Supraorbital Craniotomy: Brain Surgery Through the Eyebrow

A supraorbital craniotomy is a minimally invasive brain surgery performed through a small opening in the skull just above the eyebrow. Surgeons make an incision hidden within or along the eyebrow line, remove a coin-sized piece of bone above the eye socket, and use that window to reach tumors, aneurysms, and other problems deep inside the front of the brain. The technique has been refined over roughly three decades, with well over a thousand cases reported in the literature establishing its safety and effectiveness as a genuine alternative to larger, more traditional skull openings.

How the Approach Works

The core idea is simple in concept, though demanding in execution. The surgeon makes an incision about three to four centimeters long within the eyebrow itself. Through that incision, a small disc of bone is temporarily removed from the forehead just above the orbital rim, the bony ridge you can feel above your eye. This opening, often described as a “keyhole,” gives a direct line of sight to the underside of the frontal lobe and the structures at the base of the skull. Because the brain’s frontal lobe naturally lifts away from the skull base with gravity when the head is positioned correctly, surgeons can work beneath it without needing to retract brain tissue as aggressively as with larger openings.

The term “keyhole” captures the philosophy: a small entry point that, because of its precise placement, still provides adequate working room at depth. Think of looking through a keyhole in a door. Your field of view widens the farther you look into the room. The same geometric principle applies here. Careful preoperative planning, often assisted by image-guidance technology and sometimes virtual reality simulation, helps the surgeon place the opening exactly where it will provide the best corridor to the target.

What Conditions It Treats

The supraorbital keyhole approach is used most often for problems located along the front and center of the skull base, a region surgeons call the anterior skull base and the area around the sella (the bony saddle that cradles the pituitary gland). The most common indications include meningiomas (tumors arising from the brain’s protective membranes), craniopharyngiomas, pituitary-region cysts, and brain aneurysms in the front part of the brain’s circulation.

In one single-center series of 50 patients, the conditions treated through this approach included 23 tumors, 17 ruptured aneurysms, five traumatic frontal blood collections, three infections, and a handful of other pathologies. Gross total resection of tumors was achieved in about 87% of cases.¹ Another series focusing specifically on anterior skull base tumors found that excellent resection results were possible even with large meningiomas.² For smaller tumors around the sella with a maximum diameter under about 30 millimeters, the approach has been described as safe, effective, and time-saving.³

For brain aneurysms, the supraorbital keyhole has been applied extensively to unruptured aneurysms in the front of the brain’s arterial network, with reassuring results in terms of successful clipping, neurological outcomes, and cosmetic results.⁴ Surgeons have also used it for ruptured aneurysms, particularly those involving the anterior communicating artery, one of the most common sites of rupture. One study found it provided sufficient exposure and a high clipping rate even in the emergency setting of a ruptured aneurysm.⁵

How It Compares to Traditional Craniotomies

The classic comparison is with the pterional craniotomy, one of the most widely used approaches in neurosurgery. The pterional approach involves a larger incision behind the hairline, more extensive bone removal from the temple region, and detachment of the temporalis muscle (the muscle you can feel moving when you clench your jaw). It provides a broad working space and excellent maneuverability, which is why it has been the default for decades.

Anatomical studies confirm that the supraorbital keyhole, despite its much smaller opening, provides surprisingly adequate exposure for many of the same targets. One morphometric study found that with the head rotated about 30 degrees, the supraorbital keyhole actually offered a wider surgical field for the region above the sella than the pterional approach did.⁶ Another cadaver study measured the physical working volumes and found that while keyhole approaches had significantly smaller surface exposure, they achieved nearly equivalent maneuverability scores for most targets.⁷

There are trade-offs, though. Compared to a mini-pterional approach (a scaled-down version of the pterional), the supraorbital keyhole provides a smaller total area of exposure and more limited working angles, particularly for aneurysms located at the middle cerebral artery bifurcation.⁸ The supraorbital keyhole works best for midline and near-midline targets. Lesions that extend far to the side or are located laterally may be better reached through a wider opening.

A study comparing surgeons who transitioned from pterional to supraorbital keyhole approaches for ruptured anterior circulation aneurysms found no increase in postoperative deficits. Rates of delayed cerebral ischemia, a feared complication after aneurysm rupture, trended lower in the keyhole group (about 16% versus 24% in the pterional group), though the difference was not statistically significant.⁹

Supraorbital Keyhole Versus Endonasal Endoscopic Routes

The other major competitor is the endonasal endoscopic approach, where surgeons reach the skull base by going through the nose. Both techniques qualify as minimally invasive and target some of the same tumors, particularly meningiomas of the tuberculum sellae, the bony ridge just in front of the pituitary gland.

For olfactory groove meningiomas (tumors sitting at the very front of the skull base, near the structures involved in smell), one comparative study found that the supraorbital eyebrow approach with endoscopic assistance achieved a higher extent of resection and a lower rate of complications than a purely endonasal endoscopic approach.¹⁰

For tuberculum sellae meningiomas specifically, a case series comparing the two routes found similar gross total resection rates (roughly 95% in both groups). The endonasal approach had an edge in visual recovery, with about 84% of eyes improving versus roughly 68% in the supraorbital group. But the endonasal route carried a higher risk of cerebrospinal fluid leakage, occurring in about 16% of endonasal cases compared to none in the supraorbital group.¹¹ The practical takeaway is that surgeons should tailor the approach to the individual tumor’s anatomy, considering its lateral extension and the surgeon’s own experience with each technique.¹²

Complications and What to Watch For

The most procedure-specific complication is cerebrospinal fluid (CSF) leakage through the nose, which can happen if the frontal sinus is breached during bone removal. The frontal sinus is an air-filled cavity in the forehead bone, and its position varies from person to person. One large series of 350 patients found that about a quarter had a visible breach of the frontal sinus on postoperative imaging, but only about 2.3% developed an actual CSF leak with fluid dripping from the nose. In all of those cases, conservative treatment with a lumbar drain did not resolve the problem, and surgical revision was needed. One patient (roughly 0.3%) developed meningitis as a result.¹³

A more recent study reported an even lower CSF leak rate of about 1.1%, noting that plugging the frontal sinus during the operation can reduce the risk further. The authors also emphasized that a large frontal sinus should not be considered a reason to avoid the approach altogether.¹⁴

Beyond CSF leakage, the general surgical risks are similar to those of any craniotomy: infection, bleeding, brain swelling, and neurological deficits. In the single-center series mentioned earlier, a good clinical outcome was achieved in 78% of patients, though the 30-day mortality was 16%, a figure that reflects the inclusion of critically ill patients with ruptured aneurysms and traumatic injuries rather than the approach itself.¹⁵ Temporary numbness of the forehead on the side of the incision is common and usually resolves, caused by stretching or cutting small sensory nerve branches during the skin opening.

Cosmetic Results

One of the biggest selling points for patients is the cosmetic outcome. The incision hides within the eyebrow, and once healed, it is often nearly invisible. A systematic review and meta-analysis pooling data from multiple centers found that about 93% of patients reported favorable cosmetic results, with permanent cosmetic complications occurring in roughly 7% of cases.¹⁶ When formal scar-rating scales were applied, patients consistently scored well, with only transient numbness of the forehead noted as a minor issue.¹⁷

Bone reconstruction after the surgery matters for cosmesis too. The orbital rim, the bony edge above the eye, is often drilled down during the procedure to improve the surgical line of sight. If this bone is not carefully replaced and fixed, patients can be left with a visible or palpable depression in the forehead. Technical modifications, such as preserving the orbital rim as part of a single bone flap rather than drilling it away separately, have been developed to minimize this risk and reduce the need for hardware fixation.¹⁸

Use in Children

The supraorbital keyhole approach has been adapted for pediatric patients, which is meaningful because children are especially sensitive to the cosmetic and functional consequences of large scalp incisions and extensive bone removal. A systematic review of clinical and cosmetic outcomes found the approach to be safe and effective for reaching the region around the sella in children, with excellent cosmetic results reported across multiple institutions.¹⁹

The pediatric literature is still relatively small, but data from two tertiary centers confirmed that the approach is technically feasible in children and can access a wide range of pathologies, including anterior skull base tumors, cysts, and frontal lobe lesions.²⁰ It has even been used in pediatric trauma, such as frontal blood collections, with only one significant complication (a recurrent blood collection requiring re-operation) reported and no cosmetic complications.²¹

Technology at the Keyhole

Because the working space is so tight, surgeons often rely on technological aids that would be optional in a larger craniotomy. Image guidance systems, essentially GPS for the brain, allow real-time tracking of instruments relative to the patient’s preoperative scans. This helps ensure the bone opening is placed precisely and the surgical corridor is aimed correctly.²²

Endoscopes are frequently paired with the keyhole opening. The surgeon may use a microscope for the main dissection and then introduce an angled endoscope to peer around corners and confirm that no residual tumor is hiding out of the microscope’s direct line of sight. This hybrid “endoscope-assisted” technique has become a standard part of the approach for many teams.

Newer innovations include virtual reality planning, where three-dimensional reconstructions of the patient’s anatomy are explored before the operation to rehearse the trajectory and anticipate obstacles. Case reports have described using VR with neuronavigation to guide real-time dissection of skull base meningiomas through the supraorbital keyhole.²³

The Learning Curve

This is where the evidence gets unexpectedly interesting. You might assume that a surgeon’s early cases would take longer and that operation times would shorten with experience. One early-career surgeon tracked their first three years of supraorbital keyhole cases and found the opposite pattern: average surgery duration actually increased from about 4.2 hours in the first half of the practice to 6.0 hours in the second half, with blood loss also trending upward. The explanation was not declining skill but increasing ambition. As the surgeon gained confidence, they took on larger and more complex tumors through the same small opening.²⁴ The mean tumor diameter rose from about 22.5 mm in the first half to 28.4 mm in the second. This is a useful reminder that learning curves in surgery are not just about speed. They reflect an evolving relationship between the surgeon’s capability and the cases they select.

The approach does demand specific anatomical knowledge and comfort working in confined spaces. Patient selection is important: not every lesion is a good candidate, and trying to force a keyhole approach on a tumor that has spread widely or has complex vascular involvement can create more problems than it solves. The literature consistently emphasizes that good outcomes depend on matching the approach to the pathology, not on applying the technique to every case that happens to involve the front of the skull.

Who Is Not a Good Candidate

The supraorbital keyhole works best for midline and near-midline lesions that sit along the corridor from the front of the skull base to the area around the pituitary. Tumors with significant lateral extension, meaning they grow sideways beyond what the keyhole can see, may be better served by a wider approach. Very large tumors can sometimes still be removed this way, as demonstrated by the series that included giant meningiomas, but this pushes the technique to its limits and demands significant surgical experience.

The endonasal route may be preferred when a tumor wraps around or compresses the optic nerves from below, since the nasal corridor allows the surgeon to decompress the nerves more directly. Conversely, when a tumor extends far to the side or encases major arteries, the supraorbital route offers better lateral access.²⁵ In practice, many skull base surgery teams are proficient in both approaches and choose based on the individual tumor’s shape, location, and relationship to surrounding structures. Some have even combined the two in a single operation, approaching from both above and below to deal with tumors that no single corridor can fully address.