohlberg ◽

Noga Lipschitz ◽

Joseph T. Breen ◽

...

Keyword(s):

Facial Nerve ◽

Vestibular Schwannoma ◽

Predictive Value ◽

Evoked Potential ◽

Amplitude Ratio ◽

Motor Evoked Potential ◽

Level Of Evidence ◽

Facial Function

Objectives: Assess the utility of intraoperative transcranial facial motor-evoked potential (FMEP) monitoring in predicting and improving facial function after vestibular schwannoma (VS) resection. Study Design: Retrospective chart review. Methods: Data were obtained from 82 consecutive VS resections meeting inclusion criteria. Sixty-two cases were performed without FMEP and 20 with FMEP. Degradation of FMEP response was defined as a final-to-baseline amplitude ratio of 0.5 or less. House-Brackmann (HB) grade was assessed preoperatively, postoperatively, at follow-up assessments, and it was compared between pre- and post-FMEP cohorts. Positive predictive value (PPV) and negative predictive value (NPV), sensitivity, and specificity of FMEP degradation in predicting facial weakness were calculated. Results: In the pre-FMEP group, at length of follow-up (LOF) ⩾9 months, 83.9% (52/62) of patients exhibited HB 1-2 outcome. In the post-FMEP cohort, 75.0% (15/20) exhibited HB 1-2 function at LOF ⩾9 months. There was no difference in rates of HB 1-2 outcomes between groups in the immediate postoperative period ( P = .35) or at long-term follow-up ( P = 1.0). With respect to predicting immediate postoperative facial function, FMEP demonstrated high specificity (88.9%) and moderate sensitivity (54.5%). The PPV and NPV for immediate postoperative facial function were 85.7% and 61.5%, respectively. With respect to long-term (⩾9 months LOF) facial function, intraoperative FMEP was moderately sensitive (71.4%) and highly specific (84.6%); PPV was moderate (71.4%), and NPV was high (84.6%). Conclusions: Intraoperative FMEP is highly specific and moderately sensitive in predicting postoperative facial function for patients undergoing VS resection, but its use may not be associated with improved facial nerve outcomes. Level of Evidence: 4

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Intraoperative Motor-Evoked Potential Disappearance versus Amplitude-Decrement Alarm Criteria During Cervical Spinal Surgery: A Long-Term Prognosis

Journal of Clinical Neurology ◽

10.3988/jcn.2017.13.1.38 ◽

2017 ◽

Vol 13 (1) ◽

pp. 38 ◽

Cited By ~ 4

Author(s):

Dong-Gun Kim ◽

Young-Doo Choi ◽

Seung-Hyun Jin ◽

Chi Heon Kim ◽

Kwang-Woo Lee ◽

...

Keyword(s):

Spinal Surgery ◽

Evoked Potential ◽

Motor Evoked Potential ◽

Versus Amplitude ◽

Long Term Prognosis

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Direct corticospinal pathways contribute to neuromuscular control of perturbed stance

Journal of Applied Physiology ◽

10.1152/japplphysiol.01447.2005 ◽

2006 ◽

Vol 101 (2) ◽

pp. 420-429 ◽

Cited By ~ 125

Author(s):

Wolfgang Taube ◽

Martin Schubert ◽

Markus Gruber ◽

Sandra Beck ◽

Michael Faist ◽

...

Keyword(s):

Magnetic Stimulation ◽

Evoked Potential ◽

Cortical Excitability ◽

Motor Evoked Potential ◽

Neuromuscular Control ◽

H Reflex ◽

Compensatory Response ◽

Long Latency Responses ◽

Long Latency ◽

Posterior Translation

The antigravity soleus muscle (Sol) is crucial for compensation of stance perturbation. A corticospinal contribution to the compensatory response of the Sol is under debate. The present study assessed spinal, corticospinal, and cortical excitability at the peaks of short- (SLR), medium- (MLR), and long-latency responses (LLR) after posterior translation of the feet. Transcranial magnetic stimulation (TMS) and peripheral nerve stimulation were individually adjusted so that the peaks of either motor evoked potential (MEP) or H reflex coincided with peaks of SLR, MLR, and LLR, respectively. The influence of specific, presumably direct, corticospinal pathways was investigated by H-reflex conditioning. When TMS was triggered so that the MEP arrived in the Sol at the same time as the peaks of SLR and MLR, EMG remained unaffected. Enhanced EMG was observed when the MEP coincided with the LLR peak ( P < 0.001). Similarly, conditioning of the H reflex by subthreshold TMS facilitated H reflexes only at LLR ( P < 0.001). The earliest facilitation after perturbation occurred after 86 ms. The TMS-induced H-reflex facilitation at LLR suggests that increased cortical excitability contributes to the augmentation of the LLR peaks. This provides evidence that the LLR in the Sol muscle is at least partly transcortical, involving direct corticospinal pathways. Additionally, these results demonstrate that ∼86 ms after perturbation, postural compensatory responses are cortically mediated.

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Suppression of Motor Evoked Potential and H-reflex during Cataplexy in Narcolepsy

Journal of Korean Sleep Research Society ◽

10.13078/jksrs.07009 ◽

2007 ◽

Vol 4 (2) ◽

pp. 48-53 ◽

Cited By ~ 1

Author(s):

Sun Jung Han ◽

Eun Yeon Joo ◽

Sun Hwa Kim ◽

So-Hee Jung ◽

Seung Bong Hong

Keyword(s):

Evoked Potential ◽

Motor Evoked Potential ◽

H Reflex

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Torque gains and neural adaptations following low-intensity motor nerve electrical stimulation training

Journal of Applied Physiology ◽

10.1152/japplphysiol.00513.2019 ◽

2019 ◽

Vol 127 (5) ◽

pp. 1469-1477

Author(s):

Florian Vitry ◽

Alain Martin ◽

Maria Papaiordanidou

Keyword(s):

Electrical Stimulation ◽

Isometric Contraction ◽

Evoked Potential ◽

Motor Nerve ◽

Motor Evoked Potential ◽

H Reflex ◽

Stimulation Frequency ◽

Maximal Voluntary Isometric Contraction ◽

Neural Adaptations ◽

Low Intensity

The purpose of the study was to assess neural adaptations of the plantar-flexors induced by an electrical stimulation training applied over the motor nerve at low intensity using two different stimulation frequencies. Thirty subjects were randomly assigned into 3 groups: 20 Hz, 100 Hz, and control group. The training consisted of 15 sessions of 25 stimulation trains applied over the tibial nerve and delivered at an intensity evoking 10% maximal voluntary isometric contraction (MVIC). Before and after training, MVIC was assessed and neural adaptations were evaluated by the voluntary activation level (VAL) and the V-wave (normalized by the superimposed muscle compound action potential, V/MSUP). H-reflex and motor-evoked potential (MEP) recorded during MVIC were studied to assess spinal and corticospinal excitabilities [i.e., maximal H-reflex during maximal voluntary isometric contraction (HSUP)/MSUP and maximal motor-evoked potential during maximal voluntary isometric contraction (MEPSUP)/MSUP]. MVIC significantly increased after training only for the two training groups ( P = 0.017). This increase was accompanied by a significant increase of VAL only for these groups ( P = 0.014), whereas statistical analysis revealed a time effect for V/MSUP ( P = 0.022). HSUP/MSUP and MEPSUP/MSUP were significantly increased at post conditions only for the 100 Hz group ( P = 0.021 and P = 0.029). Results show that low-intensity electrical stimulation training applied over the motor nerve can induce torque gains, accompanied by neural adaptations. Stimulation frequency differentially affected spinal and corticospinal excitabilities, indicating that neural adaptations could have a supraspinal origin for the 20-Hz protocol, whereas spinal and supraspinal mechanisms were implicated in the torque increases after the 100-Hz training. NEW & NOTEWORTHY This study brings new insights into the neurophysiological mechanisms responsible for torque gains after electrical stimulation training using wide pulse duration and low stimulation intensity applied over the motor nerve. Stimulation frequency had a distinct impact on spinal and/or supraspinal origins of the observed neural adaptations. The use of the aforementioned stimulation parameters in rehabilitation settings can be proved beneficial in terms of strength gains while avoiding any serious discomfort because of stimulation.

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