It was extensively and successfully used by Juha Hernesniemi, 1) 2) 3) 4) it avoids the approach through the sylvian fissure (SF) and irrespective of the SF anatomy approaches the aneurysms immediately subfrontally. The SF is only partially open.
From an anatomic point of view, both approaches provide similar exposure to the sellar, suprasellar, and anterior communicating artery areas. The pterional approach provides better exposure of the retrosellar area. The ability to operate in the retrosellar area, is higher with the pterional than with the lateral supraorbital approach 5).
Sellar tumors may be removed via a LSO approach with relatively low morbidity and mortality 6).
The lateral supraorbital approach provides adequate exposure of the lesion and allows safe neurosurgical manipulation, with much shorter operation time and much smaller craniotomy, thereby decreasing surgical morbidity. Thus, the lateral supraorbital approach for clipping of unruptured intracranial aneurysm could be a good alternative to the classic pterional approach 7).
Sellar tumors can be removed via the LSO approach with relatively low morbidity and mortality. Surgical results with this fast and simple approach are similar to those obtained with more extensive, complex, and time-consuming approaches 8).
The lateral supraorbital approach is a minimally invasive approach that provides excellent exposure of the superior, lateral and medial orbit as well as the orbital apex 9).
The head is turned contralateral to the lesion 15 to 30º and minimal flexion, fixed with a 3 pins Mayfield head frame.
A curvilinear incision is made behind the hairline with minimal shaving.
A curved frontotemporal skin incision 8 to 10 cm (3.5 inches) is made behind the hairline, starting 2-3 cm (0.8 inches) above the zygoma preventing damage to the frontal branch of the seventh cranial nerve, ending incisión on the midline.
The skin is opened in one layer fashion (skin-galea-pericranium-muscle. Retraction of the frontal flap with 3 to 4 spring hooks. Baños et al recommend the placing of Raney clips on the posterior lip of the incision 10).
Detachement of the temporal muscle with a periostal retractor from it´s superior insertion (superior temporal line) previous discharge incisión of the temporal fascia.
A single burr hole over the posterior limit of superior temporal line is made for the lateral supraorbital approach. in a classical pterional approach one burr hole is placed at the posterior insertion of the zygomatic arch (Key hole) as showed with a yellow circle in the figure.
The craniotomy is performed with a craniotome previous disection of the dura from the inner table of the skull. Sometimes the Sphenoid ridge is difficult to crossover with the craniotome, this problem is solved drilling a line over the sphenoid ridge with the blade (taking out the footplate) lifting the bone flap and fracturing the drilled line.
The bone flap measures 4-5 cm x 3 cm (1.6 x 1.2 inches). One third of the bone flap extends superior to the superior temporal line and two thirds of the bone flap extends inferiorly. The cranial opening is usually big enough to approach not only the main arteries of the Circle of Willis but also to approach the cavernous sinus and the suprasellar region.
Milling of sphenoid wing to gain access to the skull base allowing a better field of vision during the surgery. A Rongeur can be used to remove as much sphenoid wing as possible but it is usually easier and faster to drill it with a high-speed drill or a diamond drill as shown in the picture.
Opening of the dura: Pedicled dural flap to the sphenoid wing is made with a curvilinear incision. Operating microscope can be use at this stage.
Retraction of the dural flap with multiple dural stiches. From this point on, the surgery should continue using the operating microscope.
The dissection starts in the frontobasal region, limiting with the proximal Sylvian fissure. The first aim of dissection is to reach the optic nerve in order to recognize the rest of vascular and nervous structures. The opening of the arachnoid membranes in the carotid-ophtalmic cistern allows the drainage of the CSF and therfore favors the relaxation of the brain avoiding the excessive use of brain retractors during the entire surgery.
With this approach it is possible to recognize the origin of the posterior communicating artery and anterior choroidal artery.
Lateral Supraorbital Approach Applied to Anterior Clinoidal Meningiomas Video 1
Lateral Supraorbital Approach Applied to Anterior Clinoidal Meningiomas Video 2
Lateral Supraorbital Approach Applied to Anterior Clinoidal Meningiomas Video 3
Lateral Supraorbital Approach Applied to Anterior Clinoidal Meningiomas Video 4
Clinical data of 23 patients with grade Ⅰ-Ⅲ ruptured anterior circulation aneurysm via LSO at the Second Hospital of Shandong University from February 2016 to December 2016 were retrospectively analyzed. The clinical data included their clinical manifestations, radiological finding, microsurgical techniques and follow-up results. Results: All patients were diagnosed as anterior circulation aneurysm by preoperative CT angiography (CTA) or Digital Subtraction Angiography (DSA). They all accepted aneurysm clipping via LSO. The operations carried out smoothly, with no operation related complications. They were followed up for 2 to 12 months, and the Glasgow outcome scales (GOS) were 5 in 18 patients (78.3%), 4 in 2 patients (8.7%), 3 in 2 patients (8.7%), and 1 in 1 patient (4.3%). Conclusion: LSO could provide adequate exposure for the anterior circulation aneurysm, so the clipping could be carried out safely and effectively. LSO is a simple and minimally invasive surgical approach, and when it is used by the skilled master of pterion approach, its advantage could be fully played 11).