title: Endonasal endoscopic approaches to the paramedian skull base.
abstract: OBJECTIVE
  To describe the technical and anatomic nuances related to endoscopic endonasal approaches (EEAs) to the paramedian skull base.
  
  
  METHODS
  Surgical indications, limitations, and technical aspects pertaining to EEAs designed to access areas oriented in the coronal plane are systematically reviewed with special attention to caveats, pitfalls, and common complications and how to avoid them. Case examples are presented.
  
  
  RESULTS
  The paramedian skull base may be divided into anterior (corresponding to the orbit and its contents), middle (corresponding to the middle cranial, pterygopalatine, and infratemporal fossae), and posterior (includes the craniovertebral junction lateral to the occipital condyles and the jugular foramen) segments. EEAs to the anterior segment offer access to the intraconal orbital space and the optic canal. A transpterygoid corridor typically precedes EEAs to the middle and posterior paramedian approaches. EEAs to the middle segment provide wide exposure of the petrous apex, middle cranial fossa (including cavernous sinus and Meckel cave), and infratemporal and pterygopalatine fossae. Finally, EEAs to the posterior segment access the hypoglossal canal, occipital condyle, and jugular foramen.
  
  
  CONCLUSIONS
  Approaches to the paramedian skull base are the most challenging and complex of all endoscopic endonasal techniques. Because of their technical complexity, it is recommended that surgeons master endoscopic endonasal anatomic approaches oriented to median structures (sagittal plane) before approaching paramedian (coronal plane) pathologies.
authors.affiliation: Department of Neurosurgery, The Ohio State University Medical Center, Columbus, Ohio, USA.
authors.forename: Danielle
authors.initials: D
authors.lastname: de Lara
authors.affiliation: Department of Neurosurgery, The Ohio State University Medical Center, Columbus, Ohio, USA.
authors.forename: Leo F S
authors.initials: LF
authors.lastname: Ditzel Filho
authors.affiliation: Department of Neurosurgery, The Ohio State University Medical Center, Columbus, Ohio, USA.
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Prevedello
authors.affiliation: Department of Otolaryngology-Head & Neck Surgery, The Ohio State University Medical Center, Columbus, Ohio, USA. Electronic address: carraurl@gmail.com.
authors.forename: Ricardo L
authors.initials: RL
authors.lastname: Carrau
authors.affiliation: Department of Otolaryngology-Head & Neck Surgery, The Ohio State University Medical Center, Columbus, Ohio, USA.
authors.forename: Pornthep
authors.initials: P
authors.lastname: Kasemsiri
authors.affiliation: Department of Otolaryngology-Head & Neck Surgery, The Ohio State University Medical Center, Columbus, Ohio, USA.
authors.forename: Bradley A
authors.initials: BA
authors.lastname: Otto
authors.affiliation: Division of Neurological Surgery, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Amin B
authors.initials: AB
authors.lastname: Kassam
mesh_terms: D004724:Endoscopy / Q000009:adverse effects / Q000379:methods*; D006801:Humans; D009296:Nasal Cavity / Q000033:anatomy & histology / Q000601:surgery*; D019635:Neurosurgical Procedures / Q000009:adverse effects / Q000379:methods*; D011183:Postoperative Complications / Q000453:epidemiology / Q000628:therapy; D019291:Skull Base / Q000033:anatomy & histology / Q000601:surgery*
keywords: Endonasal approach; Endoscopy; Infratemporal fossa; Middle cranial fossa; Posterior fossa; Pterygopalatine fossa; Skull base