Subtemporal approach [Neurosurgery Wiki]

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====== Subtemporal approach ======
It is one of the surgical routes used to reach the [[interpeduncular fossa]], offers a good access to the [[medial temporal region]].

The subtemporal [[approach]] avoids neocortical transgression and injury to the [[optic radiation]]s.
((Smith KA, Spetzler RF: Supratentorial-infraoccipital approach for posteromedial temporal lobe lesions. J Neurosurg 82:940–944, 1995))
((Tubbs RS, Oakes WJ: Relationships of the cisternal segment of the trochlear nerve. J Neurosurg 89:1015–1019, 1998)).

====Indications====
The subtemporal approach is historically known as the standard approach for the treatment of tumoral, vascular and inflammatory lesions of the [[middle cranial fossa]], the [[tentorium]], the anterior and middle [[tentorial incisura]], the upper-third of the clivus and the [[petroclival region]]. This approach had been recognized universally for many years as the best way to treat basilar artery (BA) apex, P1 and P2 posterior cerebral artery (PCA) and [[superior cerebellar artery aneurysm]]s until the introduction of the pterional approach in 1976 by Yasargil et al.
((Yasargil MG, Antic J, Laciga R, Jain KK, Hodosh RM, Smith RD. Microsurgical
pterional approach to aneurysms of the basilar bifurcation. Surg Neurol. 1976
Aug;6(2):83-91. PubMed PMID: 951657.
)).

The standard subtemporal approach and its variations are most frequently requested for sphenoidal wing meningiomas, followed by Yasargil's T1- and T2-type [[tentorial meningioma]]s arising from the inner ring of the tentorium
((Yasargil MG (1996) Microneurosurgery of CNS tumors. Thieme, New York)).

The subtemporal approach can be used for [[petroclival meningioma]]s that do not extend below the upper clivus. For lesions extending above and below the tentorium situated on the tentorial edge or in the petroclival area, only those with a small infratentorial component can be removed by the subtemporal approach.
====Drawbacks====

Access to the [[posteromedial temporal region]] needs the retraction of the [[temporal lobe]]
((Olivier A: Temporal resections in the surgical treatment of epilepsy. Epilepsy Res Suppl 5:175–188, 1992))
, with a risk of [[vein of Labbé]] sacrifice. 

Because of the inclination of the tentorium, temporal lobe retraction increases with a more posterior location of the lesion
((Campero A, Tróccoli G, Martins C, Fernandez-Miranda JC, Yasuda A, Rhoton AL Jr: Microsurgical approaches to the medial temporal region: an anatomical study. Neurosurgery 59 (4 Suppl 2):ONS279–ONS308, 2006)).

A more posterior-oriented supratentorial-infra- occipital variation of the subtemporal approach has been described, which is performed to effectively approach and resect epileptogenic lesions in PMT regions
((Russell SM, Kelly PJ: Volumetric stereotaxy and the supra- tentorial occipitosubtemporal approach in the resection of posterior hippocampus and parahippocampal gyrus lesions. Neurosurgery 50:978–988, 2002))
((Smith KA, Spetzler RF: Supratentorial-infraoccipital approach for posteromedial temporal lobe lesions. J Neurosurg 82:940–944, 1995)).


Keyhole subtemporal approaches and zygomatic arch osteotomy have been proposed in an effort to decrease the amount of temporal lobe retraction.

A keyhole and a classic subtemporal craniotomy were executed in 4 fresh-frozen silicone-injected cadaver heads. The target was defined as the area bordered by the [[superior cerebellar artery]], the [[anterior clinoid process]], supraclinoid [[internal carotid artery]], and the [[posterior cerebral artery]]. Once the target was fully visualized, Ercan et al. evaluated the amount of temporal lobe retraction by measuring the distance between the base of the middle fossa and the temporal lobe. In addition, the volume of the surgical and anatomical corridors was assessed as well as the surgical maneuverability using navigation and 3D moldings. The same evaluation was conducted after a zygomatic osteotomy was added to the two approaches. 

Temporal lobe retraction was the same in the two approaches evaluated while the surgical corridor and the maneuverability were all greater in the classic subtemporal approach. 

The zygomatic arch osteotomy facilitates the maneuverability and the surgical volume in both approaches, but the temporal lobe retraction benefit is confined to the lateral part of the middle fossa skull base and does not result in the retraction necessary to expose the selected target
((Ercan S, Scerrati A, Wu P, Zhang J, Ammirati M. Is less always better? Keyhole
and standard subtemporal approaches: evaluation of temporal lobe retraction and
surgical volume with and without zygomatic osteotomy in a cadaveric model. J
Neurosurg. 2017 Jul;127(1):157-164. doi: 10.3171/2016.6.JNS16663. Epub 2016 Sep
16. PubMed PMID: 27636184.
)).
----
With the help of an [[endoscope]], Sun et al exposed the [[internal auditory canal]] and cerebellopontine through a [[translabyrinthine approach]] and the [[inferior colliculus]] through a keyhole [[subtemporal approach]]. This double approach can be combined to expose the internal auditory canal and [[cerebellopontine angle]] and [[inferior colliculus]] satisfactorily in the same surgical setting. This combined approach can avoid retraction of the cerebellum and reduce serious adverse events and complications
((Sun JQ, Han DM, Li YX, Gong SS, Zan HR, Wang T. Combined endoscope-assisted
translabyrinthine subtemporal keyhole approach for vestibular Schwannoma and
auditory midbrain implantation: Cadaveric study. Acta Otolaryngol. 2010
Oct;130(10):1125-9. doi: 10.3109/00016481003699674. PubMed PMID: 20367538.)).

As a minimally invasive approach, this can be considered an effective method for removal of [[vestibular schwannoma]] and auditory midbrain implantation in the same surgical setting, while avoiding retraction of the cerebellum and serious adverse events and complications.

see [[Subtemporal medial transpetrous approach]].

see [[Subtemporal transtentorial approach]].
====Subtemporal Approach for AICA Aneurysm Clipping====
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The subtemporal approach represents a feasible approach for [[retrochiasmatic craniopharyngioma]]s when gross total resection is not mandatory. It provides rapid access to the tumor and a caudal-to-cranial visualization that promotes minimal manipulation of critical neurovascular structures, particularly the optic apparatus
((Wong RH, De Los Reyes K, Alikhani P, Sivaknathan S, van Gompel J, van Loveren 
H, Agazzi S. The Subtemporal Approach to Retroinfundibular Craniopharyngiomas: A 
New Look at an Old Approach. Neurosurgery. 2015 Aug 18. [Epub ahead of print]
PubMed PMID: 26287553.
)).

====Subtemporal approach for distal basilar occlusion for giant aneurysm====

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