title: Neural connections between the nervus intermedius and the facial and vestibulocochlear nerves in the cerebellopontine angle: an anatomic study.
abstract: OBJECTIVE
  Unexpected clinical outcomes following transection of single nerves of the internal acoustic meatus have been reported. Therefore, this study aimed to investigate interneural connections between the nervus intermedius and the adjacent nerves in the cerebellopontine angle.
  
  
  METHODS
  On 100 cadaveric sides, dissections were made of the facial/vestibulocochlear complex in the cerebellopontine angle with special attention to the nervus intermedius and potential connections between this nerve and the adjacent facial or vestibulocochlear nerves.
  
  
  RESULTS
  A nervus intermedius was identified on all but ten sides. Histologically confirmed neural connections were found between the nervus intermedius and either the facial or vestibulocochlear nerves on 34 % of sides. The mean diameter of these small interconnecting nerves was 0.1 mm. The fiber orientation of these nerves was usually oblique (anteromedial or posterolateral) in nature, but 13 connections traveled anteroposteriorly. Connecting fibers were single on 81 % of sides, doubled on 16 %, and tripled on 3 %, six sides had connections both with the facial nerve anteriorly and the vestibular nerves posteriorly. On 6.5 % of sides, a connection was between the nervus intermedius and cochlear nerve. For vestibular nerve connections with the nervus intermedius, 76 % were with the superior vestibular nerve and 24 % with the inferior vestibular nerve.
  
  
  CONCLUSIONS
  Knowledge of the possible neural interconnections found between the nervus intermedius and surrounding nerves may prove useful to surgeons who operate in these regions so that inadvertent traction or transection is avoided. Additionally, unanticipated clinical presentations and exams following surgery may be due to such neural interconnections.
authors.affiliation: Seattle Science Foundation, Seattle, WA, USA.
authors.forename: R
authors.initials: R
authors.lastname: Shane Tubbs
authors.affiliation: Seattle Science Foundation, Seattle, WA, USA.
authors.forename: Nicole
authors.initials: N
authors.lastname: Hose
authors.affiliation: Department of Anatomical Sciences, St. George's University, True Blue, Grenada.
authors.forename: Marios
authors.initials: M
authors.lastname: Loukas
authors.affiliation: Institute of Anatomy, University of Padova, Padua, Italy.
authors.forename: Raffaele
authors.initials: R
authors.lastname: De Caro
authors.affiliation: Goodman Campbell Brain and Spine, Department of Neurological Surgery, Indiana University School of Medicine, 355 W. 16th Street, Suite 5100, Indianapolis, IN, 46202, USA. acohenmd@gmail.com.|Indiana University Simon Cancer Center, Indianapolis, IN, USA. acohenmd@gmail.com.
authors.forename: Aaron A
authors.initials: AA
authors.lastname: Cohen-Gadol
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D063405:Anatomic Variation; D002102:Cadaver; D002530:Cerebellopontine Angle / Q000033:anatomy & histology* / Q000601:surgery; D004210:Dissection; D005154:Facial Nerve / Q000033:anatomy & histology* / Q000601:surgery; D005260:Female; D006801:Humans; D007431:Intraoperative Complications / Q000517:prevention & control; D008297:Male; D008866:Microsurgery / Q000009:adverse effects; D008875:Middle Aged; D009434:Neural Pathways / Q000033:anatomy & histology*; D019635:Neurosurgical Procedures; D013701:Temporal Bone / Q000294:innervation*; D000159:Vestibulocochlear Nerve / Q000033:anatomy & histology*
keywords: Anatomy; Facial nerve; Iatrogenic injury; Internal auditory meatus; Nervus intermedius; Ramus communicans; Skull base; Surgery; Vestibulocochlear nerve