{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,21]],"date-time":"2025-11-21T12:11:04Z","timestamp":1763727064934},"reference-count":19,"publisher":"Wiley","issue":"8","license":[{"start":{"date-parts":[[2016,10,6]],"date-time":"2016-10-06T00:00:00Z","timestamp":1475712000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Clinical Anatomy"],"published-print":{"date-parts":[[2016,11]]},"abstract":"<jats:p>The classical recommendation for paramedian approaches is needle insertion 1\u20132 cm paramedian and an angle of 10\u00b0\u201315\u00b0 medial\u2013cephalad to the plane of the back, but contact with vertebrae is frequent. A mathematical approach to individualizing punctures is proposed on the basis of skin\u2013dural sac distance (d): Optimal angle \u223c <jats:italic>inverse cosine [d<\/jats:italic>\/\n<jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"graphic\/ca22792-math-0001.png\" xlink:title=\"urn:x-wiley:08973806:media:ca22792:ca22792-math-0001\" \/> and the distance covered by the needle \u223c \n<jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"graphic\/ca22792-math-0002.png\" xlink:title=\"urn:x-wiley:08973806:media:ca22792:ca22792-math-0002\" \/> for 1 cm paramedian punctures. The inferred angles were compared to optimal angles leading to the central dorsal part of the dural sac from 1 to 2 cm paramedian, measured by Magnetic Resonance Imaging (MRI) in seven cases and in a short stature volunteer (1.58 m, Body Mass Index (BMI) 23.2), to study supine and fetal positions using both closed MR and ultrasound. The average <jats:italic>(d)<\/jats:italic> decreased rostrally [6.8 cm (L4\u2013L5)\u22124.3 cm (T11\u2013T12)] while the mean optimal incidence angles increased [8.3\u00b0\u201316.5\u00b0 (L4\u2013L5) to 12.7\u00b0\u201324.1\u00b0 (T11\u2013T12) at 1\u20132 cm paramedian, respectively] and coincided with the estimated angles with a correlation coefficient\u2009=\u20090.98. In the volunteer, the optimal lateromedial angles increased from 14.4\u00b0 to 26.7\u00b0 (L3\u2013L4) to 17.1\u00b0\u201330.3\u00b0 (T11\u2013T12) for a (<jats:italic>d<\/jats:italic>)\u2009=\u20093.7 cm (L3\u2013L4)\u22123.1 cm (T11\u2013T12) and increased \u22643.7\u00b0 and \u22645.1\u00b0 at 1 and 2 cm paramedian, respectively, in fetal positions in MR. Ultrasound yielded comparable figures. The range of possible angles for dural punctures is wider at 1 cm paramedian in lower approaches in lateral decubitus [from 3.6\u00b0 at T12L1 (12.2\u00b0\u201315.8\u00b0) to 9\u00b0 at L3L4 (8.8\u00b0\u201318.7\u00b0)]. The classically recommended angles of 10\u00b0\u201315\u00b0 differ from the optimal angles, particularly in small patients, suggesting the need for ultrasound guidance or for inferring angles prior to spinal anesthesia.  Clin. Anat. 29:1046\u20131052, 2016. \u00a9 2016 Wiley Periodicals, Inc.<\/jats:p>","DOI":"10.1002\/ca.22792","type":"journal-article","created":{"date-parts":[[2016,9,6]],"date-time":"2016-09-06T15:27:49Z","timestamp":1473175669000},"page":"1046-1052","source":"Crossref","is-referenced-by-count":10,"title":["Pythagoras and Cosines: The skin\u2013dural sac distance and optimal angles in paramedian spinal anesthesia"],"prefix":"10.1002","volume":"29","author":[{"given":"Anna","family":"Puigdell\u00edvol\u2010S\u00e1nchez","sequence":"first","affiliation":[{"name":"Human Anatomy and Embryology Unit, Faculty of Medicine University of Barcelona Barcelona 08036 Spain"},{"name":"Ant\u00f3n de Borja Primary Care Center, Terrassa Health Consortium Rub\u00ed 08191 Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Miguel A.","family":"Reina","sequence":"additional","affiliation":[{"name":"Department of Anesthesiology Madrid\u2010Montepr\u00edncipe University Hospital, and School 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