An Eyebrow, Supracarotid Triangle Approach for Lesions at the Ventral Thalamopeduncular Junction: A Technical Report.

BACKGROUND: Lesions arising at the ventral thalamopeduncular junction are difficult to resect. In addition to being relatively inaccessible, these lesions are located in one of the most sensitive areas of the brain. A critical question is whether new approaches could be developed to allow surgeons to adequately resect these lesions with reasonable outcomes. In the present report, we describe our approach to resect lesions in this region of the brain using an eyebrow craniotomy approach with a trajectory through the supracarotid triangle. METHODS: Through retrospective data collection, we present a small series of patients who had undergone an eyebrow, supracarotid triangle approach to resect lesions located at the thalamopeduncular junction. We describe our surgical technique and report patient outcomes using this approach. RESULTS: Three patients had undergone an eyebrow, supracarotid approach for resection of a lesion arising at the ventral thalamopeduncular junction. Two patients had presented with a cavernoma and one with a pilocytic astrocytoma. Complete resection of all 3 lesions was achieved during surgery without any intraoperative complications. No patient developed permanent contralateral weakness despite entering the peduncle during surgery. One patient developed permanent paresthesia in his left hand. CONCLUSIONS: Lesions arising at the ventral thalamopeduncular junction can be adequately resected with reasonable outcomes using an eyebrow, supracarotid triangle approach. This operative technique establishes another potential operative corridor by which neurosurgeons can resect lesions arising within this relatively inaccessible part of the brain.

Neurochemical supplementation in patients with depressed levels of participation after brain tumor surgery: Rationale and preliminary results.

A unique challenge in some brain tumor patients is the fact that tumors arising in certain areas of the brain involve the neural structures of consciousness or alertness, limiting the patient's ability to participate in rehabilitation following surgery. A critical question is whether neurostimulant therapy can help patients participate in rehabilitation efforts. We performed a retrospective review of all patients undergoing brain tumor surgery by the senior author from 2012 to 2018. We limited this study to patients with tumors occupying critical structures related to consciousness, alertness, and motor initiation. A combination of methylphenidate and levodopa/carbidopa was used to monitor the progress of patients through neurorehabilitation efforts. We identified 101 patients who experienced an inability to participate in rehabilitation (ITPR) in the post-operative period. Of these, 86 patients (85%) were treated with methylphenidate and levodopa/carbidopa. Cases of ITPR were related to dysfunction of the brainstem (12/86 cases, 14%), thalamus (17/86 cases, 20%), hypothalamus (14/86 cases, 16%), basal ganglia (13/86 cases, 15%), and medial frontal lobe (30/86 cases, 35%). Of the 86 individuals treated, 47/86 patients (55%) showed early improvement in their ability to participate with rehabilitation. At three month follow-up, 58/86 patients (67%) had returned to living independently or were at least interactive and cooperative during follow-up examination. This feasibility report suggests that combined therapy with methylphenidate and levodopa/carbidopa may help patients participate in neurorehabilitation efforts in the immediate post-operative period following brain tumor surgery. Randomized, controlled clinical trials are needed to explore this concept more thoroughly.

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.