title: Unusual Association Between Spontaneous Lateral Sphenoid Encephalocele and Chiari Malformation Type I: Endoscopic Repair Through a Transpterygoid Approach.
abstract: BACKGROUND
  Spontaneous meningoencephaloceles of the lateral sphenoid sinus are rare entities, and their peculiar location represents a surgical challenge due to the importance of a wide exposure and skull base reconstruction. They are thought to arise from the congenital base defect of the lateral sphenoid or in some cases have been postulated to represent a rare manifestation of altered cerebrospinal fluid (CSF) dynamics. We report the first case in the literature of a Chiari malformation type I (CMI) and a lateral sphenoid encephalocele, revising the theoretic etiology and surgical technique of endoscopic repair.
  
  
  METHODS
  A 50-year-old woman with a surgical history of symptomatic CMI presented with episodes of spontaneous CSF rhinorrhea. Radiologic investigations revealed a left mesial temporal encephalocele herniating into the lateral recess of the sphenoid sinus and radiologic features of altered CSF dynamics, which may have played an etiologic role. An endoscopic transpterygoid excision of the encephalocele and multilayer skull base repair were performed.
  
  
  CONCLUSIONS
  The association of spontaneous lateral sphenoid encephaloceles with CMI is distinctly unusual. Predisposing factors and disruption of CSF dynamics may play a major role in the development of these rare complications in patients with CMI. Because of their distinct location, transethmoid or transpterygoid endoscopic approaches represent an excellent surgical technique to treat these lesions thanks to their wide and direct visualization of the entire skull base defect following the encephalocele excision, allowing an adequate multilayer repair and lateral sphenoid recess occlusion.
authors.affiliation: Neurosurgical Service, Centre Hospitalier Universitaire Vaudois, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland. Electronic address: danielestarnoni@gmail.com.
authors.forename: Daniele
authors.initials: D
authors.lastname: Starnoni
authors.affiliation: Neurosurgical Service, Centre Hospitalier Universitaire Vaudois, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.
authors.forename: Roy Thomas
authors.initials: RT
authors.lastname: Daniel
authors.affiliation: ENT Service, Centre Hospitalier Universitaire Vaudois, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.
authors.forename: Mercy
authors.initials: M
authors.lastname: George
authors.affiliation: Neurosurgical Service, Centre Hospitalier Universitaire Vaudois, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.
authors.forename: Mahmoud
authors.initials: M
authors.lastname: Messerer
mesh_terms: D001139:Arnold-Chiari Malformation / Q000150:complications / Q000000981:diagnostic imaging / Q000601:surgery*; D004677:Encephalocele / Q000150:complications / Q000000981:diagnostic imaging / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008588:Meningocele / Q000150:complications / Q000000981:diagnostic imaging / Q000601:surgery*; D008875:Middle Aged; D044583:Neuroendoscopy / Q000379:methods*; D011626:Pterygoid Muscles / Q000000981:diagnostic imaging / Q000601:surgery; D013100:Sphenoid Bone / Q000000981:diagnostic imaging / Q000601:surgery*
keywords: Chiari malformation type I; Encephalocele; Endoscopic surgery; Meningoencephalocele; Skull base; Sphenoid sinus