Assessment Of Spinal Cord Function Research Articles

Intradural Extramedullary Spinal Tumors: A Clinical Study and Management without the Aid of Nerve Monitoring

Abstract Background: The incidence of primary spinal cord tumors is less and the true incidence is still not known and various studies are still being done. These tumors are benign and slow growing, and they generally present with pain – either radiculopathy or axial back pain or focal neurological deficits due to the loss of roots, myelopathy from spinal cord compression, or cauda equina symptoms due to chronic compression. Early diagnosis and operation are gratifying as the lesions are mostly benign and can be completely resected as well as preservation of functionality if operated as early as possible. Although rare, an inadvertent neurological injury during surgery is a concerning complication that can potentially be prevented with the assistance of intraoperative nerve monitoring (IONM). This technology enables real-time assessment of spinal cord function by providing feedback from sensory tracts, motor tracts, and individual nerve roots. However, the definitive requirement for IONM in the treatment of a highly curable condition is still under consideration. Objective: our study aims at studying the clinical features of intradural extramedullary tumors and their operative management without nerve monitoring. Material and Methods: Patients with intradural extramedullary (IDEM) spinal cord tumors who fit the inclusion criteria and who were willing to investigations, surgical procedures, and follow up were enrolled in the study, and consent was obtained. Patient assessment was done clinically by McCormick’s Scale and radiologically by magnetic resonance imaging. Patients who underwent operation were followed up. The data was collected and analysed using SPSS software. Results: Nineteen patients were enrolled in the study. The age group ranged from 6 years to 79 years. There were 13 females and 6 males in the study group. The common presenting complaints were backache and upper and lower limb pain. Nine out of the 19 patients underwent operative procedures after thorough radiological and clinical evaluation. Histopathology showed five cases of schwannoma and four cases of meningioma. The mean McCormick’s Scale preoperatively was 4.11, whereas postoperatively, it was 3.10. The operative procedures were performed without the aid of IONM, yet there were no inadvertent intraoperative injuries and postoperative outcomes were good. Our study data were comparable with other studies. Conclusion: IDEM tumors, though technically challenging to operate, have excellent results in terms of outcomes due to their benign characteristics as well as complete resectability. Therefore, it is essential to conduct a comprehensive examination and imaging for patients experiencing backaches and weakness. Following a careful evaluation, early surgical intervention should be considered, as the timeliness of the surgery contributes to enhanced outcomes. The unavailability of nerve monitoring did not portend any added risk of surgery if done meticulously though its aid would make the operative procedure safer and gross resection better.

Neurophysiological approach to the assessment of spinal cord function in kyphotic spinal deformity

The results of a comprehensive (clinical-radiological and neurophysiological) study performed in two clinical groups of patients (n = 64) with kyphotic spinal deformity of II–IV degree of severity of the thoracic and lumbar spine of various etiologies were analysed. With the progression of kyphotic spine deformity, the spinal cord (SC) located inside the spinal canal becomes involved in the pathological process. This period of dysfunction is preceded by a state of latent SM changes that are not detected clinically (prodromal period). The presence of neurological disorders is considered as a factor of increased risk of intra- and postoperative complications in the surgical treatment of kyphosis. Based on the registration and analysis of the parameters of somatosensory evoked potentials and motor responses during transcranial magnetic stimulation, electrophysiological signs of sensorimotor insufficiency of the SС nerve tracts were revealed, which correlate with the kyphotic arch value. The established electrophysiological criteria allow to verify the level of conductive lesion at the level of thoracic and lumbar SC segments, to determine its severity, to monitor recovery processes and to predict the functional outcome.

Cryopreserved human umbilical cord as a meningeal patch during in utero spina bifida repair in a modified ovine model.

Despite in utero spina bifida (SB) repair, more than two-thirds of patients with SB are unable to ambulate independently, and 1 in 4 children need surgery for tethered cord by school age. The objective of this study was to test the cryopreserved human umbilical cord (HUC) as an antiscarring material to reduce tethering and improve function in a modified in utero SB repair model. An SB defect (L2-6 levels) without myelotomy was created in fetuses of timed-pregnant ewes at gestational day (GD) 75. On GD 96, the fetal defect was exposed, and the arachnoid layer was removed to disrupt the barrier and expose the spinal cord to simulate human in utero SB repair. The fetuses were randomly assigned to two groups according to the method used to cover the spinal cord: the conventional repair (CR) group, for which myofascial closure was used (n = 7), and the HUC meningeal patch group, for which HUC was used as a meningeal patch (n = 6), followed by primary skin closure. The lambs were delivered at GD 140. Blinded clinical assessment of spinal cord function was performed using the Texas Spinal Cord Injury Scale (TSCIS). Histology of the spine was performed for quantitative assessment of spinal cord tethering, inflammatory markers, and arachnoid layer regeneration. The TSCIS scores were significantly lower in the CR than the HUC meningeal patch group (p = 0.0015) and the controls (p = 0.0018). The loss of spinal cord function in the CR group was mainly due to ataxia and loss of proprioception (p = 0.01 and 0.005 vs control and HUC, respectively). The histology at the repair site showed higher rates of spinal cord tethering in the CR lambs than the HUC lambs at all levels of the repair site (p = 0.01 and 0.02 vs control and HUC, respectively). In the CR with tethering compared with the HUC repair, there was a lower arachnoid layer covering at the repair site (p = 0.001). There was greater astrocyte activation in the posterior column in the CR than in the HUC repair group (p = 0.01). In a modified ovine SB model, the HUC as a meningeal patch allows regeneration of the arachnoid layer, prevents spinal cord tethering, and improves spinal cord function after in utero SB repair.

Degenerative cervical myelopathy

Degenerative cervical myelopathy (DCM) is the most common cause of spinal cord dysfunction in adults. Its prevalence is increasing as a result of population aging. The diagnosis of DCM is often delayed or overlooked, resulting in secondary neurologic morbidity. The natural course of DCM typically presents as a gradual neurological deterioration, with symptoms ranging from muscle weakness to complete paralysis, with variable degrees of sensory deficits and sphincter dysfunction. Magnetic resonance imaging (MRI) and electrophysiological studies allow the assessment of spinal cord function and its structural damage to determine treatment and clinical outcomes. All patients with signs and symptoms consistent with DCM should be referred to a spine surgeon for assessment and tailored treatment. Those patients with mild DCM can be managed non-operatively but require close monitoring and education about potentially alarming signs and symptoms. Surgery is not currently recommended for asymptomatic patients with evidence of spinal cord compression or cervical spinal stenosis on MRI, but they require a structured follow-up. Patients with moderate or severe DCM require surgical decompression to avoid further progression. The objective of this review is to raise awareness of degenerative cervical myelopathy and its increasing prevalence as well as to aid non-surgical healthcare workers for a timely diagnosis and management of this disabling condition.

Application of Magnetic Resonance Diffusion Tensor Imaging in the Clinical Diagnosis of Disc Herniation after Lumbar Spine Injury.

Magnetic resonance diffusion-weighted imaging (DTI) provides a unique perspective on the pathophysiological and microstructural changes during spinal cord injury, with high spatial specificity; meanwhile, NM reflects the conduction and integrity of neuroelectrical signals in spinal cord fiber tracts, with time-specific and dynamic evaluation effects. The fractional anisotropy (FA) value, SEP amplitude, and neurological function score or improvement rate are correlated. The combination of DTI and NM can more reliably quantify the spinal cord function, evaluate the effectiveness of treatment, and determine the patient's prognosis, which can provide reference for clinical decision making and future research for SCI patients. That is, the lower the preoperative FA value and the lower the SEP amplitude, the worse the preoperative and postoperative neurological function, the lower the improvement rate, and the worse the prognosis of patients. Therefore, we believe that spinal cord function can be graded according to JOA scores to find the corresponding FA and SEP amplitude ranges and that, by measuring FA and SEP amplitude in the future, we can reverse the assessment of spinal cord function, expected postoperative improvement, and long-term prognosis. At the same time, FA values can also help determine the nature of the lesion to some extent.

Multimodality Intraoperative Neuromonitoring in Severe Thoracic Deformity Posterior Vertebral Column Resection Correction

Multimodal intraoperative neuromonitoring (IONM) has been proposed as an effective way to reduce permanent neurologic injury during spinal deformity surgery. However, few studies have reported evoked potential changes at different surgical stages of thoracic posterior vertebral column resection (PVCR). A total of 82 cases with severe thoracic deformity (Yang's A type) treated by PVCR in a single institution between January 2010 and March 2015 were reviewed. Multimodal IONM including somatosensory evoked potential, motor evoked potential, and descending neurogenic evoked potential was performed for real-time assessment of spinal cord function during surgery. The risk factors of neuromonitoring events at different surgical stages were documented and analyzed. Multimodal IONM was successfully performed in all 82 cases. Thirty-nine neuromonitoring events presented in 27 (32.9%) cases. Neurologic monitoring events were more likely to occur in patients with larger scoliosis and kyphosis, longer osteotomy closure distance, more Halo gravity traction, more screw insertion, and higher PVCR segments. The reasons for monitoring changes included 6 events during screw insertion, 20 during osteotomy, 9 during osteotomy gap closure, and 4 during deformity correction. New postoperative neurologic deficits were observed in 11 (13.4%) cases including 1 incomplete paraplegia, 8 transient cord deficits, and 2 nerve root injuries. Multimodal IONM can effectively identify neurologic deficits throughout surgery. Osteotomy and osteotomy gap closure are the surgical stages with the highest neurologic risks during PVCR procedures. It is imperative to improve dexterity since the majority of neuromonitoring events are caused by surgical techniques.

Application of diffusion tensor imaging for the diagnosis of segmental level of dysfunction in cervical spondylotic myelopathy

A retrospective study. Diffusion tensor imaging (DTI) reflects pathological change in the spinal cord more sensitively than conventional magnetic resonance imaging (MRI). Electrophysiological examination enables quantitative assessment of spinal cord function. Few studies have addressed the correlation between intraoperative spinal cord-evoked potentials (SCEPs) and DTI. The purpose of this study was to examine whether DTI is an objective index for the diagnosis of the segmental level of dysfunction in cervical spondylotic myelopathy (CSM). Yamaguchi University Graduate School of Medicine, Japan. Using 3.0-Tesla MRI, DTI values for the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) were measured at the disc level C2/C3 through C6/C7 in 11 normal subjects and 10 subjects with CSM. Subjects with CSM were divided into two groups based on the extent of compression according to conventional MRI: single level (n=3) and multilevel (n=7). Intraoperative SCEPs were measured in subjects with CSM. For each group, the ADC and FA values were compared with SCEPs with respect to the segmental levels of dysfunction. For all three subjects with single-level compression and six of seven with multilevel compression, the maximal ADC value was observed at the segmental level of dysfunction as per the SCEP. Minimum FA values were observed at those sites in two of three patients with single-level compression and in only two of seven with multi-level compression. Our results suggest that ADC might serve as a supplementary diagnostic indicator of the segmental levels of dysfunction in CSM.

Cyber medicine enables remote neuromonitoring during aortic surgery

This study assessed the feasibility and effectiveness of remote neuromonitoring as an adjunct to spinal cord protection during surgical repair of descending thoracic aortic aneurysms and thoracoabdominal aortic aneurysms. Four aortic centers in three European countries participated in this prospective observational study. A similar surgical protocol was used in all centers, including assessment of spinal cord function by means of monitoring motor-evoked potentials (MEPs). MEP information was evaluated at one central neurophysiologic department in Maastricht, The Netherlands. Transfer of MEP data from all operating rooms to Maastricht was arranged by Internet connections. In all patients, the protective and surgical strategies to prevent paraplegia were based on MEPs. The on-site surgeons reacted in real time to the interpretation and feedback of the neurophysiologist. Between March 2009 and May 2011, 130 patients (85 men) were treated by open surgical repair. Extent of aneurysms was equally distributed among the centers. Neuromonitoring was technically stabile and successful in all patients. The transfer of data from the operating room in the different vascular centers was undisturbed and without any technical problems. By maintaining a mean distal aortic pressure of 60 mm Hg, MEPs were undisturbed in 65 patients (50%). In another 65 patients (50%), significant changes in MEPs prompted the surgical teams to initiate additional protective and surgical strategies to restore spinal cord perfusion. These measures were not effective in five patients (3.8%), and acute paraplegia resulted. Delayed paraplegia occurred in 10 patients (7.7%) but improved in three and recovered completely in another three. No false-negative or false-positive MEP recordings were experienced. Remote neuromonitoring of spinal cord function during open repair of descending thoracic aortic aneurysms and thoracoabdominal aortic aneurysms as a telemedicine technique is feasible and effective. It allows centralization of expertise and saves individual centers from investing in complex technology. The value of monitoring MEPs was confirmed in different aortic centers, resulting in adequate neurologic outcome after extensive aortic surgical procedures.

The value of somatosensory evoked potential in the clinical evaluation of congenital scoliosis with and without intraspinal malformations

To investigate the value of somatosensory evoked potential (SEP) in the diagnosis of congenital scoliosis (CS) with intraspinal malformation. From September 2001 to September 2007 posterior tibial nerve SEP were performed on 187 operatively treated CS patients. There were 85 male and 102 female, and the average age was 13.8 years (range from 30 to 22 years). Patients with intraspinal malformations were diagnosed by MRI. Absence of SEP waveforms, prolongation of peek latency or asymmetrical peek latency were defined as pathological change. The incidence of pathological SEP and clinical characteristics were compared between patients with and without intraspinal malformations. Of 187 patients, intraspinal malformations were diagnosed in 32 patients (17.1%). The incidence of intraspinal malformations was higher in type III (30.8%) than in type I and II CS patients (P < 0.05). The mean Cobb angle of scoliosis in patients with intraspinal malformations was greater than without intraspinal malformations, but there was no difference in kyphosis between the two groups. The ratio of abnormal SEP in patients with intraspinal malformations was 75.0% (24/32), while it was 38.7% (60/155) in patients without intraspinal malformations, and it showed significant difference between the two groups (χ(2) = 4.70, P < 0.05). SEP is a reliable tool for assessment of spinal cord function in patients with congenital scoliosis. It could be helpful for the diagnosis of intraspinal malformations, and also might provide an important reference for assessment and treatment of intraspinal malformations in congenital scoliosis.

TP3.1 Neurophysiologic assessment of spinal cord function in spine and spinal cord trauma: An intraoperative study

TP3.1 Neurophysiologic assessment of spinal cord function in spine and spinal cord trauma: An intraoperative study

Neuronal Plasticity After Spinal Cord Injury: Significance for Present and Future Treatments

Summary: Recent progress in the understanding of movement control allows us to define more precisely the requirements for successful rehabilitation of patients with neurologic deficits after a spinal cord injury (SCI). Load- and hip joint position-related afferent input seems to be of crucial importance for the generation and success of locomotor training. In addition, there is accumulating evidence from animal experiments that axonal regeneration can be induced after a SCI. Consequently, in the near future, new therapeutic approaches will be developed for the treatment of subjects with SCI. Functional training and regeneration represent complimentary approaches. Regenerating spinal tract fibers needs functional training to make the appropriate connections, and training effects will be enhanced by regenerating fibers. A clinical basis for monitoring the effects of novel interventional therapies is needed. Refined and combined clinical and neurophysiologic measures are needed for a precise qualitative and quantitative assessment of spinal cord function in patients with SCI at an early stage. This is a basic requirement for predicting functional outcome, as well as for recognizing any improvement in the recovery of function caused by a new treatment. To this aim, 14 European spinal cord injury centers involved in the rehabilitation of patients with acute SCI have built a close clinical collaboration using a standardized protocol for the assessment of the outcome after SCI and the extent of recovery achieved by actually applied therapies in a larger population of patients with SCI.

Setup of Neurophysiological Monitoring with tcMEP/SSEP During Thoracoabdominal Aneurysm Repair

The article describes a procedure for the intraoperative neurophysiological placement of electrodes to control the spinal cord function during thoracoabdominal aortic aneurysm repair. Intraoperative monitoring is performed by motor-evoked myogenic potentials after transcranial electric stimulation (tcMEP) and somatosensory-evoked potentials (SSEP). In tcMEP, the stimulating percutaneous needle electrodes are placed at C3 and C4 according to the 10 - 20 system for EEG recordings. TcMEP are recorded from the anterior tibial and gastrocnemius muscles on both sides. The SSEP electrodes are placed laterally and caudally onto the malleolus medialis in order to stimulate the tibial nerve. The stimulus is documented via electrodes attached to the scalp within the sensory cortex region. The application of the electrodes is both easy to learn and can be performed without further difficulties. Once attached, the electrodes provide a quick assessment and interpretation of spinal cord function. The identification of external sources of disturbance during the monitoring (e. g. insufficient impedance, unfavourable electrode positioning, and technical interference caused by medical equipment) enables the supervisor to differentiate between normal and abnormal neurological responses. TcMEP and SSEP allow an adequate, direct, and reliable intraoperative assessment of spinal cord function, enabling the surgeon to diagnose an impending ischaemia and act accordingly. This measurement technique provides the surgical team with a means of integrating neurological aspects during thoracoabdominal aneurysm repair.

Neurologische und funktionelle Erholung nach Querschnittl�hmung

Today, there is accumulating evidence from animal experiments that axonal regeneration and an enhanced level of functional repair can be induced after a spinal cord injury (SCI). Consequently, in the near future, new therapeutic approaches will be developed for the treatment of patients with SCI. The aim of the project presented here is to provide the required clinical basis for the implementation of novel interventional therapies. Refined and combined clinical and neurophysiological measures are needed for a precise qualitative and quantitative assessment of spinal cord function in patients with SCI at an early stage. This represents a basic requirement for recognizing any improvement in the recovery of function and to monitor any significant effect of a new treatment. The paper presents objective and refined tools as a basis for monitoring the effects of new treatment strategies.

Providing the clinical basis for new interventional therapies: refined diagnosis and assessment of recovery after spinal cord injury.

Today, there is accumulating evidence from animal experiments that axonal regeneration and an enhanced level of functional repair can be induced after a spinal cord injury (SCI). Consequently, in the near future, new therapeutic approaches will be developed for the treatment of patients with SCI. The aim of the project presented here is to provide the required clinical basis for the implementation of novel interventional therapies. Refined and combined clinical and neurophysiological measures are needed for a precise qualitative and quantitative assessment of spinal cord function in patients with SCI at an early stage. This represents a basic requirement to recognise any improvement in the recovery of function and to monitor any significant effect of a new treatment. To this aim, five European Spinal Cord Injury Centres involved in the rehabilitation of acute SCI patients have built up a close clinical collaboration to develop a standardised protocol for the assessment of the outcome after SCI and the extent of recovery achieved by actually applied therapies in a larger population of SCI patients. The project's aim is to establish objective, refined tools as a basis for monitoring the effects of new treatment strategies.

Effects of spinal cord ischemia on the refractory period of descending spinal cord evoked potential

The recovery cycle, following the conduction of action potentials along a nerve fiber, consists of the absolute refractory period (ARP), the relative refractory period (RRP) and the supernormal period (SNP). The recovery cycle of the descending conductive spinal cord evoked potential (SCEP) was shown during normal state, ischemia and after ischemia using paired stimuli in cats. During ischemia the refractory period revealed a trend towards increment. Five minutes after reperfusion the refractory period decreased transiently compared with the normal level and within 30 min the refractory period returned to the normal level. The recovery curve of the 2nd potential showed different pattern compared with that of the 1st potential. Moreover, during ischemia, firstly the 3rd potential and secondly the 2nd potential of the SCEP elicited by the 2nd stimulus were disturbed. These results demonstrated that there is increased excitability of the spinal cord to the second stimulus after a brief period of ischemia, and that the 2nd and 3rd potentials are evoked synaptically and easily disturbed during ischemia. Measuring the SCEP elicited by paired stimuli or constructing the recovery curve of the SCEP is useful for the electrophysiological assessment of spinal cord function.

Evoked potentials from direct cerebellar stimulation for monitoring of the rodent spinal cord

Although the assessment of spinal cord function by electrophysiological techniques has become important in both clinical and research environments, current monitoring methods do not completely evaluate all tracts in the spinal cord. Somatosensory and motor evoked potentials primarily reflect dorsal column and pyramidal tract integrity, respectively, but do not directly assess the status of the ventral funiculus. The present study was undertaken to evaluate the use of evoked potentials, elicited by direct cerebellar stimulation, in monitoring the ventral component of the rodent spinal cord. Twenty-nine rats underwent epidural anodal stimulation directly over the cerebellar cortex, with recording of evoked responses from the lower thoracic spinal cord, both sciatic nerves, and/or both gastrocnemius muscles. Stimulation parameters were varied to establish normative characteristics. The pathways conducting these "posterior fossa evoked potentials" were determined after creation of various lesions of the cervical spinal cord. The evoked potential recorded from the thoracic spinal cord consisted of five positive (P1 to P5) and five negative (N1 to N5) peaks. The average conduction velocity (+/- standard deviation) of the earliest wave (P1) was 53 +/- 4 m/sec, with a latency of 1.24 +/- 0.10 msec. The other components followed within 4 msec from stimulus onset. Unilateral cerebellar stimulation resulted in bilateral sciatic nerve and gastrocnemius muscle responses; there were no significant differences (p greater than 0.05) in the thresholds, amplitudes, or latencies of these responses elicited by right- versus left-sided stimulation. Recordings performed following creation of selective lesions of the cervical cord indicated that the thoracic response was carried primarily in the ventral funiculus while the sciatic and gastrocnemius responses were mediated through the dorsal half of the spinal cord. It is concluded that the posterior fossa evoked potential has research value as a method of monitoring pathways within the ventral spinal cord of the rat, and should be useful in the study of spinal cord injury.

Evaluation of spinal evoked potentials: a model for assessment of spinal cord function in isolation.

Spinal evoked potentials were recorded from the dorsal columns of in vitro mouse hemicord preparations. The response of these potentials to different periods of hypoxia was studied. A decrease in amplitude of the potential to 50% and 10% of pre-hypoxia reference occurred after 3.19 +/- 1.36 and 7.3 +/- 2.97 min, respectively. Complete recovery of the potential was seen in specimens exposed to 5 and 10 min of hypoxia. Incomplete recovery occurred with exposure to longer periods of hypoxia. In preparations that remained isoelectric for less than 5 min total recovery was seen.

The Use of Intraoperative Fluoroscopy and Spinal Cord Monitoring for Transoral Microsurgical Odontoid Resection

The transoral approach to the upper cervical spine has not gained wide acceptance. A reliable intraoperative method to determine the necessary extent of dissection and degree of decompression, as well as to evaluate spinal cord function, should improve the safety and applicability of the transoral approach. Four cases of anterior cervical cord compression were successfully treated by odontoid resection employing a microsurgical transoral approach. Intraoperative fluoroscopy monitored the depth of dissection and adequacy of decompression. Somatosensory cortical evoked potentials (SSEP) allowed assessment of spinal cord function that could be correlated with surgical decompression. In addition, follow-up examination revealed that SSEP was an intraoperative prognosticator of subsequent neurologic improvement.

Intra-operative awakening during scoliosis surgery.

A method of intra-operative awakening which allows assessment of spinal cord function during Harrington rod spinal fusion for scoliosis is described. The anaesthetic technique is based on a standard muscle relaxant, N2O anaesthetic sequence supplemented with intravenous morphine 0.1 mg/kg at the commencement of surgery and 0.2 mg/kg intramuscular premedication. This relatively large total dose of morphine may reduce intra-operative awareness, and may also provide substantial pain relief during the initial 24 h postoperative period. It has been used successfully in 20 patients aged between 6 and 16 yr. Five patients remembered being woken, but did not regard it as unpleasant. In one patient, this technique allowed intra-operative detection and correction of impaired motor function of the legs.