The vascular anatomy of the internal auditory canal. A reappraisal for function preservation surgery.

Objectives: Partial or complete loss of function of the 7^th and 8^th nerves is a common occurrence in surgery of the cerebello-pontine angle, with the causal mechanism being considered the mechanical insult on nerves and the critical loss of blood supply to nerves and labyrinth. Preventing a vascular loss requires both soft surgery and knowledge of hitherto disregarded details of vascular anatomy. The goal of this paper is to provide the missing picture of descriptive and surgical anatomy.

Methods: Data of vascular anatomy were obtained from: (i) a group of 100 injected temporal bones submitted to microdissection; (ii) a group of 30 sectioned temporal bones; (iii) a group of 30 cases who underwent surgery for small vestibular schwannoma.

Results: A detailed picture was obtained concerning position and course of the anterior inferior cerebellar artery, origin and course of internal auditory artery (IAA) and its branches. Handling and cleavage of IAA from nerves was also explored.

Conclusions: The role of blood supply in function preservation of 7^th-8^th nerves comes from preclinical studies on animals as well as anatomical studies and clinical-surgical observations in humans. Updated knowledge of vascular anatomy is expected to provide surgeons with hitherto disregarded details and contribute to function preservation.