Experimental neurology
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Experimental neurology · Mar 2006
Comparative Study Clinical TrialIntra-operative recordings of local field potentials can help localize the subthalamic nucleus in Parkinson's disease surgery.
Deep brain stimulation (DBS) of the subthalamic nucleus (STN) can be a highly effective treatment for Parkinson's disease (PD). However, therapeutic efficacy is limited by difficulties in consistently and correctly targeting this nucleus. Increasing evidence suggests that there is abnormal synchronization of beta frequency band activity (approximately 20 Hz) in the STN of PD patients, as reflected in the oscillatory nature of the local field potential (LFP). ⋯ The depth of the peak beta activity showed excellent agreement with the level of the intra-operative clinical stun effect (k coefficient = 0.792). The depth of peak beta activity also showed 100% specificity and 100% sensitivity for placement within STN in comparison to pre- and Post-operative stereotactic MRI. Functional physiological localization of STN by the on-line spectral analysis of LFPs is quick to perform and may provide information directly relevant to the position of the electrode contact actually used for DBS.
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Experimental neurology · Mar 2006
Comparative StudyPerimicrovascular edema in the frontal cortex in a rat model of intraperitoneal sepsis.
Septic encephalopathy is a complication of sepsis, and it is closely associated with the increased mortality of the sufferers. Pathophysiology of septic encephalopathy is not still completely understood. In an attempt to provide insight into the pathogenesis of septic encephalopathy, a light and electron microscopic investigation has been carried out in a rat model of intraperitoneal sepsis. ⋯ Estimation of the percentage of the microvessel area occupied by edema revealed the presence of significantly more perimicrovascular edema in the experimental fecal peritonitis group compared to both sham-operated and unoperated controls, while no significant difference was present between the latter two groups. Electron microscopic investigation confirmed the presence of distinctive perimicrovascular edema in the fecal peritonitis group although the endothelial cells were linked by tight junctions which appeared morphologically intact. Although it might be premature to draw any strict parallels between the septic encephalopathy in humans and the findings observed in the present model, the results may suggest that the edema observed around the microvessels would bare a role in the pathogenesis of the septic encephalopathy probably by affecting the exchange of oxygen and nutrients with carbon dioxide and waste products between the blood and brain parenchyma.
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Experimental neurology · Mar 2006
Comparative StudyDifferential pharmacological modulation of the spontaneous stimulus-independent activity in the rat spinal cord following peripheral nerve injury.
Peripheral nerve injury is a significant clinical problem that is often difficult to treat. The major clinical symptoms are numbness, tactile and cooling allodynia, hyperalgesias as well as ongoing pain. In animal models of neuropathy, abnormal responses to applied (or evoked) stimuli can be gauged, but spontaneous pain, a major clinical issue, has proved very difficult to assess. ⋯ Morphine administered via the systemic route produced modest but non-significant reductions of spontaneous activity. The two NMDA receptor antagonists, ketamine and memantine, and the histamine H1 receptor antagonist, mepyramine, produced minor effects at doses known to be effective on stimulus evoked measures of deep dorsal horn neurones. This may form an electrophysiological basis for the efficacy of gabapentin and spinal morphine on ongoing pain in patients with peripheral neuropathy.