Journal of neurosurgery
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Journal of neurosurgery · Oct 2009
Predictors of hearing preservation after stereotactic radiosurgery for acoustic neuroma.
Many patients with acoustic neuromas (ANs) have hearing function at diagnosis and desire to maintain it. To date, radiosurgical techniques have been focused on conformal irradiation of the tumor mass, with less attention to inner ear structures for which there was scant radiobiological information. The authors of this study evaluated tumor control and hearing preservation as they relate to tumor volume, imaging characteristics, and nerve and cochlear radiation dose following stereotactic radiosurgery (SRS) using the Gamma Knife. ⋯ As currently practiced, SRS with the Gamma Knife preserves serviceable hearing in the majority of patients. Tumor volume and anatomy relate to the hearing level before radiosurgery and influence technique. A low radiosurgical dose to the cochlea enhances hearing preservation.
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Journal of neurosurgery · Oct 2009
Relationships between essential cortical language sites and subcortical pathways.
Maps produced using either electrical stimulation or functional imaging have demonstrated a distributed network of cortical regions involved in expressive and receptive language tasks. The pattern of connectivity among components of this network has begun to be explored with diffusion tensor (DT) imaging, but has yet to be completely characterized. In this study the authors used DT imaging-based tractography to examine the interrelationship between cortical areas found to be essential for language by intraoperative electrical stimulation. ⋯ The deficits evoked by subcortical stimulation validate and demonstrate the utility of this AF localization technique, and provide further evidence that the AF is an important pathway for fluent language. Taken together, these results demonstrate that DT imaging of the AF may be used to predict the location of brain areas that will be eloquent by the standards of stimulation mapping.
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Journal of neurosurgery · Oct 2009
Sensitivity of high-resolution three-dimensional magnetic resonance angiography and three-dimensional spoiled-gradient recalled imaging in the prediction of neurovascular compression in patients with hemifacial spasm.
Hemifacial spasm is a clinical syndrome caused by vascular compression of the facial nerve in the cerebellopontine angle, which can be relieved by surgical intervention. Advances in medical imaging technology allow for direct visualization of the offending blood vessels in hemifacial spasm and similar conditions (such as trigeminal neuralgia). The utility of high resolution 3D MR angiography and 3D spoiled-gradient recalled (SPGR) imaging sequences for surgical decision-making in hemifacial spasm, as measured by sensitivity, specificity, and positive and negative predictive values, has not been previously determined. ⋯ Although high-resolution 3D MR angiography and 3D SPGR imaging was helpful in providing information about the anatomical relationship of cranial nerve VII and surrounding blood vessels, the authors determined that in the case of hemifacial spasm these types of imaging did not influence preoperative surgical decisionmaking.
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Journal of neurosurgery · Oct 2009
Case ReportsTraumatic enucleation with avulsion of the ophthalmic artery resulting in aneurysm-like subarachnoid hemorrhage.
Traumatic, nonaneurysmal subarachnoid hemorrhage (SAH) is common after closed head injury and most often results from ruptured cortical microvessels. Here, the authors present the case of a 60-year-old woman who fell and struck her head, causing traumatic enucleation and avulsion of both the optic nerve and ophthalmic artery. The arterial avulsion caused a Fisher Grade 3 SAH. ⋯ Epileptiform activity also developed, although this may have been related to concurrent Pantoea agglomerans ventriculitis. It is reasonable to suggest that intracerebral arterial avulsion with profuse arterial bleeding may be more likely than traditional traumatic SAH to result in clinical events similar to that of aneurysmal SAH. Special consideration should be given to the acute care of patients with intracranial arterial avulsions (conservative management vs surgical exploration or endovascular treatment), as well as long-term follow-up for vascular or other neurosurgical complications.
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Journal of neurosurgery · Oct 2009
Development of the Wireless Instantaneous Neurotransmitter Concentration System for intraoperative neurochemical monitoring using fast-scan cyclic voltammetry.
Emerging evidence supports the hypothesis that modulation of specific central neuronal systems contributes to the clinical efficacy of deep brain stimulation (DBS) and motor cortex stimulation (MCS). Real-time monitoring of the neurochemical output of targeted regions may therefore advance functional neurosurgery by, among other goals, providing a strategy for investigation of mechanisms, identification of new candidate neurotransmitters, and chemically guided placement of the stimulating electrode. The authors report the development of a device called the Wireless Instantaneous Neurotransmitter Concentration System (WINCS) for intraoperative neurochemical monitoring during functional neurosurgery. This device supports fast-scan cyclic voltammetry (FSCV) at a carbon-fiber microelectrode (CFM) for real-time, spatially and chemically resolved neurotransmitter measurements in the brain. ⋯ Taken together, these results demonstrate that the WINCS is well suited for intraoperative neurochemical monitoring. It is anticipated that neurotransmitter measurements at an implanted chemical sensor will prove useful for advancing functional neurosurgery.