Surgery for temporal mediobasal tumors: experience based on a series of 235 patients

Tumor Cell Infiltration into the Brain in Glioblastoma: From Mechanisms to Clinical Perspectives

Glioblastoma is the most common and malignant primary brain tumor, defined by its highly aggressive nature. Despite the advances in diagnostic and surgical techniques, and the development of novel therapies in the last decade, the prognosis for glioblastoma is still extremely poor. One major factor for the failure of existing therapeutic approaches is the highly invasive nature of glioblastomas. The extreme infiltrating capacity of tumor cells into the brain parenchyma makes complete surgical removal difficult; glioblastomas almost inevitably recur in a more therapy-resistant state, sometimes at distant sites in the brain. Therefore, there are major efforts to understand the molecular mechanisms underpinning glioblastoma invasion; however, there is no approved therapy directed against the invasive phenotype as of now. Here, we review the major molecular mechanisms of glioblastoma cell invasion, including the routes followed by glioblastoma cells, the interaction of tumor cells within the brain environment and the extracellular matrix components, and the roles of tumor cell adhesion and extracellular matrix remodeling. We also include a perspective of high-throughput approaches utilized to discover novel players for invasion and clinical targeting of invasive glioblastoma cells.

Vascularization of the uncus - Anatomical study and clinical implications

Background:

The objective of this paper was to describe the arterial supply of the uncus and quantify the branches directed to the anteromedial aspect of the human temporal cortex.

Methods:

We studied 150 human cerebral hemispheres identifying main afferent arteries supplying the anteromedial temporal cortex with particular attention to the uncus, determining the territory supplied by each artery through either cortical or perforating branches.

Results:

The uncus was supplied by 419 branches of the anterior choroidal artery (AChA), 210 branches of the internal carotid artery (ICA), 353 branches of the middle cerebral artery (MCA), and 122 branches of the posterior cerebral artery (PCA). The total of supplying vessels was 1104 among the 150 hemispheres studied, which corresponds to 7.36 arteries per uncus. The average of branches per hemisphere was as follows: 2.79 from AChA, 1.40 from ICA, 2.35 from MCA, and 0.81 from PCA. The relative contribution of each artery for the total of specimens studied was as follows: 38% from AChA, 19% from ICA, 32% from the MCA, and 11% from the PCA. We identified cortical anastomoses mostly between the MCA and PCA (27 cases).

Conclusion:

We described and quantified the uncus’ vascularization, including anatomical variations. This updated, detailed description of the mesial temporal vascularization is paramount to improve the treatment of neurosurgical conditions.

Cortical and Subcortical Anatomy of the Orbitofrontal Cortex: A White Matter Microfiberdissection Study and Case Series

BACKGROUND

The literature on white matter anatomy underlying the human orbitofrontal cortex (OFC) is scarce in spite of its relevance for glioma surgery.

OBJECTIVE

To describe the anatomy of the OFC and of the underlying white matter fiber anatomy, with a particular focus on the surgical structures relevant for a safe and efficient orbitofrontal glioma resection. Based on anatomical and radiological data, the secondary objective was to describe the growth pattern of OFC gliomas.

METHODS

The study was performed on 10 brain specimens prepared according to Klingler's protocol and dissected using the fiber microdissection technique modified according to U.T., under the microscope at high magnification.

RESULTS

A detailed stratigraphy of the OFC was performed, from the cortex up to the frontal horn of the lateral ventricle. The interposed neural structures are described together with relevant neighboring topographic areas and nuclei. Combining anatomical and radiological data, it appears that the anatomical boundaries delimiting and guiding the macroscopical growth of OFC gliomas are as follows: the corpus callosum superiorly, the external capsule laterally, the basal forebrain and lentiform nucleus posteriorly, and the gyrus rectus medially. Thus, OFC gliomas seem to grow ventriculopetally, avoiding the laterally located neocortex.

CONCLUSION

The findings in our study supplement available anatomical knowledge of the OFC, providing reliable landmarks for a precise topographical diagnosis of OFC lesions and for perioperative orientation. The relationships between deep anatomic structures and glioma formations described in this study are relevant for surgery in this highly interconnected area.

Anatomical Subpial Resection of Tumors in the Amygdala and Hippocampus

OBJECTIVE

Surgical techniques to achieve complete resection of mesial-basal temporal tumors should be pursued by neurosurgical oncologists. We describe the anatomical subpial amygdalohippocampectomy (SpAH) technique for tumor resection.

METHODS

The key anatomical landmarks and critical steps of the SpAH technique were outlined and emphasized with medical illustrations and intraoperative photographs. The senior author's 90-day surgical outcomes with this approach were reviewed.

RESULTS

Twenty-five patients (men, 17 [68%]; women, 8 [32%]; median [range] age, 59 [23-80] years) with temporal tumors involving the amygdalohippocampal region were included. SpAH was performed selectively in 8 [32%] patients, whereas 17 [68%] patients underwent SpAH in conjunction with an anterior temporal lobectomy due to tumor involvement of the anterolateral temporal cortex. The subpial resection of the amygdala protected the critical structures of the suprasellar cistern and sylvian fissure. Identifying the choroidal fissure as the superior-most aspect of hippocampal resection protected the optic tract and the thalamus. Subpial resection of the parahippocampal gyrus inferiorly protected the brainstem and critical structures of the ambient cistern. Tumors in the amygdalohippocampal region were anatomically and completely resected in all 25 patients. Of the 15 patients who presented with seizures, 13 (87%) were seizure-free at the 90-day postsurgical follow-up. Permanent neurologic deficits occurred in 3 patients (12%).

CONCLUSIONS

The SpAH technique permits complete resection of mesial-basal temporal tumors with an acceptable morbidity profile. An in-depth understanding of temporal lobe anatomy combined with a refined microsurgical technique allows for reproducible resection of tumor in the amygdalohippocampal region while protecting critical neurovascular structures.

Transcorticosubcortical Approach for Left Posterior Mediobasal Temporal Region Gliomas: A Case Series and Anatomic Review of Relevant White Matter Tracts

BACKGROUND AND OBJECTIVE

The goal of this study is to show using 5 illustrative cases that the transcortical route for resection of mediobasal temporal region (MBTR) lesions is safe and effective when performed with awake functional mapping and knowledge of the relevant subcortical anatomy. Although several have been proposed, there is a paucity of reports on transcorticosubcortical approaches to these lesions, particularly in patients with posterior-superior extension. We present a case series of 5 patients with left posterior MBTR gliomas and summarize the relevant subcortical anatomy knowledge of what is a prerequisite for safe resection.

METHODS

Five patients with left posterior MBTR gliomas underwent awake resection with functional corticosubcortical electric mapping. Details of the approach are presented with a review of relevant anatomy.

RESULTS

Gross total resection was achieved in 4 patients. One patient who had previously undergone radiation therapy had a subtotal resection. There were 4 cases of World Health Organization grade II glioma and 1 case of World Health Organization grade IV glioma. All patients underwent preoperative and postoperative neurologic and neuropsychological assessment and there were no new or worsening sensorimotor, visual, language, or cognitive deficits.

CONCLUSIONS

The transcorticosubcortical approach is a safe and effective approach to lesions of the posterior MBTR. The approach is safe and effective even in patients with superior extension, if the surgical approach is predicated on knowledge of individual functional anatomy. Awake resection with cortical and axonal mapping with well-selected paradigms is invaluable in maximizing extent of resection and ensuring patient safety.

[Surgical treatment of epilepsy in children with gloneuronal brain tumors: morphology, MRI semiology and factors affecting the outcome]

INTRODUCTION

Glioneuronal tumors (GNT) are usually found in children (less than 1.5% of all neoplasms of the brain). With rare exceptions, they are benign and usually manifest only by epilepsy, which is quite often resistant to treatment with AE drugs. Tumor removal usually helps to cope with epileptic seizures, however, a number of issues regarding diagnosis and surgical treatment (interpretation of morphological data and classification, epileptogenesis and topography of the epileptogenic zone, the value of intraoperative invasive EEG and the optimal volume of resection) remain debatable.

AIM

To describe the morphology, electro-clinical picture and MR-semiology in patients with gloneuronal brain tumors, as well as to analyse the results of their surgical treatment and the factors determining its outcome.

MATERIAL AND METHODS

152 children with a median age of 8 years were treated surgically (There were 64 gangliogliomas, 73 DNT, 15 cases where the tumor classification failed - GNT NOS). In children under 2 years of age, temporal localization of the tumor prevailed. In 81 cases, ECoG was used during the operation. Surgical treatment complications: transient neurological deficit (in 15 cases); hematomas removed without consequences (in 2 cases), infectious (osteomyelitis of bone bone flap in 2 cases). We analyzed: the age of the epilepsy onset (median - 4 years 7 months) and its duration (median - 23.5 months), the type of seizures, as well as the features of MR-semiology and morphology of tumors and adjacent areas of the brain. The volume of tumor resection was verified by MRI (in 101 cases) and CT (in each case). The follow-up was collected through face-to-face meetings, with repeated video EEG and MRI, as well as telephone interviews. We studied the effect of a number of parameters characterizing the patient and features of his/her operation on the outcome of treatmen.

RESULTS

Among 102 patients in whom the follow-up history is one year or more (median - 2 years), a favorable outcome (Engel IA) was observed in 86 of them (84%); 55 of them (54%) at the time of the last examination stopped drug AE treatment. Radical tumor removal and younger age at the time of surgery were statistically significantly associated with a favorable result.

CONCLUSION

In children with gloneuronal brain tumors, removal of the tumor is effective and relatively safe in the treatment of symptomatic epilepsy. Radical tumor resection and earlier intervention are the most important prerequisites for a favorable outcome and persistent remission of seizures.

Transcortical insular glioma resection: clinical outcome and predictors

OBJECTIVE

Insular lobe gliomas continue to challenge neurosurgeons due to their complex anatomical position. Transcortical and transsylvian corridors remain the primary approaches for reaching the insula, but the adoption of one technique over the other remains controversial. The authors analyzed the transcortical approach of resecting insular gliomas in the context of patient tumor location based on the Berger-Sinai classification, achievable extents of resection (EORs), overall survival (OS), and postsurgical neurological outcome.

METHODS

The authors studied 255 consecutive cases of insular gliomas that underwent transcortical tumor resection in their division. Tumor molecular pathology, location, EOR, postoperative neurological outcome for each insular zone, and the accompanying OS were incorporated into the analysis to determine the value of this surgical approach.

RESULTS

Lower-grade insular gliomas (LGGs) were more prevalent (63.14%). Regarding location, giant tumors (involving all insular zones) were most prevalent (58.82%) followed by zone I+IV (anterior) tumors (20.39%). In LGGs, tumor location was an independent predictor of survival (p = 0.003), with giant tumors demonstrating shortest patient survival (p = 0.003). Isocitrate dehydrogenase 1 (IDH1) mutation was more likely to be associated with giant tumors (p < 0.001) than focal tumors located in a regional zone. EOR correlated with survival in both LGG (p = 0.001) and higher-grade glioma (HGG) patients (p = 0.008). The highest EORs were achieved in anterior-zone LGGs (p = 0.024). In terms of developing postoperative neurological deficits, patients with giant tumors were more susceptible (p = 0.038). Postoperative transient neurological deficit was recorded in 12.79%, and permanent deficit in 15.70% of patients. Patients who developed either transient or permanent postsurgical neurological deficits exhibited poorer survival (p < 0.001).

CONCLUSIONS

The transcortical surgical approach can achieve maximal tumor resection in all insular zones. In addition, the incorporation of adjunct technologies such as multimodal brain imaging and mapping of cortical and subcortical eloquent brain regions into the transcortical approach favors postoperative neurological outcomes, and prolongs patient survival.

The transcortical equatorial approach for gliomas of the mesial temporal lobe: techniques and functional outcomes

OBJECTIVEMany surgical approaches have been described for lesions within the mesial temporal lobe (MTL), but there are limited reports on the transcortical approach for the resection of tumors within this region. Here, the authors describe the technical considerations and functional outcomes in patients undergoing transcortical resection of gliomas of the MTL.METHODSPatients with a glioma (WHO grades I-IV) located within the MTL who had undergone the transcortical approach in the period between 1998 and 2016 were identified through the University of California, San Francisco (UCSF) tumor registry and were classified according to tumor location: preuncus, uncus, hippocampus/parahippocampus, and various combinations of the former groups. Patient and tumor characteristics and outcomes were determined from operative, radiology, pathology, and other clinical reports that were available through the UCSF electronic medical record.RESULTSFifty patients with low- or high-grade glioma were identified. The mean patient age was 46.8 years, and the mean follow-up was 3 years. Seizures were the presenting symptom in 82% of cases. Schramm types A, C, and D represented 34%, 28%, and 38% of the tumors, and the majority of lesions were located at least in part within the hippocampus/parahippocampus. For preuncus and preuncus/uncus tumors, a transcortical approach through the temporal pole allowed for resection. For most tumors of the uncus and those extending into the hippocampus/parahippocampus, a corticectomy was performed within the middle and/or inferior temporal gyri to approach the lesion. To locate the safest corridor for the corticectomy, language mapping was performed in 96.9% of the left-sided tumor cases, and subcortical motor mapping was performed in 52% of all cases. The mean volumetric extent of resection of low- and high-grade tumors was 89.5% and 96.0%, respectively, and did not differ by tumor location or Schramm type. By 3 months' follow-up, 12 patients (24%) had residual deficits, most of which were visual field deficits. Three patients with left-sided tumors (9.4% of dominant-cortex lesions) experienced word-finding difficulty at 3 months after resection, but 2 of these patients demonstrated complete resolution of symptoms by 1 year.CONCLUSIONSMesial temporal lobe gliomas, including larger Schramm type C and D tumors, can be safely and aggressively resected via a transcortical equatorial approach when used in conjunction with cortical and subcortical mapping.

Patterns of Invasive Growth in Malignant Gliomas-The Hippocampus Emerges as an Invasion-Spared Brain Region

BACKGROUND: Widespread infiltration of tumor cells into surrounding brain parenchyma is a hallmark of malignant gliomas, but little data exist on the overall invasion pattern of tumor cells throughout the brain. METHODS: We have studied the invasive phenotype of malignant gliomas in two invasive mouse models and patients. Tumor invasion patterns were characterized in a patient-derived xenograft mouse model using brain-wide histological analysis and magnetic resonance (MR) imaging. Findings were histologically validated in a cdkn2a−/− PDGF-β lentivirus-induced mouse glioblastoma model. Clinical verification of the results was obtained by analysis of MR images of malignant gliomas. RESULTS: Histological analysis using human-specific cellular markers revealed invasive tumors with a non-radial invasion pattern. Tumors cells accumulated in structures located far from the transplant site, such as the optic white matter and pons, whereas certain adjacent regions were spared. As such, the hippocampus was remarkably free of infiltrating tumor cells despite the extensive invasion of surrounding regions. Similarly, MR images of xenografted mouse brains displayed tumors with bihemispheric pathology, while the hippocampi appeared relatively normal. In patients, most malignant temporal lobe gliomas were located lateral to the collateral sulcus. Despite widespread pathological fluid-attenuated inversion recovery signal in the temporal lobe, 74% of the “lateral tumors” did not show signs of involvement of the amygdalo-hippocampal complex. CONCLUSIONS: Our data provide clear evidence for a compartmental pattern of invasive growth in malignant gliomas. The observed invasion patterns suggest the presence of preferred migratory paths, as well as intra-parenchymal boundaries that may be difficult for glioma cells to traverse supporting the notion of compartmental growth. In both mice and human patients, the hippocampus appears to be a brain region that is less prone to tumor invasion.

Middle Temporal Gyrus Versus Inferior Temporal Gyrus Transcortical Approaches to High-Grade Astrocytomas in the Mediobasal Temporal Lobe: A Comparison of Outcomes, Functional Restoration, and Surgical Considerations

INTRODUCTION

High-grade astrocytomas of the mesial temporal lobe may pose surgical challenges. Several approaches (trans-sylvian, subtemporal, and transcortical) have been designed to circumnavigate the critical neurovascular structures and white fiber tracts that surround this area. Considering the paucity of literature on the transcortical approach for these lesions, we describe our institutional experience with transcortical approaches to Grade III/IV astrocytomas in the mesial temporal lobe.

METHODS

Between 1999 and 2009, 23 patients underwent surgery at the Johns Hopkins Medical Institutions for Grade III/IV astrocytomas involving the mesial temporal lobe (without involvement of the temporal neocortex). Clinical notes, operative records, and imaging were reviewed.

RESULTS

Thirteen patients had tumors in the dominant hemisphere. All patients underwent surgery via a transcortical approach (14 via the inferior temporal gyrus and 9 via the middle temporal gyrus). Gross total resection was obtained in 92 % of the cohort. Neurological outcomes were: clinically significant stroke (2 patients), new visual deficits (2 patients), new speech deficit (1 patient); seizure control (53 %).

CONCLUSIONS

In comparison to reported results in the literature for the transylvian and subtemporal approaches, the transcortical approach may provide the access necessary for a gross total resection with minimal neurological consequences. In our series of patients, there was no statistically significant difference in outcomes between the middle temporal gyrus versus the inferior temporal gyrus trajectories.

The transsylvian approach for resection of insular gliomas: technical nuances of splitting the Sylvian fissure

Insular gliomas represent a unique surgical challenge due to the complex anatomy and nearby vascular elements associated within the Sylvian fissure. For certain tumors, the transsylvian approach provides an effective technique for achieving maximal safe resection. The goal of this manuscript and video are to present and discuss the surgical nuances and appropriate application of splitting the Sylvian fissure. Our hope is that this video highlights the safety and efficacy of the transsylvian approach for appropriately selected insular gliomas.

Surgical assessment of the insula. Part 1: surgical anatomy and morphometric analysis of the transsylvian and transcortical approaches to the insula

OBJECT

Transcortical and transsylvian corridors have been previously described as the main surgical approaches to the insula, but there is insufficient evidence to support one approach versus the other. The authors performed a cadaveric comparative study regarding insular exposure, surgical window and freedom, between the transcortical and transsylvian approaches (with and without cutting superficial sylvian bridging veins). Surgical anatomy and skull surface reference points to the different insular regions are also described.

METHODS

Sixteen cadaveric specimens were embalmed with a customized formula to enhance neurosurgical simulation. Two different blocks were defined in the study: first, transsylvian without (TS) and with the superficial sylvian bridging veins cut (TSVC) and transcortical (TC) approaches to the insula were simulated in all (16) specimens. Insular surface exposure, surgical window and surgical freedom were calculated for each procedure and related to the Berger-Sanai insular glioma classification (Zones I–IV) in 10 specimens. Second, the venous drainage pattern and anatomical landmarks considered critical for surgical planning were studied in all specimens.

RESULTS

In the insular Zone I (anterior-superior), the TC approach provided the best insular exposure compared with both TS and TSVC. The surgical window obtained with the TC approach was also larger than that obtained with the TS. The TC approach provided 137% more surgical freedom than the TS approach. Only the TC corridor provided complete insular exposure. In Zone II (posterior-superior), results depended on the degree of opercular resection. Without resection of the precentral gyrus in the operculum, insula exposure, surgical windows and surgical freedom were equivalent. If the opercular cortex was resected, the insula exposure and surgical freedom obtained through the TC approach was greater to that of the other groups. In Zone III (posterior-inferior), the TC approach provided better surgical exposure than the TS, yet similar to the TSVC. The TC approach provided the best insular exposure, surgical window, and surgical freedom if components of Heschl’s gyrus were resected. In Zone IV (anterior-inferior), the TC corridor provided better exposure than both the TS and the TSVC. The surgical window was equivalent. Surgical freedom provided by the TC was greater than the TS approach. This zone was completely exposed only with the TC approach. A dominant anterior venous drainage was found in 87% of the specimens. In this group, 50% of the specimens had good alternative venous drainage. The sylvian fissure corresponded to the superior segment of the squamosal suture in 14 of 16 specimens. The foramen of Monro was 1.9 cm anterior and 4.42 cm superior to the external acoustic meatus. The M2 branch over the central sulcus of the insula became the precentral M4 (rolandic) artery in all specimens.

CONCLUSIONS

Overall, the TC approach to the insula provided better insula exposure and surgical freedom compared with the TS and the TSVC. Cortical and subcortical mapping is critical during the TC approach to the posterior zones (II and III), as the facial motor and somatosensory functions (Zone II) and language areas (Zone III) may be involved. The evidence provided in this study may help the neurosurgeon when approaching insular gliomas to achieve a greater extent of tumor resection via an optimal exposure.

Minimally invasive subfrontal route for the resection of medial temporal region intrinsic tumors

BACKGROUND

The mesial temporal region (MTR) comprises important components of the limbic system, as well as vital neurovascular structures. Because of its important functional role, as much healthy brain tissue as possible must be preserved while targeting resection of MTR lesions.

METHODS

A frontal minicraniotomy is used to access the MTR through a subfrontal approach. By opening the most medial part of the Sylvian fissure, the uncus-amygdala complex is exposed, and through this, the head of the hippocampus can be reached and removed as well.

CONCLUSIONS

This approach is extremely suitable for MTR lesions, as it provides the advantage of sparing the most important functional structures of the temporal lobe, the temporal stem, and the limen insulae, as well as the optic radiations and the fronto-occipital connections.

Resection of cerebral gangliogliomas causing drug-resistant epilepsy: short- and long-term outcomes using intraoperative MRI and neuronavigation

OBJECT Cerebral gangliogliomas (GGs) are highly associated with intractable epilepsy. Incomplete resection due to proximity to eloquent brain regions or misinterpretation of the resection amount is a strong negative predictor for local tumor recurrence and persisting seizures. A potential method for dealing with this obstacle could be the application of intraoperative high-field MRI (iopMRI) combined with neuronavigation. METHODS Sixty-nine patients (31 female, 38 male; median age 28.5 ± 15.4 years) suffering from cerebral GGs were included in this retrospective study. Five patients received surgery twice in the observation period. In 48 of the 69 patients, 1.5-T iopMRI combined with neuronavigational guidance was used. Lesions close to eloquent brain areas were resected with the implementation of preoperative diffusion tensor imaging tractography and blood oxygenation level-dependent functional MRI (15 patients). RESULTS Overall, complete resection was accomplished in 60 of 69 surgical procedures (87%). Two patients underwent biopsy only, and in 7 patients, subtotal resection was accomplished because of proximity to critical brain areas. Excluding the 2 biopsies, complete resection using neuronavigation/iopMRI was documented in 33 of 46 cases (72%) by intraoperative imaging. Remnant tumor mass was identified intraoperatively in 13 of 46 patients (28%). After intraoperative second-look surgery, the authors improved the total resection rate by 9 patients (up to 91% [42 of 46]). Of 21 patients undergoing conventional surgery, 14 (67%) had complete resection without the use of iopMRI. Regarding epilepsy outcome, 42 of 60 patients with seizures (70%) became completely seizure free (Engel Class IA) after a median follow-up time of 55.5 ± 36.2 months. Neurological deficits were found temporarily in 1 (1.4%) patient and permanently in 4 (5.8%) patients. CONCLUSIONS Using iopMRI combined with neuronavigation in cerebral GG surgery, the authors raised the rate of complete resection in this series by 19%. Given the fact that total resection is a strong predictor of long-term seizure control, this technique may contribute to improved seizure outcome and reduced neurological morbidity.

A case of secondary somatosensory epilepsy with a left deep parietal opercular lesion: successful tumor resection using a transsubcentral gyral approach during awake surgery

Few studies have examined the clinical characteristics of patients with lesions in the deep parietal operculum facing the sylvian fissure, the region recognized as the secondary somatosensory area (SII). Moreover, surgical approaches in this region are challenging. In this paper the authors report on a patient presenting with SII epilepsy with a tumor in the left deep parietal operculum. The patient was a 24-year-old man who suffered daily partial seizures with extremely uncomfortable dysesthesia and/or occasional pain on his right side. MRI revealed a tumor in the medial aspect of the anterior transverse parietal gyrus, surrounding the posterior insular point. Long-term video electroencephalography monitoring with scalp electrodes failed to show relevant changes to seizures. Resection with cortical and subcortical mapping under awake conditions was performed. A negative response to stimulation was observed at the subcentral gyrus during language and somatosensory tasks; thus, the transcortical approach (specifically, a transsubcentral gyral approach) was used through this region. Subcortical stimulation at the medial aspect of the anterior parietal gyrus and the posterior insula around the posterior insular point elicited strong dysesthesia and pain in his right side, similar to manifestation of his seizure. The tumor was completely removed and pathologically diagnosed as pleomorphic xanthoastrocytoma. His epilepsy disappeared without neurological deterioration postoperatively. In this case study, 3 points are clinically significant. First, the clinical manifestation of this case was quite rare, although still representative of SII epilepsy. Second, the location of the lesion made surgical removal challenging, and the transsubcentral gyral approach was useful when intraoperative mapping was performed during awake surgery. Third, intraoperative mapping demonstrated that the patient experienced pain with electrical stimulation around the posterior insular point. Thus, this report demonstrated the safe and effective use of the transsubcentral gyral approach during awake surgery to resect deep parietal opercular lesions, clarified electrophysiological characteristics in the SII area, and achieved successful tumor resection with good control of epilepsy.

Frameless stereotactic functional neuronavigation combined with intraoperative magnetic resonance imaging as a strategy in highly eloquent located tumors causing epilepsy

BACKGROUND

Intractable epilepsy due to tumors located in highly eloquent brain regions is often considered surgically inaccessible because of a high risk of postoperative neurological deterioration. Intraoperative MRI and functional navigation contribute to overcome this problem.

OBJECTIVES

To retrospectively investigate the long-term results and impact of functional neuronavigation and 1.5-tesla intraoperative MRI on patients who underwent surgery of tumors associated with epilepsy located close to or within eloquent brain areas.

METHODS

Nineteen patients (9 female, 10 male, mean age 41.4 ± 13.4 years, 11 low-grade and 8 high-grade glial tumors) were evaluated preoperatively using BOLD imaging, diffusion-tensor imaging tractography and magnetoencephalography. Functional data were implemented into neuronavigation in this multimodal approach.

RESULTS

In 14 of 19 patients (74%), complete resection was achieved, and in 5 patients significant tumor volume reduction was accomplished. Eight of 14 (57%) complete resections were achieved only by performing an intraoperative image update. Neurological deterioration was found permanently in 2 patients. After a mean follow-up of 43.8 ± 23.8 months, 15 patients (79%) became seizure free (Engel class Ia).

CONCLUSIONS

Despite the highly eloquent location of tumors causing intractable epilepsy, our multimodal approach led to complete resection in more than two-thirds of patients with an acceptable neurological morbidity and excellent long-term seizure control.

Effect of valproic acid on seizure control and on survival in patients with glioblastoma multiforme

BACKGROUND

To examine the efficacy of valproic acid (VPA) given either with or without levetiracetam (LEV) on seizure control and on survival in patients with glioblastoma multiforme (GBM) treated with chemoradiation.

METHODS

A retrospective analysis was performed on 291 patients with GBM. The efficacies of VPA and LEV alone and as polytherapy were analyzed in 181 (62%) patients with seizures with a minimum follow-up of 6 months. Cox-regression survival analysis was performed on 165 patients receiving chemoradiation with temozolomide of whom 108 receiving this in combination with VPA for at least 3 months.

RESULTS

Monotherapy with either VPA or LEV was instituted in 137/143 (95.8%) and in 59/86 (68.6%) on VPA/LEV polytherapy as the next regimen. Initial freedom from seizure was achieved in 41/100 (41%) on VPA, in 16/37 (43.3%) on LEV, and in 89/116 (76.7%) on subsequent VPA/LEV polytherapy. At the end of follow-up, seizure freedom was achieved in 77.8% (28/36) on VPA alone, in 25/36 (69.5%) on LEV alone, and in 38/63 (60.3%) on VPA/LEV polytherapy with ongoing seizures on monotherapy. Patients using VPA in combination with temozolomide showed a longer median survival of 69 weeks (95% confidence interval [CI]: 61.7-67.3) compared with 61 weeks (95% CI: 52.5-69.5) in the group without VPA (hazard ratio, 0.63; 95% CI: 0.43-0.92; P = .016), adjusting for age, extent of resection, and O(6)-DNA methylguanine-methyltransferase promoter methylation status.

CONCLUSIONS

Polytherapy with VPA and LEV more strongly contributes to seizure control than does either as monotherapy. Use of VPA together with chemoradiation with temozolomide results in a 2-months' longer survival of patients with GBM.

Transsylvian-transinsular approaches to the insula and basal ganglia: operative techniques and results with vascular lesions

BACKGROUND

Lesions in the insula and basal ganglia can be risky to resect because of their depth and proximity to critical structures, particularly in the dominant hemisphere. Transsylvian approaches shorten the surgical distance to these lesions, preserve perisylvian temporal and frontal cortex, and minimize brain transgression.

OBJECTIVE

To report our experience with transsylvian-transinsular approaches to vascular lesions.

METHODS

The anterior approach opened the sphenoidal and insular portions of the sylvian fissure and exposed the limen insulae and short gyri, whereas the posterior approach opened the insular and opercular portions of the sylvian fissure and exposed the circular sulcus and long gyri.

RESULTS

Forty-one patients with vascular lesions (24 arteriovenous malformations [AVMs] and 17 cavernous malformations) were treated surgically with a transsylvian-transinsular approach. Complete resection was obtained in 87.5% of AVMs and 95% of cavernous malformations. Permanent neurological morbidity related to surgery was observed in 2 AVM patients (5%), with the remaining 39 patients (95%) improved or unchanged postoperatively (modified Rankin Scale scores 0-2 in 83%). There were no new language deficits in patients with dominant hemisphere lesions.

CONCLUSION

Transsylvian-transinsular approaches safely expose vascular pathology in or deep to the insula while preserving overlying eloquent cortex in the frontal and temporal lobes. The anterior transsylvian-transinsular approach can be differentiated from the posterior approach based on technical differences in splitting the sylvian fissure and anatomic differences in final exposure. Discriminating patient selection and careful microsurgical technique are essential.

Interhemispheric approach to tumors of the posterior gyrus cinguli

OBJECTIVE

Posterior gyrus cinguli tumors are a well-defined group of tumors that pose considerable challenges in creating surgical access and manipulating adjacent eloquent areas (visual and motor). Here we report our 5-year experience in the surgical treatment of these tumors and describe tumor characteristics, surgical steps, critical aspects, and prognostic factors.

METHODS

This series comprises 37 patients operated on for glioma (high-grade in 28, low-grade in 9), often presenting with motor impairment (n=20), intracranial hypertension (n=15), seizures (n=11), and/or hemianopia (n=9). Preoperative assessment was performed with magnetic resonance imaging. Half of the tumors were more than 4 cm in size, and the majority presented secondary extension into the fronto-parieto-occipital area, the temporo-mesial area, and/or the corpus callosum. Positioning and assisted surgery were optimized in each patient based on preoperative planning.

RESULTS

The ipsilateral interhemispheric approach was elected in all cases. Tumor size and extension were significantly associated with the degree of tumor removal. Total removal was achieved in 25 patients (65%); 4 (10%) had persistent morbidity (visual or motor deficits). The occurrence of local and systemic complications was negligible.

CONCLUSIONS

Surgical treatment of posterior gyrus cinguli tumors can be safely approached via the interhemispheric route as it permits several beneficial operative maneuvers in selected cases.

Epilepsy surgery after treatment of pediatric malignant brain tumors

Epilepsy surgery is common in the face of benign brain tumors, but rarely for patients with a history of malignant brain tumors. Seizures are a common sequelae in survivors of malignant pediatric brain tumors. Medical management alone may not adequately treat epilepsy, including in this group. We report four cases of patients who previously underwent gross total resection, radiation therapy, and chemotherapy for successful treatment of malignant brain neoplasia, yet suffered from medically intractable seizures. All underwent surgery for treatment of epilepsy with extension of the original resection. Despite the aggressive primary treatment of the neoplasm, and the potential for diffuse cerebral insults, all benefited from focal surgical resection. Aggressive surgical management of intractable epilepsy can be considered in survivors of malignant brain tumors.

The paramedian supracerebellar-transtentorial approach to the entire length of the mediobasal temporal region: an anatomical and clinical study

Object

The exploration of lesions in the mediobasal temporal region (MTR) has challenged generations of neurosurgeons to achieve an appropriate approach. To address this challenge, the extensive use of the paramedian supracerebellar-transtentorial (PST) approach to expose the entire length of the MTR, as well as the fusiform gyrus, was investigated.

Methods

The authors studied the microsurgical aspects of the PST approach in 20 cadaver brains and 5 cadaver heads under the operating microscope. They evaluated the features, advantages, difficulties, and limitations of the PST approach and refined the surgical technique. They then used the PST approach in 15 patients with large intrinsic MTR tumors (6 patients), tumor in the posterior fusiform gyrus with mediobasal temporal epilepsy (MTE) (1 patient), cavernous malformations in the posterior MTR including the fusiform gyrus (2 patients), or intractable MTE with hippocampal sclerosis (6 patients) from December 2007 to May 2010. Patients ranged in age from 11 to 63 years (mean 35.2 years), and in 9 patients (60%) the lesion was located on the left side.

Results

In all patients with neuroepithelial tumors or cavernous malformations, the lesions were completely and safely resected. In all patients with intractable MTE with hippocampal sclerosis, the anterior two-thirds of the parahippocampal gyrus and hippocampus, as well as the amygdala, were removed selectively through the PST approach. There was no surgical morbidity or mortality in this series. Three patients (20%) with high-grade neuroepithelial tumors underwent postoperative radiotherapy and chemotherapy but needed a second surgery for recurrence during the follow-up period. In all patients with MTE, antiepileptic medication could be decreased to a single drug at lower doses, and no seizure activity has occurred until this point.

Conclusions

The PST approach provides the surgeon precise anatomical orientation when exposing the entire length of the MTR, as well as the fusiform gyrus, for removing any lesion. This is a novel technique especially for removing tumors involving the entire MTR in a single session without damaging neighboring neural or vascular structures. This approach can also be a viable alternative for selective removal of the parahippocampal gyrus, hippocampus, and amygdala in patients with MTE due to hippocampal sclerosis.

Surgical management of glioneuronal tumors with drug-resistant epilepsy

In this review, we discuss the options for the surgical management of glioneuronal tumors (GNTs) associated with drug-resistant epilepsy, with an emphasis on the surgical issues involved in addressing the epileptogenic nature of these lesions. We briefly summarize the pathological hallmarks of these lesions in order to outline how these tumors contribute to seizure activity. Understanding the pathophysiology of these lesions is important in discussing the advantages and disadvantages of different surgical strategies. There have been a number of studies that have investigated the utility of different surgical approaches in improving seizure outcome, and we highlight some of these studies in order to shed light on surgical issues related to these tumors.

Transsylvian-transcisternal selective lesionectomy for pediatric lesional mesial temporal lobe epilepsy

BACKGROUND

The optimal extent of resection for surgical treatment of lesional epilepsy is a controversial issue.

OBJECTIVE

For patients with mesial temporal lobe lesions visible on magnetic resonance imaging, we compared the surgical outcome of selective lesionectomy with that of standard anterior temporal lobectomy (ATL) and amygdalohippocampectomy.

METHODS

We conducted a retrospective analysis of the seizure outcome of 40 patients treated for lesional mesial temporal lobe epilepsy between 1993 and 2008. Before 2006, patients were managed by ATL (n=29) and from 2006 onward, by selective lesionectomy via the transsylvian-transcisternal approach (n=11).

RESULTS

The postoperative seizure-free rates for the 2 groups were comparable: 93% (27/29) for the ATL group and 91% (10/11) for the selective lesionectomy group (P=.814). In both groups, patients with persistent seizures commonly showed incomplete lesion resection, with complete resection often improving seizure outcome. Postoperative visual field defects were more common in the ATL group (21%) than in the selective lesionectomy group (0%) (P=.102).

CONCLUSION

Transsylvian-transcisternal selective lesionectomy is an effective and safe therapeutic modality in children with lesional mesial temporal lobe epilepsy. Completeness of resection is an important variable for seizure control regardless of surgical modality.

The place for surgical treatment for AVM involving the temporal lobe

OBJECTIVE

The objective of this study was to analyze preoperative symptoms and late clinical outcomes in patients who underwent surgical treatment of arterio-venous malformations (AVMs) of the temporal lobe, including those involving the Sylvian fissure (SF) and the lateral wall of the inferior ventricular horns-with special respect to postoperative hemiparesis and visual field defects (VFD).

METHODS

Between 1990 and 2007, 44 patients (n = 22 women, n = 22 men) with a mean age of 41 (12-67) years were operated on an AVM of the temporal lobe. All data had been collected prospectively. Patients' charts, as well as surgical reports and outpatient files, were analyzed. Thirteen patients showed an involvement of the SF, and six were localized partially in the lateral wall of the temporal horn. Eight AVMs were located in the temporo-mesial region. Fourteen patients had an AVM located mainly within the visual pathway. In 24 cases, the AVM was located in the dominant hemisphere. The AVMs were classified by the Spetzler-Martin grading system (SM). Visual fields were assessed in all patients pre- and postoperatively by independent ophthalmological examiners.

RESULTS

The initial symptoms leading to the diagnosis of the AVM were seizures in 20 cases (45%), headache without hemorrhage in six cases (14%), incidental finding in five cases (11%), and tinnitus in two cases (5%). Hemorrhage had occurred in 15 cases (34%). Based on SM, 7 AVMs were grade I, 17 grade II, 17 grade III, and 3 grade IV. Preoperatively, seven patients presented with a VFD and two with a hemiparesis. Postoperatively, 8 of 44 (18%) patients presented with a new hemiparesis, remaining permanent in 3 of 44 (7%). In two of these patients, the AVMs were localized temporo-mesially (n = 2/8, 25%). Seven patients (19%) showed a new significant postoperative VFD, and in addition, three patients had worsening of their preexisting VFD (3/7, 43%). Postoperative angiography verified complete AVM occlusion in 43 of 44 (98%) cases. One patient needed reoperation for residual AVM; hence, in all patients, complete occlusion before discharge was achieved.

CONCLUSION

Treatment of temporal lobe AVMs is demanding due to their close spatio-anatomical relationship with important neurovascular structures and the optic radiation. In this surgically treated series, morbidity for a new permanent hemiparesis was 7% and preservation of the visual field could be achieved in almost 90% of all cases. This is a calculable risk for most patients that renders microsurgical resection a justifiable option, even in light of other treatment modalities. The risk for new permanent motor deficits is elevated in temporo-mesial AVMs, and these patients have to be advised accordingly for surgical treatment.

Through the choroidal fissure: a quantitative anatomic comparison of 2 incisions and trajectories (transsylvian transchoroidal and lateral transtemporal)

BACKGROUND

We compared the transsylvian transchoroidal (TSTC) approach with the lateral transtemporal (LTT) approach. Both approaches proceed through the choroidal fissure but through different incisions and along different trajectories.

METHODS

Four fixed, silicon-injected heads (8 sides) were used. Nine strategic anatomic points within the dissections were compared between the TSTC and LTT approaches in 7 other silicon-injected heads (14 sides). Neuronavigation was used to gather coordinates from selected points of both approaches to calculate surgical angles and distances to common targets.

RESULTS

The surgical angle of the TSTC approach for the inferior choroidal point was wider compared with the LTT approach (P < .05). The surgical angles for the P2a-P2p point were similar for both approaches. In the TSTC approach, the P2-P3 point angle was smaller than in the LTT approach (P < .05). The TSTC approach provided (except for the P2-P3 point) significantly shorter distances to all defined anatomic targets compared with the LTT approach. When the posterior cerebral artery was the target in the TSTC approach, the hippocampus was retracted 3 to 8 mm compared with 8 to 13 mm in the LTT approach.

CONCLUSION

We quantitatively described anatomic features of the TSTC approach and compared them with the LTT approach. For approaching the mesial temporal region, the TSTC approach offers an adequate surgical angle and shorter or similar distances proximal to P2-P3 and requires less temporal lobe and hippocampal retraction than the LTT approach. Such information can help surgeons select the optimal approach to the mesial temporal lobe and its surrounding structures. The TSTC approach should be considered for lesions located in the medial temporal region.

18Fluoroethyl-L-tyrosine-PET in long-term epilepsy associated glioneuronal tumors

PURPOSE

Long-term epilepsy associated tumors (LEATs) are a frequent cause of drug-resistant partial epilepsy. A reliable tumor diagnosis has an important impact on therapeutic strategies and prognosis in patients with epilepsy, but often is difficult by magnetic resonance imaging (MRI) only. Herein we analyzed a large LEAT cohort investigated by 18fluoroethyl-L-tyrosine-positron emission tomography (FET-PET).

METHODS

Thirty-six patients with chronic partial epilepsy and a LEAT-suspect MRI lesion were analyzed by FET-PET using visual inspection and quantitative analysis of standard uptake values (SUV). PET results were correlated with clinical and histopathologic data.

RESULTS

FET-PET study was positive in 22 of 36 analyzed lesions and in 14 of 22 histologically verified LEAT lesions. The precise World Health Organization (WHO) tumoral entity was not predicted by FET-PET. Notably, FET uptake correlated strikingly with age at epilepsy onset (p = 0.001). Further correlations were seen for age at surgery (p = 0.007) and gadolinium-contrast enhancement on MRI (p < 0.05).

DISCUSSION

FET-PET is a helpful tool for LEAT diagnosis, particularly when MRI readings are ambiguous. FET uptake, which is likely mediated by the l-amino acid transporter (LAT) family, might indicate a principally important biologic property of certain LEATs, since LAT molecules also are involved in cell growth regulation.

Seizures in patients with low-grade gliomas--incidence, pathogenesis, surgical management, and pharmacotherapy

Seizures complicate the clinical course of > 80% of patients with low-grade gliomas. Patients with some tumor variants almost always have epilepsy. Diffuse low-grade gliomas (LGG) are believed to cause epilepsy through partial deafferentiation of nearby brain cortex (denervation hypersensitivity). Glioneural tumors may interfere with local neurotransmitter levels and are sometimes associated with structural abnormalities of the brain which may produce seizures. The severity of tumor associated epilepsy varies considerably between patients. Some cases may present with a first seizure. Others suffer from long-standing pharmacoresistant epilepsy. Seizure control rates of > 70-80% can be expected after complete tumor resections. Patients with drug-resistant epilepsy require a comprehensive preoperative epileptological work-up which may include the placement of subdural (and intraparenchymal) electrodes or intraoperative electrocorticography (ECoG) for the delineation of extratumoral seizure foci. Partial and subtotal tumor resections are helpful in selected cases, i.e. for gliomas involving the insula. In one series, 40% of patients presented for surgery with uncontrolled seizures, i.e. medical therapy alone often fails to control tumor-related epilepsy. Use of the newer (second generation) non-enzyme inducing antiepileptic drugs (non-EIAED) is encouraged since they seem to have lesser interactions with other medications (e.g. chemotherapy). Chemotherapy and irradiation may have some minor beneficial effects on the patients' seizure disorder. Overall 60-70% of patients may experience recurrent epilepsy during long-term follow-up. Recurrent seizures (not infrequently heralding tumor recurrence) after surgery continue to pose significant clinical problems.

Insular glioma resection: assessment of patient morbidity, survival, and tumor progression

Object

Insular gliomas remain surgically challenging cases due to complex anatomy, including surrounding vasculature and the relationship to functional structures. To define the morbidity profile associated with aggressive insular glioma removal as well as its impact on long-term outcome, the authors retrospectively evaluated the extent of resection (EOR) in the context of this complex anatomy and function and assessed its role in determining disease progression, malignant transformation, and, ultimately, patient survival.

Methods

The study population included adults who had undergone initial or repeat resection of insular gliomas of all grades. Tumor location was identified according to a proposed quadrant-style classification (Zones I–IV) of the insula. Low- and high-grade gliomas were volumetrically analyzed using FLAIR and contrast-enhanced T1-weighted MR imaging, respectively.

Results

One hundred fifteen procedures involving 104 patients with insular gliomas were identified. Patients presented with low-grade gliomas (LGGs) in 70 cases (60%) and high-grade gliomas (HGGs) in 45 (40%). Zone I (anterior-superior) was the most common site within the insula (40 patients [39%]), followed by Zone I+IV (anteriorsuperior + anterior-inferior; 26 patients [25%]). The median EOR was 82% (range 31–100%) for low-grade lesions and 81% (range 47–100%) for high-grade lesions. Zone I was associated with the highest median EOR (86%), and among all lesion grades, the insular quadrant anatomy was predictive of the EOR (p = 0.0313). Overall, there were 16 deaths (15%) during a median follow-up of 4.2 years. There were no surgery-related deaths, and new, permanent postoperative deficits were noted in 6 patients (6%). Among LGGs, tumor progression and malignant transformation were identified in 20 (29%) and 14 cases (20%), respectively. Among HGGs, progression was identified in 16 cases (36%). Patients with LGGs resected ≥ 90% had a 5-year overall survival (OS) rate of 100%, whereas those with lesions resected < 90% had a 5-year OS rate of 84%. Patients with HGGs resected ≥ 90% had a 2-year OS rate of 91%; when the EOR was < 90%, the 2-year OS rate was 75%. The EOR was predictive of OS both in cases of LGGs (hazard ratio [HR] 0.955, 95% CI 0.921–0.992, p = 0.017) and HGGs (HR 0.955, 95% CI 0.918–0.994, p = 0.024). Progression-free survival (PFS) was also predicted by the EOR in both LGGs (HR 0.973, 95% CI 0.948–0.998, p = 0.0414) and HGGs (HR 0.958, 95% CI 0.919–0.999, p = 0.0475). Interestingly, among patients with LGGs, malignant progression was also significantly associated with a lower EOR (HR 0.968, 95% CI 0.393–0.998, p = 0.0369).

Conclusions

Aggressive resection of insular gliomas of all grades can be accomplished with an acceptable morbidity profile and is predictive of improved OS and PFS. Among insular LGGs, a greater EOR is also associated with longer malignant PFS. Data in this study also suggest that insular gliomas generally follow a more indolent course than similar lesions in other brain regions.

Outcome of fully awake craniotomy for lesions near the eloquent cortex: analysis of a prospective surgical series of 79 supratentorial primary brain tumors with long follow-up

BACKGROUND

Despite possible advantages, few surgical series report specifically on awake craniotomy for intrinsic brain tumors in eloquent brain areas.

OBJECTIVES

Primary: To evaluate the safety and efficacy of fully awake craniotomy (FAC) for the resection of primary supratentorial brain tumors (PSBT) near or in eloquent brain areas (EBA) in a developing country. Secondary: To evaluate the impact of previous surgical history and different treatment modalities on outcome.

PATIENTS AND METHODS

From 1998 to 2007, 79 consecutive FACs for resection PSBT near or in EBA, performed by a single surgeon, were prospectively followed. Two groups were defined based on time period and surgical team: group A operated on from March 1998 to July 2004 without a multidisciplinary team and group B operated on from August 2004 to October 2007 in a multidisciplinary setting. For both time periods, two groups were defined: group I had no previous history of craniotomy, while group II had undergone a previous craniotomy for a PSBT. Forty-six patients were operated on in group A, 46 in group B, 49 in group I and 30 in group II. Psychological assessment and selection were obligatory. The preferred anesthetic procedure was an intravenous high-dose opioid infusion (Fentanil 50 microg, bolus infusion until a minimum dose of 10 microg/kg). Generous scalp and periosteous infiltrations were performed. Functional cortical mapping was performed in every case. Continuous somato-sensory evoked potentials (SSEPs) and phase reversal localization were available in 48 cases. Standard microsurgical techniques were performed and monitored by continuous clinical evaluation.

RESULTS

Clinical data showed differences in time since clinical onset (p < 0.001), slowness of thought (p = 0.02) and memory deficits (p < 0.001) between study periods and also time since recent seizure onset for groups I and II (p = 0.001). Mean tumor volume was 51.2 +/- 48.7 cm3 and was not different among the four groups. The mean extent of tumor reduction was 90.0 +/- 12.7% and was similar for the whole series. A trend toward a larger incidence of glioblastoma multiforme occurred in group B (p = 0.05) and I (p = 0.04). Recovery of previous motor deficits was observed in 75.0% of patients, while motor worsening in 8.9% of cases. Recovery of semantic language deficits, control of refractory seizures and motor worsening were statistically more frequent in group B (p = 0.01). Satisfaction with the procedure was reported by 89.9% of patients, which was similar for all groups. Clinical complications were minimal, and surgical mortality was 1.3%.

CONCLUSIONS

These data suggest that FAC is safe and effective for the resection of PSBT in EBA as the main technique, and in a multidisciplinary context is associated with greater clinical and physiological monitoring. The previous history of craniotomy for PSBT did not seem to influence the outcome.

Brain tumors in the mesial temporal lobe: long-term oncological outcome

OBJECT

Surgical treatment of brain tumors in the mesial temporal lobe (MTL) is a highly demanding procedure. Only a few studies describing the surgery of MTL tumors have been reported, and they have been focused on the operative techniques and immediate results of the surgery. The authors have analyzed the long-term oncological outcome in patients with MTL tumors.

METHODS

Thirty-six patients with an MTL tumor were studied. The mean patient age at surgery was 32 years (range 13-62 years). The tumors were confined to the MTL (Schramm Type A) in 25 patients (69%). Extension of the tumor into the fusiform gyrus (Schramm Type C) and temporal stem (Schramm Type D) was observed in 4 and 7 patients (11 and 19%), respectively. There was a significant difference in the tumor size according to Schramm types (p = 0.001). Complete tumor resection was achieved in 26 patients (72%). All tumors were low-grade lesions except for 1 anaplastic astrocytoma.

RESULTS

After a median follow-up period of 50.5 months, 7 patients showed progression of the disease. The actuarial progression-free survival rates were 97% in the 1st year, 84% in the 2nd year, and 80% in the 5th year. The degree of tumor resection was significantly related to the tumor control failure (p < 0.001) and malignant transformation of a low-grade tumor (p < 0.001). Univariate analyses using a Cox proportional hazards model showed that the following factors were significantly associated with a failure to control the tumor: 1) extent of the tumor (Schramm Type D; p = 0.003, relative risk [RR] 12.04); 2) size of the tumor (p = 0.033, RR 1.052/mm); 3) patient age at surgery >or= 50 years (p = 0.007, RR 8.312); and 4) short duration of epilepsy (< 6 months; p = 0.001, RR 21.54).

CONCLUSIONS

Surgery is the principal treatment for MTL tumors, despite its technical difficulty. Complete tumor resection is strongly recommended for long-term tumor control. The MTL tumors are heterogeneous in their prognosis. Older age, short duration of epilepsy, and tumor size are all associated with poor outcome. Patients with these characteristics may have a more aggressive form of the disease than those with MTL tumors associated with chronic epilepsy.

Gliomas of the cingulate gyrus: surgical management and functional outcome

Object

In this paper, the authors' goal was to summarize their experience with the surgical treatment of gliomas arising from the cingulate gyrus.

Methods

The authors analyzed preoperative data, surgical strategies, complications, and functional outcome in a series of 34 patients (mean age 42 years, range 12–69 years; 14 females) who underwent 38 operations between May 2001 and November 2008.

Results

In 7 cases (18%) the tumor was located in the posterior (parietal) part of the cingulate gyrus, and in 31 (82%) the tumor was in the anterior (frontal) part. In 10 cases (26%) the glioma was solely located in the cingulate gyrus, and in 28 cases (74%) the tumor extended to the supracingular frontal/parietal cortex. Most cases (23 [61%]) had seizures as the presenting symptom, 8 patients (24%) suffered from a hemiparesis/hemihypesthesia, and 4 patients (12%) had aphasic symptoms.

The authors chose an interhemispheric approach for tumor resection in 11 (29%) and a transcortical approach in 27 (71%) cases; intraoperative electrophysiological monitoring was applied in 23 (61%) and neuronavigation in 15 (39%) cases. A > 90% resection was achieved in 32 (84%) and > 70% in another 5 (13%) cases. Tumors were classified as low-grade gliomas in 11 cases (29%). A glioblastoma multiforme (WHO Grade IV, 10 cases [26%]) and oligoastrocytoma (WHO Grade III, 9 cases [24%]) were the most frequent histopathological results.

Postoperatively, patients in 13 cases suffered from a transient supplementary motor area syndrome (34%), all of whom had tumors in the anterior cingulate gyrus. In the early postoperative period (30 days) a new deficit occurred in 5 cases (13%, mild motor deficits or aphasic symptoms). One patient had a major bleeding episode 2 days after surgery and was in a persistent vegetative state.

Conclusions

Gliomas arising from the cingulate gyrus are rare. A gross-total resection is often possible and acceptably safe; intraoperative monitoring and neuronavigation are helpful adjuncts. In case of resection of gliomas arising from the anterior cingulate gyrus a supplementary motor area syndrome has to be considered, particularly when the tumor extends to the supracingular cortex

Limited access inferior temporal gyrus approach to mesial basal temporal lobe tumors

Object

In this retrospective review, the authors examine the clinical characteristics, diagnosis, and outcome of surgery in 25 consecutive patients with mesial basal temporal lobe (MBTL) tumors. A limited access approach to the inferior temporal gyrus (ITG) was used.

Methods

Patients with MBTL tumors were identified from the epilepsy and tumor surgery database at the authors' institution. Intraaxial tumors localized to the mesial basal structures, and without involvement of the cortical surface of the temporal lobe, temporal stem, and basal ganglia were included. Preoperative and postoperative MR images were obtained in all patients. The mean follow-up period was 24 months (range 9–36 months). Preoperative symptoms, neurological deficits, outcomes, surgical complications, and a technical description of the approach are discussed.

Results

Intraaxial MBTL tumors in 25 patients (mean age 44 years, range 8–76 years) were resected using a limited access approach via the ITG. The largest groups of tumors were high-grade gliomas and dysembryoblastic neuroepithelial tumors (8 in each group), followed by oligodendrogliomas, cerebral metastases, and gangliogliomas. Seizures, headaches, and disorientation were the most common preoperative symptoms. Postoperative MR images demonstrated gross-total resection in all cases. There were 2 surgical complications (a superficial wound infection and a transient frontalis branch palsy). There were no permanent neurological complications or significant new hemianoptic defects.

Conclusions

A limited access ITG approach performed with intraoperative image guidance offers an alternative corridor for resection of MBTL tumors (Schramm Type A). This approach may be technically less demanding than the transsylvian or subtemporal approach. Gross-total resection is feasible utilizing this approach and compares favorably with other, more classical approaches.

Surgical management of intracranial gliomas

Surgery is indicated in almost all glioma patients at some point during the course of their disease. The surgical intervention aims at obtaining a tissue diagnosis, providing symptom relief, improving patient survival by reducing the tumor burden, and in rare cases even effecting a cure.A resection will reduce symptoms related to the mass effect of the tumor, and offers a good chance for seizure control. An increasing body of data suggests that glioma patients will benefit from a maximal safe surgical cytoreduction. However, the size of the effect may vary for the different glioma entities. Modern adjuvant neuro-oncological treatment strategies rely heavily on the histological diagnosis. A (stereotactic) biopsy should therefore be offered to patients with nonresectable gliomas to allow for histology-guided adjuvant therapy. Some gliomas can be managed successfully with stereotactic interstitial radiosurgery (brachytherapy). Intra- and extraoperative electrophysiological mapping and/or monitoring, functional MRI, intraoperative imaging, and neuronavigation are increasingly used in many neurosurgical centers in order to reduce surgical morbidity. A definite effect on long-term outcome needs yet to be proven.Advances in computers, imaging, and other technologies will continue to play a large role in the evolution of neurosurgical treatment for gliomas. This may well lead to further centralization of care. There will be an increasing pressure on neurosurgeons to justify the costs involved by showing that patients will actually benefit from complex treatments in highly specialized centers.

Temporal mediobasal tumors: a proposal for classification according to surgical anatomy

OBJECTIVE

Development of a classification for temporal mediobasal tumors based on anatomical and neuroradiological aspects to help evaluate surgical accessibility and risk.

METHODS

Preoperative magnetic resonance imaging, surgical approaches and outcomes of 235 patients with a temporal mediobasal tumor were analyzed retrospectively. Surgical landmarks were defined in accordance with operative anatomy. Previous classifications of these tumors were reviewed and a new classification system was developed.

RESULTS

The new classification system recognises four types of temporal mediobasal tumor based on anatomical landmarks, location, and size. Type A comprises lesions confined to the uncus, hippocampus, parahippocampus, and/or amygdala. Type B comprises lesions in the area immediately lateral to the structures where type A tumors are located but sparing lateral gyri. Type C tumors are larger lesions, which occupy the area of type A and type B simultaneously. Type D tumors originate from the temporal mediobasal region and invade into the adjacent structures of the temporal stem, insular cortex, claustrum, putamen, or pallidum. The area occupied by a tumor in the axial plane was divided into anterior (a) and posterior (p) subregions. Progressive grading from A to D and from "a" to "p" was based on the view that larger and more posteriorly growing tumors were more difficult to remove. Lesions located in the anterior subregion (n = 173) were easier to remove by the transsylvian route (39%) or after partial anterior lobectomy (32%). For the posterior lesions (n = 62), a subtemporal approach was more appropriate (75%).

CONCLUSIONS

Based on a series of 235 temporal mediobasal tumors, a classification system was designed to aid in decision making about operability, surgical risk, and approach.

Trephine Epilepsy Surgery: The Inferior Temporal Gyrus Approach

Objective:

To describe our technique for temporal lobe epilepsy surgery using a minimal-access approach.

Methods:

Our epilepsy surgery registry was reviewed, and all patients with at least 2 years follow-up were queried. Clinical data included age, sex, side of lesion, presence of mesial temporal sclerosis, surgical complications, and Engel class outcome. Our operation was performed through a 6- to 8-cm linear vertical incision extending upward from just anterior to the tragus. An oval trephine (2×3 cm) craniotomy was performed flush with the middle fossa floor. Resection of part of the inferior temporal gyrus provided a corridor to the mesial temporal lobe. Identification of the temporal horn of the lateral ventricle was followed by resection of the parahippocampal gyrus, the amygdala, and the uncus. Segregation of the hippocampus and its subsequent resection in subpial fashion preserved perimesencephalic vasculature. Use of a fine suture for skin closure produced a cosmetic result.

Results:

In our 8-year series of 201 patients with a minimum follow-up duration of 2 years, we have observed a low number (1.5%) of complications and a 78% rate of Engel Class I seizure-free outcome. Surgery times were short (average, 2–5 h; range, 2 h 20 min-4 h 10 min) and hospital stays brief (&lt;3 d; range, 1–4 d).

Conclusion:

Our results suggest that the trephine craniotomy with the inferior temporal gyrus approach has the advantage of minimal invasiveness, including brief operative times and postoperative stays, and also effectively reduces or eradicates medically intractable seizures.

Epilepsy surgery in children: outcomes and complications

OBJECT

Ideal epilepsy surgery would eliminate seizures without causing any functional deficits. The aim of the present study was to assess seizure outcomes and complications after epilepsy surgery in children with intractable epilepsy.

METHODS

Data obtained in 134 children (75 boys and 59 girls) age 17 years or younger who underwent epilepsy surgery at Seoul National University Children's Hospital between 1993 and 2005 were retrospectively reviewed. Epilepsy surgery included temporal resection (59 cases), extratemporal resection (56 cases), functional hemispherectomy (7 cases), callosotomy (9 cases), multiple subpial transection (1 case), and disconnection of a hamartoma (2 cases). The mean follow-up duration was 62.3 months (range 12-168 months).

RESULTS

The overall seizure-free rate was 69% (93 of 134 cases). The seizure-free rate was significantly higher in children who underwent temporal resection than in those in whom extratemporal resection was performed (88 vs 55%, p < 0.05). The most frequent causes of treatment failure were related to the absence of structural abnormality demonstrated on magnetic resonance imaging, development-associated disease, widespread disease documented by postoperative electroencephalography, and limited resection due to the presence of functional cortex. There were no postoperative deaths. Visual field defects were the most common complication after temporal resection (22% [13 of 59 cases]), whereas hemiparesis (mostly transient) was the most common morbidity after extratemporal resection (18% [10 of 56 cases]).

CONCLUSIONS

Epilepsy surgery is an effective and safe therapeutic modality in childhood. In children with extratemporal epilepsy, more careful interpretation of clinical and investigative data is needed to achieve favorable seizure outcome.

Magnetic resonance imaging of implanted deep brain stimulators: experience in a large series

Magnetic resonance imaging (MRI) is a commonly used and important imaging modality to evaluate lead location and rule out complications after deep brain stimulation (DBS) surgery. Recent safety concerns have prompted new safety recommendations for the use of MRI in these patients, including a new recommendation to limit the specific absorption rate (SAR) of the MRI sequences used to less than 0.1 W/kg. Following SAR recommendations in real-world situations is problematic for a variety of reasons. We review our experience scanning patients with implanted DBS systems over a 7-year period using a variety of scanning techniques and four scanning platforms. 405 patients with 746 implanted DBS systems were imaged using 1.5-tesla MRI with an SAR of up to 3 W/kg. Many of the DBS systems were imaged multiple times, for a total of 1,071 MRI events in this group of patients with no adverse events. This series strongly suggests that the 0.1 W/kg recommendation for SAR may be unnecessarily low for the prevention of MRI-related adverse events.