Tips for Surgical Technique. Bermans Iskandar, M.D.
Risk for blood loss: The foramen magnum and then the dorsal arch of C1 are exposed with care taken not to extend this dissection laterally beyond the edges of the dura. Further lateral exposure would place the patient at risk of vascular injury. The vertebral venous plexus is medial to and encompasses the vertebral artery. Venous bleeding laterally can almost always be controlled with coagulation and/or packing with thrombotic material.
Ligamentous laxity: When waxing the opened ring of C1, especially in young infants, one should keep in mind that these structures are mobile, thus the force used during this maneuver should be minimized. By leaving the muscle attachments and laminae of C2 intact, the severity of postoperative pain and the potential for spinal instability are minimized. Maintenance of C2 is possible even if the tonsils descend under the lamina. In these cases, the tonsils are gently withdrawn from underneath the lamina.
Status of foramen of Magendie: The dura is opened in a Y fashion exposing the tonsils from origin to tips. If the tonsils are pulsating and CSF is exiting the foramen of Magendie, closure is started. If Magendie is occluded, the arachnoid is opened to ensure the absence of an obstructing veil. At the authors' center, the tonsils are not coagulated or reduced in size.
Autogenous graft used for duroplasty: A nuchal ligament graft harvested during the opening from the intermuscular plane is used to patch the dura with a running 5-0 PDS suture in a watertight closure, thus creating a capacious sac.