Propofol disrupts functional interactions between sensory and high-order processing of auditory verbal memory.

Current theories suggest that disrupting cortical information integration may account for the mechanism of general anesthesia in suppressing consciousness. Human cognitive operations take place in hierarchically structured neural organizations in the brain. The process of low-order neural representation of sensory stimuli becoming integrated in high-order cortices is also known as cognitive binding. Combining neuroimaging, cognitive neuroscience, and anesthetic manipulation, we examined how cognitive networks involved in auditory verbal memory are maintained in wakefulness, disrupted in propofol-induced deep sedation, and re-established in recovery. Inspired by the notion of cognitive binding, an functional magnetic resonance imaging-guided connectivity analysis was utilized to assess the integrity of functional interactions within and between different levels of the task-defined brain regions. Task-related responses persisted in the primary auditory cortex (PAC), but vanished in the inferior frontal gyrus (IFG) and premotor areas in deep sedation. For connectivity analysis, seed regions representing sensory and high-order processing of the memory task were identified in the PAC and IFG. Propofol disrupted connections from the PAC seed to the frontal regions and thalamus, but not the connections from the IFG seed to a set of widely distributed brain regions in the temporal, frontal, and parietal lobes (with exception of the PAC). These later regions have been implicated in mediating verbal comprehension and memory. These results suggest that propofol disrupts cognition by blocking the projection of sensory information to high-order processing networks and thus preventing information integration. Such findings contribute to our understanding of anesthetic mechanisms as related to information and integration in the brain.

Care Bundle Approach to Minimizing Infection Rates after Neurosurgical Implants for Neuromodulation: A Single-Surgeon Experience.

INTRODUCTION: Implant-related infections carry a high morbidity. Infectious rates for neuromodulation implants range from 1% to 9% for deep brain stimulation (DBS), 0% to 10% for spinal cord stimulation (SCS) systems, and 3% to 15% for intrathecal (IT) pump systems. Meanwhile, studies of care bundles report infection rate reduction to 1.0% for SCS and 0.3% for cardiac implants. Herein, we evaluate the effectiveness of an infection prevention bundle (IPB) in minimizing infections after surgeries for neuromodulation implants. METHODS: An IPB focused on preoperative checklists, screening questionnaires, methicillin-resistant and methicillin-sensitive Staphylococcus aureus decolonization, weight-based antibiotic prophylaxis, strict draping and surgical techniques, and wound care education was implemented in our functional neurosurgery division in April 2015. We retrospectively reviewed all surgeries for implantation or replacement of SCS, DBS, and IT pump system components from March 2013 to October 2017. The patients were divided into pre-IPB and post-IPB groups. All procedures were performed by a single surgeon. Each surgical site was considered a unique surgical case. Infection rates were calculated for pre-IPB and post-IPB groups. RESULTS: A total of 688 patients underwent 1161 unique surgical procedures (222 DBS electrodes, 419 IPG, 203 SCS, 317 IT pumps) during the study period. There were 546 pre-IPB and 615 post-IPB surgical procedures. The pre-IPB infection rates were 0%, 1.3%, and 8.7% for SCS, DBS, and IT pumps, respectively. The post-IPB infection rates were 0%, 0.3%, and 1.8% for SCS, DBS, and IT pumps, respectively. CONCLUSIONS: Implementation of a standardized IPB approach reduced the number of infections for all neuromodulation implants studied. This approach can be adopted within any specialty to potentially decrease the incidence of implant-related infections.