Supraorbital Craniotomy

Indications

• Supraorbital craniotomy allows for relatively easy and rapid access to structures in the anterior cranial fossa and sellar and parasellar regions. This minimally invasive technique provides a subfrontal approach with minimal disruption of normal anatomy, excellent cosmetic results, shorter operation times and hospital stays with faster recovery, and less morbidity.

• T1his approach can be used to treat many different intraaxial and extraaxial pathologies in or near the frontal lobes, including extraaxial lesions (i.e., anterior skull base meningiomas, craniopharyngiomas, epidural abscesses) and intraaxial lesions (i.e., gliomas, metastatic lesions) of the frontal lobe.

• The decision to use this technique versus other approaches to the frontal lobe (e.g., bicoronal or pterional craniotomy) is based on the desired anatomic and operative trajectory (i.e., subfrontal vs. anterolateral approach). The decision requires detailed preoperative examination of the location of the lesion, its relationship to other vital structures, the size of the lesion, edema and mass effect of the lesion, the planned angle of dissection, and the patient’s comorbidities and overall health.

• The supraorbital approach can be combined with an orbital osteotomy to provide additional visualization of structures and lesions above the level of the anterior communicating artery complex.

Contraindications

• Supraorbital craniotomy is not ideal for lesions with significant middle fossa or cavernous sinus involvement.

• Lesions with significant edema and associated hydrocephalus are relative contraindications. We have placed preoperative lumbar subarachnoid drains in situations in which the lesion may restrict early intraoperative access to the cisterns that would otherwise be fenestrated to facilitate brain manipulation.

• Superior and more posterior frontal lobe lesions are difficult to access from this approach.

• A large frontal sinus is a contraindication.

• Lesions requiring significant vascular manipulation and dissection are contraindications.

Planning and positioning

• Preoperative planning includes assessment of the patient’s cardiopulmonary status, evaluation of comorbidities, and basic laboratory tests, including a basic metabolic panel, complete blood count, coagulation profile, and type and screen. Baseline chest x-ray and electrocardiogram are also useful.

• Preoperative magnetic resonance imaging (MRI) with fiducial markers is obtained for intraoperative navigation. • Within 60 minutes of skin incision, perioperative antibiotics are administered. If the 1surgery is to entail significant manipulation or violation of the frontal cortex, an antiepileptic is administered before the start of surgery. • Brain relaxation can be achieved by administering mannitol and dexamethasone, mild hyperventilation, and preoperative lumbar drain placement.

• After anesthesia induction and Mayfield clamp fixation, the head is elevated and extended to allow the frontal lobe to fall away from the floor of the anterior fossa. Thereafter, the head is rotated to the contralateral side from 15 to 60 degrees depending on the anatomic location of the lesion. The orientation of the head is of paramount importance—considering the relative limited working space, ideal rotation maximizes the surgeon’s view of the lesion in relation to surrounding structures. The extent of rotation performed is as follows: 15 degrees for ipsilateral sylvian fissure, 20 degrees for lateral suprasellar, 30 degrees for anterior suprasellar, and 60 degrees for olfactory groove and cribriform plate region.

• The focus here is on the traditional supraorbital craniotomy without orbital osteotomy. The planned eyebrow skin incision is drawn where the medialmost extent of the incision extends to the supraorbital neurovascular bundle, preserving the nerve. The incision typically extends laterally to the edge of the eyebrow; if necessary, it can be extended posteriorly to one of the patient’s facial creases. The patient is prepared and draped in usual sterile fashion.