The importance of petrous apex and peri-carotid pneumatisation in subtotal petrosectomy and blind sac closure: a radiological study.

OBJECTIVE: To ascertain in what proportion the vertical segment of the intratemporal carotid artery on its medial aspect anatomically separates the peri-tubal cells and Eustachian tube from the remainder of the pneumatised spaces of the temporal bone.

METHOD: A retrospective review was conducted of 222 adult and 29 paediatric consecutive computed tomography scans of petrous temporal bones from a single tertiary referral centre.

RESULTS: In 96 per cent of temporal bones, the carotid artery formed a lateral barrier (with no communication pathway medially) between air spaces anterior and posterior to it. This equated to 94 per cent when chronic otitis media cases were excluded.

CONCLUSION: The degree of separation of middle-ear air cells from the Eustachian tube or nasopharynx, and the relevant anatomy, are reviewed. This knowledge helps to optimise the outcome of subtotal petrosectomy and blind sac closure. The frequency and process of pneumatisation of the petrous apex, and its connections with the middle ear, have been radiologically confirmed.