Postoperative Motor Dysfunction Research Articles

The application value and improved warning criterion of D-wave monitoring in intramedullary spinal cord tumor surgery

BACKGROUND CONTEXTThe primary treatment method for intramedullary spinal cord tumor (IMSCT) is surgical resection, but this procedure carries a significant risk of neurological damage. Intraoperative neurophysiological monitoring (IONM) has become a necessary adjunctive tool for IMSCT resection. PURPOSEThe current study aimed to explore the application value of D-wave monitoring in IMSCT surgery, and tried to investigate a tailored criterion for its early warning. STUDY DESIGNA retrospective clinical study. PATIENT SAMPLEA retrospective analysis was conducted based on the data of patients who underwent IMSCT surgeries performed by the same neurosurgical team at our hospital. IONM was applied in all surgeries. According to inclusion and exclusion criteria, ultimately 90 patients were enrolled in the study. OUTCOME MEASURESThe McCormick Scale (MMS) was applied to assess the functional outcome through outpatient visits or telephone follow-up at one month and six months postoperatively. Patients with an MMS grade over II one month after surgery were considered to have newly developed postoperative motor dysfunction (PMD). If the MMS grade could be restored to I or II six months after surgery, it was defined as a short-term PMD. Otherwise, it was defined as a long-term PMD. METHODSThe predictive value of different IONM modalities, including somatosensory evoked potential (SEP), muscle motor evoked potential (MEP), and D-wave for PMD, was assessed with sensitivity, specificity, positive predictive value, negative predictive value, and subsequent logistic regression analysis. At last, the cut-off value of the D-wave amplitude reduction ratio for predicting PMD was obtained through the receiver operating characteristic (ROC) curve analysis. RESULTSSEP showed the worst performance in predicting short-term and long-term PMD. Significant MEP changes were indicated as an independent predictive factor for short-term PMD (OR 5.062, 95% CI 1.947–13.166, p=.001), while D-wave changes were demonstrated as an independent predictor for long-term PMD (OR 339.433, 95% CI 11.337–10770.311, p=.001). The optimum cut-off value of the D-wave amplitude reduction ratio for predicting long-term PMD was 42.18%, with a sensitivity of 100% and a specificity of 93.8% (AUC=0.981, p<.001). CONCLUSIONSD-wave monitoring showed extremely high specificity in predicting PMD compared to SEP and MEP monitoring. Moreover, the authors suggested that a D-wave amplitude reduction of over 40% during IMSCT surgery generally indicates long-term PMD for patients.

Application of intraoperative evoked potential monitoring in patients with anterior cerebral artery aneurysms

ObjectivesThe location of the aneurysm can affect the relationship between changes in intraoperative neurophysiological monitoring indicators and postoperative outcomes. The current study aimed to evaluate the application value of motor evoked potential and somatosensory evoked potential monitoring in anterior cerebral artery aneurysm surgery. MethodsThe data of 219 patients with anterior cerebral artery aneurysms treated via surgical clipping were retrospectively reviewed. The correlation of motor/somatosensory evoked potential monitoring with postoperative motor dysfunction was assessed using false positive rate, false negative rate, sensitivity, and specificity. Binary multivariate logistic regression analysis was applied to identify potential predictors for postoperative motor dysfunction. ResultsMotor evoked potential monitoring showed satisfactory effectiveness in predicting postoperative motor dysfunction (Sensitivity, 60.00%; Specificity, 85.43%; False positive rate, 14.57%; False negative rate, 40%). While somatosensory evoked potential did not (Sensitivity, 15.00%; Specificity, 96.98%; False positive rate, 3.02%; False negative rate, 85%). Abnormal motor evoked potential was identified as the only independent predictor for both short-term (odds ratio, 8.893; 95% confidence interval, 2.749-28.773; p<0.001) and long-term postoperative motor dysfunction (odds ratio, 7.877; 95% confidence interval, 2.144-28.945; p=0.002). ConclusionsDuring intraoperative neurophysiological monitoring for patients with anterior cerebral artery aneurysms, paying more attention to motor evoked potential changes was a reasonable choice. And somatosensory evoked potential monitoring can serve as an auxiliary reference.

Neuromonitoring in Neurosurgery : An imperative redemption

With the refinement in biomedical gadgetry, it has been a modern day requisite to safeguard the indigenous neuro-architecture and henceforth foretell the postoperative neurological outcome. The intraoperative neuro-physiological monitoring (IONM) comes as no surprise to be the only credible paradigm which can cluethe standing of neural pathway directly during general anesthesia. By engaging with the IONM appliance, the operating surgeon can acknowledge the risk of injury to critical neural structure while dealing with the pathology within its vicinity. Based on the province of the encephalon, a disparate methods of IONM such as MEP, SSEP, ABR, VEP, BCR, AMR etc have unfolded over time. Intraoperative monitoring of motor evoked potentials (MEPs) has been believed to be advantageousin preventing postoperative motor dysfunction while coping up with aneurysmal surgery involving the internal carotid artery (ICA) and middle cerebral artery (MCA) and resection of tumor near sensorimotor areas or corticospinal tract.3–6The fundamental essence of MEP monitoring is based on the detection of a pyramidal tract insult expressed as a decrease of the amplitude of the waveform elicited by electrical stimulation. Conversely, Somatosensory evoked potentials (SSEPs) embraces a series of wave forms that emulate sequential activation of neural structures along the somatosensory pathways.7 The representative stimulation sites classically used for clinical diagnostic in the course of SSEPs studies are the median nerve at the wrist, the common peroneal nerve at the knee, and the posterior tibial nerve at the ankle. Over and above that, SSEPs have been used as an indicator of cerebral ischemia during CEA, although far less commonly and as a surrogate alternative to EEG. SSEPs primarily gauge the integrity of the dorsal (sensory) column of the spinal cord. It furnishes with the real-time examination of spinal tracts at risk during surgical manipulation of the spinal cord such as spinal tumor and pedicle screw instrumentation. Likewise, Auditory brainstem response (ABR) is a test which can assess the brain wave activity and diagnose dysfunctions of the auditory pathways within the auditory nerve and brainstem that occurs in response to an stimuli with clicks or certain tones.8This is notably useful in the surgery of CP angle tumor such as vestibular schwannoma, Microvascular decompression for hemifacial spasm and trigeminal neuralgia. In any neurosurgical endeavour, where a visual field impairment is contemplated during the intraoperative period, the monitoring of flash visual evoked potential (VEP) comes as a rescue to evaluate the state of visual function.9This manoeuvre is explicitly virtuous while performing tumorectomy at the optic chiasm of pituitary adenomas, craniopharyngiomas, tuberculum sellae meningiomas, and other tumors; the removal of brain tumors from the optic pathway and structures in its vicinity such as the optic nerve, optic radiation, and occipital lobe; and clip ligation of aneurysm involving the internal carotid artery, which strike a pose of risking injury and impeding blood flow to the ophthalmic artery.9 Monitoring intraoperative flash visual evoked potentials (VEPs) estimate the functionality of the optic pathway from the retina to the visual cortical area, and hence allows visual impairment to be avoided or minimized. The bulbocavernosus reflex (BCR) is anillustrious somatic reflex that is convenient in gaining information about the state of the sacral spinal cord segments.10 When present, it is indicative of an intact spinal reflex arcs (S2–S4 spinal segments) with afferent and efferent nerves through the pudendal nerve. BCR is of the greatest utility for the monitoring of sacral function in detethering of the tethered cord syndrome.11 A surface electrode is used to electrically stimulate the pudendal afferent fibers at the clitoris or penis and recording of the analogous triggered EMG in external anal sphincter using a subdermal needle electrode. The abnormal muscle response (AMR), which is also known as lateral pread response, is adopted in the microvascular decompression (MVD) for hemifacial spasm.12A complete disappearance of AMR after a convincing MVD from root exit zone implicate a postoperative disappearance of the hemifacial spasm. Nonetheless, the persistence of the AMR does not mean incomplete MVD.

A comparison of 0.375% ropivacaine psoas compartment block and 2% prilocaine spinal anaesthesia in dogs undergoing tibial plateau levelling osteotomy

BackgroundIn dogs undergoing routine elective orthopaedic surgeries carried out as same-day surgeries regional anaesthetic techniques (RATs) should aim to produce analgesia but minimising the postoperative motor dysfunction. Our objective was to compare the perioperative analgesic effects and the time to motor recovery between spinal anaesthesia (SA) with hyperbaric solution of prilocaine 2% (mg = 4 x [0.3 × BW (kg) + 0.05 × SCL (cm)]) and morphine (0.03 mg/kg) and combined ultrasound (US) and electro stimulator-guided psoas compartment and ischiatic nerve block (PB) with ropivacaine 0.375% (0.45 mL/kg). Dogs undergoing tibial plateau levelling osteotomy (TPLO) were randomly assigned to receive either SA or PB. Procedural failure, perioperative rescue analgesia, motor block recovery and complications were recorded.ResultsProcedural failure rate (PFR) was 19% (7 out of 36) for SA and 9% (3 out of 32) for PB (p = 0.31). Intraoperative rescue analgesia was administered to 6/29 (21%) SA group dogs and in 15/29 (52%) PB group dogs, respectively (p = 0.03). At 3 h after RAT, percentage of dogs with complete block recovery was 25/29 (86%) and 25/29 (86%) in group SA and PB, respectively (p = 1). Two cases of pruritus and one case of urinary retention were recorded in the SA group. Residual ischiatic nerve block was noted at 12 h after RAT in 2/15 (13%) of dogs in group PB; it completely resolved 24 h after RAT.ConclusionsSA with prilocaine 2% and PB with ropivacaine 0.37% were found suitable for dogs undergoing same-day TPLO surgery. Pruritus and urinary retention in SA and residual block in both groups might occasionally delay the time of discharge.

Timeliness of postnatal surgery in newborns with open neural tube defects: a single center experience.

This study aims to evaluate the experience of a tertiary health center on the timeliness of postnatal management in newborns with open neural tube defects (NTDs). This is a retrospective review of 38 neonates with NTDs who were treated surgically at a tertiary health care center between January 2009 and January 2019. Five neonates with genetic syndromes were excluded. Twenty-six neonates with NTD underwent surgery on the first postnatal day while 12 neonates with NTD had surgery after the first postnatal day. The reasons for the latency in operative treatment were the delay in the referral of the affected newborn from other health care centers (n=8) and the transient abnormalities in coagulation tests (n=4). Rural residence was significantly more frequent, gestational age at delivery was significantly lower, preterm delivery was significantly more frequent and prenatal diagnosis was significantly less frequent in neonates that underwent surgery for NTD repair after the first postnatal day (p=0.001, p=0.048, p=0.024 and p=0.003 respectively). Postoperative motor dysfunction was significantly more severe (p=0.002), postoperative complications were significantly more frequent (p=0.008), the reoperation and postoperative mortality rates were significantly higher (p=0.009 and p=0.048 respectively) and the duration of hospital stay was significantly longer (p=0.033) for the neonates who underwent surgery after the first postnatal day. Our study appears to favor the early repair of NTD`s within the first 24 hours of life. Such an approach may reduce the risk of infectious and neurological complications significantly.

Awake craniotomy for gliomas involving motor-related areas: classification and function recovery.

Motor mapping with direct cortical stimulation (DCS) is useful for motor function preservation. Nevertheless, many patients still experience postoperative motor dysfunction after motor mapping. This study aimed to provide a classification of gliomas involved in motor-related areas to help understand which types ofgliomas are prone to induce postoperative motor impairments. Sixty-four patients were retrospectively recruited. Based on tumor location, four typesof gliomas were identified: (I) precentral gyrus; (II) premotor and/or supplementary motor areas but not invading pre-central gyrus; (III) adjacent to the posterior limb of the internal capsule; and (IV) other supra-tentorial area. The recovery of motor function was evaluated by muscle strength testing before surgery and 3days, 7days, 14days, and 3months after surgery. Half of the patients experienced postoperative transient motor impairment within a week. Six patients suffered from permanent motor dysfunction, and four of them had type III glioma. Compared with types I and IV, patients with type III gliomas took more than three times as long to recover. Furthermore, patients with types I and II gliomas were more susceptible to preoperative epilepsy than those with types III and IV. There was no difference in postoperative seizure control between the four types. Our classification of gliomas involvingmotor-related eloquent areas was useful for predicting postoperative motor functional prognosis in patients who underwent motor mapping with DCS. Even if no positive sites were detected, a conservative strategy of tumor resection is recommended in cases that gliomas located close to the posterior limb of the internal capsule.

Prediction of postoperative motor deficits using intraoperative motor-evoked potentials in middle cerebral artery aneurysm.

To explore the relationship between postoperative motor deficits and the duration of reduced motor-evoked potentials (MEPs) in patients with middle cerebral artery (MCA) aneurysm. This study included 285 cases of MCA aneurysm treated with clipping surgery with MEP monitoring. The effects of MEP changes on postoperative motor function were assessed, and the key time point for minimizing the incidence of postoperative motor dysfunction was found through receiver operating characteristic (ROC) curve analysis. Motor dysfunction was significantly associated with the occurrence of MEP changes, and patients with irreversible changes were more likely to suffer motor dysfunction than were those with reversible changes. The critical duration of MEP changes that minimized the risk of postoperative motor dysfunction was 8.5min. This study revealed that MEP monitoring is an effective method for preventing ischemic brain injury during surgical treatment of MCA aneurysm and proposes a critical cutoff for the duration of MEP deterioration of 8.5min for predicting postoperative motor dysfunction.

A practical guide for anesthetic management during intraoperative motor evoked potential monitoring

Postoperative motor dysfunction can develop after spinal surgery, neurosurgery and aortic surgery, in which there is a risk of injury of motor pathway. In order to prevent such devastating complication, intraoperative monitoring of motor evoked potentials (MEP) has been conducted. However, to prevent postoperative motor dysfunction, proper understanding of MEP monitoring and proper anesthetic managements are required. Especially, a variety of anesthetics and neuromuscular blocking agent are known to attenuate MEP responses. In addition to the selection of anesthetic regime to record the baseline and control MEP, the measures to keep the level of hypnosis and muscular relaxation at constant are crucial to detect the changes of MEP responses after the surgical manipulation. Once the changes of MEP are observed based on the institutional alarm criteria, multidisciplinary team members should share the results of MEP monitoring and respond to check the status of monitoring and recover the possible motor nerve injury. Prevention of MEP-related adverse effects is also important to be considered. The Working Group of Japanese Society of Anesthesiologists (JSA) developed this practical guide aimed to help ensure safe and successful surgery through appropriate anesthetic management during intraoperative MEP monitoring.

The role of blood oxygenation level-dependent functional magnetic resonance imaging (BOLD-fMRI) combined with diffusion tensor imaging (DTI) in surgery for tumors involving motor pathways

<sec><strong>Objective:</strong> Blood oxygenation level-dependent functional magnetic resonance imaging (BOLD-fMRI) in combination with diffusion tensor imaging (DTI) can clearly show the specific relationship between brain tumors and motor pathways. The purpose of this study was to investigate the role of this combination in surgery for brain tumors involving motor pathways. </sec><sec><strong>Methods:</strong> From September 2018 to March 2019, preoperative BOLD-fMRI and DTI examinations were performed in patients with brain tumors involving motor pathways who were being treated in a neurosurgery department. The patients were divided into two groups according to the combined examination results. In one group, the motor pathways were intact; in the other, motor pathways were infiltrated by tumors. The surgical plan was total resection of the tumor as far as possible and with no damage to the motor pathway. The preoperative and postoperative motor dysfunction and the rate of total resection in the two groups were compared. </sec><sec><strong>Results:</strong> Of the 20 patients with intact motor pathways, 15 had normal preoperative motor function, and 5 had preoperative motor dysfunction; of those 5 patients, 3 exhibited postoperative aggravation of motor dysfunction. Total excision was performed in 16 patients with intact motor pathways and incomplete excision in 4. Of the 22 patients with motor pathway infiltration, 8 had normal preoperative motor function and 14 had preoperative motor dysfunction; of those 14, 10 exhibited a postoperative increase in motor dysfunction. Total excision was performed in 8 patients with infiltrated motor pathways and incomplete excision in 14. Statistical analysis showed that there were significant differences between the two groups in preoperative motor function, postoperative changes in motor function, and total surgical resection rate (all <i>p</i> < 0.05). </sec><sec><strong>Conclusions:</strong> First, whether tumors invade the motor pathway is an important factor affecting the degree of preoperative motor dysfunction. Second, the risk for postoperative motor dysfunction was lower in patients with intact motor pathways than in patients with infiltrated motor pathways. Third, the rate of total tumor resection was higher in patients with intact motor pathways than in patients with infiltrated motor pathways. Last, the combination of BOLD-fMRI and DTI aided in the decision to perform total resection. </sec>

Awake craniotomy with transcortical motor evoked potential monitoring for resection of gliomas in the precentral gyrus: utility for predicting motor function.

Resection of gliomas in the precentral gyrus carries a risk of severe motor dysfunction. To prevent permanent, severe postoperative motor dysfunction, reliable intraoperative predictors of postoperative function are required. Since 2005, the authors have removed gliomas in the precentral gyrus with combined functional mapping and estimation of intraoperative voluntary movement (IVM) during awake craniotomy and transcortical motor evoked potentials (MEPs). The purpose of the current study was to evaluate whether intraoperative findings of combined monitoring of IVM during awake craniotomy and transcortical MEP monitoring were useful for predicting postoperative motor function of patients with gliomas in the precentral gyrus. The current study included 30 patients who underwent resection of precentral gyrus gliomas during awake craniotomy from April 2000 to January 2018. All tumors were removed with monitoring of IVM during awake craniotomy and transcortical MEPs. Postoperative motor function was classified as stable or declined, with the extent of decline categorized as mild, moderate, or severe. We defined moderate and severe deficits were those that hindered daily life. In 28 of 30 cases, available waveforms were obtained with transcortical MEPs. The mean extent of resection (EOR) was 93%. Relative to preoperative status, motor function 6 months after surgery was considered stable in 20 patients and was considered to show mild decline in 7, moderate decline in 2, and severe decline in 1. Motor function 6 months after surgery was significantly correlated with IVM (p = 0.0096), changes in transcortical MEPs (decline ≤ or > 50%) (p = 0.0163), EOR, and ischemic lesions on postoperative MRI. Six patients with no change in IVM showed stable motor function 6 months after surgery. Only 2 patients with a decline in IVM and a decline in MEPs ≤ 50% had a decline in motor function 6 months after surgery (18%; 2/11 patients), whereas 11 patients with a decline in IVM and a decline in MEPs > 50% had such a decline in motor function (73%; 8/11 patients) including 2 patients with moderate and 1 with severe deficits. Three patients with moderate or severe motor deficits showed the lowest MEP values (< 100 µV). Combined judgment from monitoring of IVM during awake craniotomy and transcortical MEPs is useful for predicting postoperative motor function during removal of gliomas in the precentral gyrus. Maximum resection was achieved with an acceptable morbidity rate. Thus, these tumors should not be considered unresectable.

Evaluation of retraction time as a predictor of postoperative motor dysfunction after minimally invasive transpsoas interbody fusion at L4-L5

BackgroundComplications associated with the lateral lumbar transpsoas approach largely comprise various nerve-related syndromes particularly at L4-5. Quadriceps weakness can occur from stretch injury to the femoral nerve during retraction. ObjectiveThe purpose of this study is to evaluate the role of retraction time in the development of postoperative neuropathic motor weakness at the L4-5 level. MethodsA retrospective review of a prospectively collected database at a single institution was reviewed over a two-year period (March 2014–2016) for a single surgeon. Twenty-six patients undergoing single level LLIF at L4-5 were identified. Pre- and postoperative data collection obtained included motor function grading (0–5/5) with a minimum of 3-month postoperative follow-up. Intraoperative data collection included retraction time (RT) defined as the time the retraction system was affixed to the spine and expanded to the time of closure and removal. Two-Tailed T-Test was used to determine clinical significance. Results50% of patients had leg weakness after surgery (13/26). All postoperative motor deficits were at least antigravity strength (>3/5) and all deficits resolved. The mean RT for the motor dysfunction cohort was 29 min (14–51) compared to 27.5 min for the cohort without postoperative weakness (19–37) (p = 0.685). ConclusionThe results of this study suggest that longer retraction time (within a range of 14–51 min) did not correlate with a greater risk of postoperative neuropathic quadriceps muscle dysfunction for lateral lumbar interbody fusions performed at L4-5. Other factors may contribute to postoperative neurologic dysfunction regardless of RT. Motor deficits resolved quickly after surgery.

Feasibility of intraoperative motor-evoked potential monitoring for skull base tumors with a high risk of postoperative motor deterioration

To establish the validity and utility of motor-evoked potential (MEPs) monitoring for skull base tumor resection, we explored the relationship between MEP monitoring results and postoperative motor function. MEPs were successfully monitored during 76 operations in 68 patients with a high risk of motor morbidity. MEP monitoring data were correlated with perioperative clinical motor function. MEPs remained stable in 56 operations (73.7%), and no postoperative motor deterioration was observed. Transient or permanent deterioration of MEPs (<50% of the initial amplitude before surgery) occurred in 20 operations (26.3%). This deterioration was reversible after intervention in seven cases (9.2%). Irreversible deterioration in MEPs was seen in 13 cases (17.1%). In five cases, the final amplitude was greater than 10%. Two of these patients experienced transient loss of MEPs and moderate to severe hemiparesis. Both patients showed full recovery within 6months after the operation. The other three patients experienced no postoperative worsening of motor function. The final MEP amplitude was less than 10% in the other eight patients, including five with permanent MEP loss. All of these patients experienced severe postoperative motor dysfunction. Recovery of motor function was worse in most participants in this group compared with those in the other groups. Intraoperative MEP monitoring is a valid indicator of pyramidal tract pathway function for skull base tumor surgery.

Evaluation of Combined Use of Transcranial and Direct Cortical Motor Evoked Potential Monitoring During Unruptured Aneurysm Surgery

The feasibility and reliability of combined use of transcranial and direct cortical motor evoked potential (MEP) monitoring during unruptured aneurysm surgery were evaluated. Forty-eight patients with unruptured cerebral aneurysms underwent craniotomy and neck clipping accompanied by muscle MEP monitoring. MEPs were elicited successfully by transcranial electrical stimulation in all patients. Direct cortical stimulation elicited MEPs in 44 patients. Reduction in MEP amplitude to less than 50% of baseline was considered significant. No postoperative motor paresis occurred in 39 patients in whom transcranial and direct MEPs remained unchanged. Four patients in whom direct MEPs could not be recorded had no intraoperative abnormality in transcranial MEPs and no postoperative motor dysfunction. Four of the other 5 patients manifested significant transient direct MEP changes without transcranial MEP changes. The transient MEP changes were observed in 3 patients during temporary clipping of the parent artery and in one patient with inadequate clipping of an middle cerebral artery aneurysm, and were considered due to insufficiency of blood flow. Decrease or disappearance of direct MEP waves recovered immediately after re-application of the clip and release of the temporary clip. Direct MEP waves disappeared and did not recover until the end of microsurgical procedures in one patient, although transcranial MEP amplitude remained at less than 50% of baseline. She developed hemiparesis postoperatively, which recovered within 6 hours. The duration of temporary occlusion in patients with direct MEP changes was significantly longer than that in patients without (p < 0.05). Direct MEP was sensitive in detecting ischemic stress to descending motor pathways during aneurysm surgery. Transcranial MEPs could be elicited in patients in whom direct MEPs could not be obtained, and during periods such as craniotomy or after dural closure, in which direct MEPs could not be recorded. These findings suggest that combined transcranial and direct cortical MEP recording may improve the feasibility and reliability of MEP monitoring during unruptured aneurysm surgery.

Acute Rejection in Allogeneic Rodent Small Bowel Transplantation Causes Smooth Muscle Dysfunction via an Inflammatory Response Within the Intestinal Muscularis

Introduction Isogeneic intestinal transplantation elicits an inflammatory response within the intestinal muscularis that is associated with dysmotility. Usually the inflammation and the postoperative motor dysfunction resolve within a few days after small bowel transplantation (SBTx). However, the onset of acute rejection in allogeneic SBTx is again associated with dysmotility. We hypothesized that dysmotility during acute rejection is based on coexpression of kinetically active mediators by the alloreactive leucocyte infiltrate. Materials and methods Rat SBTx (BN to Lew and BN to BN) was performed without immunosuppression. Animals were sacrificed at 1, 4, and 7 days after SBTx. Leukocyte infiltration was investigated in muscularis whole mounts by immunohistochemistry. Mediator mRNA expression was determined by reverse transcriptase polymerase chain reaction. Muscle contractility was assessed in a standard organ bath. Results Transplanted animals showed a significant inflammatory response within the muscularis at day 1 after SBTx. However, allogeneic transplanted animals exhibited a significant second inflammatory peak at day 7 (mRNA induction: iNOS 150-fold; tumor necrosis factor-α 18-fold; interferon-γ 397-fold), parallel to the onset of rejection. This change was associated with a significant leukocyte infiltration. Compared to controls, allogeneic transplanted animals showed a 29% decrease in smooth muscle contractility on days 1 and 4 and a 71% decrease of contractility on postoperative day 7. Conclusions The motor dysfunction of transplanted small bowel during acute rejection is associated with an inflammatory reaction in the intestinal muscularis. The initial unspecific inflammation process immediately after transplantation is reactivated and intensified during acute rejection.

Intraoperative corticomuscular motor evoked potentials for evaluation of motor function: a comparison with corticospinal D and I waves

The goal of this study was to compare motor evoked potentials recorded from muscles (muscle MEPs or corticomuscular MEPs) with corticospinal MEPs recorded from the cervical epidural space (spinal MEPs or corticospinal MEPs) to assess their efficacy in the intraoperative monitoring of motor function. Muscle and spinal MEPs were simultaneously recorded during surgery in 80 patients harboring brain tumors. Each case was assigned to one of four groups according to final changes in the MEPs: (1) Group A, in which there was an increased amplitude in the muscle MEP with an increased 13 wave amplitude (12 cases); (2) Group B, in which there was no significant change in the MEP (43 cases); (3) Group C, in which there was a decreased muscle MEP amplitude (< 35% of the control) with a decreased I wave amplitude but an unchanged D wave (15 cases); or (4) Group D, in which there was an absent muscle MEP with a decreased D wave amplitude (10 cases). In patients in Group A, the increase in the amplitude of the muscle MEP (range of increase 128-280%, mean increase 188.75 +/- 48.79%) was well correlated with the increase in the 13 wave in corticospinal MEPs. Most of these patterns were observed in patients harboring meningiomas (10 [83.3%] of 12 cases). Patients in Group B displayed no changes in muscle and corticospinal MEPs and no signs of postoperative neurological deterioration. Patients in Group C showed a substantial decrease in the amplitude of the muscle MEP (range of decrease 5.3-34.8% based on the control waveform, mean change 21.81 +/- 10.93%) without deterioration in the corticospinal D wave, and exhibited severe immediate postoperative motor dysfunction. This indicates dysfunction of the cortical gray matter, including the motor cortices, which are supposed to generate I waves. Patients in Group D exhibited decreases in the corticospinal D wave (range of decrease 21.5-55%, mean decrease 39.75 +/- 11.45%) and an immediate cessation of the muscle MEP as well as severe permanent motor paresis. These results indicate that, during surgery, monitoring of corticomuscular MEPs (which are related to I waves) is a much more sensitive method for the detection of immediate motor cortical damage than monitoring of corticospinal MEPs (D wave).

脳血管障害における術中経頭蓋ＭＥＰモニタリングの有用性

We clinically examined the efficacy of motor evoked potential (MEP) by transcranial high-voltage electrical stimulation for intraoperative monitoring in cerebro-vascular disease. In 49 neurosurgical operations for cerebro-vascular disease, transcranial MEP (TCMEP) was recorded by 300-1000 V bipolar stimulation using the screw electrodes with the anode on the affected side. Surface electrodes for electromyographic responses were placed on the bilateral abductor pollicis brevis (APB) and bilateral abductor hallucis (AH) muscles. To remove effects of muscle relaxants on TCMEP, compound muscle action potential (CMAP) by supra-maximum stimulation of the median nerve 2 seconds after transcranial stimulation was recorded in 30 recent operations. In all 40 operations under propofol anesthesia and 6 among 7 cases under volatile anesthesia, MEP was successfully recorded. Postoperative motor paresis occurred in 6 limbs of 4 patients among 54 limbs of 30 patients who had received TCMEP compensated by CMAP by peripheral nerve stimulation and all compensated relative amplitude indexes (CRAIs) of these 6 limbs were less than 0.2. In contrast, in all 48 limbs of 26 patients who had no postoperative motor dysfunction, CRAI had been more than 0.2. These results suggest that our intraoperative TCMEP monitoring by relatively low-voltage (300-400 V) stimulation and compensated by CMAP after peripheral nerve stimulation was safe, easy (no need to expose the motor cortex), relatively accurate and less invasive, and useful especially in cerebro-vascular disease, which often requires a temporary occlusion of the cerebral arteries.