Orbital Rim Sparing Single-piece Fronto-orbital Keyhole Craniotomy Through Eyebrow Incision: A Technical Report and Comparative Review

Background: The classical eyebrow supraorbital keyhole craniotomy has limited working volume due to the thick incurving of the frontal bone necessitating generous drilling of the frontal base. However, the basal variant with sectioning of the orbital rim results in increased periorbital edema. Objective: We describe a novel orbital rim sparing single-piece fronto-orbital keyhole approach, probably the first such report with a comparative review of relevant literature. Methods: Following eyebrow incision, bidirectional drilling with a ball tip behind the fronto-zygomatic suture exposes the periorbita and frontal dura, with orbital roof in-between. The craniotomy is fashioned with an angled fronto-orbital cut parallel to and sparing the orbital rim with dura-guard over the periorbita, a frontal cut over the dura, and an optional cut along the lateral orbital roof from within the burr hole. A comparative review of this technique with traditional methods is also carried out. Results: Compared to the classical supraorbital keyhole, this minimally invasive approach yields a wider basal exposure with greater working volume for intracranial and orbital lesions. Compared to the basal variant of keyhole fronto-orbital approach, this technique results in the least disturbance to periorbita's attachment with the orbital margin, maintenance of orbital contour, better cosmesis with use of simple tools and self-fitting flap. Conclusion: The orbital rim sparing single-piece fronto-orbital keyhole craniotomy is an easy and novel minimally invasive approach with greater working volume without the disadvantages of sectioning the orbital rim.