gms | German Medical Science

Objective: Extracranial to intracranial (EC-IC) bypass using superficial temporal artery (STA) donor represents a versatile technique in the treatment of Moyamoya, complex aneurysms and controversially also in cerebrovascular insufficiency. STA harvest is usually performed with a direct skin incision over the course of the parietal branch, which is also ideal for craniotomy targeting the distal Sylvian fissure. In some patients, however, frontal branch is also needed, requiring a larger curvilinear incision or a second incision. This increases morbidity and the risk of pseudomeningocele and skin necrosis, and may cause esthetic problems especially in patients with low STA bifurcation. This anatomical study presents the technique for endoscopic-assisted harvesting of the STA frontal branch.

Methods: In the Heinrich Heine University neurovascular research lab, a cadaveric specimen was treated with Thiel-fixation. After flushing vessels, red- and blue-colored latex injections were used to enhance visualization of the vascular tree. After microsurgical harvesting of the STA parietal branch, the frontal division was endoscopically dissected using a 0° optic (Karl Storz, Tuttlingen, Germany).

Results: A linear skin incision is performed starting 1cm ventral to the tragus and extending cranially to the superior temporal line. After division of the galea, STA parietal branch running in the loose areolar tissue over the temporal fascia superficial lamina is exposed along with the superficial temporal vein parietal branch and the trigeminal nerve auriculotemporal branch dorsal to the artery. The STA parietal branch is then isolated microsurgically proximal to distal, dividing small anastomotic and muscular branches. After identification of the proximal STA frontal division at the bifurcation, endoscopic vision is used to dissect the artery rostrally in the subgaleal space as far as the frontal bone where the artery turns superiorly and courses over the frontalis muscle. Temporal and zygomatic branches of the facial nerve are exposed caudal to the STA frontal division along with the frontal branch of the superficial temporal vein. Major arterial branches are divided with respect to the continuity of the main trunk. After a typical incision of the temporoparietalis muscle, craniotomy and dural opening, the frontal and parietal branches of the STA are distally interrupted to prepare the bypass.

Conclusion: Endoscopic-assisted harvesting of the STA frontal branch is advantageous for use in EC-IC bypass surgery. This technique avoids complications associated with a longer curvilinear or a second skin incision, reduces morbidity, and improves cosmetic outcome. Meticulous knowledge of neurovascular anatomy, particularly of the subgaleal space, is required to perform a safe dissection avoiding facial nerve injury.