title: Endoscopic Transnasal Transclival Resection of Endodermal Cyst on Ventral Surface of Brainstem.
abstract: BACKGROUND
  Endodermal cysts are a rare pathology of the central nervous system located mostly in the upper thoracic or cervical regions. Seldomly, the cysts are found intracranially, most often in the subtentorial area (on the ventral surface of the brainstem, pontocerebellar angle, and fourth ventricle). Traditional approaches to the ventral surface of the brainstem are complicated and traumatic, and they do not provide a good view of the tumor's central and contralateral parts. In this case report, we present an alternative approach for resection of the endodermal cyst on the ventral surface of the brainstem.
  
  
  METHODS
  Our patient, 27 years old, was observed for 6 years with a preliminary diagnosis of pilocytic astrocytoma. Previously, the patient had an Ommaya system implanted into the cyst and underwent stereotactic radiotherapy (54 Gy). The tumor was resected through an extended transsphenoidal transclival endonasal endoscopic approach. Histologic examination confirmed the diagnosis of endodermal cyst. Significant regression of the symptoms was noted. Complications were not seen.
  
  
  CONCLUSIONS
  The main advantage of the transclival transnasal approach is the direct access to the clivus and ventral surface of the brainstem without traction of the cerebral structures. If the transsphenoidal transclival approach is used, the cranial nerves are out of the approach area that minimizes the risk to damage it. An extended transsphenoidal transclival endonasal endoscopic approach is an alternative to traditional microsurgical approaches to pathologic processes on the ventral surface of the brainstem (cavernomas, endodermal cysts), located centrally.
authors.affiliation: Department of Skull Base Surgery, Burdenko Neurosurgical Institute, Moscow, Russian Federation. Electronic address: dfomichev@list.ru.
authors.forename: Dmitry
authors.initials: D
authors.lastname: Fomichev
authors.affiliation: Department of Skull Base Surgery, Burdenko Neurosurgical Institute, Moscow, Russian Federation.
authors.forename: Pavel
authors.initials: P
authors.lastname: Kalinin
authors.affiliation: Department of Skull Base Surgery, Burdenko Neurosurgical Institute, Moscow, Russian Federation.
authors.forename: Andrey
authors.initials: A
authors.lastname: Gavrushin
mesh_terms: D000328:Adult; D020295:Brain Stem Neoplasms / Q000473:pathology* / Q000601:surgery*; D020863:Central Nervous System Cysts / Q000473:pathology* / Q000601:surgery*; D003388:Cranial Fossa, Posterior / Q000473:pathology / Q000601:surgery; D006801:Humans; D044583:Neuroendoscopy / Q000379:methods*; D016896:Treatment Outcome
keywords: Cerebrospinal fluid; Endoscopic; Enterogenous cyst; Neurenteric cyst; Skull base surgery; Transnasal approach; Transsphenoidal approach