Introduction:
Petrous apicotomy can be used therapeutically for drainage of cholesterol granuloma,
mucocele, symptomatic effusion or purulent infection, and diagnostically to gain access
for biopsies of tumorous lesion. Larger access to the petrous apex can be gained through
a transtemporal/middle fossa or a retrosigmoid approach e.g. for surgically treating
petrous apex lesions (petrous apicectomy). There are two main routes for the lesser
invasive petrous apicotomy: the infracochlear and the infralabyrinthine route.
Method:
This video illustrates the infracochlear approach to the petrous apex in case of a
diagnostic indication in a patient with an incidental, asymptomatic tumorous lesion
of the right petrous apex with bony erosion.
Results:
After the bone of the floor of the ear canal and the hypotympanon were removed, the
carotid artery and the jugular bulb were identified using a diamond burr. The route
to the petrous apex is triangled by the cochlea superiorly, the jugular bulb posteriorly,
and the carotid artery, anteriorly. After reaching the petrous apex lesion, biopsies
were taken. The defect in the floor of the ear canal and the hypotympanon were reconstructed
with cartilage and temporalis fascia. The patient recovered quickly from surgery without
vertigo or hearing loss. Histological evaluation showed a chondrosarcoma. The patient
opted for primary radiation therapy (C12, 63 Gy).
Conclusions:
The infracochlear approach is minimally invasive and can offer access to the petrous
apex with minimal morbidity. The pathway, however, is narrow and deep and bounded
by the jugular bulb and the carotid artery. The available space can be estimated from
preoperative CT scans and if possible 3D reconstructions (as shown in the video).
Navigation can additionally enhance safety.
