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Year : 2021  |  Volume : 69  |  Issue : 2  |  Page : 441--445

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

Sivashanmugam Dhandapani, Lomesh S Wankhede 
 Department of Neurosurgery, Post Graduate Institute of Medical Education and Research (PGIMER), Chandigarh, India

Correspondence Address:
Sivashanmugam Dhandapani
Department of Neurosurgery, PGIMER, Chandigarh - 160 012


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.

How to cite this article:
Dhandapani S, Wankhede LS. Orbital Rim Sparing Single-piece Fronto-orbital Keyhole Craniotomy Through Eyebrow Incision: A Technical Report and Comparative Review.Neurol India 2021;69:441-445

How to cite this URL:
Dhandapani S, Wankhede LS. Orbital Rim Sparing Single-piece Fronto-orbital Keyhole Craniotomy Through Eyebrow Incision: A Technical Report and Comparative Review. Neurol India [serial online] 2021 [cited 2021 Jun 20 ];69:441-445
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Full Text

Since the popularization of keyhole concept by Perneczky et al.,[1] the supraorbital keyhole craniotomy has become a standard minimally invasive approach for treating anterior circulation aneurysms and suprasellar-planum lesions.[2],[3],[4],[5] It is increasingly being adopted due to decreased pain, hospital stay, wound complications, and better cosmesis.[6],[7]

The original supraorbital keyhole craniotomy posed several technical issues, limiting the manoeuvrability of instruments.[8] Due to the incurving of the inner surface of the basal frontal bone, the craniotomy is either not flush with the anterior cranial fossa required drilling of the inner layer of inferior craniotomy margin or a longer footed dura-guard.[1],[9],[10] The single-piece basal supraorbital craniotomy incorporating orbital rim was introduced, therefore, for greater exposure.[11],[12],[13] However, this modification resulted in significantly higher postoperative periorbital edema.[14] The increased periorbital edema is reported mostly due to the disruption of the periorbita's attachment to the orbital margin. This method also needs additional tools to cut across the orbital rim and precise bony fixation to maintain the orbital contour and cosmesis.

As the maneuverability of instruments is limited only by the frontal portion of the orbital bar and roof, but seldom by the downward pointing orbital rim, we have proposed a novel technique of orbital rim sparing single-piece lateral fronto-orbital keyhole craniotomy [Figure 1]. A detailed description of our method and comparative review with other techniques are presented.{Figure 1}{Figure 2}

 Description of the Technique

Positioning & incision

Under general anesthesia, the patient is placed supine with the upper torso elevated 30°, neck in extension, the head turned 30° to the opposite side, and secured in skull clamp. The skin incision is given at the eyebrow's upper border, parallel to the follicles, starting from the supraorbital foramen to around 1 cm lateral to the temporal line's ridge. The pericranium is incised 4 mm away and parallel to the orbital margin, starting just lateral to the supraorbital foramen till the fronto-zygomatic suture laterally and along the superior temporal line posteriorly. The anterior part of the temporalis muscle is also dissected away from the frontal bone's zygomatic process, and the soft tissues kept retracted using hooks.


Bidirectional high-speed drilling with a 6 mm ball tip, centered 5 mm behind the fronto-zygomatic suture [Figure 2]a, creates a hole of around 8 mm, exposing the periorbita inferomedially (shown in white arrow) and frontal dura superomedially (shown in solid black arrow), with the lateral part of orbital roof in-between [Figure 2]b. There is a single opening in the outer table and two openings in the inner table. Care must be exercised to gently separate the periorbita at the inner hole margins and keeping it intact. The first cut is fashioned with dura-guard footplate over the periorbita in burr hole, positioned at an angle towards the orbit [Figure 1], cutting parallel to and sparing the orbital rim, medially till the supraorbital bundle [Figure 2]c. The second cut is performed from the burr hole over the frontal dura in a curve to join the medial end of the previous cut [Figure 1]. The third cut may be made in cases with a thick orbital roof, partially along the lateral orbital roof within the burr hole [Figure 1]. As this keyhole method is laterally placed, normal-sized frontal sinuses usually do not come in the way. Part of the large sinuses extending laterally into the bone flap may be either exteriorized or reconstituted. The free bone flap is then elevated gently by fracturing the orbital roof along the third cut. A single piece fronto-orbital keyhole bone flap is thus raised [Figure 2]d. The lesser sphenoid wing and the ridges over the superior surface of the posterior orbital roof may be drilled further as per the need with dural protection. The dura is then opened in a U-shaped manner, reflected over the periorbita, and kept retracted with sutures [Figure 2]e.


Following surgery, the dura is closed with a suture. The bone flap is self-fitting due to its threefold support (from the orbital rim, frontal bone, and posterior orbital roof) [Figure 1] and [Figure 2]f, [Figure 1]g, [Figure 1]h, [Figure 1]i. Bony fixation with Titanium mini-plates or clamps may be utilized if needed. The soft tissues are reapproximated and sutured using absorbable stitches, followed by subcuticular suturing of skin [Figure 2]h.

We have used this approach in more than 30 patients with aneurysms and meningiomas. In all these, there was comfortable instrument maneuverability, no periorbital edema, and excellent cosmesis.


Over the last decade, minimally invasive procedures have acquired an essential role in the armamentarium of neurosurgery.[1],[2],[3],[4],[5],[15],[16] The supraorbital technique has been reported in several variations for tumors and vascular lesions along the subfrontal & trans-sylvian corridor.[9],[10],[17],[18],[19],[20]

The conflicting philosophies of minimalism, instrument maneuverability, and cosmesis have driven several modifications of the supraorbital approach to balance this triad. As early as 1913, Frazier had proposed removing the orbital roof along with frontal craniotomy to avoid frontal lobe retraction.[21] The extensive scalp incisions with resultant cosmetic issues gradually paved the way to the pterional trans-sylvian approach using an incision behind the hairline popularized by Yasargil.[22] Though Wilson[23] had proposed limited cranial opening for the first time in 1971, Brock & Dietz[24] later detailed a small craniotomy subfrontal corridor in 1978. The keyhole approach became popular with a trans-ciliary incision only two decades later, providing good cosmesis due to the eyebrow concealing the scar.[9],[10],[11],[17],[25]

The original trans-ciliary method of Lindert & Pernecky consisted of a simple supraorbital bone flap [Figure 3]a.[9] This was noted to have limited maneuverability for complex procedures due to the thickened incurving of basal frontal bone necessitating additional drilling and the associated bone loss.[1],[8],[9],[10] Jho had proposed the basal variant of one-piece orbital roof craniotomy flap, including the orbital rim.[9],[11] The basal variants [Figure 3]b, either through eyebrow[13] or eyelid[26] incisions, including the orbital bar, had the advantages of an increased working volume and reduced working depth, compared to the traditional approach.[12] However, the additional morbidity of periorbital edema and the need for elaborate bony fixation were the notable disadvantages of the basal supraorbital craniotomy.[12],[14]{Figure 3}

The orbital bar recommended to be removed by Zador et al. and others seems to denote the whole of the thick fronto-orbital junction, having two parts: orbital rim pointing downward and the frontal portion, which limits working volume.[12] Our technique spares the orbital rim while incorporating the thick frontal portion of the orbital bar. While the frontal portion of the orbital bar is often extensively drilled in the traditional supraorbital keyhole to provide optimum exposure, the bone loss associated with this mandates meticulous fixation to avoid cosmetic issues such as depression over the forehead.

Our trans-ciliary subfrontal technique utilizes the enhanced working volume of basal supraorbital approach without disturbing the orbital rim and its associated morbidity [Figure 3]c. The threefold support makes this bone flap self-fitting, without the need for extensive fixation, as well as maintaining good cosmesis under the eyebrow. As the craniotomy encompasses the basal frontal bone, medial extensions of the frontal sinus may even possibly be reconstituted. This approach is highly relevant for complex cases, as the other mini-craniotomy variants developed for the trans-sylvian corridor using a small incision around the hairline were noted to have a greater incidence of pain on mastication and some handling of the brain.[14],[27],[28] The detailed comparison between our technique and others is given in [Table 1].{Table 1}

As patients' discomfort in the postoperative period is mainly due to extensive handling of tissues, the keyhole surgery is not to aim at the smaller incision and craniotomy for the sake of minimalism but to allow adequate access to the lesion with the least damage to nearby structures, most importantly brain, followed by others.[1],[10],[29] While minimally invasive surgery is increasingly being adopted in several conditions, some such as superficial vascular tumors, still may need large bony exposures.[30],[31] Among supraorbital keyhole variants, our proposed technique optimally balances the sufficiency of exposure with minimal invasiveness and cosmesis. This keyhole approach can be useful for both intracranial and orbital pathology.

The only technically demanding step of our craniotomy is the fronto-orbital cut parallel to and sparing the orbital rim keeping the periorbita intact. Though instrument maneuverability may be enhanced with our approach, illumination and visualization of hidden recesses are still a challenge with the microscope and may need panoramic and angled optics provided by endoscopes.[32],[33] It is also imperative to study whether such kind of technical innovations results in any change in patient outcomes.[34],[35]


The orbital rim sparing single-piece fronto-orbital keyhole craniotomy is an easy and novel minimally invasive approach having several advantages over the traditional keyhole approaches, such as a higher working volume with simple tools, self-fitting flap, least disturbance to the attachment of periorbita with the orbital margin, maintenance of orbital contour, and cosmesis.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflict of interest

The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

Ethical approval

Performed as per the ethical standards of the IEC of PGIMER.


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