Surgical exposure in translabyrinthine approaches--an anatomical study

Translabyrinthine approach (TLA) is a procedure of choice for the removal of vestibular schwannomas in cases of profound hearing loss. There is a lack of anatomic studies reviewing the surgical anatomy of the cerebellopontine angle (CPA) as seen in the classical and enlarged TLAs.

Seven formalin-preserved cadavers were dissected. Structures, visualized in the CPA through the TLA, were scored according to the degree of their exposure (1, structure not seen; 2, partial exposure; 3, full exposure).

The acousticofacial bundle, anterior inferior cerebellar artery and flocculus had the highest scores in both types of surgery. However. the fifth, ninth, and tenth cranial nerves, prepontine cistern, pons, superior cerebellar artery, and posterior inferior cerebellar artery had higher scores, i.e. better exposure, in the enlarged TLA than in the classical TLA.

These findings suggest that the enlarged TLA be preferred in cases of larger tumors extending to either jugular foramen or middle fossa whereas the indications of the classical TLA should be limited to vestibular neurectomy and removal of smaller tumors.