Motor-eloquent Lesions Research Articles

Exploring the Role of Specialist Physiotherapy in Awake Craniotomy Surgery for the Neuro-Oncology Patient

Abstract AIMS To describe the methods used to assess and monitor motor function during awake craniotomy surgery for tumour resection. METHOD A service review was carried out over 10 months. Patients with highly motor eloquent lesions – invasion of primary motor cortex or fronto-parietal connections involved in motor cognition – were included. Clinical notes were reviewed and summarised using descriptive analysis. Dexterity and grip strength were measured using 9-hole peg test and handheld dynameter pre/intra and post-operatively. Patient occupation/interests were reported to guide bespoke assessments to trial intra-operatively. RESULTS From April 2021 to January 2022, 13 patients (mean age 39.7 years, 4 female:10 male, 9 low grade:5 high grade gliomas) were included. Mean score 9-hole peg test 22.2sec pre-operatively, 30.6sec post-operatively; handheld dynameter 26.7kg pre-operatively, 18.4kg post-operatively. At discharge 5 of 7 impaired patients demonstrated motor improvement. For motor coordination, motor tasks used frequently included repetitive finger tapping, open/closed hand. Bespoke tasks included texting/writing, playing instruments, and computer games. Movement was closely monitored and verbal feedback given to the neurosurgeons throughout. With video analysis movement comparisons were made. CONCLUSION The role of physiotherapy in awake surgery is evolving to provide movement analysis for complex motor tasks such as upper limb sequencing and dexterity. A combination of standard and bespoke assessments have been trialled and their feasibility within surgery tested. A post-operative deterioration of motor function (power and cognition) is expected after surgery for highly eloquent motor gliomas. However, intraoperative motor assessment for motor cognition allows function preservation and potentiates its recovery.

P 13. The added benefit of intraoperative neuromonitoring for resection of motor eloquent brain lesions: A comparative study

Objective. Resection remains the most important form of treatment for patients with intracranial malignancies. The advantages of surgical resection must be balanced with the risk of surgery. Intraoperative neuromonitoring (IOM) is utilized to improve safety and enlarge the resection extent. However, comparative data on the use if IOM is scarce. Methods. Retrospective analysis of patients following resection of motor eloquent lesions between June 2018 and June 2020 was performed. A comparative analysis of the extend of resection; neurological squeal were compared between resections with or without IOM. Results. 66 patients (31 female, 35 male, age median, SD 62+/− 11,2) were identified. IOM was performed in 34 (51%) cases. 46% were female with a median age of 62 (range 31–82). There were no differences in baseline patient“s characteristics between both groups. 14% and 3% had a temporary neurological deterioration in the IOM and non-IOM group ( P = 0,198), respectively. 3% and 15% had a permanent neurological in the IOM and non-IOM group, respectively ( P = 0.100). 65% and 35% of resections were total and subtotal in both the IOM and non-IOM group ( P = 0.027), respectively. Conclusion. IOM is associated with lower rates of new postoperative neurological deterioration with the same rate resection quality following resection of motor eloquent lesions.

Intraoperative mapping of pre-central motor cortex and subcortex: a proposal for supplemental cortical and novel subcortical maps to Penfield\u2019s motor homunculus

Penfield’s motor homunculus describes a caricaturised yet useful representation of the map of various body parts on the pre-central cortex. We propose a supplemental map of the clinically represented areas of human body in pre-central cortex and a novel subcortical corticospinal tract map. We believe this knowledge is essential for safe surgery in patients with eloquent brain lesions. A single-institution retrospective cohort study of patients who underwent craniotomy for motor eloquent lesions with intraoperative motor neuromonitoring (cortical and subcortical) between 2015 and 2020 was performed. All positive cortical and subcortical stimulation points were taken into account and cartographic maps were produced to demonstrate cortical and subcortical areas of motor representation and their configuration. A literature review in PubMed was performed. One hundred and eighty consecutive patients (58.4% male, 41.6% female) were included in the study with 81.6% asleep and 18.4% awake craniotomies for motor eloquent lesions (gliomas 80.7%, metastases 13.8%) with intraoperative cortical and subcortical motor mapping. Based on the data, we propose a supplemental clinical cortical and a novel subcortical motor map to the original Penfield’s motor homunculus, including demonstration of localisation of intercostal muscles both in the cortex and subcortex which has not been previously described. The supplementary clinical cortical and novel subcortical motor maps of the homunculus presented here have been derived from a large cohort of patients undergoing direct cortical and subcortical brain mapping. The information will have direct relevance for improving the safety and outcome of patients undergoing resection of motor eloquent brain lesions.

Short-Interval Intracortical Facilitation Improves Efficacy in nTMS Motor Mapping of Lower Extremity Muscle Representations in Patients with Supra-Tentorial Brain Tumors.

Simple SummaryPresurgical motor mapping of cortical muscle representations by single-pulse navigated transcranial magnetic stimulation (sp-nTMS) is used to localize and enclose motor function in patients harboring motor-eloquent lesions. This study investigates paired-pulse nTMS (pp-nTMS) with biphasic pulses for motor mapping of lower extremity (lE) muscle representations, showing that significantly lower stimulation intensities are needed while reliable motor maps can be achieved even in the most demanding patient cases in whom conventionally used sp-nTMS fails. Thus, novel pp-nTMS with biphasic pulses may have potential to considerably facilitate improvements of currently used nTMS-based mapping procedures in the preoperative workup of neurooncological patients.Navigated transcranial magnetic stimulation (nTMS) is increasingly used for mapping of motor function prior to surgery in patients harboring motor-eloquent brain lesions. To date, single-pulse nTMS (sp-nTMS) has been predominantly used for this purpose, but novel paired-pulse nTMS (pp-nTMS) with biphasic pulse application has been made available recently. The purpose of this study was to systematically evaluate pp-nTMS with biphasic pulses in comparison to conventionally used sp-nTMS for preoperative motor mapping of lower extremity (lE) muscle representations. Thirty-nine patients (mean age: 56.3 ± 13.5 years, 69.2% males) harboring motor-eloquent brain lesions of different entity underwent motor mapping of lE muscle representations in lesion-affected hemispheres and nTMS-based tractography of the corticospinal tract (CST) using data from sp-nTMS and pp-nTMS with biphasic pulses, respectively. Compared to sp-nTMS, pp-nTMS enabled motor mapping with lower stimulation intensities (61.8 ± 13.8% versus 50.7 ± 11.6% of maximum stimulator output, p < 0.0001), and it provided reliable motor maps even in the most demanding cases where sp-nTMS failed (pp-nTMS was able to provide a motor map in five patients in whom sp-nTMS did not provide any motor-positive points, and pp-nTMS was the only modality to provide a motor map in one patient who also did not show motor-positive points during intraoperative stimulation). Fiber volumes of the tracked CST were slightly higher when motor maps of pp-nTMS were used, and CST tracking using pp-nTMS data was also possible in the five patients in whom sp-nTMS failed. In conclusion, application of pp-nTMS with biphasic pulses enables preoperative motor mapping of lE muscle representations even in the most challenging patients in whom the motor system is at high risk due to lesion location or resection.

Paired-pulse navigated TMS is more effective than single-pulse navigated TMS for mapping upper extremity muscles in brain tumor patients

ObjectiveSingle-pulse navigated transcranial magnetic stimulation (sp-nTMS) is used for presurgical motor mapping in patients with motor-eloquent lesions. However, recently introduced paired-pulse nTMS (pp-nTMS) with biphasic pulses could improve motor mapping. MethodsThirty-four patients (mean age: 56.0 ± 12.7 years, 53.0% high-grade glioma) with motor-eloquent lesions underwent motor mapping of upper extremity representations and nTMS-based tractography of the corticospinal tract (CST) by both sp-nTMS and pp-nTMS with biphasic pulses for the tumor-affected hemisphere before resection. ResultsIn three patients (8.8%), conventional sp-nTMS did not provide motor-positive points, in contrast to pp-nTMS that was capable of generating motor maps in all patients. Good concordance between pp-nTMS and sp-nTMS in the spatial location of motor hotspots and center of gravity (CoG) as well as for CST tracking was observed, with pp-nTMS leading to similar motor map volumes (585.0 ± 667.8 vs. 586.8 ± 204.2 mm3, p = 0.9889) with considerably lower resting motor thresholds (35.0 ± 8.8 vs. 32.8 ± 7.6% of stimulator output, p = 0.0004). ConclusionsPp-nTMS with biphasic pulses may provide motor maps even in highly demanding cases with tumor-affected motor structures or edema, using lower stimulation intensity compared to sp-nTMS. SignificancePp-nTMS with biphasic pulses could replace standardly used sp-nTMS for motor mapping and may be safer due to lower stimulation intensity.

The Impact of Diffusion Tensor Imaging Fiber Tracking of the Corticospinal Tract Based on Navigated Transcranial Magnetic Stimulation on Surgery of Motor-Eloquent Brain Lesions.

Navigated transcranial magnetic stimulation (nTMS) enables preoperative mapping of the motor cortex (M1). The combination of nTMS with diffusion tensor imaging fiber tracking (DTI-FT) of the corticospinal tract (CST) has been described; however, its impact on surgery of motor-eloquent lesions has not been addressed. To analyze the impact of nTMS-based mapping on surgery of motor-eloquent lesions. In this retrospective case-control study, we reviewed the data of patients operated for suspected motor-eloquent lesions between 2012 and 2015. The patients underwent nTMS mapping of M1 and, from 2014, nTMS-based DTI-FT of the CST. The impact on the preoperative risk/benefit analysis, surgical strategy, craniotomy size, extent of resection (EOR), and outcome were compared with a control group. We included 35 patients who underwent nTMS mapping of M1 (group A), 35 patients who also underwent nTMS-based DTI-FT of the CST (group B), and a control group composed of 35 patients treated without nTMS (group C). The patients in groups A and B received smaller craniotomies (P = .01; P = .001), had less postoperative seizures (P = .02), and a better postoperative motor performance (P = .04) and Karnofsky Performance Status (P = .009) than the controls. Group B exhibited an improved risk/benefit analysis (P = .006), an increased EOR of nTMS-negative lesions in absence of preoperative motor deficits (P = .01), and less motor and Karnofsky Performance Status worsening in case of preoperative motor deficits (P = .02, P = .03) than group A. nTMS-based mapping enables a tailored surgical approach for motor-eloquent lesions. It may improve the risk/benefit analysis, EOR and outcome, particularly when nTMS-based DTI-FT is performed.

Preoperative navigated transcranial magnetic stimulation in patients with motor eloquent lesions with emphasis on metastasis.

Navigated transcranial magnetic stimulation (nTMS) is a frequently used, non-invasive method to map the motor cortex. It is of great value in the preoperative workup of patients that suffer from motor eloquent brain lesions. Here, we present a single-center experience using preoperative nTMS in cortical motor eloquent lesions with emphasis on metastasis. All patients that underwent preoperative nTMS between June 2013 and January 2016 were evaluated. A total of 61 patients underwent nTMS before undergoing surgery for a motor eloquent brain lesion. Patients suffered from cerebral metastasis (23), glioblastoma (16), high grade glioma WHO III (4), low grade glioma WHO II (4), lymphoma (2), meningioma (8), cavernous hemangioma (3), or arteriovenous malformation (1). Thirty patients (49.2%) presented with a preoperative motor deficit. One week after surgery, paresis had resolved or improved in 56.7% of the patients. Out of the patients with postoperative paresis, 89.5% experienced an improvement of motor status at follow-up. All metastatic lesions were completely resected compared to 78.9% of non-metastatic lesions (P = 0.02). Only 4.3% of patients with a metastatic lesion, but 26.3% of patients with a non-metastatic lesion experienced deterioration of motor function after surgery (P = 0.04). Preoperative nTMS is suitable for mapping of a variety of motor eloquent brain lesions resulting in favorable neurological outcome. Particularly in metastatic motor eloquent lesion, motor function appears to be preserved after surgery. Clin. Anat. 29:925-931, 2016. © 2016 Wiley Periodicals, Inc.

Intraoperative subcortical motor evoked potential stimulation: how close is the corticospinal tract?

Subcortical stimulation is a method used to evaluate the distance from the stimulation site to the corticospinal tract (CST) and to decide whether the resection of an adjacent lesion should be terminated to prevent damage to the CST. However, the correlation between stimulation intensity and distance to the CST has not yet been clearly assessed. The objective of this study was to investigate the appropriate correlation between the subcortical stimulation pattern and the distance to the CST. Monopolar subcortical motor evoked potential (MEP) mapping was performed in addition to continuous MEP monitoring in 37 consecutive patients with lesions located in motor-eloquent locations. The proximity of the resection cavity to the CST was identified by subcortical MEP mapping. At the end of resection, the point at which an MEP response was still measurable with minimal subcortical MEP intensity was marked with a titanium clip. At this location, different stimulation paradigms were executed with cathodal or anodal stimulation at 0.3-, 0.5-, and 0.7-msec pulse durations. Postoperatively, the distance between the CST as defined by postoperative diffusion tensor imaging fiber tracking and the titanium clip was measured. The correlation between this distance and the subcortical MEP electrical charge was calculated. Subcortical MEP mapping was successful in all patients. There were no new permanent motor deficits. Transient new postoperative motor deficits were observed in 14% (5/36) of cases. Gross-total resection was achieved in 75% (27/36) and subtotal resection (> 80% of tumor mass) in 25% (9/36) of cases. Stimulation intensity with various pulse durations as well as current intensity was plotted against the measured distance between the CST and the titanium clip on postoperative MRI using diffusion-weighted imaging fiberitracking tractography. Correlational and regression analyses showed a nonlinear correlation between stimulation intensity and the distance to the CST. Cathodal stimulation appeared better suited for subcortical stimulation. Subcortical MEP mapping is an excellent intraoperative method to determine the distance to the CST during resection of motor-eloquent lesions and is highly capable of further reducing the risk of a new neurological deficit.

Continuous subcortical motor evoked potential stimulation using the tip of an ultrasonic aspirator for the resection of motor eloquent lesions.

Resection of a motor eloquent lesion has become safer because of intraoperative neurophysiological monitoring (IOM). Stimulation of subcortical motor evoked potentials (scMEPs) is increasingly used to optimize patient safety. So far, scMEP stimulation has been performed intermittently during resection of eloquently located lesions. Authors of the present study assessed the possibility of using a resection instrument for continuous stimulation of scMEPs. An ultrasonic surgical aspirator was attached to an IOM stimulator and was used as a monopolar subcortical stimulation probe. The effect of the aspirator's use at different ultrasound power levels (0%, 25%, 50%, 75%, and 100%) on stimulation intensity was examined in a saline bath. Afterward monopolar stimulation with the surgical aspirator was used during the resection of subcortical lesions in the vicinity of the corticospinal tract in 14 patients in comparison with scMEP stimulation via a standard stimulation electrode. During resection, the stimulation current at which an MEP response was still measurable with subcortical stimulation using the surgical aspirator was compared with the corresponding stimulation current needed using a standard monopolar subcortical stimulation probe at the same location. The use of ultrasound at different energy levels did result in a slight but irrelevant increase in stimulation energy via the tip of the surgical aspirator in the saline bath. Stimulation of scMEPs using the surgical aspirator or monopolar probe was successful and almost identical in all patients. One patient developed a new permanent neurological deficit. Transient new postoperative paresis was observed in 28% (4 of 14) of cases. Gross-total resection was achieved in 64% (9 of 14) cases and subtotal resection (> 80% of tumor mass) in 35% (5 of 14). Continuous motor mapping using subcortical stimulation via a surgical aspirator, in comparison with the sequential use of a standard monopolar stimulation probe, is a feasible and safe method without any disadvantages. Compared with the standard probe, the aspirator offers continuous information on the distance to the corticospinal tract.

Preoperative motor mapping by navigated transcranial magnetic brain stimulation improves outcome for motor eloquent lesions

Navigated transcranial magnetic stimulation (nTMS) has been proven to influence surgical indication and planning. Yet there is still no clear evidence how these additional preoperative functional data influence the clinical course and outcome. Thus, this study aimed to compare patients with motor eloquently located supratentorial lesions investigated with or without preoperative nTMS in terms of clinical outcome parameters. A prospectively enrolled cohort of 100 patients with supratentorial lesions located in motor eloquent areas was investigated by preoperative nTMS (2010-2013) and matched with a control of 100 patients who were operated on without nTMS data (2006-2010) by a matched pair analysis. Patients in the nTMS group showed a significantly lower rate of residual tumor on postoperative MRI (OR 0.3828; 95% CI 0.2062-0.7107). Twelve percent of patients in the nTMS and 1% of patients in the non-nTMS group improved while 75% and 81% of the nTMS and non-nTMS groups, respectively, remained unchanged and 13% and 18% of patients in the nTMS and non-nTMS groups, respectively, deteriorated in postoperative motor function on long-term follow-up (P = .0057). Moreover, the nTMS group showed smaller craniotomies (nTMS 22.4 ± 8.3 cm(2); non-nTMS 26.7 ± 11.3 cm(2); P = .0023). This work increases the level of evidence for preoperative motor mapping by nTMS for rolandic lesions in a group comparison study. We therefore strongly advocate nTMS to become increasingly used for these lesions. However, a randomized trial on the comparison with the gold standard of intraoperative mapping seems mandatory.