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Sebastian Ille, Jens Gempt, Bernhard Meyer, and Sandro M. Krieg

Navigated transcranial magnetic stimulation (nTMS) allows for preoperative mapping for eloquent gliomas. Besides surgical planning, it also guides intraoperative stimulation mapping. The authors’ routine includes preoperative nTMS plus nTMS-based tractography for motor and language to consult patients, plan surgery, craniotomy, and guide cortical and subcortical stimulation.

Here, the authors present this routine in a 48-year-old woman with a glioma of the left middle and superior frontal gyrus reaching the precentral gyrus and superior longitudinal fascicle. Gross-total resection via awake surgery was achieved without deficit.

The nTMS data and nTMS-based tractography augment eloquent glioma management far beyond its current application.

The video can be found here: https://youtu.be/h4ldgMXL1ys.

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Maria Wostrack, Ehab Shiban, Thomas Obermueller, Jens Gempt, Bernhard Meyer, and Florian Ringel

Object

Intradural cauda equina and conus medullaris tumors (CECMTs) are rare. Only a few large clinical series exist to date. Therefore, clinical symptoms, surgical complications, and outcomes are poorly understood. The aim of the present study was to evaluate outcome after surgery of CECMTs and to identify the factors associated with a worse clinical prognosis based on the results of a series with sufficiently high number of cases.

Methods

All cases of intradural CECMTs treated surgically at the authors' department between March 2006 and May 2012 were retrospectively evaluated. Arachnoid cysts and multifocal tumors were excluded. Sixty-eight adult patients met the inclusion criteria (35 female and 33 male patients; median age 56 years). Follow-up data were available for 72% (n = 49) in a median period of 9 months.

Results

Overall, 18 tumors were located intramedullary and 50 extramedullary. The majority were nerve sheath tumors (n = 27), ependymomas (n = 17), and meningiomas (n = 9). The most common preoperative symptom was pain. The rate of new transient postoperative impairment was 18% (n = 12), and new permanent deficits were observed in only 6% (n = 4). Overall neurological improvement was achieved in 62%. The reversibility of preoperative symptoms was related to the interval between the time of symptom onset and the time of surgery and to the presence of preoperative neurological deficits. Surgery of ependymoma and carcinoma metastases was associated with a higher rate of morbidity.

Conclusions

Intradural CECMTs present as a group of tumors with varying histological features and clinical symptoms. Symptomatic manifestation is usually unspecific, mimicking degenerative lumbar spine syndromes. Despite a significant risk of transient deterioration, early surgery is advisable because more than 94% of patients maintain at least their preoperative status and more than 60% improve during follow-up. The reversibility of preoperative symptoms is related to the duration between symptom onset and surgery and to the presence of preoperative neurological deficits. The prognosis for recovery from cauda equina or conus medullaris syndrome is less favorable than for other deficits. Surgery of ependymoma is associated with a higher morbidity rate than other benign entities.

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Laura B. Ngwenya and E. Antonio Chiocca

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Stefanie Bette, Jens Gempt, Thomas Huber, Claire Delbridge, Bernhard Meyer, Claus Zimmer, Jan S. Kirschke, and Tobias Boeckh-Behrens

OBJECTIVE

Recent studies have indicated that a signal intensity increase of the fluid within the resection cavity on FLAIR images may predict tumor recurrence after glioma surgery. The aim of this study was to assess the increase in FLAIR signal intensity in a large patient cohort and in subgroups to assess its prognostic value for early tumor recurrence in glioma patients.

METHODS

A total of 212 patients (213 cases) who had undergone surgery for an intracranial glioma (WHO Grade IV [n = 103], WHO Grade III [n = 57], and WHO Grade II [n = 53]) were included in this retrospective study. FLAIR signal within the resection cavity at the time of tumor recurrence/last contact and on the previous MRI study was assessed qualitatively and quantitatively. Appearance of FLAIR signal increase was studied over time using Kaplan-Meier estimates in subgroups.

RESULTS

Patients with WHO Grade II glioma and connection of the resection cavity to CSF who did not undergo radiotherapy did not regularly develop this sign and were excluded from further analysis. For the remaining 87 cases, FLAIR signal intensity increase was observed in 27 cases. Recurrent disease was found in 26 of these 27 cases, resulting in a specificity of 80.0%, a sensitivity of 31.7%, and positive and negative predictive values of 96.3% and 6.7%, respectively. In 4 cases this sign had been observed prior (range 2.8–8.5 months) to tumor recurrence defined by standard criteria. Quantitative analysis underlined the results of qualitative analysis, but it did not add a diagnostic value.

CONCLUSIONS

Signal intensity increase of the fluid within the resection cavity on FLAIR images is a rare but highly specific and early sign for tumor recurrence/tumor progression in completely and incompletely resected high-grade glioma without connection of the resection cavity to CSF and with radiotherapy.

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Sandro M. Krieg, Ehab Shiban, Niels Buchmann, Jens Gempt, Annette Foerschler, Bernhard Meyer, and Florian Ringel

Object

Navigated transcranial magnetic stimulation (nTMS) is a newly evolving technique. Despite its supposed purpose (for example, preoperative central region mapping), little is known about its accuracy compared with established modalities like direct cortical stimulation (DCS) and functional MR (fMR) imaging. Against this background, the authors performed the current study to compare the accuracy of nTMS with DCS and fMR imaging.

Methods

Fourteen patients with tumors in or close to the precentral gyrus were examined using nTMS for motor cortex mapping, as were 12 patients with lesions in the subcortical white matter motor tract. Moreover, preoperative fMR imaging and intraoperative mapping of the motor cortex were performed via DCS, and the outlining of the motor cortex was compared.

Results

In the 14 cases of lesions affecting the precentral gyrus, the primary motor cortex as outlined by nTMS correlated well with that delineated by intraoperative DCS mapping, with a deviation of 4.4 ± 3.4 mm between the two methods. In comparing nTMS with fMR imaging, the deviation between the two methods was much larger: 9.8 ± 8.5 mm for the upper extremity and 14.7 ± 12.4 mm for the lower extremity. In 13 of 14 cases, the surgeon admitted easier identification of the central region because of nTMS. The procedure had a subjectively positive influence on the operative results in 5 cases and was responsible for a changed resection strategy in 2 cases. One of 26 patients experienced nTMS as unpleasant; none found it painful.

Conclusions

Navigated TMS correlates well with DCS as a gold standard despite factors that are supposed to contribute to the inaccuracy of nTMS. Moreover, surgeons have found nTMS to be an additional and helpful modality during the resection of tumors affecting eloquent motor areas, as well as during preoperative planning.

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Jens Gempt, Annette Förschler, Niels Buchmann, Haiko Pape, Yu-Mi Ryang, Sandro M. Krieg, Claus Zimmer, Bernhard Meyer, and Florian Ringel

Object

The aim of surgical treatment of glioma is the complete resection of tumor tissue with preservation of neurological function. Inclusion of diffusion-weighted imaging (DWI) in the postoperative MRI protocol could improve the delineation of ischemia-associated postoperative neurological deficits. The present study aims to assess the incidence of infarctions following resection of newly diagnosed gliomas in comparison with recurrent gliomas and the influence on neurological function.

Methods

Patients who underwent glioma resection for newly diagnosed or recurrent gliomas had early postoperative MRI, including DWI and apparent diffusion coefficient (ADC) maps. Postoperative areas of restricted diffusion were classified as arterial territorial infarctions, terminal branch infarctions, or venous infarctions. Tumor entity, location, and neurological function were recorded.

Results

New postoperative ischemic lesions were identified in 26 (31%) of 84 patients with newly diagnosed gliomas and 20 (80%) of 25 patients with recurrent gliomas (p < 0.01). New permanent and transient neurological deficits were more frequent in patients with recurrent gliomas than in patients with newly diagnosed tumors. Patients with neurological deficits had a significantly higher rate of ischemic lesions.

Conclusions

Postoperative infarctions occur frequently in patients with newly diagnosed and recurrent gliomas and do have an impact on postoperative neurological function. In this patient cohort there was a higher risk for ischemic lesions and for deterioration of neurological function after resection of recurrent tumors. Radiogenic and postoperative tissue changes could contribute to the higher risk of an ischemic infarction in patients with recurrent tumors.

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Sandro M. Krieg, Michael Schäffner, Ehab Shiban, Doris Droese, Thomas Obermüller, Jens Gempt, Bernhard Meyer, and Florian Ringel

Object

Resection of gliomas in or adjacent to the motor system is widely performed using intraoperative neuromonitoring (IOM). For resection of cerebral metastases in motor-eloquent regions, however, data are sparse and IOM in such cases is not yet widely described. Since recent studies have shown that cerebral metastases infiltrate surrounding brain tissue, this study was undertaken to assess the value and influence of IOM during resection of supratentorial metastases in motor-eloquent regions.

Methods

Between 2006 and 2011, the authors resected 206 consecutive supratentorial metastases, including 56 in eloquent motor areas with monitoring of monopolar direct cortically stimulated motor evoked potentials (MEPs). The authors evaluated the relationship between the monitoring data and the course of surgery, clinical data, and postoperative imaging.

Results

Motor evoked potential monitoring was successful in 53 cases (93%). Reduction of MEP amplitude correlated better with postoperative outcomes when the threshold for significant amplitude reduction was set at 80% (only > 80% reduction was considered significant decline) than when it was set at 50% (> 50% amplitude reduction was considered significant decline). Evidence of residual tumor was seen on MR images in 28% of the cases with significant MEP reduction. No residual tumor was seen in any case of stable MEP monitoring. Moreover, preoperative motor deficit, recursive partitioning analysis Class 3, and preoperative radiotherapy were independent risk factors for a new surgery-related motor weakness (occurring in 64% of patients with and 11% of patients without radiotherapy, p > 0.01).

Conclusions

Continuous MEP monitoring provides reliable monitoring of the motor system and also influences the course of operation in resection of cerebral metastases. However, in establishing warning criteria, only an amplitude decline > 80% of the baseline should be considered significant.

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Martin N. Stienen, Oliver P. Gautschi, Karl Schaller, David Netuka, Andreas K. Demetriades, Florian Ringel, Jens Gempt, and Dominique Kuhlen

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Jens Gempt, Julia Gerhardt, Vivien Toth, Stefanie Hüttinger, Yu-Mi Ryang, Maria Wostrack, Sandro M. Krieg, Bernhard Meyer, Annette Förschler, and Florian Ringel

Object

Brain metastases occur in 10% to 40% of patients harboring cancer. In cases of neurosurgical metastasis resection, all postoperative neurological deterioration should be avoided. Reasons for postoperative deficits can be direct tissue damage due to resection, hemorrhage, venous congestive infarcts, or arterial ischemic events leading to tissue infarction. The aim of this study was to evaluate whether postoperative ischemic infarctions occur in surgery for brain metastasis and to determine their influence on new postoperative neurological deficits.

Methods

Patients who underwent resection of brain metastases and had preoperative and early postoperative (within 48 hours) MRI scans, including diffusion-weighted imaging sequences and apparent diffusion coefficient maps, between January 2009 and May 2012 were included in this study. Clinical and histopathological data (histopathological results, pre- and postoperative neurological status, and previous tumor-specific therapy) were recorded.

Results

One hundred twenty-two patients (56 male, 66 female) who underwent resection of brain metastases were included. The patients' mean age was 60 years (range 21–89 years). The mean time span from initial tumor diagnosis to resection of brain metastasis was 44 months (range 0–338 months). The mean preoperative Karnofsky Performance Status was 80% (exact mean 76% ± 17% [SD]), and the mean postoperative value was 80% (exact mean 78% ± 17%). Twelve (9.8%) of the 122 patients had postoperative permanent worsening of a neurological deficit or a new permanent neurological deficit; 44 (36.1%) of the 122 patients had postoperative ischemic lesions. When comparing patients with and without previous brain irradiation, 53.8% of patients with previous brain irradiation had ischemic lesions on postoperative imaging compared with 31.3% of patients without previous brain irradiation (p = 0.033). There was a significant association between ischemia and postoperative neurological status deterioration (transient or permanent); 13 (29.5%) of 44 patients with ischemic lesions had deterioration of their neurological status compared with 7 (9%) of the 78 patients who did not have ischemic lesions (p = 0.003).

Conclusions

This study demonstrates a high prevalence of vascular incidents in patients undergoing resection for metastatic brain disease. Patients harboring postoperative ischemic lesions detected by MRI have a higher rate of neurological deficits (transient or permanent). Patients who had previous irradiation therapy are at higher risk of developing postoperative ischemic lesions. A large number of postoperative neurological deficits are caused by ischemic incidents.

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Jens Gempt, Sandro M. Krieg, Stefanie Hüttinger, Niels Buchmann, Yu-Mi Ryang, Ehab Shiban, Bernhard Meyer, Claus Zimmer, Annette Förschler, and Florian Ringel

Object

The aim of surgical glioma treatment is the complete resection of tumor tissue while preserving neurological function. Surgery-related neurological deficits arise from direct damage to the cortical or subcortical structures or from ischemia. The authors aimed to assess the incidence of resection-related ischemia of newly diagnosed or recurrent supratentorial gliomas and the sensitivity of intraoperative neuromonitoring (IOM) of motor evoked potentials (MEPs) for detecting such ischemic events and their influence on neurological motor function.

Methods

Between January 2009 and December 2010, 70 patients with tumors in motor-eloquent brain areas underwent intraoperative MEP monitoring during glioma resection and were examined by early postoperative MRI including diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) mapping. Postoperative areas of restricted diffusion were assessed by investigators blinded to the course of intraoperative MEPs and the neurological course.

Results

Among the 70 enrolled patients, a MEP amplitude decline below 50% of the baseline level was observed in 21 patients (30%). Sixteen of these patients (76%) had ischemic lesions identified on postoperative MRI scans. Forty-nine patients (70%) showed no decline in MEP amplitude, and only 16 (33%) of these patients harbored ischemic lesions. Moreover, 9 (69%) of 13 patients with a permanent loss of MEP amplitude showed postoperative ischemic lesions. Factors that promoted the occurrence of postoperative infarction were previous radiotherapy and location of the tumor close to the central arteries.

Conclusions

Alterations in the MEP amplitude during tumor resection and postoperative ischemic lesions are associated with postoperative impairment of motor function. Rather than cortical or subcortical structural damage of eloquent brain tissue alone, peri- or postoperative ischemic lesions play a crucial role in the development of surgery-related motor deficits.