development-cadaveric-multiport-model-posterior-circulation-aneurysm

Development of a Cadaveric Multiport Model of Posterior Circulation Aneurysm Clipping for Neurosurgery and Otolaryngology Residents

Posterior circulation aneurysms are difficult to treat with the current methods of coiling and clipping. To address limitations in training, we developed ...

establishing-multidisciplinary-cavernous-carotid-injury-simulation-to

Establishing a Multidisciplinary Cavernous Carotid Injury Simulation to Train Neurosurgical, Otolaryngology, and Anesthesia Residents

Carotid artery injuries are serious complications of endoscopic endonasal surgery. As these occur rarely, simulation training offers an avenue for ...

Oregon Health & Science University

The role of potassium conductances in determining input resistance was studied in 166 genioglossal (GG) motoneurons using sharp electrode recording in brain stem slices of the rats aged 5-7 days, 13-15 days, and 19-24 days postnatal (P). A high magnesium (Mg(2+); 6 mM) perfusate was used to block calcium-mediated synaptic release while intracellular or extracellular cesium (Cs(+)) and/or extracellular tetraethylammonium (TEA) or barium (Ba(2+)) were used to block potassium conductances. In all cases, the addition of TEA to the high Mg(2+) perfusate generated a larger increase in both input resistance (R(n)) and the first membrane time constant (tau(0)) than did high Mg(2+) alone indicating a substantial nonsynaptic contribution to input resistance. With intracellular injection of Cs(+), GG motoneurons with lower resistance (<40 MOmega), on the average, showed a larger percent increase in R(n) than cells with higher resistance (>40 MOmega). There was also a significant increase in the effect of internal Cs(+) on R(n) and tau(0) with age. The largest percent increase (67%) in the tau(0) due to intracellular Cs(+) occurred at P13-15, a developmental stage characterized by a large reduction in specific membrane resistance. Addition of external Cs(+) blocked conductances (further increasing R(n) and tau(0)) beyond those blocked by the TEA perfusate. Substitution of external calcium with 2 mM barium chloride produced a significant increase in both R(n) and tau(0) at all ages studied. The addition of either intracellular Cs(+) or extracellular Ba(2+) created a depolarization shift of the membrane potential. The amount of injected current required to maintain the membrane potential was negatively correlated with the control R(n) of the cell at most ages. Thus low resistance cells had, on the average, more Cs(+)- and Ba(2+)-sensitive channels than their high resistance counterparts. There was also a disproportionately larger percent increase in tau(0) as compared with R(n) for both internal Cs(+) and external Ba(2+). Based on a model by Redman and colleagues, it might be suggested that the majority of these potassium conductances underlying membrane resistance are initially located in the distal dendrites but become more uniformly distributed over the motoneuron surface in the oldest animals.

Role of potassium conductances in determining input resistance of developing brain stem motoneurons.

The development of respiratory motoneurons provides unique data that may be generalized to other mammalian motoneuron populations. Like other motoneurons, respiratory motoneurons undergo developmental changes in the shape of the action potential and their repetitive firing. The unique observations concern the postnatal change in the recruitment pattern of cat phrenic motoneurons that is correlated with a halving of mean input resistance, a stasis of growth in the cell membrane and a reduction in the complexity of the dendritic tree. A similar pattern of change was observed for hypoglossal motoneurons studied in rat brainstem slices. Without an increase in total membrane surface area, the decreased resistance must result from a reduced specific membrane resistance. Two mechanisms are proposed to explain this decrease in resistance: proliferation and redistribution of either synaptic inputs and/or potassium channels. Although there was a significant contribution of synaptic input in determining input resistance throughout postnatal development, it was the density of cesium- or barium-sensitive potassium conductances that differentiated low resistance from high resistance motoneurons. Low resistance motoneurons had more cesium- and barium-sensitive channels than their high resistance counterparts. Based on the variations in the relative changes observed in input resistance versus membrane time constant with these two potassium channel blockers (cesium and barium), it is proposed that the distribution of these potassium channels change with age. Initially, their distribution is skewed toward the dendrites but as development progresses, the distribution becomes more uniform across the motoneuron membrane. During postnatal development, the rapid decrease in input resistance results from a proliferation of potassium channels in the membrane and of synaptic inputs converging onto developing respiratory motoneurons while the membrane is being spatially redistributed but not expanded.

Physiological changes accompanying anatomical remodeling of mammalian motoneurons during postnatal development.

A role for neuroscientists in engaging young minds.

Strategy for engaging the Society for Neuroscience in science education.

The NIH roadmap has among its goals, to promote studies designed to improve public understanding of biomedical and behavioral science, and to develop strategies for promoting collaborations between scientists and communities toward improving the public's health. Here, we report findings on the impact of a partnership between the Oregon Health and Science University (OHSU) and the Oregon Museum of Science and Industry (OMSI) designed to inform the public about health research being conducted in Oregon, which was linked to a 17-week traveling exhibition of BodyWorlds3. Measures included the public's understanding of health knowledge, attitudes, intended health behaviors, and visitor experience in their interactions with OHSU experts/volunteers, which were collected using exit surveys administered verbally. Nine hundred fifty-three surveys were included in analyses. Among those who felt that health behavior change was relevant to them, 67.4% of smokers (n = 133) intended to change their smoking behavior, 58.6% (of 677) intended to change their eating habits, 60.3% (of 667) intended to change their exercise routine, and 47% (of 448) intended to change their dental care habits. Forty-six percent of these visited the OHSU research exhibits (n = 437), and responded to how the exhibit changed their understanding about and openness to participate in health research. Greater than 85% had a much improved understanding of NIH research at OHSU and >58% reported they would be willing to participate in future research studies at OHSU. In conclusion, research partnerships between academic institutions and community-based museums appear to be viable ways to inform the public about research, stimulate their interest as future participants, and possibly influence their intention to improve health behaviors.

Educating the public about research funded by the National Institutes of Health using a partnership between an academic medical center and community-based science museum.

Health information technology (HIT) offers a resource for public empowerment through tailored information.

Let's Get Healthy! Health awareness through public participation in an education and research exhibit.

Engaging community members in research can help cultivate effective partnerships while providing experiential training and continuing education opportunities. Several studies have involved communities in this way, though many have been small in the scale of community involvement or have included little detail of the institutional review board process by which community members became approved researchers in the study. This article presents findings on an evaluation of the training procedures and experiences of 703 first-time community-based volunteer researchers who were recruited in their communities and trained on-site to enroll research participants, collect data, and provide individualized consultation of results at travelling health education and research fairs. Open-ended registration prompts and postfair surveys assessed volunteers' reasons for participating, comfort with their volunteer experiences, and attitudes toward the biomedical research process. An open-ended survey assessed two key community partners' perspectives about their organizations' involvement with supporting the research throughout the process. Volunteers reported their experience to be a unique training opportunity, citing its ability to help them engage with their community, advance research, and obtain additional experience in their health field of interest, particularly nursing, allied health, and medicine-related careers. Community partners cited that their community's participation as volunteer researchers served as a tool to educate the larger community about research, which enabled other research projects to gain acceptance. Together, these results demonstrate that using volunteer researchers can strengthen community research partnerships while providing valuable training experience in public health research for current and aspiring health personnel.

Experiential Learning Through Participatory Action Research in Public Health Supports Community-Based Training of Future Health Professionals.

Endoscopic surgical treatment of pituitary tumors, lateral invading tumors, or aneurysms requires surgeons to operate adjacent to the cavernous sinus. During these endoscopic endonasal procedures, the carotid artery is vulnerable to surgical injury at its genu. The objective of this simulation model was to evaluate trainees regarding management of a potentially life-threatening vascular injury.

Endoscopic Management of Cavernous Carotid Surgical Complications: Evaluation of a Simulated Perfusion Model.

 Endoscopic skull base approaches are being used to address complicated neurovascular pathology. These approaches are safest when proximal vascular control of the cavernous carotid artery (CavCA) can be obtained.  We present a cadaver-based anatomic simulation study showing the feasibility of clip placement for the CavCA as it courses through the cavernous sinus. The arterial vessels were injected with red microfil (Flow Tech, Carver, Massachusetts) to enhance visibility. The endoscope was directed through a precaruncular transorbital approach and instrumentation was managed through an endonasal transsphenoidal approach.  The dual approach minimized the "coning down" and instrument "sword fighting" that occurs as the rod lens endoscope and instruments are used laterally and posterior toward the clivus and brainstem. The precaruncular transorbital approach improved visualization of the clip application and improved the functional working area. The transorbital port allowed better appreciation of the distal clip tines, and the laterally positioned cranial nerves.  The advantages may be most realized in the setting of endoscopic endonasal resection of highly vascular lesions and/or bleeding from a ruptured aneurysm being clipped. Simulated training provides an excellent opportunity to enhance skill sets and increase familiarity with anatomical visualization before entering the operative arena.

Dual Endoscopic Endonasal Transsphenoidal and Precaruncular Transorbital Approaches for Clipping of the Cavernous Carotid Artery: A Cadaveric Simulation.

Arthroscopic surgical simulation, including the use of cadaveric tissue, is valuable for training orthopedic surgery residents. However, it is unclear how often fresh-frozen cadaveric tissue can be reused to provide a reproducible model for developing arthroscopic skills.

William E. Cameron

Oregon Health & Science University

Development of a Cadaveric Multiport Model of Posterior Circulation Aneurysm Clipping for Neurosurgery and Otolaryngology Residents

Establishing a Multidisciplinary Cavernous Carotid Injury Simulation to Train Neurosurgical, Otolaryngology, and Anesthesia Residents