Use of the train-of-five bipolar technique to provide reliable, spatially accurate motor cortex identification in asleep patients.

OBJECTIVE: Intraoperative cortical and subcortical mapping techniques have become integral for achieving a maximal safe resection of tumors that are in or near regions of eloquent brain. The recent literature has demonstrated successful motor/language mapping with lower rates of stimulation-induced seizures when using monopolar high-frequency stimulation compared to traditional low-frequency bipolar stimulation mapping. However, monopolar stimulation carries with it disadvantages that include more radiant spread of electrical stimulation and a theoretically higher potential for tissue damage. The authors report on the successful use of bipolar stimulation with a high-frequency train-of-five (TOF) pulse physiology for motor mapping. METHODS: Between 2018 and 2019, 13 patients underwent motor mapping with phase-reversal and both low-frequency and high-frequency bipolar stimulation. A retrospective chart review was conducted to determine the success rate of motor mapping and to acquire intraoperative details. RESULTS: Thirteen patients underwent both high- and low-frequency bipolar motor mapping to aid in tumor resection. Of the lesions treated, 69% were gliomas, and the remainder were metastases. The motor cortex was identified at a significantly greater rate when using high-frequency TOF bipolar stimulation (n = 13) compared to the low-frequency bipolar stimulation (n = 4) (100% vs 31%, respectively; p = 0.0005). Intraoperative seizures and afterdischarges occurred only in the group of patients who underwent low-frequency bipolar stimulation, and none occurred in the TOF group (31% vs 0%, respectively; p = 0.09). CONCLUSIONS: Using a bipolar wand with high-frequency TOF stimulation, the authors achieved a significantly higher rate of successful motor mapping and a low rate of intraoperative seizure compared to traditional low-frequency bipolar stimulation. This preliminary study suggests that high-frequency TOF stimulation provides a reliable additional tool for motor cortex identification in asleep patients.

Damned if you monitor, damned if you don't: medical malpractice and intraoperative neuromonitoring for spinal surgery.

OBJECTIVE: The aim of this study was to identify trends in medical malpractice litigation related to intraoperative neuromonitoring. METHODS: The Westlaw Edge legal research service was queried for malpractice litigation related to neuromonitoring in spine surgery. Cases were reviewed to determine if the plaintiff's assertion of negligence was due to either failure to use neuromonitoring or negligent monitoring. Comparative statistics and a detailed qualitative analysis of the resulting cases were performed. RESULTS: Twenty-six cases related to neuromonitoring were identified. Spinal fusion was the procedure in question in all cases, and defendants were nearly evenly divided between orthopedic surgeons and neurosurgeons. Defense verdicts were most common (54%), followed by settlements (27%) and plaintiff verdicts (19%). Settlements resulted in a mean $7,575,000 damage award, while plaintiff verdicts resulted in a mean $4,180,213 damage award. The basis for litigation was failure to monitor in 54% of the cases and negligent monitoring in 46%. There were no significant differences in case outcomes between the two allegations of negligence. CONCLUSIONS: The use and interpretation of intraoperative neuromonitoring findings can be the basis for a medical malpractice litigation. Spine surgeons can face malpractice risks by not monitoring when required by the standard of care and by interpreting or reacting to neuromonitoring findings inappropriately.

Spinal neurovascular complications with anterior thoracolumbar spine surgery: a systematic review and review of thoracolumbar vascular anatomy.

OBJECTIVE: Spinal cord infarction due to interruption of the spinal vascular supply during anterior thoracolumbar surgery is a rare but devastating complication. Here, the authors sought to summarize the data on this complication in terms of its incidence, risk factors, and operative considerations. They also sought to summarize the relevant spinal vascular anatomy. METHODS: They performed a systematic literature review of the PubMed, Scopus, and Embase databases to identify reports of spinal cord vascular injury related to anterior thoracolumbar spine procedures as well as operative adjuncts and considerations related to management of the segmental artery ligation during such anterior procedures. Titles and abstracts were screened, and studies meeting inclusion criteria were reviewed in full. RESULTS: Of 1200 articles identified on the initial screening, 16 met the inclusion criteria and consisted of 2 prospective cohort studies, 10 retrospective cohort studies, and 4 case reports. Four studies reported on the incidence of spinal cord ischemia with anterior thoracolumbar surgery, which ranged from 0% to 0.75%. Eight studies presented patient-level data for 13 cases of spinal cord ischemia after anterior thoracolumbar spine surgery. Proposed risk factors for vasculogenic spinal injury with anterior thoracolumbar surgery included hyperkyphosis, prior spinal deformity surgery, combined anterior-posterior procedures, left-sided approaches, operating on the concavity side of a scoliotic curve, and intra- or postoperative hypotension. In addition, eight studies analyzed operative considerations to reduce spinal cord ischemic complications in anterior thoracolumbar surgery, including intraoperative neuromonitoring and preoperative spinal angiography. CONCLUSIONS: While spinal cord infarction related to anterior thoracolumbar surgery is rare, it warrants proper consideration in the pre-, intra-, and postoperative periods. The spine surgeon must be aware of the relevant risk factors as well as the pre- and intraoperative adjuncts that can minimize these risks. Most importantly, an understanding of the relevant spinal vascular anatomy is critical to minimizing the risks associated with anterior thoracolumbar spine surgery.

Minimally invasive lateral corpectomy for thoracolumbar traumatic burst fractures.

OBJECTIVE: The need for anterior column reconstruction after thoracolumbar burst fractures remains controversial. Here, the authors present their experience with minimally invasive lateral thoracolumbar corpectomies for traumatic fractures. METHODS: Between 2012 and 2019, 59 patients with 65 thoracolumbar fractures underwent 65 minimally invasive lateral corpectomies (MIS group). This group was compared to 16 patients with single-level thoracolumbar fractures who had undergone open lateral corpectomies with the assistance of general surgery between 2007 and 2011 (open control group). Comparisons of the two groups were made with regard to operative time, estimated blood loss, time to ambulation, and fusion rates at 1 year postoperatively. The authors further analyzed the MIS group with regard to injury mechanism, fracture characteristics, neurological outcome, and complications. RESULTS: Patients in the MIS group had a significantly shorter mean operative time (228.3 ± 27.9 vs 255.6 ± 34.1 minutes, p = 0.001) and significantly shorter mean time to ambulation after surgery (1.8 ± 1.1 vs 5.0 ± 0.8 days, p < 0.001) than the open corpectomy group. Mean estimated blood loss did not differ significantly between the two groups, though the MIS group did trend toward a lower mean blood loss. There was no significant difference in fusion status at 1 year between the MIS and open groups; however, this comparison was limited by poor follow-up, with only 32 of 59 patients (54.2%) in the MIS group and 8 of 16 (50%) in the open group having available imaging at 1 year. Complications in the MIS group included 1 screw misplacement requiring revision, 2 postoperative femoral neuropathies (one of which improved), 1 return to surgery for inadequate posterior decompression, 4 pneumothoraces requiring chest tube placement, and 1 posterior wound infection. The rate of revision surgery for the failure of fusion in the MIS group was 1.7% (1 of 59 patients). CONCLUSIONS: The minimally invasive lateral thoracolumbar corpectomy approach for traumatic fractures appears to be relatively safe and may result in shorter operative times and quicker mobilization as compared to those with open techniques. This should be considered as a treatment option for thoracolumbar spine fractures.

Stem cell therapies for acute spinal cord injury in humans: a review.

Recent advances in stem cell biology present significant opportunities to advance clinical applications of stem cell-based therapies for spinal cord injury (SCI). In this review, the authors critically analyze the basic science and translational evidence that supports the use of various stem cell sources, including induced pluripotent stem cells, oligodendrocyte precursor cells, and mesenchymal stem cells. They subsequently explore recent advances in stem cell biology and discuss ongoing clinical translation efforts, including combinatorial strategies utilizing scaffolds, biogels, and growth factors to augment stem cell survival, function, and engraftment. Finally, the authors discuss the evolution of stem cell therapies for SCI by providing an overview of completed (n = 18) and ongoing (n = 9) clinical trials.

When imaging meets neurophysiology: the value of navigated transcranial magnetic stimulation for preoperative neurophysiological mapping prior to brain tumor surgery.

Maximal safe resection is the modern goal for surgery of intrinsic brain tumors located in or close to brain eloquent areas. Nowadays different neuroimaging techniques provide important anatomical and functional information regarding the brain functional organization that can be used to plan a customized surgical strategy to preserve functional networks, and to increase the extent of tumor resection. Among these techniques, navigated transcranial magnetic stimulation (nTMS) has recently gained great favor among the neurosurgical community for preoperative mapping and planning prior to brain tumor surgery. It represents an advanced neuroimaging technique based on the neurophysiological mapping of the functional cortical brain organization. Moreover, it can be combined with other neuroimaging techniques such as diffusion tensor imaging tractography, thus providing a reliable reconstruction of brain eloquent networks. Consequently, nTMS mapping may provide reliable noninvasive brain functional mapping, anticipating information that otherwise may be available to neurosurgeons only in the operating theater by using direct electrical stimulation. The authors describe the reliability and usefulness of the preoperative nTMS-based approach in neurosurgical practice, and briefly discuss their experience using nTMS as well as currently available evidence in the literature supporting its clinical use. In particular, special attention is reserved for the discussion of the role of nTMS as a novel tool for the preoperative neurophysiological mapping of motor and language networks prior to surgery of intrinsic brain tumors located in or close to eloquent networks, as well as for future and promising applications of nTMS in neurosurgical practice.

Deep brain stimulation of the cerebellum for poststroke motor rehabilitation: from laboratory to clinical trial.

Ischemic stroke is a leading cause of disability worldwide, with profound economic costs. Poststroke motor impairment is the most commonly encountered deficit resulting in significant disability and is the primary driver of stroke-associated healthcare expenditures. Although many patients derive some degree of benefit from physical rehabilitation, a significant proportion continue to suffer from persistent motor impairment. Noninvasive brain stimulation, vagal nerve stimulation, epidural cortical stimulation, and deep brain stimulation (DBS) have all been studied as potential modalities to improve upon the benefits derived from physical therapy alone. These neuromodulatory therapies aim primarily to augment neuroplasticity and drive functional reorganization of the surviving perilesional cortex. The authors have proposed a novel and emerging therapeutic approach based on cerebellar DBS targeted at the dentate nucleus. Their rationale is based on the extensive reciprocal connectivity between the dentate nucleus and wide swaths of cerebral cortex via the dentatothalamocortical and corticopontocerebellar tracts, as well as the known limitations to motor rehabilitation imposed by crossed cerebellar diaschisis. Preclinical studies in rodent models of ischemic stroke have shown that cerebellar DBS promotes functional recovery in a frequency-dependent manner, with the most substantial benefits of the therapy noted at 30-Hz stimulation. The improvements in motor function are paralleled by increased expression of markers of synaptic plasticity, synaptogenesis, and neurogenesis in the perilesional cortex. Given the findings of preclinical studies, a first-in-human trial, Electrical Stimulation of the Dentate Nucleus Area (EDEN) for Improvement of Upper Extremity Hemiparesis Due to Ischemic Stroke: A Safety and Feasibility Study, commenced in 2016. Although the existing preclinical evidence is promising, the results of this Phase I trial and subsequent clinical trials will be necessary to determine the future applicability of this therapy.

Instrumented fusion for spinal deformity after laminectomy or laminoplasty for resection of intramedullary spinal cord tumors in pediatric patients.

OBJECTIVE Spinal deformity has become a well-recognized complication of intramedullary spinal cord tumor (IMSCT) resection. In particular, laminectomy can result in biomechanical instability caused by loss of the posterior tension band. Therefore, laminoplasty has been proposed as an alternative to laminectomy. Here, the authors describe the largest current series of pediatric patients who have undergone laminoplasty for IMSCT resection and investigate the need for surgical fusion after both laminectomy and laminoplasty. METHODS The medical records of pediatric patients who underwent resection of an IMSCT at a single institution between November 2003 and May 2014 were reviewed retrospectively. Demographic, clinical, radiological, surgical, histopathological, and follow-up data were collected. RESULTS Sixty-six consecutive patients underwent resection of an IMSCT during the study period. Forty-three (65%) patients were male. The patients had a median age of 12.9 years (interquartile range [IQR] 7.2-16.5 years) at the time of surgery. Patients typically presented with a tumor that involved the cervical and/or thoracic spine. Nineteen (29%) patients underwent laminectomy, and 47 (71%) patients underwent laminoplasty. Patients in each cohort had a similar rate of postoperative deformity. Overall, 10 (15%) patients required instrumented spinal fusion for spinal deformity. Four patients required revision of the primary fusion. CONCLUSIONS These findings show that among pediatric patients with an IMSCT, postoperative surgical fusion rates remain high, even after laminoplasty. Known risk factors, such as the age of the patient, location of the tumor, and the number of involved levels, might play a larger role than replacement of the laminae in determining the rate of surgical fusion after IMSCT resection.

Electrophysiological monitoring during preoperative angiography to guide decisions regarding permanent occlusion of major radicular arteries in patients undergoing total en bloc spondylectomy.

OBJECTIVE Preoperative embolization is performed before spine tumor surgery when significant intraoperative hemorrhage is anticipated. Occlusion of radicular and segmental arteries may result in spinal ischemia. The goal of this study was to check whether neurophysiological monitoring during preoperative angiography in patients scheduled for total en bloc spondylectomy (TES) of spine tumors improves the safety of vessel occlusion. METHODS This was a case series study of patients who underwent tumor embolization under somatosensory evoked potential (SSEP) and motor evoked potential (MEP) monitoring in preparation for TES in treating spine tumors. The angiography findings, the embolized vessels, and the results are presented. RESULTS Five patients whose ages ranged from 33 to 75 years and who had thoracic spine tumors are reported. Four patients suffered from primary tumor and 1 patient had a metastatic tumor. Radicular arteries at the tumor level, 1 level above, and 1 level below were permanently occluded when SSEPs and MEPs were preserved during temporary occlusion. No complications were encountered during or after the angiography procedure and embolization. CONCLUSIONS Temporary occlusion with electrophysiological monitoring during preoperative angiography may improve the safety of permanent radicular artery occlusion, including the artery of Adamkiewicz in patients undergoing TES for the treatment of spine tumors.

Contribution of combined intraoperative electrophysiological investigation with 3-T intraoperative MRI for awake cerebral glioma surgery: comprehensive review of the clinical implications and radiological outcomes.

OBJECTIVE: This study aimed to assess the clinical efficiency of combined awake craniotomy with 3-T intraoperative MRI (iMRI)-guided resection of gliomas adjacent to eloquent cortex performed at a single center. It also sought to explore the contribution of iMRI to surgeons' learning process of maximal safe resection of gliomas. METHODS: All patients who underwent an awake craniotomy and iMRI for resection of eloquent area glioma during the 53 months between January 2011 and June 2015 were included. The cases were analyzed for short- and long-term neurological outcome, progression-free survival (PFS), overall survival (OS), and extent of resection (EOR). The learning curve was assessed after dividing the cohort into Group A (first 27 months) and Group B (last 26 months). Statistical analyses included univariate logistic regression analysis on clinical and radiological variables. Kaplan-Meier and Cox regression models were used for further analysis of OS and PFS. A p value < 0.05 was considered statistically significant. RESULTS: One hundred six patients were included in the study. Over an average follow-up period of 24.8 months, short- and long-term worsening of the neurological function was noted in 48 (46.2%) and 9 (8.7%) cases, respectively. The median and mean EOR were 100% and 92%, respectively, and complete radiographic resection was achieved in 64 (60.4%) patients. The rate of gross-total resection (GTR) in the patients with low-grade glioma (89.06% ± 19.6%) was significantly lower than that in patients with high-grade glioma (96.4% ± 9.1%) (p = 0.026). Thirty (28.3%) patients underwent further resection after initial iMRI scanning, with a 10.1% increase of the mean EOR. Multivariate Cox proportional hazards modeling demonstrated that the final EOR was a significant predictor of PFS (HR 0.225, 95% CI 0.070-0.723, p = 0.012). For patients with high-grade glioma, the GTR (p = 0.033), the presence of short-term motor deficit (p = 0.027), and the WHO grade (p = 0.005) were independent prognostic factors of OS. Performing further resection after the iMRI (p = 0.083) and achieving GTR (p = 0.05) demonstrated a PFS benefit trend for the patients affected by a low-grade glioma. Over time, the rate of performing further resection after an iMRI decreased by 26.1% (p = 0.005). A nonsignificant decrease in the rate of short-term (p = 0.101) and long-term (p = 0.132) neurological deficits was equally noted. CONCLUSIONS: Combined awake craniotomy and iMRI is a safe and efficient technique allowing maximal safe resection of eloquent area gliomas with possible subsequent OS and PFS benefits. Although there is a learning curve for applying this technique, it can also improve the surgeon's ability in eloquent glioma surgery.

The role of intraoperative MRI in resective epilepsy surgery for peri-eloquent cortex cortical dysplasias and heterotopias in pediatric patients.

OBJECTIVE: Previous studies have demonstrated that an important factor in seizure freedom following surgery for lesional epilepsy in the peri-eloquent cortex is completeness of resection. However, aggressive resection of epileptic tissue localized to this region must be balanced with the competing objective of retaining postoperative neurological functioning. The objective of this study was to investigate the role of intraoperative MRI (iMRI) as a complement to existing epilepsy protocol techniques and to compare rates of seizure freedom and neurological deficit in pediatric patients undergoing resection of perieloquent lesions. METHODS: The authors retrospectively reviewed the medical records of pediatric patients who underwent resection of focal cortical dysplasia (FCD) or heterotopia localized to eloquent cortex regions at the Children's National Health System between March 2005 and August 2015. Patients were grouped into two categories depending on whether they underwent conventional resection (n = 18) or iMRI-assisted resection (n = 11). Patient records were reviewed for factors including demographics, length of hospitalization, postoperative seizure freedom, postoperative neurological deficit, and need for reoperation. Postsurgical seizure outcome was assessed at the last postoperative follow-up evaluation using the Engel Epilepsy Surgery Outcome Scale. RESULTS: At the time of the last postoperative follow-up examination, 9 (82%) of the 11 patients in the iMRI resection group were seizure free (Engel Class I), compared with 7 (39%) of the 18 patients in the control resection group (p = 0.05). Ten (91%) of the 11 patients in the iMRI cohort achieved gross-total resection (GTR), compared with 8 (44%) of 18 patients in the conventional resection cohort (p = 0.02). One patient in the iMRI-assisted resection group underwent successful reoperation at a later date for residual dysplasia, compared with 7 patients in the conventional resection cohort (with 2/7 achieving complete resection). Four (36%) of the patients in the iMRI cohort developed postoperative neurological deficits, compared with 15 patients (83%) in the conventional resection cohort (p = 0.02). CONCLUSIONS: These results suggest that in comparison with a conventional surgical protocol and technique for resection of epileptic lesions in peri-eloquent cortex, the incorporation of iMRI led to elevated rates of GTR and postoperative seizure freedom. Furthermore, this study suggests that iMRI-assisted surgeries are associated with a reduction in neurological deficits due to intraoperative damage of eloquent cortex.

Intraoperative neurophysiological mapping and monitoring in spinal tumor surgery: sirens or indispensable tools?

Spinal tumor (ST) surgery carries the risk of new neurological deficits in the postoperative period. Intraoperative neurophysiological monitoring and mapping (IONM) represents an effective method of identifying and monitoring in real time the functional integrity of both the spinal cord (SC) and the nerve roots (NRs). Despite consensus favoring the use of IONM in ST surgery, in this era of evidence-based medicine, there is still a need to demonstrate the effective role of IONM in ST surgery in achieving an oncological cure, optimizing patient safety, and considering medicolegal aspects. Thus, neurosurgeons are asked to establish which techniques are considered indispensable. In the present study, the authors focused on the rationale for and the accuracy (sensitivity, specificity, and positive and negative predictive values) of IONM in ST surgery in light of more recent evidence in the literature, with specific emphasis on the role of IONM in reducing the incidence of postoperative neurological deficits. This review confirms the role of IONM as a useful tool in the workup for ST surgery. Individual monitoring and mapping techniques are clearly not sufficient to account for the complex function of the SC and NRs. Conversely, multimodal IONM is highly sensitive and specific for anticipating neurological injury during ST surgery and represents an important tool for preserving neuronal structures and achieving an optimal postoperative functional outcome.

Functional cortical reorganization in cases of cervical spondylotic myelopathy and changes associated with surgery.

OBJECTIVE The physiological mechanisms underlying the recovery of motor function after cervical spondylotic myelopathy (CSM) surgery are poorly understood. Neuronal plasticity allows neurons to compensate for injury and disease and to adjust their activities in response to new situations or changes in their environment. Cortical reorganization as well as improvement in corticospinal conduction happens during motor recovery after stroke and spinal cord injury. In this study the authors aimed to understand the cortical changes that occur due to CSM and following CSM surgery and to correlate these changes with functional recovery by using blood oxygen level-dependent (BOLD) functional MRI (fMRI). METHODS Twenty-two patients having symptoms related to cervical cord compression due to spondylotic changes along with 12 age- and sex-matched healthy controls were included in this study. Patients underwent cervical spine MRI and BOLD fMRI at 1 month before surgery (baseline) and 6 months after surgery. RESULTS Five patients were excluded from analysis because of technical problems; thus, 17 patients made up the study cohort. The mean overall modified Japanese Orthopaedic Association score improved in patients following surgery. Mean upper-extremity, lower-extremity, and sensory scores improved significantly. In the preoperative patient group the volume of activation (VOA) was significantly higher than that in controls. The VOA after surgery was reduced as compared with that before surgery, although it remained higher than that in the control group. In the preoperative patient group, activations were noted only in the left precentral gyrus (PrCG). In the postoperative group, activations were seen in the left postcentral gyrus (PoCG), as well as the PrCG and premotor and supplementary motor cortices. In postoperative group, the VOA was higher in both the PrCG and PoCG as compared with those in the control group. CONCLUSIONS There is over-recruitment of sensorimotor cortices during nondexterous relative to dexterous movements before surgery. After surgery, there was recruitment of other cortical areas such as the PoCG and premotor and supplementary motor cortices, which correlated with improvement in dexterity, but activation in these areas was greater than that found in controls. The results show that improvement in dexterity and finer movements of the upper limbs is associated with recruitment areas other than the premotor cortex to compensate for the damage in the cervical spinal cord.

Hemilaminectomy approach for intradural extramedullary spinal tumors: an analysis of 164 patients.

OBJECT The authors report their experience with the use of a minimally invasive hemilaminectomy approach for the excision of intradural extramedullary (IDEM) tumors of the spinal cord. METHODS Included were 164 consecutive patients (167 tumors in total), treated between January 2004 and December 2014, in whom the hemilaminectomy approach for IDEM spinal cord tumors was planned. The clinicoradiological data of patients presenting to Christian Medical College were analyzed retrospectively using a computerized chart-review method. Preoperative MRI localization was used in 51 cases. RESULTS The mean age (± SD) of the patients was 42.6 ± 16.6 years, and the mean duration of symptoms was 20.8 ± 27.8 months. The average tumor size was 2.4 ± 1.7 cm. Forty-four tumors were cervical, 5 were cervicothoracic, 72 were thoracic, 7 were thoracolumbar, and 39 were lumbar. Forty-two tumors were ventrally located, whereas 11 were ventrolateral; the rest were either dorsal or dorsolateral. The most common pathologies were schwannoma (110 cases) and meningioma (31 cases). Total excision was achieved for 93% of the tumors. The average duration of surgery was 1.6 ± 0.6 hours. CONCLUSIONS The hemilaminectomy approach to the removal of intradural tumors was quick and safe and resulted in minimal morbidity and no mortality. Preoperative MRI localization improved accuracy and reduced operating time by eliminating the need for intraoperative fluoroscopy.

Intramedullary spinal cavernoma: clinical presentation, microsurgical approach, and long-term outcome in a cohort of 48 patients.

OBJECT Intramedullary spinal cavernoma (ISC) is a rare entity and accounts for approximately 5%-12% of all spinal vascular pathologies. The purpose of the present study was to examine the influence of clinical presentation, localization, and different surgical approaches on long-term outcome in patients treated for ISC. METHODS The authors performed a retrospective single-center study of 48 cases of ISC treated microsurgically over the past 28 years. Analyzed factors included preoperative clinical history, microsurgical strategies, neurological outcome (American Spinal Injury Association [ASIA] grade, Epstein and Cooper grade), and the occurrence of postoperative spinal ataxia. Univariate analysis was performed to identify factors influencing long-term outcome. RESULTS Preoperatively, 18.8% of all patients experienced a slow, progressive decline in neurological function and 33.3% suffered repetitive episodes of acute neurological deterioration over a time frame of months to years. Moreover, 16.7% noted the sudden onset of a severe neurological deficit, whereas 25% experienced the sudden onset of symptoms with a subsequent gradually progressive decline in neurological function. On long-term follow-up after treatment (mean ± SD, 79.3 ± 35.2 months), 70.8% of patients showed no change in neurological function, 6.3% suffered from a decline, and 22.9% improved neurologically. Thoracolumbar localization (p = 0.043), low preoperative Epstein and Cooper grade for the lower extremities (p < 0.001), and a low preoperative ASIA grade (p < 0.001) were identified as factors associated with an unfavorable outcome (ASIA Grade A-C). The rate of spinal ataxia related to surgical approach was 16.7%. CONCLUSION Postoperative neurological function in ISC patients is determined by the preoperative neurological status. On long-term follow-up after microsurgical treatment, 93.7% of patients presented with a stable or improved condition (ASIA grade); thus, definite microsurgical treatment should be considered as long as patients present with only mild symptoms after the diagnosis of symptomatic ISC.

Functional preoperative and intraoperative mapping and monitoring: increasing safety and efficacy in glioma surgery.

Greater extent of resection (EOR) of low-grade gliomas is associated with improved survival. Proximity to eloquent cortical regions often limits resectability and elevates the risk of surgery-related deficits. Therefore, functional localization of eloquent cortex or subcortical fiber tracts can enhance the EOR and functional outcome. Imaging techniques such as functional MRI and diffusion tensor imaging fiber tracking, and neurophysiological methods like navigated transcranial magnetic stimulation and magnetoencephalography, make it possible to identify eloquent areas prior to resective surgery and to tailor indication and surgical approach but also to assess the surgical risk. Intraoperative monitoring with direct cortical stimulation and subcortical stimulation enables surgeons to preserve essential functional tissue during surgery. Through tailored pre- and intraoperative mapping and monitoring the EOR can be maximized, with reduced rates of surgery-related deficits.

Intraoperative monopolar mapping during 5-ALA-guided resections of glioblastomas adjacent to motor eloquent areas: evaluation of resection rates and neurological outcome.

OBJECT: Resection of glioblastoma adjacent to motor cortex or subcortical motor pathways carries a high risk of both incomplete resection and postoperative motor deficits. Although the strategy of maximum safe resection is widely accepted, the rates of complete resection of enhancing tumor (CRET) and the exact causes for motor deficits (mechanical vs vascular) are not always known. The authors report the results of their concept of combining monopolar mapping and 5-aminolevulinic acid (5-ALA)-guided surgery in patients with glioblastoma adjacent to eloquent tissue. METHODS: The authors prospectively studied 72 consecutive patients who underwent 5-ALA-guided surgery for a glioblastoma adjacent to the corticospinal tract (CST; < 10 mm) with continuous dynamic monopolar motor mapping (short-train interstimulus interval 4.0 msec, pulse duration 500 µsec) coupled to an acoustic motor evoked potential (MEP) alarm. The extent of resection was determined based on early (< 48 hours) postoperative MRI findings. Motor function was assessed 1 day after surgery, at discharge, and at 3 months. RESULTS: Five patients were excluded because of nonadherence to protocol; thus, 67 patients were evaluated. The lowest motor threshold reached during individual surgery was as follows (motor threshold, number of patients): > 20 mA, n = 8; 11-20 mA, n = 13; 6-10 mA, n = 10; 4-5 mA, n = 13; and 1-3 mA, n = 23. Motor deterioration at postsurgical Day 1 and at discharge occurred in 30% (n = 20) and 10% (n = 7) of patients, respectively. At 3 months, 3 patients (4%) had a persisting postoperative motor deficit, 2 caused by vascular injury and 1 by mechanical injury. The rates of intra- and postoperative seizures were 1% and 0%, respectively. Complete resection of enhancing tumor was achieved in 73% of patients (49/67) despite proximity to the CST. CONCLUSIONS: A rather high rate of CRET can be achieved in glioblastomas in motor eloquent areas via a combination of 5-ALA for tumor identification and intraoperative mapping for distinguishing between presumed and actual motor eloquent tissues. Continuous dynamic mapping was found to be a very ergonomic technique that localizes the motor tissue early and reliably.

Primary germinoma of the medulla oblongata: illustrative case.

BACKGROUND: Primary central nervous system germinomas of the medulla oblongata are extremely rare and usually have been found in young female Asian patients. The authors present an illustrative case of a patient who presented with severe medullary and posterior cord syndrome, the first South American case published to date, to the authors' knowledge. OBSERVATIONS: Initially, the radiological differential diagnosis did not include this entity. The lesion was located at the obex and exhibited a well-delineated contrast enhancement without hydrocephalus. An emergency decompressive partial resection following functional limits was performed. After histological confirmation, radiotherapy was indicated, with complete remission achieved at a 6-month follow-up. The patient, however, continued to have a severe proprioceptive disorder. The literature review identified 21 other such patients. The mean age for this location was 23 years, with a strong female and Asian origin predilection. All tumors exhibited contrast enhancement, and only one presented with hydrocephalus. LESSONS: In the absence of elevated tumor markers, radiological clues such as a well-delineated, contrast-enhanced lesion arising from the obex, without hydrocephalus, associated with demographic features such as young age, female sex, and Asian heritage, should evoke a high level of suspicion for this diagnosis. Gross total resection must not be attempted, because this tumor is potentially curable with high-dose radiotherapy.

Cloward's approach for Pancoast neurogenic tumors: illustrative cases.

BACKGROUND: Pancoast tumors are a wide range of tumors located in the apex of the lung. Traditional surgery for Pancoast neurogenic tumors frequently involves extensive approaches, whether anterior or posterior or a combination, in which osteotomies are sometimes required. In this study, the authors proposed a less invasive surgical strategy using the standard Cloward's approach for complete resection of a schwannoma arising from the T1 nerve root. OBSERVATIONS: Two patients, each harboring a large T1 tumor, one on each side, underwent Cloward's approach with and without thoracoscopic surgery. Both patients had complete resection of the tumor. Considering the benign and encapsulated nature of neurogenic tumors, Cloward's approach under neuromonitoring, which is a common procedure for anterior cervical discectomy for most neurosurgeons, is a safe and less invasive alternative for Pancoast neurogenic tumors. For patients whose tumor cannot be removed completely via Cloward's approach, video-assisted thoracoscopic surgery is a viable backup plan with minimal invasiveness. LESSONS: Cloward's approach is a viable option for Pancoast neurogenic tumors.

Conservative rehabilitation for a patient presenting with severe orthostatic hypotension after surgical management of brainstem tumor: illustrative case.

BACKGROUND: Blood pressure (BP) dysregulation is frequently observed in patients after surgical management of brainstem lesions; however, there has been no standard rehabilitation. Considering the conflicting risks for hypoperfusion and disuse syndrome in these patients, a safe and effective rehabilitative strategy is warranted. OBSERVATIONS: A 50-year-old man who had undergone craniotomy for resection of a recurrent dorsal medullary epidermoid cyst developed persistent orthostatic hypotension. It was resistant to physical exercise, pharmacological therapy, abdominal binders, and compression stockings; therefore, it inhibited postoperative rehabilitation. Although the responsible lesion was not clearly visible on the postoperative image, accompanying symptoms, including segmental sensory impairment, implied an improvement in BP control. Although there was a trade-off between the risk of developing disuse syndrome and a delay in functional recovery, the authors decided to continue a conservative rehabilitation strategy rather than increasing the workload. The patient's BP control was gradually restored by the seventh postoperative week, and the authors proceeded with basic activity training. LESSONS: A conservative prognostic prediction-based rehabilitation strategy was applied in this case. The precise evaluation of the accompanying neurological symptoms was helpful in deciding the treatment regimen. The conflicting risks for hypoperfusion and disuse syndrome in such cases must be considered.