Functional petrosectomy via a suboccipital retrosigmoid approach: guidelines and topography.

Functional petrosectomy via a suboccipital retrosigmoid approach: guidelines and topography.

World Neurosurg. 2015 Dec 14;

Authors: Colasanti R, Abbasali Tailor AR, Zhang J, Ammirati M

Abstract
OBJECTIVE: Recent reports have validated the use of retrosigmoid approach extensions to deal with posterior fossa lesions extending laterally extracranially or superiorly into the petroclival areas. Purpose of our research is to describe the topographic retrosigmoid anatomy of the petrous pyramid providing guidelines for its neurovascular sparing drilling, hence for a functional petrosectomy, via this surgical route.
METHODS: Supra- and infra-meatal retrosigmoid approach extensions were performed bilaterally in six specimens in the semisitting position. Pertinent labyrinthine landmarks topographic relationships with evident posterolateral cranial base structures were measured using neuronavigation.
RESULTS: Excellent exposure of inframeatal/petroclival regions as well as of extracranial posterior infratemporal area was accomplished in all the specimens. In the inframeatal region, petrous bone drilling was limited by the labyrinth and the internal auditory canal superiorly, and by the jugular bulb, the inferior petrosal sinus, and the lower cranial nerves inferiorly. Intrapetrous ICA represented the antero-lateral limit. In the suprameatal area, the drilling was limited laterally by the labyrinth (i.e. by the posterior part of the superior semicircular canal, the upper part of the posterior semicircular canal, and the common crus). The internal auditory canal was the inferior limit, while the superior petrosal sinus and the trigeminal nerve limited the drilling superiorly. Multiple topographic relationships among key landmarks were quantified.
CONCLUSIONS: Knowledge of the examined labyrinthine structures topographic anatomy may be useful (combined with a careful assessment of the preoperative imaging, and with the use of neuronavigation and of the endoscope) to accomplish a retrosigmoid neuro-vascular sparing petrosectomy.

PMID: 26700748 [PubMed - as supplied by publisher]

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