A Simplified Method of Accurate Postprocessing of Diffusion Tensor Imaging for Use in Brain Tumor Resection.

BACKGROUND: Use of diffusion tensor imaging (DTI) in brain tumor resection has been limited in part by a perceived difficulty in implementing the techniques into neurosurgical practice. OBJECTIVE: To demonstrate a simple DTI postprocessing method performed without a neuroscientist and to share results in preserving patient function while aggressively resecting tumors. METHODS: DTI data are obtained in all patients with tumors located within presumed eloquent cortices. Relevant white matter tracts are mapped and integrated with neuronavigation by a nonexpert in < 20 minutes. We report operative results in 43 consecutive awake craniotomy patients from January 2014 to December 2014 undergoing resection of intracranial lesions. We compare DTI-expected findings with stimulation mapping results for the corticospinal tract, superior longitudinal fasciculus, and inferior fronto-occipital fasciculus. RESULTS: Twenty-eight patients (65%) underwent surgery for high-grade gliomas and 11 patients (26%) for low-grade gliomas. Seventeen patients had posterior temporal lesions; 10 had posterior frontal lesions; 8 had parietal-temporal-occipital junction lesions; and 8 had insular lesions. With DTI-defined tracts used as a guide, a combined 65 positive maps and 60 negative maps were found via stimulation mapping. Overall sensitivity and specificity of DTI were 98% and 95%, respectively. Permanent speech worsening occurred in 1 patient (2%), and permanent weakness occurred in 3 patients (7%). Greater than 90% resection was achieved in 32 cases (74%). CONCLUSION: Accurate DTI is easily obtained, postprocessed, and implemented into neuronavigation within routine neurosurgical workflow. This information aids in resecting tumors while preserving eloquent cortices and subcortical networks.

A Technique for Resecting Occipital Pole Gliomas Using a Keyhole Lobectomy.

OBJECTIVE: Our purpose is to describe a method of resecting occipital pole gliomas through a keyhole lobectomy and share the patient outcomes of this technique. METHODS: We performed a retrospective review of data obtained on all patients who underwent resection of occipital pole gliomas by the senior author between 2012 and 2016. We describe our technique for resecting these tumors using a keyhole lobectomy and share the patient outcomes of this operation. RESULTS: Eight patients were included in this study. Four patients (50%) had not received previous surgery. One patient (13%) was diagnosed with a World Health Organization grade II tumor, and 7 patients (88%) were diagnosed with glioblastoma. Two tumors (25%) were left sided and 6 (75%) right sided. The median size of resection was 28 cm3. The median extent of resection was 96%, and at least 90% of the tumor was resected in all cases. None of the patients experienced permanent postoperative complications. Temporary neurologic complications included 3 patients (38%) with encephalopathy and 1 patient (13%) with aphasia. There were no neurosurgical complications. CONCLUSIONS: Our study provides details on the technical aspects of occipital keyhole lobectomies and gives the outcomes of patients who have received an operation for tumors in this uncommon location. Taking white matter tract anatomy into consideration, we show that the keyhole method can be applied to gliomas of the occipital lobe.

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

INTRODUCTION: 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. METHODS: Data of 10 healthy adult controls from the Human Connectome Project were used for tractography analysis. All IPL connections were mapped in both hemispheres, and distances were recorded between cortical landmarks and major tracts. Ten postmortem dissections were then performed using a modified Klingler technique to serve as ground truth. RESULTS: We identified three major types of connections of the IPL. (1) Short association fibers connect the supramarginal and angular gyri, and connect both of these gyri to the superior parietal lobule. (2) Fiber bundles from the IPL connect to the frontal lobe by joining the superior longitudinal fasciculus near the termination of the Sylvian fissure. (3) Fiber bundles from the IPL connect to the temporal lobe by joining the middle longitudinal fasciculus just inferior to the margin of the superior temporal sulcus. CONCLUSIONS: We present a summary of the relevant anatomy of the IPL as part of a larger effort to understand the anatomic connections of related networks. This study highlights the principle white-matter pathways and highlights key underlying connections.