Relationship between anterior inferior cerebellar artery and facial-vestibulocochlear nerve complex: an anatomical and magnetic resonance images correlation study.

For the successful microneurosurgical treatment of CP angle located pathologies, an understanding of the relationship and variations between neural and vascular structures and a certain diagnosis are the most valuable factors for surgeons. CP angle lesions have now become a visible area by advances in magnetic resonance imaging (MRI) technology. An evaluation of this area and the decision for a neurosurgical decompression procedure are easier than before. Twenty unfixed adult human cadaver specimens, that have no sign of central nervous system pathology, were obtained and dissected bilaterally at routine autopsy. The facial-vestibulocochlear (VII - VIIIth) nerve complex and the anterior inferior cerebellar artery (AICA) were identified in all specimens. Thirteen of the 40 (32.5 %) AICA were situated ventrally and fourteen (35 %) were located dorsally to the VII - VIIIth nerve complex. Thirteen (32.5 %) passed between the VIIth and the VIIIth nerve fibers. Five of the 40 (12.5 %) AICA had a loop near the nerve complex and then passed the nerves ventrally or dorsally. In an MRI study 74 adult persons (148 sides) were investigated by using three-dimensional Fourier transformation constructive interference in the steady state technique (3D FT-CISS) on a 1.5 Tesla MRI system (Siemens Magnetom, Erlangen, Germany). The results were as follows; 48 AICA (32.4 % of all 148 AICA) were situated ventrally to the VII-VIIIth nerve complex, 45 AICA (30.4 %) were situated dorsally to the VII-VIIIth nerve complex, and the AICA passed between the VIIth and VIIIth nerves in 51 samples (34.5 %). In four of the 148 CP angles (2.7 %), the AICA was not identified. There was an AICA loop coursing to the internal acoustic meatus in 15 patients (10.1 %). In this study, we examined the relations between VIIth and VIIIth nerve complex and the AICA in cadaver and MRI materials for an understanding of the value and reliability of the radiological data. This study also shows the anatomical variation between these structures.