stimulation, and MRI fiber tracking can facilitate surgical planning, direct cortical and subcortical stimulation remains the gold standard for determining function. 18 Of the above techniques, only MRI tractography can reliably identify subcortical motor pathways; 19 however, intraoperative localization of deep pathways using neuronavigation becomes increasingly inaccurate as tumor is resected and brain shift increases. 20 Bipolar stimulation is the most well-established technique for motor mapping. Initially described in humans by Wilder Penfield and colleagues in the
Andrew J. Gogos, Jacob S. Young, Ramin A. Morshed, Lauro N. Avalos, Roger S. Noss, Javier E. Villanueva-Meyer, Shawn L. Hervey-Jumper and Mitchel S. Berger
Phiroz E. Tarapore, Matthew C. Tate, Anne M. Findlay, Susanne M. Honma, Danielle Mizuiri, Mitchel S. Berger and Srikantan S. Nagarajan
T he management of brain tumors in and around the rolandic cortex presents a specific challenge to the operative neurosurgeon. The desire to resect as extensively as possible must be balanced by a constant attention to preserving a patient's existing function. Although DCS remains the gold standard for generating maps of the motor system, 10 , 16 , 35 noninvasive methods of motor mapping are becoming increasingly accurate and useful. Magnetoencephalography imaging refers to the reconstruction of the spatiotemporal dynamics of brain sources from
Vicki M. Butenschön, Sebastian Ille, Nico Sollmann, Bernhard Meyer and Sandro M. Krieg
, no study has been conducted on the economic evaluation of nTMS for preoperative motor mapping. Thus, the aim of this study is to estimate the financial burden of disease and the cost-effectiveness of nTMS for HGG patients. This study also provides a model that can be used in the future to analyze any new treatment option in neuro-oncology in terms of its general cost-effectiveness. Methods Patients We included cohort patients in our simulation model, based on adults older than 18 years with histologically diagnosed HGG (WHO grades III and IV) who underwent surgical
Michael A. Mooney and Nader Sanai
The contralateral interhemispheric approach has several advantages for approaching parasagittal lesions, including lesions involving or approaching the medial precentral gyrus. Supplementing the interhemispheric approach with asleep motor mapping is useful for confirming the location of the corticospinal tracts from the contralateral transfalcine corridor and identifying subcortical motor fibers at the deep aspect of the resection cavity. The authors describe the contralateral interhemispheric, transfalcine approach with asleep motor mapping to resect a parasagittal metastatic lesion involving the medial precentral gyrus.
The video can be found here: https://youtu.be/L-fJ6m5kOWs.
Philippe Schucht, Kathleen Seidel, Michael Murek, Lennart Henning Stieglitz, Natalie Urwyler, Roland Wiest, Maja Steinlin, Kurt Leibundgut, Andreas Raabe and Jürgen Beck
motor thresholds correlate with a closer location to eloquent tissue. 13 , 23 As the resection approached the interface between the lesion and functionally eloquent tissue, mapping was repetitively performed to define a safe dissection plane. In accordance with a previously published internal protocol, 34 we alternated tumor resection and motor mapping, repeating threshold assessment every 1–2 mm of tumor resection with the highest possible temporal and spatial frequency, especially when coming to motor thresholds less than 7 mA (motor threshold is defined as the
Kurtis I. Auguste, Alfredo Quinones-Hinojosa, Chirag Gadkary, Gabriel Zada, Kathleen R. Lamborn and Mitchel S. Berger
benefit for patients undergoing craniotomy for tumor. 49, 55 Compression stockings have also been shown to reduce the incidence of thromboembolism as effectively as EPC devices. 17 The use of these devices and compression stockings in combination provides a relatively risk-free form of prophylaxis for patients undergoing neurosurgery. Cases in which intraoperative cortical motor mapping is required present an added challenge to VTE prophylaxis. Stimulation of cortical and subcortical areas allows for radical tumor resection with the least possible impairment of
Kathleen Seidel, Jürgen Beck, Lennart Stieglitz, Philippe Schucht and Andreas Raabe
probe was performed in deep white matter during dissection and tumor removal at the discretion of the surgeons. To identify the MT of every stimulation site, the stimulation current was systematically increased until an MEP response was elicited (maximum 22 mA), or it was started at 22 mA and then decreased until the MEP response was lost. 42 Considering the fact that lower MTs correspond to a closer distance to the CST, 18 , 20 , 28 , 42 quantitative values of the MT were used to functionally guide the surgeon. Approaching values below 10 mA, motor mapping was
Todd W. Vitaz, William Marx, Jonathan D. Victor and Philip H. Gutin
The surgical treatment of tumors located near eloquent cortex carries a high risk of inducing worsening neurological deficits. Intraoperative electrocorticography techniques have been developed to help identify these areas at the time of surgery in an effort to minimize such risks. The optimal anesthetic technique for conducting these procedures, however, has never been determined.
The authors conducted a retrospective study to compare patients who underwent intraoperative motor mapping between September 2000 and May 2002. Demographic and neurophysiological monitoring data were collected from the hospital records. Patients were divided into two groups based on the anesthetic technique used for surgery: in Group 1 general anesthesia was used, and in Group 2 conscious sedation.
Group 1 comprised 24 patients (mean age 47 years) with 16 right- and eight left-sided lesions. Group 2 consisted of 21 patients (mean age 46 years) with 18 right- and three left-sided lesions. Pathological diagnoses were similar between the two groups. Motor stimulation was elicited in 12 patients (50%) in Group 1 and in 21 patients (100%) in Group 2 (p < 0.001). In addition, the mean stimulation amplitude required was significantly higher (13 mA) in patients in whom conscious sedation was used as opposed to general anesthesia (5 mA, p < 0.0001). Electrographic evidence of seizures was seen in 29% of Group 1 cmpared with 10% of Group 2 patients (p > 0.05).
The use of conscious sedation as an anesthetic technique for motor mapping not only improves the chances of achieving successful stimulation and identification of motor cortex in relationship to the lesion, but it also allows for repetitive monitoring of the patient's motor function during resection of the lesion.
Hagen Schiffbauer, Mitchel S. Berger, Paul Ferrari, Dirk Freudenstein, Howard A. Rowley and Timothy P. L. Roberts
produced a stimulus response, requiring a less intense electrical current to evoke a response than that used during motor mapping. If movement or EMG activity persisted after removal of the stimulating electrode, cold, lactated Ringer solution was applied to the exposed cortex; if this was insufficient, methohexital was administered to terminate the activity. 50 Depending on the location of the tumor, subcortical stimulation was sometimes used to identify the corona radiata and the internal capsule at the border of the resection area. Before closure of the dura mater
Tizian Rosenstock, Thomas Picht, Heike Schneider, Peter Vajkoczy and Ulrich-Wilhelm Thomale
N avigated transcranial magnetic stimulation (nTMS) has proven to be a safe examination method for the analysis of cortical motor and speech areas prior to brain tumor surgery. 1 , 2 Preoperative nTMS motor mapping correlates well with intraoperative direct cortical stimulation, offering the possibility to adapt and optimize the surgical approach. 3 To better estimate the surgical risk for developing motor deficits, the combination of nTMS data and diffusion tensor imaging (DTI) data can be used to visualize the spatial relationships among tumor, motor cortex