Reply to the Editor

Abstract

We thank Lin and colleagues for their questions in response to our original article.1Al-Ali S. Chen B.S. Papali’i-Curtin A.T. Timmings A.R. Bergin C. Raudkivi P. et al.Adequacy of brain and spinal blood supply with antegrade cerebral perfusion in a rat model.J Thorac Cardiovasc Surg. 2011; 141: 1070-1076PubMed Scopus (7) Google Scholar Despite their assertions that removal of the spinal cord en bloc is not easy, however, we ourselves found no difficulty in the method we used as outlined in our article.1Al-Ali S. Chen B.S. Papali’i-Curtin A.T. Timmings A.R. Bergin C. Raudkivi P. et al.Adequacy of brain and spinal blood supply with antegrade cerebral perfusion in a rat model.J Thorac Cardiovasc Surg. 2011; 141: 1070-1076PubMed Scopus (7) Google Scholar Dissection of the spinal cord was performed under a desk magnifying lamp with a pair of fine, sharp-pointed scissors, a fine-bladed scalpel, a corneoscleral punch instrument, and a dissecting probe and seeker. To summarize, we dissected to expose the spinous processes and laminae bilaterally. Next, we performed horizontal amputation of the spinous processes, followed by bilateral laminotomy with the punch instrument, beginning at the level of the cervical spine. We removed small fragments of laminae along the entire length of the vertebra and lifted to expose the spinal cord enclosed in dura. Although there are variations in the spinal cord vasculature in rats, the longitudinal spinal arteries show little variability.2Tveten L. Spinal cord vascularity. IV. The spinal cord arteries in the rat.Acta Radiol Diagn (Stockh). 1976; 17: 385-398PubMed Google Scholar In our experience, all the rats that we dissected had 2 dorsal (posterior) spinal arteries running the entire length of the spinal cord. Nevertheless, we still confirmed vasculature filling and penetration of the neural tissue by cross-sectional histologic examination. We would therefore suggest that Lin and colleagues examine the spinal cords that they have dissected under surgical stereomicroscopy, as there appear to be dorsal spinal arteries running longitudinally in the image they have provided, or extend their dissection laterally, as the dorsal spinal arteries often appear more dorsolateral.2Tveten L. Spinal cord vascularity. IV. The spinal cord arteries in the rat.Acta Radiol Diagn (Stockh). 1976; 17: 385-398PubMed Google Scholar In the cases in which dorsal spinal arteries were incomplete or absent, cross-sectional histologic examination would determine extent of internal supply to the spinal cord afforded by whichever variation of antegrade cerebral perfusion was being examined. The length of the spinal cord from the brain stem to the conus medullaris was measured after the dura mater was incised. At no point did we attempt to determine the length of the cord with the dura mater intact, as suggested by Lin and colleagues. Nevertheless once exposed, the conus medullaris is easily distinguishable from the cauda equina because it is distinctly thick and midline, whereas the cauda equina is oblique and thin.3Wall E.J. Cohen M.S. Massie J.B. Rydevik B. Garfin S.R. Cauda equina anatomy. I: Intrathecal nerve root organization.Spine (Phila Pa 1976). 1990; 15: 1244-1247Crossref PubMed Scopus (42) Google Scholar, 4Arslan M. Cömert A. Açar H.I. Özdemir M. Elhan A. Tekdemir İ et al.Lumbosacral intrathecal nerve roots: an anatomical study.Acta Neurochirurgica. 2011; 153: 1435-1442Crossref PubMed Scopus (14) Google Scholar En bloc removal of the brain and spinal cord for perfusion studiesThe Journal of Thoracic and Cardiovascular SurgeryVol. 143Issue 3PreviewWe were a little puzzled during our reading of Al-Ali and colleagues’ recent article.1 They mentioned that the brain and spinal cord were photographed and then carefully removed en bloc. Because the epidural space between spinal cord and vertebrae is small, spinal cord removed en bloc was not easy even if the spinal cords were fixed. Which methods and equipment were applied by Al-Ali and colleagues? In our experience, the vertebral column and cranium was decalcified first. Then craniotomy and laminectomy were easily performed to expose the brain and spinal cord in situ. Full-Text PDF