Supratrigeminal zone [Neurosurgery Wiki]

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====== Supratrigeminal zone ======

Thirteen safe entry zones have been reported and validated for approaching [[brainstem lesion]]s, including the anterior mesencephalic zone, lateral mesencephalic sulcus, intercollicular region, peritrigeminal zone, supratrigeminal zone, lateral pontine zone, supracollicularzone, infracollicularzone, median sulcus of the fourth ventricle, anterolateral and posterior median sulci of the medulla, olivary zone, and lateral medullary zone. A discussion of the approaches, anatomy, and limitations of these entry zones is included. 

A detailed understanding of the anatomy, area of exposure, and safe entry zones for each major approach allows for improved surgical planning and dissemination of the techniques required to successfully resect intrinsic brainstem lesions
((Cavalcanti DD, Preul MC, Kalani MY, Spetzler RF. Microsurgical anatomy of safe
entry zones to the brainstem. J Neurosurg. 2016 May;124(5):1359-76. doi:
10.3171/2015.4.JNS141945. Epub 2015 Oct 9. PubMed PMID: 26452114.
)).
----
A 73-year-old man with a history of 3 episodes of [[intracranial hemorrhage]] associated with a [[cavernous hemangioma]] located in the right ventral [[pons]]. The [[hemangioma]] was removed via the supratrigeminal zone of the [[brainstem]] using an [[anterior transpetrosal approach]] (ATPA). ATPA was first described in 1985 for upper petroclival lesions by Kawase.

This approach requires epidural [[subtemporal]] procedures to expose the [[petrous apex]] adequately. The petrous apex must be totally resected and the dura of the [[temporal lobe]] and [[posterior fossa]] is then cut to ligate the [[superior petrosal sinus]] and [[tentorium]]. In this procedure, the most important things are to preserve the [[internal carotid artery]] (C2 segment) and [[greater superficial petrosal nerve]] (GSPN). To identify the GSPN, [[facial nerve integrity monitor]] ([[Medtronic]] Inc, Dublin, Ireland) is very useful. In the extradural bone removal, [[Sonopet]] Ultrasonic Aspirator ([[Stryker]] Ltd, Portage, Michigan) is a very excellent surgical tool for avoiding the injury of the internal carotid artery. As demonstrated by Cavalcanti, ATPA is particularly useful for accessing lesions located in the upper ventral pons via the [[supratrigeminal]] zone because it provides a wide and shallow surgical field above the trigeminal nerve without requiring retraction of the cerebellum. We received written informed consent from the patient for this publication
((Yokoyama K, Kawanishi M, Sugie A, Yamada M, Tanaka H, Ito Y, Yamshita M.
Microsurgical Resection of a Ventral Pontine Cavernoma via Supratrigeminal Zone
by Anterior Transpetrosal Approach: 2-Dimensional Operative Video. Oper Neurosurg
(Hagerstown). 2018 Jul 19. doi: 10.1093/ons/opy177. [Epub ahead of print] PubMed 
PMID: 30032310.
)).