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

Abstract

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.

Petrous apex pneumatisation in children: a radiological study

“…A previous study of 29 paediatric CT scans found evidence of pneumatisation occurring in a child as young as five years. 22 In our study, the youngest child with evidence of petrous apex pneumatisation was a one-year-old female, with 1 per cent of her petrous apices being pneumatised. The extent of pneumatisation was also found to vary with age in a study of 299 CT scans, with younger age being associated with greater pneumatisation; however, that study did not focus on children, with the median age of patients being 50 years (interquartile range, 33-63 years).…”

“…For example, when performing a subtotal petrosectomy with blind sac closure, the degree of petrous apex pneumatisation affects the extent of temporal bone resection. 22 Limitations High-resolution CT scanning is not typically used for neuroimaging in children in New Zealand because of radiation exposure, unless clinically indicated, often as a result of temporal bone or otological disease. The 4 mm thickness between slices meant an assumption had to be made that there was no variability in air cell area between slices that might affect the accuracy of the volume calculations.…”

“…10,[17][18][19] The presence of pneumatisation also has operative implications during procedures such as subtotal petrosectomy with blind sac closure, in which mucosa-lined air cells are obliterated to treat disorders including recalcitrant otitis media. 22 In summary, petrous apex pneumatisation is a normal anatomical variant, but has potentially significant implications for otological pathology and surgery. Although other aspects of the temporal bone have been widely studied, such as the volume of mastoid air cells, there has been minimal research investigating pneumatisation of the petrous apex, particularly using computed tomography (CT).…”

“…10,17–19 The presence of pneumatisation also has operative implications during procedures such as subtotal petrosectomy with blind sac closure, in which mucosa-lined air cells are obliterated to treat disorders including recalcitrant otitis media. 22…”

Impact of occlusive material and cochlea‐carotid artery relation on eustachian tube occlusion in subtotal petrosectomy

“…24 However, since in 96% of temporal bones the carotid artery forms a barrier between the air spaces anterior and posterior, particular attention to the carotid artery is warranted to achieve successful ET occlusion. 25 Ugo Fisch, the name giver of "subtotal petrosectomy," recommended that the internal carotid artery should be followed with diamond burr in order to remove the bony ET as far as the isthmus. 26 After the mucosa is coagulated the obliteration should be done "with bone wax, which is firmly packed with a suction tip covered with a neurosurgical cottonoid."…”