Neurosurgery
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The intraoperative combination of an open magnetic resonance imaging (MRI) system with neurophysiological localization and continuous monitoring techniques allows for the best available anatomic and physiological orientation as well as real-time functional monitoring. Methodological aspects and technical adaptations for this combination of methods and the experience in 29 patients with tumors in the central region are reported. ⋯ Neurophysiological monitoring for evoked potentials and direct cortical stimulation can be performed with standard quality within a low-field intraoperative MRI system. Electrodes fixed to the head should be of low magnetic susceptibility to guarantee optimal imaging quality. The combined use of an open ultra low-field MRI system and intraoperative monitoring allows for resection control and continuous functional monitoring.
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Case Reports
Microvascular decompression in hemifacial spasm resulting from a cerebellopontine angle lipoma: case report.
Hemifacial spasm caused by a cerebellopontine angle lipoma is extremely rare. We describe a patient with left-sided hemifacial spasm caused by vascular compression of the facial and vestibulocochlear cranial nerves by the anteroinferior cerebellar artery embedded within a cerebellopontine angle lipoma. ⋯ This case demonstrates that relief of the vascular compression, when present, of the VIIth cranial nerve is sufficient for resolution of hemifacial spasm symptoms, even when associated with nearby, benign lesions.
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To evaluate the differences in spinal stability and stabilizing potential of instrumentation after cervical corpectomy and spondylectomy. ⋯ Circumferential fixation provides more stability than anterior instrumentation alone after cervical corpectomy. After corpectomy or spondylectomy, long circumferential instrumentation provides better stability than short circumferential fixation except during axial rotation. Circumferential fixation more effectively prevents axial rotation after corpectomy than after spondylectomy.
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Transsphenoidal adenomectomy carries the possibility of new pituitary failure and recovery. Herein, we present rates and determinants of postoperative hormonal status. ⋯ After transsphenoidal adenomectomy, new unplanned hypopituitarism occurs in approximately 5% of patients, whereas improved hormonal function occurs in 50% of patients. The likelihood of new hormonal loss or recovery appears to depend on several factors. New hypopituitarism occurs most commonly in patients with tumors larger than 20 mm in size, whereas hormonal recovery is most likely to occur in younger, nonhypertensive patients and those without an intraoperative cerebrospinal fluid leak.
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Although frameless stereotactic techniques have become indispensable in neurosurgery, their technical complexity requires careful definition and evaluation. Navigation is of particular concern when it is applied to approach a complex, tight surgical area like the temporal bone, where every millimeter is important. Theoretically, the temporal bone is an ideal location in which to use image-guided navigation because its bony construct precludes pre- and intraoperative shift. In this context, the feasibility of using a navigational system is determined by the system's accuracy and by the spatial characteristics of the targets. Literature addressing the accuracy of image guidance techniques in temporal bone surgery is relatively sparse. Accuracy of these systems within the temporal bone is still under investigation. We investigated the application accuracy of computed tomography-based, frameless, image-guided navigation to identify various bony structures in the temporal bone via a retrosigmoid approach. ⋯ Using high-resolution computed tomography and bone-implanted reference markers, frameless navigation can be as accurate as frame-based stereotaxy in providing a guide to maximize safe surgical approaches to the temporal bone. Although error-free navigation is not possible with the submillimetric accuracy required by direct anatomic contouring of tiny structures within temporal bone, it still provides a road map to maximize safe surgical exposure.