Posts Tagged ‘Electrophysiology’
Background: Accurate localization of the subthalamic nucleus (STN) is critical to the success of deep brain stimulation (DBS) surgery for Parkinson’s disease (PD). Recent developments in high field strength magnetic resonance imaging (MRI) have made it possible to visualize the STN in greater detail. However, the relationship of the MR-visualized STN to the anatomic, electrophysiological, or atlas-predicted STN remains controversial.
Objective: To evaluate the size of the STN visualized on 3T MRI compared to anatomic measurements in cadaver studies, and to compare the predictions of 3T MRI to those of the Schaltenbrand-Wahren (SW) atlas for intraoperative STN microelectrode recordings (MER).
Methods: We evaluated the STN by 3T MRI and intraoperative MER in twenty PD patients undergoing DBS surgery. We compared our findings to anatomic cadaver studies and to the individually scaled SW-atlas based predictions for each patient.
Ahead of Print: Safe Resection of Arteriovenous Malformations in Eloquent Motor Areas Aided by Functional Imaging and Intraoperative Monitoring
BACKGROUND: Arteriovenous malformations (AVMs) proximal to motor cortical areas or motor projection systems are challenging to manage due to the risk of severe sensory and motor impairment. Surgical indication in these cases therefore remains controversial.
OBJECTIVE: To propose a standardized approach for centrally situated AVMs, based on functional imaging and intraoperative electrophysiological evaluation.
METHODS: We conducted a retrospective analysis of 15 patients who underwent surgical treatment for AVMs in motor cortical areas or proximal to motor projections. Preoperative assessment included fMRI and 3D-tractography. Operations were performed under continuous electrophysiological monitoring aided by direct brain stimulation. We identified critical bloody supply to the motor areas by temporary occluding the feeding vessels under electrophysiological monitorization. Clinical outcome was evaluated using the modified Rankin Scale.
Ahead of Print: Fractional Anisotropy Levels Derived From Diffusion Tensor Imaging in Cervical Syringomyelia
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Roser, Florian MD; Ebner, Florian MD; Maier, Gottlieb MD; Tatagiba, Marcos MD; Nägele, Thomas MD, PhD; Klose, Uwe PhD
BACKGROUND: Syringomyelia can result in major functional disability. Conventional imaging techniques frequently fail to detect the underlying cause of syringomyelia. The prediction as to whether syringomyelia might lead to neurological deficits is still challenging.
OBJECTIVE: We hypothesized that fractional anisotropy (FA) derived from diffusion tensor imaging (DTI) is a parameter to detect dynamic forms of syringomyelia.
METHODS: Six patients with cervical syringomyelia, all comparable in size, shape, and location, were examined, along with 2 volunteers. Patients underwent electrophysiological recordings (somatosensory evoked potentials, motor evoked potentials, silent periods). Magnetic resonance imaging (1.5 T) was performed with a 6-element spine coil. Anatomic images were acquired with a 3-dimensional, constructive interference in steady-state sequence, and DTI with an echo-planar imaging sequence (5-mm thickness, b value 800 s/mm2) using the generalized autocalibrating partially parallel acquisitions technique. The positions were centered on the syrinx in the volunteers between the C2 and Th1. DTI data were interpolated to a spatial resolution of 0.5 mm. After calculation of a diffusion tensor in each pixel, an FA map was calculated and profiles of the FA values across the spinal cord were calculated in all slices.