Anatomical Variability and Biomedical Imaging for Spinal Anesthesia Individualization

Abstract

Spinal anesthesia can be affected by gaps in the ligamentum flavum that may confuse epidural needle placement; cause Quincke needle deformation if the vertebral bone is hit, expanding the dural sac hole and leading to cerebrospinal fluid (CSF) leakage and post-dural puncture headache; and variability in CSF volume, altering intrathecal drug dilution and anesthetic efficacy. Paramedian approaches with previously calculated optimal angles can be adopted, and CSF volumes may be estimated using threshold selection within the grayscale range following anatomical criteria. Angles can be determined by previously quantifying the skin-dural sac distance using ultrasound. Here, the relevant anatomical structures are illustrated (ligaments, the ligamentum flavum gap, vertebrae, meninges, cauda equina roots) using a freely available 3D PDF tool (http://hdl.handle.net/2445/55225), the additional inconvenience of variability in vertebra rotation is quantified, a free guide for optimizing spinal puncture is presented (http://hdl.handle.net/2445/179594), and the possibility of individualizing intrathecal drug dosages is discussed.