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

Combined External Ventricular Drainage and Endoscope-Assisted Microsurgery Using the Middle Frontal Gyrus Approach in Severe Ventricular Hemorrhage with Casting of the Fourth Ventricle

OBJECTIVE

To investigate combined external ventricular drainage and endoscope-assisted microsurgery using the middle frontal gyrus approach in patients with severe ventricular hemorrhage with casting of the fourth ventricle and patients' recovery after this treatment.

METHODS

Patients with severe ventricular hemorrhage with casting of the fourth ventricle (n = 41) were randomly assigned to intervention and control groups. Modified Graeb score was used to assess 3-day hematoma clearance rate before and after surgery, drainage tube extubation time for the 2 groups was compared, and time when blood clot in the fourth ventricle was not blocked with cerebrospinal fluid was compared. Glasgow Coma Scale was used to assess consciousness after surgery; Glasgow Coma Scale scores recorded 1 and 7 days after surgery were also compared. Modified Rankin Scale was used to evaluate patients' recovery 1 and 6 months after surgery. Hydrocephalus and intracranial infections in patients after surgery were recorded for 90 days.

RESULTS

The 3-day hematoma clearance rate was dramatically higher in the intervention group. Modified Graeb score showed that more hemorrhage was delimited in 3 days in the intervention group. The intervention group exhibited significantly reduced length of block of the fourth ventricle and drainage tube extubation time. High Glasgow Coma Scale and modified Rankin Scale scores and significantly low incidence of complications (e.g., hydrocephalus and intracranial infection) were observed in patients in the intervention group.

CONCLUSIONS

Combined external ventricular drainage and endoscope-assisted microsurgery using the middle frontal gyrus approach can effectively improve severe ventricular hemorrhage with casting of the fourth ventricle and enhance patients' neurological function and recovery.

Role of the parietooccipital fissure and its implications in the pathophysiology of posterior medial temporal gliomas

OBJECTIVE

The parietooccipital fissure is an anatomical landmark that divides the temporal, occipital, and parietal lobes. More than 40% of gliomas are located in these three lobes, and the temporal lobe is the most common location. The parietooccipital fissure is located just posterior to the medial temporal lobe, but little is known about the clinical significance of this fissure in gliomas. The authors investigated the anatomical correlations between the parietooccipital fissure and posterior medial temporal gliomas to reveal the radiological features and unique invasion patterns of these gliomas.

METHODS

The authors retrospectively reviewed records of all posterior medial temporal glioma patients treated at their institutions and examined the parietooccipital fissure. To clarify how the surrounding structures were invaded in each case, the authors categorized tumor invasion as being toward the parietal lobe, occipital lobe, isthmus of the cingulate gyrus, insula/basal ganglia, or splenium of the corpus callosum. DSI Studio was used to visualize the fiber tractography running through the posterior medial temporal lobe.

RESULTS

Twenty-four patients with posterior medial temporal gliomas were identified. All patients presented with a parietooccipital fissure as an uninterrupted straight sulcus and as the posterior border of the tumor. Invasion direction was toward the parietal lobe in 13 patients, the occipital lobe in 4 patients, the isthmus of the cingulate gyrus in 19 patients, the insula/basal ganglia in 3 patients, and the splenium of the corpus callosum in 8 patients. Although the isthmus of the cingulate gyrus and the occipital lobe are located just posterior to the posterior medial temporal lobe, there was a significantly greater preponderance of invasion toward the isthmus of the cingulate gyrus than toward the occipital lobe (p = 0.00030, McNemar test). Based on Schramm's classification for the medial temporal tumors, 4 patients had type A and 20 patients had type D tumors. The parietooccipital fissure determined the posterior border of the tumors, resulting in a unique and identical radiological feature. Diffusion spectrum imaging (DSI) tractography indicated that the fibers running through the posterior medial temporal lobe toward the occipital lobe had to detour laterally around the bottom of the parietooccipital fissure.

CONCLUSIONS

Posterior medial temporal gliomas present identical invasion patterns, resulting in unique radiological features that are strongly affected by the parietooccipital fissure. The parietooccipital fissure is a key anatomical landmark for understanding the complex infiltrating architecture of posterior medial temporal gliomas.

Microsurgical and Tractographic Anatomical Study of Transtemporal-Transchoroidal Fissure Approaches to the Ambient Cistern

BACKGROUND

Approaching ambient cistern lesions is still a challenge because of deep location and related white matter tracts (WMTs) and neural structures.

OBJECTIVE

To investigate the white matter anatomy in the course of 3 types of transtemporal-transchoroidal fissure approaches (TTcFA) to ambient cistern by using fiber dissection technique with translumination and magnetic resonance imaging fiber tractography.

METHODS

Eight formalin-fixed cerebral hemispheres were dissected on surgical corridor from the temporal cortex to the ambient cistern by using Klingler's method. The trans-middle temporal gyrus, trans-inferior temporal sulcus (TITS), and trans-inferior temporal gyrus (TITG) approaches were evaluated. WMTs that were identified during dissection were then reconstructed on the Human Connectome Project 1021 individual template for validation.

RESULTS

The trans-middle gyrus approach interrupted the U fibers, arcuate fasciculus (AF), the ventral segment of inferior frontoocipital fasciculus (IFOF), the temporal extensions of the anterior commissure (AC) posterior crura, the tapetum (Tp) fibers, and the anterior loop of the optic radiation (OR). The TITS approach interrupted U fibers, inferior longitudinal fasciculus (ILF), IFOF, and OR. The TITG approach interrupted the U fibers, ILF, and OR. The middle longitudinal fasciculus, ILF, and uncinate fasciculus (UF) were not interrupted in the trans-middle gyrus approach and the AF, UF, AC, and Tp fibers were not interrupted in the TITS/gyrus approaches.

CONCLUSION

Surgical planning of the ambient cistern lesions requires detailed knowledge about WMTs. Fiber dissection and tractography techniques improve the orientation during surgery and may help decrease surgical complications.

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.

Minimally invasive trans-sulcal parafascicular surgical resection of cerebral tumors: translating anatomy to early clinical experience

The minimally invasive port-based trans-sulcal parafascicular surgical corridor (TPSC) has incrementally evolved to provide a safe, feasible, and effective alternative to access subcortical and intraventricular pathologies. A detailed anatomical foundation is important in mitigating cortical and white matter tract injury with this corridor. Thus, the aims of this study are (1) to provide a detailed anatomical construct and overview of TPSCs and (2) to translate an anatomical framework to early clinical experience. Based on regional anatomical constraints, suitable parafascicular entry points were identified and described. Fiber tracts at both minimal and increased risks for each corridor were analyzed. TPSC-managed cases for metastatic or primary brain tumors were retrospectively reviewed. Adult patients 18 years or older with Karnofsky Performance Status (KPS) ≥ 70 were included. Subcortical brain metastases between 2 and 6 cm or primary brain tumors between 2 and 5 cm were included. Patient-specific corridors and trajectories were determined using MRI-tractography. Anatomy: The following TPSCs were described and translated to clinical practice: superior frontal, inferior frontal, inferior temporal, intraparietal, and postcentral sulci. Clinical: Eleven patients (5 males, 6 females) were included (mean age = 52 years). Seven tumors were metastatic, and 4 were primary. Gross total, near total, and subtotal resection was achieved in 7, 3, and 1 patient(s), respectively. Three patients developed intraoperative complications; all recovered from their intraoperative deficits and returned to baseline in 30 days. A detailed TPSC anatomical framework is critical in conducting safe and effective port-based surgical access. This review may represent one of the few early translational TPSC studies bridging anatomical data to clinical subcortical and intraventricular surgical practice.

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.

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.

Postoperative Seizure Rate After Transcortical Resection of Subcortical Brain Tumors and Colloid Cysts: A Single Surgeon's Experience

When deciding on a surgical route to reach subcortical brain tumors and colloid cysts, many surgeons advocate the use of transcallosal, transsulcal, or skull base approaches over transcortical approaches due to a high reported incidence of postoperative seizures. We have retrospectively analyzed all patients operated upon by a senior neurosurgeon (Ricardo J. Komotar) who undertook transcortical approaches for the resection of subcortical brain tumors and colloid cysts. We have also performed a comprehensive review of the literature to estimate postoperative seizure risk after transcortical approaches for the resection of deep tumors and colloid cysts. Of 27 patients who underwent transcortical approaches for the resection of subcortical brain tumors and colloid cysts, zero had postoperative seizures. A comprehensive review of the literature shows an 8.3% postoperative risk of seizures after the transcortical approach. Our institution has never experienced a postoperative seizure following the transcortical approach for the resection of deep tumors and colloid cysts. For this reason, we advocate selecting a surgical approach that obtains adequate lesion exposure and minimizes the violation and retraction of eloquent cortex, venous structures, and white matter tracts, rather than on presumed postoperative seizure risk.