Temporal Lobe Epilepsy: Differential Pattern of Damage in Temporopolar Cortex and White Matter

Human Brain Mapping. Aug, 2008  |  Pubmed ID: 17636561

Our purpose was to quantify structural changes of the temporopolar cortex (TPC) and its white matter (TPWM) in temporal lobe epilepsy (TLE) using MRI volumetry and texture analysis. We studied 23 patients with hippocampal atrophy, and 20 healthy controls. Gradient magnitude and entropy were calculated to model signal intensity blurring on T1-MRI. Two observers assessed signal changes and atrophy visually. Compared to controls, TLE patients had a decrease in TPC and TPWM volume ipsilateral to the seizure focus. The gradient magnitude and entropy were decreased ipsilateral to the focus only in TPWM, indicating blurring of this compartment. Eighty-seven percent of TLE patients had at least one volumetric or textural abnormality. Although sensitivity of visual and quantitative assessment of TPC atrophy was comparable (43 and 39%), specificity was higher for volumetry (54% vs. 95%). Compared to visual analysis of signal changes in TPWM on T1-MRI, texture metrics had higher sensitivity (65% vs. 17%) and specificity (100% vs. 69%). The proportion of patients with blurring of TPWM as determined by texture analysis was higher than that seen on visual inspection of T2 images (78% vs. 43%). We found no clear association between volumetric or textural changes of TPC and TPWM and outcome after surgery. Structural changes of the anatomically distinct TPC and TPWM are found ipsilateral to the seizure focus in the majority of TLE patients with hippocampal sclerosis. MRI post-processing allows dissociating different pathological tissue characteristics and shows that atrophy involves gray and white matter, whereas blurring is confined to white matter.

Comparative Study of Cranial Topographic Procedures: Broca's Legacy Toward Practical Brain Surgery

Neurosurgery. Feb, 2008  |  Pubmed ID: 18382308

In many locations, neurosurgeons still use stereotactic- or anatomic-based craniocerebral topography systems to identify cortical landmarks. However, their predictive value for identifying two key landmarks--the central sulcus (CS) and lateral sulcus (LS)--has never been evaluated. We quantitatively compare leading craniocerebral topographic methods and review their historical significance for neurosurgery.

Neurosurgical Implications of Mannitol Accumulation Within a Meningioma and Its Peritumoral Region Demonstrated by Magnetic Resonance Spectroscopy: Case Report

Journal of Neurosurgery. May, 2008  |  Pubmed ID: 18447720

Mannitol is widely considered the hyperosmolar therapy of choice in routine neurosurgical practice for the reduction of intracranial pressure (ICP). The authors present a unique case of a patient with a large meningioma treated with mannitol, in which mannitol accumulation within the tumor and its surrounding parenchyma was shown using in vivo magnetic resonance spectroscopy (MRS). This rare appearance of mannitol on MRS was characterized by a wide-based peak at 3.8 ppm, which remained detectable several hours after the last dose. These findings provide the first in vivo evidence in support of the prevailing theory that mannitol leakage into the peritumoral edematous region may contribute to rebound increases in ICP and suggest that this phenomenon has the potential to occur in extraaxial tumors. Judicious use of mannitol in the setting of elevated ICP due to tumor may be indicated to avoid potentially deleterious side effects caused by its accumulation.

Prospective Serial Proton MR Spectroscopic Assessment of Response to Tamoxifen for Recurrent Malignant Glioma

Journal of Neuro-oncology. Oct, 2008  |  Pubmed ID: 18600428

Early prediction of imminent failure during chemotherapy for malignant glioma has the potential to guide proactive alterations in treatment before frank tumor progression. We prospectively followed patients with recurrent malignant glioma receiving tamoxifen chemotherapy using proton magnetic resonance spectroscopic imaging ((1)H-MRSI) to identify intratumoral metabolic changes preceding clinical and radiological failure.

Bilateral Thalamic Infarction Following Transsphenoidal Surgery

The Canadian Journal of Neurological Sciences. Le Journal Canadien Des Sciences Neurologiques. Sep, 2008  |  Pubmed ID: 18973077

Activated Autologous Macrophage Implantation in a Large-animal Model of Spinal Cord Injury

Neurosurgical Focus. 2008  |  Pubmed ID: 18980477

Axonal regeneration may be hindered following spinal cord injury (SCI) by a limited immune response and insufficient macrophage recruitment. This limitation has been partially surmounted in small-mammal models of SCI by implanting activated autologous macrophages (AAMs). The authors sought to replicate these results in a canine model of partial SCI.

Explicit Separation of Growth and Motility in a New Tumor Cord Model

Bulletin of Mathematical Biology. Apr, 2009  |  Pubmed ID: 19067082

We investigate a new model of tumor growth in which cell motility is considered an explicitly separate process from growth. Bulk tumor expansion is modeled by individual cell motility in a density-dependent diffusion process. This model is implemented in the context of an in vivo system, the tumor cord. We investigate numerically microscale density distributions of different cell classes and macroscale whole tumor growth rates as functions of the strength of transitions between classes. Our results indicate that the total tumor growth follows a classical von Bertalanffy growth profile, as many in vivo tumors are observed to do. This provides a quick validation for the model hypotheses. The microscale and macroscale properties are both sensitive to fluctuations in the transition parameters, and grossly adopt one of two phenotypic profiles based on their parameter regime. We analyze these profiles and use the observations to classify parameter regimes by their phenotypes. This classification yields a novel hypothesis for the early evolutionary selection of the metastatic phenotype by selecting against less motile cells which grow to higher densities and may therefore induce local collapse of the vascular network.

The Metabolic Epicenter of Supratentorial Gliomas: a 1H-MRSI Study

The Canadian Journal of Neurological Sciences. Le Journal Canadien Des Sciences Neurologiques. Nov, 2009  |  Pubmed ID: 19960747

Assessing the impact of glioma location on prognosis remains elusive. We approached the problem using multivoxel proton magnetic resonance spectroscopic imaging (1H-MRSI) to define a tumor "metabolic epicenter", and examined the relationship of metabolic epicenter location to survival and histopathological grade.

Miniaturized Handheld Confocal Microscopy for Neurosurgery: Results in an Experimental Glioblastoma Model

Neurosurgery. Feb, 2010  |  Pubmed ID: 20087141

Recent developments in optical science and image processing have miniaturized the components required for confocal microscopy. Clinical confocal imaging applications have emerged, including assessment of colonic mucosal dysplasia during colonoscopy. We present our initial experience with handheld, miniaturized confocal imaging in a murine brain tumor model.

Brain Retraction and Thickness of Cerebral Neocortex: an Automated Technique for Detecting Retraction-induced Anatomic Changes Using Magnetic Resonance Imaging

Neurosurgery. Sep, 2010  |  Pubmed ID: 20679923

Treating deep-seated cerebral lesions often requires retracting the brain. Retraction, however, causes clinically significant postoperative neurological deficits in 3% to 9% of intracranial cases.

Right Hemisphere Language

Journal of Neurosurgery. Apr, 2011  |  Pubmed ID: 21235312

Pediatric Traumatic Retroclival Epidural Hematoma

The Canadian Journal of Neurological Sciences. Le Journal Canadien Des Sciences Neurologiques. Mar, 2011  |  Pubmed ID: 21320842

Magnetic Resonance Imaging and Deep Brain Stimulation

Journal of Neurosurgery. Oct, 2011  |  Pubmed ID: 21699483

Deep Brain Stimulation Emerging Indications

Progress in Brain Research. 2011  |  Pubmed ID: 21867796

There are a number of emerging surgical indications for deep brain stimulation. We have shown that modulation of activity within motor, mood, and cognitive circuits has beneficial effects in patients with Parkinson's disease, treatment-resistant depression, and perhaps Alzheimer's type dementia. We review the rationale, safety, and efficacy for each of these indications, focusing on disease mechanisms and relevant data that are necessary to document therapeutic value in each case. The review closes with some thoughts on possible future directions for deep brain stimulation. It is likely that applications for deep brain stimulation will continue to expand as accumulating data establish its safety and efficacy profile in these and other conditions.

Surgical Approach to L-dopa-induced Dyskinesias

International Review of Neurobiology. 2011  |  Pubmed ID: 21907086

Many patients treated chronically with l-dopa for Parkinson disease (PD) become functionally disabled by l-dopa-induced dyskinesias (LID). Evolved from early empirical procedures, modern stereotactic surgical lesioning techniques and deep brain stimulation (DBS) can effectively treat LID while simultaneously improving the cardinal motor symptoms of PD. Here we review the common surgical targets used to treat LID, and compare their relative efficacy. We explain the anti-dyskinetic action of surgery at each of these targets based on evolving models of basal ganglia function. Finally, we discuss the appropriate selection of patients with LID for surgery and address relevant technical and management issues in these patients.

Functional Neurosurgery and Hemorrhage

Journal of Neurosurgery. Jan, 2012  |  Pubmed ID: 21905797