title: Delayed paradoxical herniation after a decompressive craniectomy: case report.
abstract: BACKGROUND
  Paradoxical herniation can occur as a complication of lumbar puncture in patients who had a decompressive craniectomy. The supposed mechanism is the development of a negative pressure gradient that allows the brain to shift toward the infratentorial space with subsequent herniation. Trendelenburg position plus early cranioplasty has been the suggested treatment to eliminate the gradient.
  
  
  METHODS
  A 53-year-old woman had a decompressive hemicraniectomy for SAH-related swelling. A lumbar puncture was performed on postoperative day 5 to rule out infection. She remained neurologically stable until 6 weeks later, when she deteriorated because of a paradoxical herniation. Head positioning and cranioplasty were only temporarily helpful. She developed a second episode of decline a few days later due to an extraaxial CSF collection. A lumbar blood patch plus drainage of the collection successfully allowed full neurologic recovery.
  
  
  CONCLUSIONS
  Cranioplasty and head positioning alone might not be sufficient to eliminate the negative pressure gradient. A blood patch should be part of the management of paradoxical herniation.
authors.affiliation: Department of Neurological Surgery, Harborview Medical Center, University of Washington, Seattle, WA 98104, USA. mdvilela@u.washington.edu
authors.forename: Marcelo Duarte
authors.initials: MD
authors.lastname: Vilela
mesh_terms: D003399:Craniotomy / Q000379:methods*; D019299:Decompression, Surgical / Q000379:methods; D004677:Encephalocele / Q000000981:diagnostic imaging / Q000209:etiology / Q000601:surgery; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000150:complications; D008875:Middle Aged; D011183:Postoperative Complications; D013129:Spinal Puncture; D013345:Subarachnoid Hemorrhage / Q000209:etiology / Q000601:surgery; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D017287:Ventriculoperitoneal Shunt