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Recognition and correct evaluation of basal ganglia abnormalities, together with a proper neurological examination and laboratory findings, may enable the identification of each of these clinical entities and lead to earlier diagnosis.

BACKGROUND AND PURPOSE:Cervical transforaminal epidural steroid injections are commonly performed for temporary pain relief or diagnostic presurgical planning in patients with cervical radiculopathy. Intravascular injection of steroids during the procedure can potentially result in cord infarct, stroke, and even death. CT-fluoroscopy allows excellent anatomic resolution and precise needle positioning. This study sought to determine the safest needle tip position during CT-guided cervical transforaminal epidural steroid injection as determined by the incidence of intravascular injection.

Motion contrast contributes to the segregation of a two-dimensional figure from its background, yet many questions remain about its neural mechanisms. We measured steady-state visual evoked potential (SSVEP) responses to moving dot displays in which figure regions emerged from and disappeared into the background at a specific temporal frequency (1.2Hz, F1), based on regional differences of dot direction and global direction coherence. The goal was to measure the cortical response function across a range of motion contrast magnitudes. In two experiments using both a low channel count electrode array (Experiment 1) and a high density array (Experiment 2), we observed two distinct phase-locked evoked responses that were similar across motion contrast type. A response at 1.2Hz (1F1) increased in amplitude with increasing magnitudes of direction or coherence contrast. A response at 2.4Hz (2F1) increased in amplitude, but saturated at low levels of direction or coherence contrast. The two components showed different scalp distributions - the 1F1 was strongest along medial occipital channels, while the 2F1 was bilaterally distributed. Taken together, the studies suggest that figures defined by different types of motion contrast are processed by cortical systems with similar dynamics, and that there are separable neural systems devoted to (i) signaling the absolute magnitude of motion contrast and (ii) detecting when a figure defined by motion contrast appears and disappears from view.

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