Assessment of the incidence and nature of adverse events and their association with human error in neurosurgery. A prospective observation.

Introduction: Adverse events in surgery are a relevant cause of costs, disability, or death, and their incidence is a key quality indicator that plays an important role in the future of health care. In neurosurgery, little is known about the frequency of adverse events and the contribution of human error. Research question: To determine the incidence, nature and severity of adverse events in neurosurgery, and to investigate the contribution of human error. Material and methods: Prospective observation of all adverse events occurring at an academic neurosurgery referral center focusing on neuro-oncology, cerebrovascular and spinal surgery. All 4176 inpatients treated between September 2019 and September 2020 were included. Adverse events were recorded daily and their nature, severity and a potential contribution of human error were evaluated weekly by all senior neurosurgeons of the department. Results: 25.0% of patients had at least one adverse event. In 25.9% of these cases, the major adverse event was associated with human error, mostly with execution (18.3%) or planning (5.6%) deficiencies. 48.8% of cases with adverse events were severe (≥SAVES-v2 grade 3). Patients with multiple adverse events (8.6%) had more severe adverse events (67.6%). Adverse events were more severe in cranial than in spinal neurosurgery (57.6 vs. 39.4%). Discussion and conclusion: Adverse events occur frequently in neurosurgery. These data can serve as benchmarks when discussing quality-based accreditation and reimbursement in upcoming health care reforms.The high frequency of human performance deficiencies contributing to adverse events shows that there is potential to further eliminate avoidable patient harm.

Clinical efficiency of operating room-based sliding gantry CT as compared to mobile cone-beam CT-based navigated pedicle screw placement in 853 patients and 6733 screws.

PURPOSE: Multiple solutions for navigation-guided pedicle screw placement are available. However, the efficiency with regard to clinical and resource implications has not yet been analyzed. The present study's aim was to analyze whether an operating room sliding gantry CT (ORCT)-based approach for spinal instrumentation is more efficient than a mobile cone-beam CT (CBCT)-based approach. METHODS: This cohort study included a random sample of 853 patients who underwent spinal instrumentation using ORCT-based or CBCT-based pedicle screw placement due to tumor, degenerative, trauma, infection, or deformity disorders between November 2015 and January 2020. RESULTS: More screws had to be revised intraoperatively in the CBCT group due to insufficient placement (ORCT: 98, 2.8% vs. CBCT: 128, 4.0%; p = 0.0081). The mean time of patients inside the OR (Interval 5 Entry-Exit) was significantly shorter for the ORCT group (ORCT: mean, [95% CI] 256.0, [247.8, 264.3] min, CBCT: 283.0, [274.4, 291.5] min; p < 0.0001) based on shorter times for Interval 2 Positioning-Incision (ORCT: 18.8, [18.1, 19.9] min, CBCT: 33.6, [32.2, 35.5] min; p < 0.0001) and Interval 4 Suture-Exit (ORCT: 24.3, [23.6, 26.1] min, CBCT: 29.3, [27.5, 30.7] min; p < 0.0001). CONCLUSIONS: The choice of imaging technology for navigated pedicle screw placement has significant impact on standard spine procedures even in a high-volume spine center with daily routine in such devices. Particularly with regard to the duration of surgeries, the shorter time needed for preparation and de-positioning in the ORCT group made the main difference, while the accuracy was even higher for the ORCT.

Radiographic measurements of cervical alignment, fusion and subsidence after ACDF surgery and their impact on clinical outcome.

BACKGROUND: Some recent studies indicate correlations between cervical alignment and clinical outcome after anterior cervical discectomy and fusion (ACDF) surgery. However, there still are no established criteria for the interpretation of alignment, fusion and subsidence in relation to clinical outcome. METHODS: A retrospective analysis of 208 radiographs of patients following ACDF with stand-alone PEEK cage implantation was performed. The measurements were obtained on plain radiographs in lateral and anteroposterior projections as well as flexion/extension radiographs. Cervical alignment was measured using the Gore, Laing and Cobb methods; fusion was evaluated by an assortment of radiographic hallmarks: the presence of bridging bone, the Cobb angle and the distances between the tips and bases of the spinous processes of the operated segments, respectively. For assessment of subsidence, we used the Mochida method in addition to ventral and dorsal segmental height reduction. Correlation analysis between the different radiological characteristics and clinical outcome at a minimum follow-up of 12 months was conducted. RESULTS: Two hundred and eight patients were evaluated for alignment, fusion and subsidence. Cervical alignment using the Gore and Cobb methods correlated among each other, but failed to exhibit significant correlation with clinical outcome. Interpretation of fusion rates varied greatly (43.9 to 89.4%) depending on the criteria used. Pearson coefficients between radiographic presence of pseudarthrosis and the measurements of the spinous process distances (0.595; p < 0.001), the Cobb angles (0.187; p = 0.007) and the presence of bridging bone (0.224; p < 0.001) each exhibited statistical significance. None of the methods employed significantly correlated with clinical outcome. Regarding subsidence, we found rates of 62%, 48% and 27% using the Mochida, ventral and dorsal segmental height reduction assessment methods, respectively. Pearson correlations between pairs of Mochida/ventral (r = 0.39; p = 0.66) and Mochida/dorsal (r = 0.007; p = 0.921) height reduction assessment methods were weak and no significant correlation between subsidence rates and clinical outcome was shown. CONCLUSION: All measured parameters varied depending in the measurement method used. This was most pronounced for fusion. There was a moderate positive correlation between neck pain and subsidence as measured by the Mochida method.

Working ability and use of healthcare resources for patients with trigeminal neuralgia treated via microvascular decompression.

BACKGROUND: Trigeminal neuralgia (TN) is defined as sudden, usually unilateral, severe, brief, stabbing and recurrent episodes of pain in one or more branches of the trigeminal nerve. In patients with TN refractory to medical therapy, microvascular decompression (MVD) is considered. TN interferes with daily functioning and is associated with depression and anxiety. Direct costs of MVD are high, but the procedure is believed to improve working ability and reduce the use of medical resources. This study aims to analyse MVD's effects on TN patients regarding work capacity, healthcare utilisation and health-related quality of life (hrQoL). METHODS: We conducted a cross-sectional survey of patients who underwent MVD for TN between 2007 and 2016 (n = 46). The patients' outcome, work capacity and use of medical resources were assessed via the Barrow Neurological Institute Pain Intensity Score (BNI Score), with questions regarding patients' employment status, restrictions in work capacity, healthcare utilisation and completion of the EQ5D questionnaire. RESULTS: The response rate was 28/46 (61%). The majority of the participants (20/28) reported feeling strongly/quite handicapped in productivity due to TN preoperatively, which was also indicated by a few participants (3/28) postoperatively (p = < 0.01). Pain-related days off work were reduced postoperatively from 21 to 4 (p = 0.059) on average. Postoperative hrQoL did not differ from the general German population. Further reductions in healthcare utilisation and private costs were shown. CONCLUSION: In TN, MVD alleviates patient burden, especially concerning productivity and the consumption of health resources.

Intraoperative neuromonitoring for function-guided resection differs for supratentorial motor eloquent gliomas and metastases.

BACKGROUND: Recent data show differences in intraoperative neuromonitoring (IOM) in relation to the operated brain lesion. Due to the recently shown infiltrative nature of cerebral metastases, this work investigates the differences of IOM for cerebral metastases and glioma resection concerning sensitivity, specificity, and predictive values when aiming on preservation of motor function. METHODS: Between 2006 and 2011 we resected 171 eloquently located tumors (56 metastases, 115 gliomas) associated with the rolandic cortex or the pyramidal tract using IOM via direct cortical motor evoked potentials (MEPs). Postoperatively, MEP data were re-analyzed with respect to surgery-related paresis, residual tumor, and postoperative MRI with two different thresholds for MEP decline (50 and 80 % below baseline). RESULTS: MEP monitoring was successful in 158 cases (92.4 %). MEPs were stable in 54.7 % of all metastases cases and in 65.2 % of all glioma cases (p < 0.0001). After metastases resection, 21.4 % of patients improved and 21.9 % deteriorated in motor function. Glioma patients improved in only 5.4 % and worsened in 31.3 % of cases (p < 0.05). Resection was stopped due to MEP decline in 8.0 % (metastases) and 34.8 % of cases (gliomas) (p < 0.0002). CONCLUSION: There is significant difference between glioma and metastases resection. Post-hoc, metastases show more stable MEPs but a surprisingly high rate of surgery-related paresis and therefore a higher rate of false negative IOM.

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

OBJECT: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

OBJECT: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.

Impairment of preoperative language mapping by lesion location: a functional magnetic resonance imaging, navigated transcranial magnetic stimulation, and direct cortical stimulation study.

OBJECT: Language mapping by repetitive navigated transcranial magnetic stimulation (rTMS) is increasingly used and has already replaced functional MRI (fMRI) in some institutions for preoperative mapping of neurosurgical patients. Yet some factors affect the concordance of both methods with direct cortical stimulation (DCS), most likely by lesions affecting cortical oxygenation levels. Therefore, the impairment of the accuracy of rTMS and fMRI was analyzed and compared with DCS during awake surgery in patients with intraparenchymal lesions. METHODS: Language mapping was performed by DCS, rTMS, and fMRI using an object-naming task in 27 patients with left-sided perisylvian lesions, and the induced language errors of each method were assigned to the cortical parcellation system. Subsequently, the receiver operating characteristics were calculated for rTMS and fMRI and compared with DCS as ground truth for regions with (w/) and without (w/o) the lesion in the mapped regions. RESULTS: The w/ subgroup revealed a sensitivity of 100% (w/o 100%), a specificity of 8% (w/o 5%), a positive predictive value of 34% (w/o: 53%), and a negative predictive value (NPV) of 100% (w/o: 100%) for the comparison of rTMS versus DCS. Findings for the comparison of fMRI versus DCS within the w/ subgroup revealed a sensitivity of 32% (w/o: 62%), a specificity of 88% (w/o: 60%), a positive predictive value of 56% (w/o: 62%), and a NPV of 73% (w/o: 60%). CONCLUSIONS: Although strengths and weaknesses exist for both rTMS and fMRI, the results show that rTMS is less affected by a brain lesion than fMRI, especially when performing mapping of language-negative cortical regions based on sensitivity and NPV.

Changing the clinical course of glioma patients by preoperative motor mapping with navigated transcranial magnetic brain stimulation.

BACKGROUND: Mapping of the motor cortex by navigated transcranial magnetic stimulation (nTMS) can be used for preoperative planning in brain tumor patients. Just recently, it has been proven to actually change outcomes by increasing the rate of gross total resection (GTR) and by reducing the surgery-related rate of paresis significantly in cohorts of patients suffering from different entities of intracranial lesions. Yet, we also need data that shows whether these changes also lead to a changed clinical course, and can also be achieved specifically in high-grade glioma (HGG) patients. METHODS: We prospectively enrolled 70 patients with supratentorial motor eloquently located HGG undergoing preoperative nTMS (2010-2014) and matched these patients with 70 HGG patients who did not undergo preoperative nTMS (2007-2010). RESULTS: On average, the overall size of the craniotomy was significantly smaller for nTMS patients when compared to the non-nTMS group (nTMS: 25.3 ± 9.7 cm(2); non-nTMS: 30.8 ± 13.2 cm(2); p = 0.0058). Furthermore, residual tumor tissue (nTMS: 34.3%; non-nTMS: 54.3%; p = 0.0172) and unexpected tumor residuals (nTMS: 15.7%; non-nTMS: 32.9%; p = 0.0180) were less frequent in nTMS patients. Regarding the further clinical course, median inpatient stay was 12 days for the nTMS and 14 days for the non-nTMS group (nTMS: CI 10.5 - 13.5 days; non-nTMS: CI 11.6 - 16.4 days; p = 0.0446). 60.0% of patients of the nTMS group and 54.3% of patients of the non-nTMS group were eligible for postoperative chemotherapy (OR 1.2630, CI 0.6458 - 2.4710, p = 0.4945), while 67.1% of nTMS patients and 48.6% of non-nTMS patients received radiotherapy (OR 2.1640, CI 1.0910 - 4.2910, p = 0.0261). Moreover, 3, 6, and 9 months survival was significantly better in the nTMS group (p = 0.0298, p = 0.0015, and p = 0.0167). CONCLUSIONS: With the limitations of this study in mind, our data show that HGG patients might benefit from preoperative nTMS mapping.

The impact of repetitive navigated transcranial magnetic stimulation coil positioning and stimulation parameters on human language function.

BACKGROUND: Repetitive navigated transcranial magnetic stimulation (rTMS) in combination with object naming is able to elicit naming errors by stimulating language-related brain regions. However, stimulation results mainly depend on coil positioning and stimulation parameters, which have not been investigated since the implementation of neuronavigation to transcranial magnetic stimulation. Therefore, the following three parameters were systematically examined in the present study: coil angulation, stimulation frequency, and stimulation intensity. METHODS: Five healthy, right-handed subjects underwent rTMS language mapping of Broca's as well as Wernicke's areas of the left hemisphere. During mapping sessions, coil angulation was changed clockwise in 45° steps, and the stimulation frequency and intensity were varied within a considerably wide range. For angulation, the anterior-posterior (ap) coil orientation was used as reference position. RESULTS: An angulation of 90° to ap coil orientation led to the highest rate of naming errors within Broca's area, whereas an inhomogeneous distribution of angulations was observed during stimulation of Wernicke's area. Therefore, ap coil orientation, which is regarded as standard in rTMS language mapping, could not be approved as the optimal position. With regard to stimulation parameters, 20 Hz and 120% of the resting motor threshold (RMT) were defined as optimal. CONCLUSIONS: Coil angulation, stimulation frequency, and stimulation intensity have significant impacts on language impairment during rTMS mapping. The variation of only one of these parameters already leads to a clearer disruption of language performance. Therefore, individually adapted stimulation protocols have to be determined prior to language mapping in order to improve mapping results.

Combined noninvasive language mapping by navigated transcranial magnetic stimulation and functional MRI and its comparison with direct cortical stimulation.

OBJECT: Repetitive navigated transcranial magnetic stimulation (rTMS) is now increasingly used for preoperative language mapping in patients with lesions in language-related areas of the brain. Yet its correlation with intraoperative direct cortical stimulation (DCS) has to be improved. To increase rTMS's specificity and positive predictive value, the authors aim to provide thresholds for rTMS's positive language areas. Moreover, they propose a protocol for combining rTMS with functional MRI (fMRI) to combine the strength of both methods. METHODS: The authors performed multimodal language mapping in 35 patients with left-sided perisylvian lesions by using rTMS, fMRI, and DCS. The rTMS mappings were conducted with a picture-to-trigger interval (PTI, time between stimulus presentation and stimulation onset) of either 0 or 300 msec. The error rates (ERs; that is, the number of errors per number of stimulations) were calculated for each region of the cortical parcellation system (CPS). Subsequently, the rTMS mappings were analyzed through different error rate thresholds (ERT; that is, the ER at which a CPS region was defined as language positive in terms of rTMS), and the 2-out-of-3 rule (a stimulation site was defined as language positive in terms of rTMS if at least 2 out of 3 stimulations caused an error). As a second step, the authors combined the results of fMRI and rTMS in a predefined protocol of combined noninvasive mapping. To validate this noninvasive protocol, they correlated its results to DCS during awake surgery. RESULTS: The analysis by different rTMS ERTs obtained the highest correlation regarding sensitivity and a low rate of false positives for the ERTs of 15%, 20%, 25%, and the 2-out-of-3 rule. However, when comparing the combined fMRI and rTMS results with DCS, the authors observed an overall specificity of 83%, a positive predictive value of 51%, a sensitivity of 98%, and a negative predictive value of 95%. CONCLUSIONS: In comparison with fMRI, rTMS is a more sensitive but less specific tool for preoperative language mapping than DCS. Moreover, rTMS is most reliable when using ERTs of 15%, 20%, 25%, or the 2-out-of-3 rule and a PTI of 0 msec. Furthermore, the combination of fMRI and rTMS leads to a higher correlation to DCS than both techniques alone, and the presented protocols for combined noninvasive language mapping might play a supportive role in the language-mapping assessment prior to the gold-standard intraoperative DCS.

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

BACKGROUND: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.

Risks of postoperative paresis in motor eloquently and non-eloquently located brain metastases.

BACKGROUND: When treating cerebral metastases all involved multidisciplinary oncological specialists have to cooperate closely to provide the best care for these patients. For the resection of brain metastasis several studies reported a considerable risk of new postoperative paresis. Pre- and perioperative chemotherapy (Ctx) or radiotherapy (Rtx) alter vasculature and adjacent fiber tracts on the one hand, and many patients already present with paresis prior to surgery on the other hand. As such factors were repeatedly considered risk factors for perioperative complications, we designed this study to also identify risk factors for brain metastases resection. METHODS: Between 2006 and 2011, we resected 206 brain metastases consecutively, 56 in eloquent motor areas and 150 in non-eloquent ones. We evaluated the influences of preoperative paresis, previous Rtx or Ctx as well as recursive partitioning analysis (RPA) class on postoperative outcome. RESULTS: In general, 8.7% of all patients postoperatively developed a new permanent paresis. In contrast to preoperative Ctx, previous Rtx as a single or combined treatment strategy was a significant risk factor for postoperative motor weakness. This risk was even increased in perirolandic and rolandic lesions. Our data show significantly increased risk of new deficits for patients assigned to RPA class 3. Even in non-eloquently located brain metastases the risk of new postoperative paresis has not to be underestimated. Despite the microsurgical approach, our cohort shows a high rate of unexpected residual tumors in postoperative MRI, which supports recent data on brain metastases' infiltrative nature but might also be the result of our strict study protocol. CONCLUSIONS: Surgical resection is a safe treatment of brain metastases. However, preoperative Rtx and RPA score 3 have to be taken into account when surgical resection is considered.

Conus medullaris and cauda equina tumors: clinical presentation, prognosis, and outcome after surgical treatment: clinical article.

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.

Surgery of highly eloquent gliomas primarily assessed as non-resectable: risks and benefits in a cohort study.

BACKGROUND: Today, the treatment of choice for high- and low-grade gliomas requires primarily surgical resection to achieve the best survival and quality of life. Nevertheless, many gliomas within highly eloquent cortical regions, e.g., insula, rolandic, and left perisylvian cortex, still do not undergo surgery because of the impending risk of surgery-related deficits at some centers. However, pre and intraoperative brain mapping, intraoperative neuromonitoring (IOM), and awake surgery increase safety, which allows resection of most of these tumors with a considerably low rate of postoperatively new deficits. METHODS: Between 2006 and 2012, we resected 47 out of 51 supratentorial gliomas (92%), which were primarily evaluated to be non-resectable during previous presentation at another neurosurgical department. Out of these, 25 were glioblastomas WHO grade IV (53%), 14 were anaplastic astrocytomas WHO grade III (30%), 7 were diffuse astrocytomas WHO grade II (15%), and one was a pilocytic astrocytoma WHO grade I (2%). All data, including pre and intraoperative brain mapping and monitoring (IOM) by motor evoked potentials (MEPs) were reviewed and related to the postoperative outcome. RESULTS: Awake surgery was performed in 8 cases (17%). IOM was required in 38 cases (81%) and was stable in 18 cases (47%), whereas MEPs changed the surgical strategy in 10 cases (26%). Thereby, gross total resection was achieved in 35 cases (74%). Postoperatively, 17 of 47 patients (36%) had a new motor or language deficit, which remained permanent in 8.5% (4 patients). Progression-free follow-up was 11.3 months (range: 2 weeks - 64.5 months) and median survival was 14.8 months (range: 4 weeks - 20.5 months). Median Karnofsky Performance Scale was 85 before and 80 after surgery). CONCLUSIONS: In specialized centers, most highly eloquent gliomas are eligible for surgical resection with an acceptable rate of surgery-related deficits; therefore, they should be referred to specialized centers.

Surgical treatment of symptomatic cerebral cavernous malformations in eloquent brain regions.

BACKGROUND: Despite the increased risk of hemorrhage and deteriorating neurological function of once-bled cerebral cavernous malformations (CM), the management of eloquently located CMs remains controversial. METHODS: All eloquently located CMs (n = 45) surgically treated between 03/2006 and 04/2011 in our department were consecutively evaluated. Eloquence was characterized according to Spetzler and Martin's definition. The following locations were approached: brainstem, n = 16; sensorimotor, n = 8; visual pathway, n = 7; cerebellum (deep nuclei and peduncles), n = 7; basal ganglia, n = 4, and language, n = 3. Follow-up data was available for 41 patients (91 %) with a median interval of 14 months. Outcomes were evaluated according to the Glasgow outcome and the modified Rankin scale. RESULTS: Immediately after surgery, 47 % (n = 21) had a new deficit. At follow-up, 80 % (n = 36) recovered to at least preoperative status or were better than before surgery, 9 % (n = 4) exhibited a slight, and 7 % (n = 3) had a moderate neurological impairment. Only two cases (4 %) with a new permanent severe deficit were observed, both related to dorsal brainstem surgery. The outcome after the surgery of otherwise located brainstem CMs was as beneficial as that for non-brainstem CMs. Patients with initially poor neurological performance fared worse than oligosymptomatic patients. CONCLUSIONS: Despite the high postoperative transient morbidity, the majority improved profoundly during follow-ups. Compared with natural history, surgical treatment should be considered for all eloquent symptomatic CMs. Dorsal brainstem location and poor preoperative neurological status are associated with an increased postoperative morbidity.