Joshua D. Burks

A method for safely resecting anterior butterfly gliomas: the surgical anatomy of the default mode network and the relevance of its preservation

OBJECTIVE Gliomas invading the anterior corpus callosum are commonly deemed unresectable due to an unacceptable risk/benefit ratio, including the risk of abulia. In this study, the authors investigated the anatomy of the cingulum and its connectivity within the default mode network (DMN). A technique is described involving awake subcortical mapping with higher attention tasks to preserve the cingulum and reduce the incidence of postoperative abulia for patients with so-called butterfly gliomas. METHODS The authors reviewed clinical data on all patients undergoing glioma surgery performed by the senior author during a 4-year period at the University of Oklahoma Health Sciences Center. Forty patients were identified who underwent surgery for butterfly gliomas. Each patient was designated as having undergone surgery either with or without the use of awake subcortical mapping and preservation of the cingulum. Data recorded on these patients included the incidence of abulia/akinetic mutism. In the context of the study findings, the authors conducted a detailed anatomical study of the cingulum and its role within the DMN using postmortem fiber tract dissections of 10 cerebral hemispheres and in vivo diffusion tractography of 10 healthy subjects. RESULTS Forty patients with butterfly gliomas were treated, 25 (62%) with standard surgical methods and 15 (38%) with awake subcortical mapping and preservation of the cingulum. One patient (1/15, 7%) experienced postoperative abulia following surgery with the cingulum-sparing technique. Greater than 90% resection was achieved in 13/15 (87%) of these patients. CONCLUSIONS This study presents evidence that anterior butterfly gliomas can be safely removed using a novel, attention-task based, awake brain surgery technique that focuses on preserving the anatomical connectivity of the cingulum and relevant aspects of the cingulate gyrus.

Results with Expanded Endonasal Resection of Skull Base Meningiomas Technical Nuances and Approach Selection Based on an Early Experience.

AIM Reconstruction technique advances have created renewed enthusiasm for the expanded endonasal approach (EEA). However, as with any new technique, early experiences inevitably lead to more selective use of these techniques. We reviewed our experience of the expanded endonasal endoscopic approach for skull base meningiomas and place it in context of the literature. MATERIAL AND METHODS We performed retrospective review of all endonasal cases performed at our center for histologically proven meningioma. Tumor locations in 26 patients included the olfactory groove (n=9), tuberculum sellae (n=7), optic nerve sheath (n=1), planum sphenoidale (n=2), clival (n=1) petroclival (n=3), cavernous sinus (n=2) and extensive pan-basal meningioma (n=1). RESULTS The median follow-up was 38.6 months. Excluding 3 patients with tumors found incidentally, pre-operative symptoms improved in 14 of 23 (61%), were the same in 8 of 23 (35%) and worsened in one of 23 patients (4%) at time of last follow-up. Of all 26 patients, 16 (62%) had complete macroscopic resection of their tumor, 5 (19%) underwent at least 90% resection, and 5 (19%) underwent subtotal resection. There were two neurological complications and one cerebrospinal fluid leak. CONCLUSION This study presents outcomes of patients treated with endonasal endoscopic meningioma surgery. We believe that very low rates of morbidity can be achieved in carefully selected patients, thus avoiding brain manipulation.

The Use of the Target Cancellation Task to Identify Eloquent Visuospatial Regions in Awake Craniotomies: Technical Note.

The success of awake craniotomies relies on the patient’s performance of function-specific tasks that are simple, quick, and reproducible. Intraoperative identification of visuospatial function through cortical and subcortical mapping has utilized a variety of intraoperative tests, each with its own benefits and drawbacks. In light of this, we developed a simple software program that aids in preventing neglect by simulating a target-cancellation task on a portable electronic device. In this report, we describe the interactive target cancellation task and have reviewed seven consecutive patients who underwent awake craniotomy for parietal and/or posterior temporal infiltrating brain tumors of the non-dominant hemisphere. Each of these patients performed target cancellation and line bisection tasks intraoperatively. The outcomes of each patient and testing scenario are described. Positive intraoperative cortical and subcortical sites involved with visuospatial processing were identified in three of the seven patients using the target cancellation and confirmed utilizing the line-bisection task. No identification of visuospatial function was accomplished utilizing the line-bisection task alone. Complete visuospatial function mapping was completed in less than 10 minutes in all patients. No patients had preoperative or postoperative hemineglect. Our findings highlight the feasibility of the target cancellation technique for use during awake craniotomy to aid in avoiding postoperative hemineglect. Target cancellation may offer an alternative method of cortical and subcortical visuospatial mapping in patients unable to perform other commonly used modalities.

White matter connections of the inferior parietal lobule: A study of surgical anatomy

Interest in the function of the inferior parietal lobule (IPL) has resulted in increased understanding of its involvement in visuospatial and cognitive functioning, and its role in semantic networks. A basic understanding of the nuanced white‐matter anatomy in this region may be useful in improving outcomes when operating in this region of the brain. We sought to derive the surgical relationship between the IPL and underlying major white‐matter bundles by characterizing macroscopic connectivity.

Anatomic Variations of the Floor of the Third Ventricle: An Endoscopic Study

OBJECTIVE Anatomical variations of the floor of the third ventricle are common in hydrocephalic patients and can significantly affect outcomes of endoscopic third ventriculostomy (ETV). We sought to categorize variations in third ventricle anatomy and to discuss the implications of these variations for ETV. METHODS Intraoperative videos and pictures of 50 patients who underwent ETV between April 2001 and August 2010 were reviewed. Twenty-seven patients with clearly demonstrable third ventricular floors that satisfied our criteria were selected for the study. RESULTS Images of variations were organized into the following categories: 1) thinned floor, 2) thickened floor, 3) partially effaced floor, 4) ballooning/herniating floor, 5) small prepontine interval, 6) narrowed third ventricle, and 7) other significant anomalies. CONCLUSIONS The third ventricle is a common site for anatomical variations in hydrocephalic patients. A good knowledge of these variations is essential before performing ETV, because they have the potential to increase operative risk.

368 Anatomy and White Matter Connections of the Orbitofrontal Gyrus.

INTRODUCTION The orbitofrontal cortex is understood to have a role in outcome evaluation and risk assessment, and is commonly involved by infiltrative tumors. A detailed understanding of the exact location and nature of associated white tracts could go far to prevent postoperative morbidity related to declining capacity. Through diffusion tensor imaging (DTI)-based fiber tracking validated by gross anatomical dissection as ground truth, we have characterized these connections based on relationships to other well-known structures. METHODS Diffusion imaging from the Human Connectome Project for 10 healthy adult controls was used for tractography analysis. We evaluated the orbitofrontal cortex as a whole based on connectivity with other regions. All orbitofrontal cortex tracts were mapped in both hemispheres, and lateralization index was calculated with resultant tract volumes. Ten postmortem dissections were then performed using a modified Klingler technique to demonstrate the location of major tracts. RESULTS We identified 3 major connections of the orbitofrontal cortex: a bundle to the thalamus and anterior cingulate gyrus passing inferior to the caudate and medial to the vertical fibers of the thalamic projections; a bundle to the brainstem traveling lateral to the caudate and medial to the internal capsule; and radiations to the parietal and occipital lobes traveling with the inferior fronto-occipital fasciculus. There was no significant lateralization for any of the tracts described. CONCLUSION The orbitofrontal cortex is an important center for processing visual, spatial, and emotional information. Subtle differences in executive functioning following surgery for frontal lobe tumors may be better understood in the context of the fiber-bundle anatomy highlighted by this study.

Symptom resolution in infiltrating WHO grade II-IV glioma patients undergoing surgical resection

Past studies of morbidity in patients with infiltrating gliomas have focused on the impact of surgery on quality of life. Surprisingly, little attention has been given to the rate at which the presenting symptoms improve after surgery, even though this is often the patients first concern. This study is an initial effort to provide useful information about symptom resolution and factors predicting persistence of symptoms in glioma patients who undergo surgery. We conducted a retrospective analysis on patients who underwent surgery for World Health Organization (WHO) grade II-IV astrocytoma/oligodendroglioma/oligoastrocytoma at our institution. All patients were seen 2-4months postoperatively, and asked about the persistence of symptoms they experienced preoperatively. Symptoms reported in clinic were assessed against symptoms reported prior to surgery. Our study includes 56 consecutive patients undergoing surgery for gliomas. Of patients who experienced symptoms initially, headache resolved in 18/27 postoperatively, weakness resolved in 8/14 postoperatively, altered mental status resolved in 8/12 postoperatively, vision problems resolved in 7/11 postoperatively, nausea resolved in 5/7 postoperatively, and ataxia resolved in 4/5 postoperatively. Headache was more likely to resolve in patients with frontal or temporal tumors (p=0.02). Preoperative Karnofsky Performance Scale (KPS) of 70 or less was associated with longer postsurgical hospital stay (p<0.01). Younger patients were more likely to experience a resolution of altered mental status (p=0.04). Our analysis provides data regarding the rate at which surgery alleviates patient symptoms and considers variables predicting likelihood of symptom resolution. Some patients will experience symptom resolution following resection of WHO grade II-IV gliomas in the months following surgery.

Anatomy and white matter connections of the orbitofrontal gyrus

OBJECTIVE The orbitofrontal cortex (OFC) is understood to have a role in outcome evaluation and risk assessment and is commonly involved with infiltrative tumors. A detailed understanding of the exact location and nature of associated white matter tracts could significantly improve postoperative morbidity related to declining capacity. Through diffusion tensor imaging-based fiber tracking validated by gross anatomical dissection as ground truth, the authors have characterized these connections based on relationships to other well-known structures. METHODS Diffusion imaging from the Human Connectome Project for 10 healthy adult controls was used for tractography analysis. The OFC was evaluated as a whole based on connectivity with other regions. All OFC tracts were mapped in both hemispheres, and a lateralization index was calculated with resultant tract volumes. Ten postmortem dissections were then performed using a modified Klingler technique to demonstrate the location of major tracts. RESULTS The authors identified 3 major connections of the OFC: a bundle to the thalamus and anterior cingulate gyrus, passing inferior to the caudate and medial to the vertical fibers of the thalamic projections; a bundle to the brainstem, traveling lateral to the caudate and medial to the internal capsule; and radiations to the parietal and occipital lobes traveling with the inferior fronto-occipital fasciculus. CONCLUSIONS The OFC is an important center for processing visual, spatial, and emotional information. Subtle differences in executive functioning following surgery for frontal lobe tumors may be better understood in the context of the fiber-bundle anatomy highlighted by this study.

Risk of failure in pediatric ventriculoperitoneal shunts placed after abdominal surgery

OBJECTIVE Experience has led us to suspect an association between shunt malfunction and recent abdominal surgery, yet information about this potential relationship has not been explored in the literature. The authors compared shunt survival in patients who underwent abdominal surgery to shunt survival in our general pediatric shunt population to determine whether such a relationship exists. METHODS The authors performed a retrospective review of all cases in which pediatric patients underwent ventriculoperitoneal shunt operations at their institution during a 7-year period. Survival time in shunt operations that followed abdominal surgery was compared with survival time of shunt operations in patients with no history of abdominal surgery. Univariate and multivariate analyses were used to identify factors associated with failure. RESULTS A total of 141 patients who underwent 468 shunt operations during the period of study were included; 107 of these 141 patients had no history of abdominal surgery and 34 had undergone a shunt operation after abdominal surgery. Shunt surgery performed more than 2 weeks after abdominal surgery was not associated with time to shunt failure (p = 0.86). Shunt surgery performed within 2 weeks after abdominal surgery was associated with time to failure (adjusted HR 3.6, 95% CI 1.3-9.6). CONCLUSIONS Undergoing shunt surgery shortly after abdominal surgery appears to be associated with shorter shunt survival. When possible, some patients may benefit from shunt placement utilizing alternative termini.

Dural Closure in Confined Spaces of the Skull Base with Nonpenetrating Titanium Clips

BACKGROUND Dural repair in areas with limited operative maneuverability has long been a challenge in skull base surgery. Without adequate dural closure, postoperative complications, including cerebrospinal fluid (CSF) leak and infection, can occur. OBJECTIVE To show a novel method by which nonpenetrating, nonmagnetic titanium microclips can be used to repair dural defects in areas with limited operative access along the skull base. METHODS We reviewed 53 consecutive surgical patients in whom a dural repair technique utilizing titanium microclips was performed from 2013 to 2016 at our institution. The repairs primarily involved difficult-to-reach dural defects in which primary suturing was difficult or impractical. A detailed surgical technique is described in 3 selected cases involving the anterior, middle, and posterior fossae, respectively. An additional 5 cases are provided in more limited detail to demonstrate clip artifact on postoperative imaging. Rates of postoperative CSF leak and other complications are reported. RESULTS The microclip technique was performed successfully in 53 patients. The most common pathology in this cohort was skull base meningioma (32/53). Additional surgical indications included traumatic dural lacerations (9/53), nonmeningioma tumors (8/53), and other pathologies (4/53). The clip artifact present on postoperative imaging was minor and did not interfere with imaging interpretation. CSF leak occurred postoperatively in 3 (6%) patients. No obvious complications attributable to microclip usage were encountered. CONCLUSION In our experience, intracranial dural closure with nonpenetrating, nonmagnetic titanium microclips is a feasible adjunct to traditional methods of dural repair.