Optimal timing of post-operative enoxaparin after neurosurgery: A single institution experience.

PURPOSE: Venous thromboembolism (VTE) is a well-known problem in patients with intracranial tumors, especially high-grade gliomas. Optimal management of VTE complications is critical given that the development of deep vein thrombosis (DVT) and/or pulmonary embolism can exacerbate medical comorbidities and increase mortality. However, little is known about the optimum time to initiate post-operative anticoagulant prophylaxis. Therefore, there is a keen interest amongst neurosurgeons to develop evidence-based protocols to prevent VTE in post-operative brain tumor patients. METHODS: We retrospectively identified adult patients who underwent elective craniotomy for intracranial tumor resection between 2012 and 2017. Patients were categorized according to the time at which they began receiving prophylactic enoxaparin in the immediate post-operative period, within one day (POD 1), two days (POD 2), three days (POD 3), five days (POD 5), or seven days (POD 7). RESULTS: A total of 1087 patients had a craniotomy for intracranial tumor resection between 2012 and 2017. Multivariate binomial logistic regression analysis demonstrated that initiation of prophylactic enoxaparin within 72 h of surgery was protective against the likelihood of developing a lower extremity DVT (OR: 0.32; CI: 0.10-0.95; p = 0.049) while controlling for possible risk factors for DVTs identified on univariate analysis. Furthermore, complication rates between the anticoagulation and non-anticoagulation groups were not statistically significant. CONCLUSION: Initiating anticoagulant prophylaxis with subcutaneous enoxaparin sodium 40 mg once per day within 72 h of surgery can be done safely while reducing the risk of developing lower extremity DVT.

Anatomy and White Matter Connections of the Inferior Temporal Gyrus.

BACKGROUND: The inferior temporal gyrus (ITG) is known to be involved in high-cognitive functions, including visual and language comprehensions and emotion regulation. A detailed understanding of the nature of association fibers could significantly improve postoperative morbidity related to declining capacity. Through diffusion spectrum imaging-based fiber tracking, we have characterized these connections on the basis of their relationships to other cortical areas. METHODS: Diffusion spectrum images from 10 healthy adults of the Human Connectome Project were randomly selected and used for tractography analysis. We evaluated the ITG as a whole based on connectivity with other regions. All ITG tracts were mapped in both hemispheres, and a lateralization index was calculated with resultant tract volumes. RESULTS: We identified 5 major connections of the ITG: U-fiber, inferior longitudinal fasciculus, vertical occipital fasciculus, arcuate fasciculus, and uncinate fasciculus. There was no fiber lateralization detected. CONCLUSIONS: This study highlights the principal white-matter pathways of the ITG and demonstrates key underlying connections. We present a summary of the relevant clinical anatomy for this region of the cerebrum as part of a larger effort to understand it in its entirety.

Beyond eloquence and onto centrality: a new paradigm in planning supratentorial neurosurgery.

PURPOSE: Minimizing post-operational neurological deficits as a result of brain surgery has been one of the most pertinent endeavours of neurosurgical research. Studies have utilised fMRIs, EEGs and MEGs in order to delineate and establish eloquent areas, however, these methods have not been utilized by the wider neurosurgical community due to a lack of clinical endpoints. We sought to ascertain if there is a correlation between graph theory metrics and the neurosurgical notion of eloquent brain regions. We also wanted to establish which graph theory based nodal centrality measure performs the best in predicting eloquent areas. METHODS: We obtained diffusion neuroimaging data from the Human Connectome Project (HCP) and applied a parcellation scheme to it. This enabled us to construct a weighted adjacency matrix which we then analysed. Our analysis looked at the correlation between PageRank centrality and eloquent areas. We then compared PageRank centrality to eigenvector centrality and degree centrality to see what the best measure of empirical neurosurgical eloquence was. RESULTS: Areas that are considered neurosurgically eloquent tended to be predicted by high PageRank centrality. By using summary scores for the three nodal centrality measures we found that PageRank centrality best correlated to empirical neurosurgical eloquence. CONCLUSION: The notion of eloquent areas is important to neurosurgery and graph theory provides a mathematical framework to predict these areas. PageRank centrality is able to consistently find areas that we consider eloquent. It is able to do so better than eigenvector and degree central measures.

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.

Measuring graphical strength within the connectome: A neuroanatomic, parcellation-based study.

INTRODUCTION: Graph theory is a promising mathematical tool to study the connectome. However, little research has been undertaken to correlate graph metrics to functional properties of the brain. In this study, we report a unique association between the strength of cortical regions and their function. METHODS: Eight structural graphs were constructed within DSI Studio using publicly available imaging data derived from the Human Connectome Project. Whole-brain fiber tractography was performed to quantify the strength of each cortical region comprising our atlas. RESULTS: Rank-order analysis revealed 27 distinct areas with high average strength, several of which are associated with eloquent cortical functions. Area 4 localizes to the primary motor cortex and is important for fine motor control. Areas 2, 3a and 3b localize to the primary sensory cortex and are involved in primary sensory processing. Areas V1-V4 in the occipital pole are involved in primary visual processing. Several language areas, including area 44, were also found to have high average strength. CONCLUSIONS: Regions of average high strength tend to localize to eloquent areas of the brain, such as the primary sensorimotor cortex, primary visual cortex, and Broca's area. Future studies will examine the dynamic effects of neurologic disease on this metric.

An Awake Contralateral, Transcallosal Approach for Deep-Seated Gliomas of the Basal Ganglia.

BACKGROUND: The basal ganglia and thalamus are uncommon locations for infiltrating gliomas. Tumors here are usually managed with biopsy and adjuvant therapy, with relatively poor results. Rarely do patients undergo extensive surgical intervention. It seems reasonable to suggest that successful cytoreduction may help these patients. However, this hypothesis has not been studied because of the general view that it is not possible to remove deep-seated brain tumors with acceptable outcomes. METHODS: Through retrospective data collection, we describe a small case series of patients undergoing awake contralateral, transcallosal surgery for deep-seated brain tumors affecting the basal ganglia. We describe our patient cohort, report on patient outcomes, and describe our surgical technique. RESULTS: Four patients underwent awake contralateral, transcallosal surgery for glioblastoma invading the basal ganglia. All 4 patients demonstrated hemibody weakness contralateral to the side of their tumors, with 3 patients confined to wheelchairs at presentation. Their ages ranged from 25 to 64 years. Tumor volumes ranged from 14 to 93 cm3. More than 50% resection of each tumor was achieved during surgery. In 2 cases, approximately 90% resection was achieved. Motor strength improved in 1 patient who presented with hemiplegia. Two patients required ventriculoperitoneal shunting for complications related to hydrocephalus. At the writing of this article, 2 of our patients were still alive, functional, and free of tumor progression. CONCLUSIONS: We present the results of our attempts to resect large gliomas infiltrating the basal ganglia in 4 patients. Our technique combined a contralateral, transcallosal approach with awake neuromonitoring. Our results suggest it is possible to remove these tumors with reasonable outcomes.

The Artery of Aphasia, A Uniquely Sensitive Posterior Temporal Middle Cerebral Artery Branch that Supplies Language Areas in the Brain: Anatomy and Report of Four Cases.

BACKGROUND: Arterial disruption during brain surgery can cause devastating injuries to wide expanses of white and gray matter beyond the tumor resection cavity. Such damage may occur as a result of disrupting blood flow through en passage arteries. Identification of these arteries is critical to prevent unforeseen neurologic sequelae during brain tumor resection. In this study, we discuss one such artery, termed the artery of aphasia (AoA), which when disrupted can lead to receptive and expressive language deficits. METHODS: We performed a retrospective review of all patients undergoing an awake craniotomy for resection of a glioma by the senior author from 2012 to 2018. Patients were included if they experienced language deficits secondary to postoperative infarction in the left posterior temporal lobe in the distribution of the AoA. The gross anatomy of the AoA was then compared with activation likelihood estimations of the auditory and semantic language networks using coordinate-based meta-analytic techniques. RESULTS: We identified 4 patients with left-sided posterior temporal artery infarctions in the distribution of the AoA on diffusion-weighted magnetic resonance imaging. All 4 patients developed substantial expressive and receptive language deficits after surgery. Functional language improvement occurred in only 2/4 patients. Activation likelihood estimations localized parts of the auditory and semantic language networks in the distribution of the AoA. CONCLUSIONS: The AoA is prone to blood flow disruption despite benign manipulation. Patients seem to have limited capacity for speech recovery after intraoperative ischemia in the distribution of this artery, which supplies parts of the auditory and semantic language networks.