Keyhole Approaches in Neurosurgery

Keyhole approaches in neurosurgery represent a paradigm shift towards the smallest possible craniotomy tailored to the lesion’s location and pathology. By employing precise, often sub-3 cm bone windows, surgeons gain targeted access to intracranial aneurysms, skull-base tumours, haemorrhages and other lesions while preserving surrounding tissue and reducing cosmetic impact. Common trajectories include the supraorbital route via an eyebrow incision, the pterional corridor through the temporal hairline and transsylvian windows across the Sylvian fissure. Technological adjuncts such as endoscopic illumination, neuronavigation and three-dimensional imaging enhance intraoperative visualisation, compensate for limited exposure and streamline anatomical orientation. Clinical benefits encompass shorter operating times, reduced brain retraction, faster recovery and improved patient satisfaction. Nevertheless, these techniques demand meticulous preoperative planning, advanced microsurgical skills and a thorough understanding of regional anatomy. As keyhole neurosurgery matures, global collaboration and standardised training will be essential to ensure safe application across diverse healthcare settings.

Research from Nature Portfolio

A recent clinical series evaluated transcranial neuroendoscopy combined with the supraorbital eyebrow-arch keyhole approach in nearly forty patients presenting with aneurysms, intracranial masses, trauma and cerebrospinal fluid leaks. Surgeons achieved high rates of lesion clearance and good prognoses, with craniotomy dimensions averaging under 4 cm by 2.5 cm, and endoscopic guidance ensured thorough haematoma evacuation while limiting collateral tissue disruption. Outcomes suggest this approach is safe and effective for anterior skull-base and haemorrhagic pathologies, although further prospective, multicentre validation is warranted. A complementary comparative study in a resource-limited setting assessed supraorbital minicraniotomy versus standard pterional craniotomy for anterior circulation aneurysms. Using identical microsurgical instruments, the minimally invasive group demonstrated significantly shorter operating times and higher cosmetic satisfaction without compromising angiographic cure or complication rates, underscoring the feasibility of keyhole techniques even where specialised equipment is scarce.

Keyhole Approaches in Neurosurgery publication trend

The graph below shows the total number of articles in keyhole approaches in neurosurgery across all publications each year (not limited to Nature Index journals).

Technical terms

Keyhole craniotomy: A minimal bone opening, typically under 3 cm in diameter, designed to limit soft-tissue dissection and maximise surgical efficiency.

Supraorbital approach: A keyhole technique utilising an eyebrow or upper eyelid incision to access anterior cranial fossa and orbital rim lesions.

Pterional approach: A frontotemporal craniotomy through the pterion, offering access to anterior circulation aneurysms and basal frontal structures.

Mini-pterional craniotomy: A reduced-size variant of the pterional approach, maintaining anatomical landmarks while minimising incision length and bone removal.

Transsylvian corridor: A natural fissure-based route through the Sylvian fissure used to reach deep basal regions such as the circle of Willis.

Endoscope-assisted neurosurgery: The use of rigid or flexible endoscopes to provide illumination, magnification and angled views within confined cranial spaces.

Modified Rankin Scale (mRS): A clinical scale measuring the degree of disability or dependence in daily activities following a neurological event.

References

1. Clinical application of transcranial neuroendoscopy combined with supraorbital keyhole approach in minimally invasive surgery of the anterior skull base. Scientific Reports (2024).
2. Comparative study between minimally invasive supraorbital craniotomy and pterional craniotomy for treating anterior circulation cerebral aneurysms in a low-resource setting. Scientific Reports (2021).
3. International expert consensus statement about methods and indications for keyhole microneurosurgery from International Society on Minimally Invasive Neurosurgery. Neurosurgical Review (2019).
4. How I do it—Helsinki style mini-pterional craniotomy for clipping of middle cerebral artery bifurcation aneurysms. Acta Neurochirurgica (2022).
5. Clipping of anterior circulation aneurysms using fully endoscopic-assisted minimally invasive keyhole craniotomy: a clinical study and analysis. Neurosurgical Review (2025).