title: Comparison of surgical exposure and maneuverability associated with microscopy and endoscopy in the retrolabyrinthine and transcrusal approaches to the retrochiasmatic region: a cadaveric study.
abstract: BACKGROUND
  The retrolabyrinthine and transcrusal approaches (RLA and TCA, respectively) are the two most often used posterior transpetrosal approaches that are used to treat lesions in the retrochiasmatic region. Endoscopes are increasingly used in neurosurgical practice. To determine whether a difference exists between the two transpetrosal approaches in the retrochiasmatic region, we evaluated and compared the exposure and maneuverability associated with the microscope and the endoscope in these approaches.
  
  
  METHODS
  Seven formalin-fixed cadaveric heads were dissected bilaterally through the two approaches: four for evaluation and three injected with colored latex for photography. The retrochiasmatic region was divided into four sub-compartments: the compartment before the infundibulum, which was further divided into two parts, (1) the ipsilateral and (2) the contralateral compartments; (3) the retroinfundibulum compartment; (4) the third ventricle. After each approach, exposure and maneuverability of the structures in these four compartments obtained by microscopy and endoscopy were scored under a guidance of a numerical grading system for further comparison.
  
  
  RESULTS
  The TCA provided better exposure and maneuverability at the retrochiasmatic region than the RLA in both the microscopy model [scores of 39.75 ± 2.12 and 32.38 ± 2.56 respectively (p < 0.05)] and the endoscopy model [scores of 82.13 ± 3.40 and 43.75 ± 1.67 respectively (p < 0.05)].
  
  
  CONCLUSIONS
  The TCA is better than the RLA at offering exposure and manipulation to structures in the retrochiasmatic region, especially in patients whose lesion is located high into the third ventricle and/or expanded into the contralateral part. Endoscopes may be helpful in TCA in terms of exposing and maneuvering structures in the contralateral and interpeduncle fossa areas. However, in RLA, not enough room is available for simultaneously maneuvering an endoscope and a surgical instrument.
authors: Institute of Minimal Invasive Surgical Anatomy, Department of Anatomy, School of Basic Medicine Science, Southern Medical University, Tonghe, 510515, Guangzhou, China.
authors: Jie
authors: J
authors: Yang
authors: Department of Otolaryngology, The Third Affiliated Hospital of Southern Medical University, Guangzhou, 510630, Guangdong, China.
authors: Fang
authors: F
authors: Zhang
authors: Department of Otolaryngology, The First College of Clinical Medical Science, China Three Gorges University & Yichang Central People's Hospital, Yichang, 443003, Hubei, China.
authors: Aiguo
authors: A
authors: Xu
authors: Department of Neurosurgery, Lingyi People's Hospital, Lingyi, 276003, Shandong, China.
authors: Huadong
authors: H
authors: Li
authors: Institute of Minimal Invasive Surgical Anatomy, Department of Anatomy, School of Basic Medicine Science, Southern Medical University, Tonghe, 510515, Guangzhou, China. 2723475906@qq.com.
authors: Zihai
authors: Z
authors: Ding
mesh_terms: D001921:Brain / Q000601:surgery*; D007758:Ear, Inner / Q000601:surgery*; D006801:Humans; D008866:Microsurgery / Q000379:methods*; D044583:Neuroendoscopy / Q000379:methods*; D038361:Neuronavigation / Q000379:methods*
keywords: Endoscopy; Posterior transpetrosal approach; Retrochiasmatic region; Retrolabyrinthine approach; Transcrusal approach