Technical NoteVenous-Preserving Sylvian Dissection
Introduction
The Sylvian fissure lies between the frontal and temporal lobes from lateral to medial, making it possible to approach the deep lesions through this fissure. Sylvian dissection is one of the requisite skills for microneurosurgeons, because the Transsylvian approach, combined with frontotemporal craniotomy and its modifications, is one of the most versatile and commonly performed approaches 3, 6, 7, 13, 19.
The superficial Sylvian veins, one of the three dominant venous drainage systems of the lateral cerebrum, lie on the surface of the Sylvian fissure. They usually drain into the dural sinus along the sphenoid wing. In other words, they bridge the brain and the dura, which can obstruct the surgeon’s perspective or prevent the brain from retracting. Therefore, the superficial Sylvian veins, especially the frontal superficial Sylvian veins, are occasionally sacrificed during dissection 13, 15, 19. Venous infarction or severe cerebral edema caused by venous congestion may follow, resulting in neurologic deficits 11, 15, 17.
Considering it is difficult or impossible to foresee the consequence of sacrificing the veins, the surgeon should endeavor to save the superficial Sylvian veins while reserving a wide enough space within the surgical field for safe manipulation. Few techniques to preserve these veins, however, have been described 5, 12, 18. We think that identification of the correct dissecting plane is of great importance. Several tips and tenets described here are useful to save the veins.
Section snippets
Materials and Methods
We describe technical nuances for dissection of the Sylvian fissure with an emphasis on preserving the superficial Sylvian veins. We usually split the lateral Sylvian fissure widely in a distal (lateral-to-medial) fashion, even for deep lesions around the basal cisterns, but we believe that at least a part of this technique can be applied to the proximal (medial-to-lateral) transsylvian approach or an approach with a small Sylvian opening (3).
Between April 2011 and March 2015, we operated on 66
Craniotomy
The patient is placed in the supine position with the head rotated and the neck extended according to the location of the lesion. A typical frontotemporal craniotomy is made, and the greater wing of the sphenoid bone is removed. The dura is opened by a semicircular incision, revealing the Sylvian fissure and the frontal and temporal lobe. Then, we introduce an operative microscope for Sylvian dissection.
Opening the Surface of the Sylvian Fissure between the Superficial Sylvian Veins
The superficial Sylvian veins vary in size and number among patients and between the 2 sides
Discussion
This report described technical nuances of venous-preserving Sylvian dissection, which is different from the conventional Sylvian split with sacrificing of the frontal veins. Accurate recognition of the anatomy of the superficial veins and “microvascular Sylvian fissure” helps the surgeon find the best dissection plane. This plane may be between the frontal vessels and the temporal vessels, between the frontal lobe and the temporal vessels, or between the temporal lobe and the frontal vessels.
Conclusion
Preserving the veins is of great importance in modern neurosurgery to decrease postoperative morbidity. The traditional Sylvian split that mechanically sacrifices the frontal superficial Sylvian veins and its tributaries should be reconsidered. With the use of the technique described in the present report, the Sylvian fissure is divided safely, and a wide surgical corridor is achieved.
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Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.