{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,2]],"date-time":"2026-07-02T16:20:29Z","timestamp":1783009229714,"version":"3.54.5"},"reference-count":24,"publisher":"American Veterinary Medical Association (AVMA)","issue":"7","license":[{"start":{"date-parts":[[2026,7,1]],"date-time":"2026-07-01T00:00:00Z","timestamp":1782864000000},"content-version":"unspecified","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["ajvr"],"published-print":{"date-parts":[[2026,7,1]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec id=\"sc_a1\">\n                    <jats:title>Objective<\/jats:title>\n                    <jats:p>To quantify ultrasonographic changes in cisternal subarachnoid space dimensions across graded neck-flexion angles and to identify the angle providing adequate expansion for CSF collection in dogs.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sc_a2\">\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>The study included 6 healthy adult male Beagles at a single veterinary teaching hospital (July 14 through August 14, 2025). Under general anesthesia in right lateral recumbency, the neck was flexed to 10\u00b0, 15\u00b0, 20\u00b0, 30\u00b0, 60\u00b0, and 90\u00b0. Transverse-plane images were used to measure subarachnoid space depth and area, and sagittal-plane images were used to measure atlanto-occipital membrane length. Three measurements\/angle\/variable were obtained. Data were analyzed using repeated-measures ANOVA and linear mixed models.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sc_a3\">\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      All dogs completed the study without adverse events. Subarachnoid space depth increased from 1.31 \u00b1 0.13 mm at 10\u00b0 to 2.26 \u00b1 0.51 mm at 60\u00b0 and 2.19 \u00b1 0.33 mm at 90\u00b0 (60\u00b0 vs 90\u00b0). Subarachnoid space area reached 29.9 \u00b1 14.8 mm\n                      <jats:sup>2<\/jats:sup>\n                      at 60\u00b0 and then declined to 26.8 \u00b1 9.9 mm\n                      <jats:sup>2<\/jats:sup>\n                      at 90\u00b0. Membrane length rose from 7.6 \u00b1 1.3 mm at 30\u00b0 to 10.2 \u00b1 1.0 mm at 60\u00b0 and 11.4 \u00b1 1.1 mm at 90\u00b0.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sc_a4\">\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>Neck flexion up to 60\u00b0 achieved sufficient expansion of the cisternal subarachnoid space and atlanto-occipital membrane, with no meaningful gain beyond this angle.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sc_a5\">\n                    <jats:title>Clinical Relevance<\/jats:title>\n                    <jats:p>Routine 90\u00b0 flexion provides no benefit over 60\u00b0 and may increase risk; practitioners who flex beyond 60\u00b0 may compromise patient safety without enhancing access, supporting moderate positioning as effective and safe.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.2460\/ajvr.26.02.0058","type":"journal-article","created":{"date-parts":[[2026,3,27]],"date-time":"2026-03-27T14:59:51Z","timestamp":1774623591000},"source":"Crossref","is-referenced-by-count":0,"title":["Neck flexion to 60\u00b0 maximizes cisternal subarachnoid space for cerebrospinal fluid collection in dogs"],"prefix":"10.2460","volume":"87","author":[{"given":"Junsoo","family":"Kim","sequence":"first","affiliation":[{"name":"Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Taehoon","family":"Sung","sequence":"additional","affiliation":[{"name":"Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Changhoon","family":"Nam","sequence":"additional","affiliation":[{"name":"Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Inhyung","family":"Lee","sequence":"additional","affiliation":[{"name":"Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5431-3254","authenticated-orcid":true,"given":"Won-gyun","family":"Son","sequence":"additional","affiliation":[{"name":"Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1272","reference":[{"issue":"1","key":"B1","series-title":"Vet J","first-page":"15","article-title":"The function, composition and analysis of cerebrospinal fluid in companion animals: part II - analysis","author":"Di Terlizzi R","year":"2009","unstructured":"Di Terlizzi R, Platt SR. The function, composition and analysis of cerebrospinal fluid in companion animals: part II - analysis. Vet J. 2009;180(1):15\u201332. doi:10.1016\/j.tvjl.2007.11.024"},{"key":"B2","series-title":"Cowell and Tyler\u2019s Diagnostic Cytology and Hematology of the Dog and the Cat","first-page":"210","article-title":"Cerebrospinal fluid and central nervous system cytology","author":"Levine GJ","year":"2019","unstructured":"Levine GJ, Cook JR. Cerebrospinal fluid and central nervous system cytology. In: Valenciano AC, Cowell RL, eds. Cowell and Tyler\u2019s Diagnostic Cytology and Hematology of the Dog and the Cat. 5th ed. Elsevier; 2019:210\u2013228."},{"key":"B3","series-title":"Textbook of Veterinary Internal Medicine: Diseases of the Dog and the Cat","first-page":"447","article-title":"Cerebrospinal fluid collection, myelography, epidurography and discography","author":"Adamo PF","year":"2010","unstructured":"Adamo PF. Cerebrospinal fluid collection, myelography, epidurography and discography. In: Ettinger SJ, Feldman EC, eds. Textbook of Veterinary Internal Medicine: Diseases of the Dog and the Cat. 7th ed. Elsevier; 2010:447\u2013450."},{"issue":"1","key":"B4","series-title":"J Neurosurg Anesthesiol","first-page":"10","article-title":"Effects of neck position and head elevation on intracranial pressure in anaesthetized neurosurgical patients: preliminary results","author":"Mavrocordatos P","year":"2000","unstructured":"Mavrocordatos P, Bissonnette B, Ravussin P. Effects of neck position and head elevation on intracranial pressure in anaesthetized neurosurgical patients: preliminary results. 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Cureus. 2024;16(3):e55760. doi:10.7759\/cureus.55760"},{"issue":"2","key":"B7","series-title":"Anesthesiology","first-page":"169","article-title":"Comparison of the effects of positive end-expiratory pressure and jugular venous compression on canine cerebral venous pressure","author":"Toung TJ","year":"1984","unstructured":"Toung TJ, Ngeow YK, Long DL, Rogers MC, Traystman RJ. Comparison of the effects of positive end-expiratory pressure and jugular venous compression on canine cerebral venous pressure. Anesthesiology. 1984;61(2):169\u2013172. doi:10.1097\/00000542-198408000-00010"},{"issue":"1","key":"B8","series-title":"J Anat","first-page":"13","article-title":"Utility of a flexed neck sagittal magnetic resonance imaging sequence for the assessment of cerebellomedullary cistern in dogs","author":"Sivolapenko D","year":"2022","unstructured":"Sivolapenko D, Duncan J, Eivers C, Liuti T, Marioni-Henry K. 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Complications after cerebrospinal fluid collection in dogs with brain neoplasm. Pesq Vet Bras. 2022;42:e06984. doi:10.1590\/1678-5150-pvb-6984"},{"issue":"1","key":"B11","series-title":"J Anesth","first-page":"120","article-title":"Upper airway obstruction associated with flexed cervical position after posterior occipitocervical fusion","author":"Tagawa T","year":"2011","unstructured":"Tagawa T, Akeda K, Asanuma Y, et al. Upper airway obstruction associated with flexed cervical position after posterior occipitocervical fusion. J Anesth. 2011;25(1):120\u2013122. doi:10.1007\/s00540-010-1069-0"},{"issue":"3","key":"B12","series-title":"Can J Anesth","first-page":"289","article-title":"Cervical spine overflexion in a halo orthosis contributes to complete upper airway obstruction during awake bronchoscopic intubation: a case report","author":"White ANJ","year":"2015","unstructured":"White ANJ, Wong DT, Goldstein CL, Wong J. 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