====== Sylvian fissure dissection ======
 
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[[Sylvian fissure]] [[dissection]] provides a narrow corridor
for resection of most insular tumors. In addition,
MCA branches often tether the frontal lobe to the temporal
lobe, limiting elevation of the frontal lobe and undermining
of its operculum to remove tumor underneath
((Rey-Dios R, Cohen-Gadol AA. Technical nuances for surgery of insular gliomas: 
lessons learned. Neurosurg Focus. 2013 Feb;34(2):E6. doi:
10.3171/2012.12.FOCUS12342. Review. PubMed PMID: 23373451.)).
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This technique is one of the most important principles in microsurgery. 

Dissection of the fissure starts with opening of the thick arachnoid bands along the superior aspect of the fissure. 

Generous arachnoidal dissection provides adequate intercisternal pathways to find vascular pathology within the fissure. And at the same time minimizes the use of forceful retraction to immobilize the frontal and temporal lobes. An ample amount of time is spent to sharply dissect the arachnoid bands while minimizing peel injury. 
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A wide [[sylvian fissure]] opening, with either a proximal or distal start, has been standard for microsurgical management of [[middle cerebral artery]] (MCA) [[aneurysm]]s. However, extensive sylvian dissection is potentially associated with increased incidence of iatrogenic injury to the brain and neurovascular structures. 

The focused sylvian opening is a less-invasive alternative to the classical wide sylvian opening for the microsurgical management of most MCA aneurysms 
((Elsharkawy A, Niemelä M, Lehečka M, Lehto H, Jahromi BR, Goehre F, Kivisaari
R, Hernesniemi J. Focused opening of the sylvian fissure for microsurgical
management of MCA aneurysms. Acta Neurochir (Wien). 2014 Jan;156(1):17-25. doi:
10.1007/s00701-013-1894-7. Epub 2013 Oct 8. PubMed PMID: 24101289.)).

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[[Arachnoid dissection]] is often challenging because of tight corridors, microvasculature crossing the membranes, and a narrow operative field. It is often said that "splitting" the [[sylvian fissure]] measures the [[talent]] of a cerebro[[vascular neurosurgeon]], and there are as many styles of [[sylvian fissure dissection]] as neurosurgical schools.
Benet et al. principle is to dissect the [[subarachnoid space]] sharply and with minimal trauma to neither the microvasculature nor the [[pia mater]]. They developed a technique that allows efficient and safe sharp dissection through the subarachnoid space: the "microcisternal [[drainage]]" technique. This technique (Video 1) involves applying a pledget to a narrow cistern and suctioning the [[cerebrospinal fluid]] while maintaining uplifting retraction with the suction shaft. Clear trabeculae are dissected sharply to release microvessels at the convexity of their turns. This technique is especially advantageous when cisterns are narrow (e.g., pia-to-pia) or highly formal structures are at risk. The main advantages over conventional cisternal dissection are avoidance of refractive effect, enhanced identification of the microvasculature from the trabeculae, and preservation of pia matter. Using the [[microcisternal drainage]] technique, the microvasculature, arachnoid membranes, and pia reveal themselves, and we avoid the cerebrospinal fluid-related refractive effect, maximizing depth perception. They report an example of the "microcisternal drainage" technique to split the sylvian fissure during the treatment of an irregular [[middle cerebral artery bifurcation aneurysm]] on a 56-year-old woman. The patient tolerated the procedure well, was discharged without neurologic deficits, and resumed everyday life with no aneurysm remnant
((Benet A, Yoshikawa K, Noda K, Tanikawa R. "Microcisternal Drainage" Technique for Clipping a Middle Cerebral Artery Aneurysm. World Neurosurg. 2023 Jan 26;172:34. doi: 10.1016/j.wneu.2023.01.074. Epub ahead of print. PMID: 36708990.)).

===== Videos =====

https://www.neurosurgicalatlas.com/volumes/cerebrovascular-surgery/aneurysms/techniques-of-sylvian-fissure-split