We would like to thank the Thoracic Surgery Foundation for Research and Education for their Financial Support of this project.

1. Preoperative Preparation and Anesthesia
<ol>
	<li>Be sure to observe sterile technique throughout the procedure.&#160;Lay out all instruments.</li>
	<li>Turn on the temperature control bed prior to anesthetic induction so that it may warm to the appropriate temperature (36.5 &#176;C).&#160; Power on the laser Doppler perfusion monitor so that it may boot during induction.</li>
	<li>Place the mouse in the induction chamber.
	<ol>
		<li>Carefully monitor the respiratory rate of the mouse during induction.</li>
		<li>A...

<ol>
	<li>Conrad, M. F., Ye, J. Y., Chung, T. K., Davison, J. K., Cambria, R. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spinal+cord+complications+after+thoracic+aortic+surgery:+long-term+survival+and+functional+status+varies+with+deficit+severity.">Spinal cord complications after thoracic aortic surgery: long-term survival and functional status varies with deficit severity.</a> J. Vasc. Surg. 48, 47-53 (2008).</li><li>Okita, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fighting+spinal+cord+complication+during+surgery+for+thoracoabdominal+aortic+disease.">Fighting spinal cord complication during surgery for thoracoabdominal aortic disease.</a> Gen. Thorac. Cardiovasc. Surg. 59, 79-90 (2011).</li><li>Wong, D. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Delayed+spinal+cord+deficits+after+thoracoabdominal+aortic+aneurysm+repair.">Delayed spinal cord deficits after thoracoabdominal aortic aneurysm repair.</a> Ann. Thorac. Surg. 83, 1345-1355 (2007).</li><li>Taira, Y., Marsala, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+proximal+arterial+perfusion+pressure+on+function,+spinal+cord+blood+flow,+and+histopathologic+changes+after+increasing+intervals+of+aortic+occlusion+in+the+rat.">Effect of proximal arterial perfusion pressure on function, spinal cord blood flow, and histopathologic changes after increasing intervals of aortic occlusion in the rat.</a> Stroke. 27, 1850-1858 (1996).</li><li>Naslund, T. C., Hollier, L. H., Money, S. R., Facundus, E. C., Skenderis, B. 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The authors declare&#160;no competing financial interests.

Paraplegia secondary to spinal cord ischemia&#160;reperfusion is the result of a complex of poorly understood pathologies9. While this is most commonly seen after thoracoabdominal aortic surgery, a variety of other insults such as&#160; aortic dissections, trauma, embolic phenomena, vasculitis, and systemic hypotension10 can result in paraplegia.&#160;To gain further understanding of this injury and provide future targets to eliminate this injury, animal models have become a necessity.
<p class=...

Lower extremity paralysis continues to complicate thoracoabdominal interventions. The injury, known as spinal cord ischemia-reperfusion injury (SCIR), results in paralysis in up to 20% of high risk patients1. Surgical adjuncts such as left heart bypass, lumbar cerbrospinal fluid drains,&#160;hypothermic circulatory arrest and intercostal artery reimplantation have reduced the incidence of this complication2; however, far too many patients continue to be affected.
Clinically, spinal cord ischemia and reperfusion injury is seen as either immediate or delayed paralysis following intervention3.&#160;However, our understanding of this injury has been stifled by a lack of mechanistic detail.&#160;As a result, few options are available to attenuate the injury once it has occurred.
We have thus enlisted a small animal, murine, model of spinal cord ischemia, and reperfusion injury to better characterize its pathogenesis.&#160;The majority of studies to date have used larger animal models to characterize this injury, namely rat4, rabbit5, and pig6 models.&#160; However, these are limited by their cost, complexity, variable reproducibility, and, most importantly, lack of available techniques for genetic manipulation.&#160;&#160;The most reliable of these published animal models involves infrarenal cross&#160;clamping of the abdominal aorta in rabbits.&#160;However, human anterior spinal neurons most often derive their vascular supply from more proximal branches7.&#160;Variable vascular anatomy of the spinal cord in these models adds to difficulty in transitioning their results into clinical use.
This manuscript presents a model for immediate or delayed paraplegia following thoracic aortic occlusion that is clinically relevant and easy to employ. Exposure of the aortic arch via mini&#160;sternotomy is less invasive and can elicit highly reproducible results with minimal morbidity and mortality. While this model in not without challenges and technical nuances, these can be overcome with careful dissection and tissue handling to produce a model of hind&#160;limb paralysis that can be easily implemented.

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		<tr height="21">
			<td height="21" style="height:21px;width:216px;">VMS Anesthesia Machine</td>
			<td style="width:247px;">MDS Matrx</td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Isoflurane</td>
			<td style="width:247px;">Vet One</td>
			<td style="width:119px;">13985-528-60</td>
			<td>2.0% through nose cone&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Induction Chamber</td>
			<td style="width:247px;">Vet Equip</td>
			<td>941444</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Heating Bed</td>
			<td style="width:247px;">Vestavia Scientific</td>
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			<td></td>
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		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Laser Doppler Monitor</td>
			<td style="width:247px;">Moor Instruments</td>
			<td style="width:119px;">VMS-LDF1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">5-0 Suture, Polyester</td>
			<td style="width:247px;">Surgidac</td>
			<td style="width:119px;">VD-551</td>
			<td>Taper Needel</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:216px;">Microdissecting Clips</td>
			<td style="width:247px;">Biomedical Research Insturments</td>
			<td style="width:119px;">14-1030, 14-1060</td>
			<td></td>
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		<tr height="25">
			<td height="25" style="height:25px;width:216px;">Surgical Instruments</td>
			<td style="width:247px;">Fine Surgical Instruments</td>
			<td style="width:119px;"></td>
			<td>Forceps, needle holder</td>
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reproducable paraplegia by thoracic aortic occlusion in a murine model of spinal cord ischemia-reperfusion

Background 
Lower extremity paralysis continues to complicate aortic interventions. The lack of understanding of the underlying pathology has hindered advancements to decrease the occurrence this injury.&#160;The current model demonstrates reproducible lower&#160;extremity paralysis following thoracic aortic occlusion.
Methods 
Adult male C57BL6 mice were anesthetized with isoflurane. Through a cervicosternal incision the aorta was exposed. The descending thoracic aorta and left subclavian arteries were identified without entrance into pleural space. Skeletonization of these arteries was followed by immediate closure (Sham) or occlusion for 4 min (moderate ischemia) or 8 min (prolonged ischemia). The sternotomy and skin were closed and the mouse was transferred to warming bed for recovery.&#160; Following recovery, functional analysis was obtained at 12 hr intervals until 48 hr.
Results 
Mice that underwent sham surgery showed no observable hind&#160;limb deficit. Mice subjected to moderate ischemia for 4 min had minimal functional deficit at 12 hr followed by progression to complete paralysis at 48 hr. Mice subjected to prolonged ischemia had an immediate paralysis with no observable hind-limb movement at any point in the postoperative period. There was no observed intraoperative or post&#160;operative mortality.
Conclusion 
Reproducible lower extremity paralysis whether immediate or delayed can be achieved in a murine model. Additionally, by using a median sternotomy and careful dissection, high survival rates, and reproducibility can be achieved.

Mice underwent sham surgery (n=3) or aortic occlusion for 4 (n=3) to 8 min (n=3). Postoperatively mice were graded by the Basso Mouse Score (Figure 1).&#160;Mice that underwent sham surgery had no observable functional deficits at any point postoperatively. Mice subjected to moderate ischemia (4 min) had near normal hind-limb function at 12 hr with progressive functional decline to complete paralysis by 48 hr. Mice in prolonged ischemia group (8min) had complete paralysis following surgery without any re...

Watch this Scientific Journal Video about Reproducable Paraplegia by Thoracic Aortic Occlusion in a Murine Model of Spinal Cord Ischemia-reperfusion at JoVE.com

Reproducable Paraplegia by Thoracic Aortic Occlusion in a Murine Model of Spinal Cord Ischemia-reperfusion

The lack of mechanistic understanding of spinal cord ischemia-reperfusion injury has hindered further adjuncts to prevent paraplegia following high risk aortic operations. Thus, the development of animal models is imperative. This manuscript demonstrates reproducible lower extremity paralysis following thoracic aortic occlusion in a murine model.

Background
Lower extremity paralysis continues to complicate aortic interventions. The lack of understanding of the underlying pathology has hindered ...

reproducable-paraplegia-thoracic-aortic-occlusion-murine-model-spinal

Research

JoVE Journal

Medicine

11.9K visualizações.  University of Colorado.  A falta de entendimento mecanicista da medula espinhal lesão de isquemia-reperfusão tem dificultado mais adjuntos para evitar paraplegia após operação da aorta alto risco. Assim, o desenvolvimento de modelos animais é imperativo. Este manuscrito demonstra reprodutível menor paralisia extremidade após oclusão da aorta torácica em um modelo murino. 