Endoscopic endonasal skull base surgery is a way of reaching tumours and other lesions at the base of the skull through the nose, using a thin endoscope instead of opening the skull. It grew out of transsphenoidal pituitary surgery and now reaches areas from the front of the skull base down to the top of the spine. For the right tumour, it can avoid brain retraction and a scalp incision. For the wrong tumour, an open approach is still safer. This guide explains how the operation works, which conditions it is used for, how the surgical team repairs the skull base afterwards, and what recovery usually involves.
The information here is general. Whether an endonasal route suits you depends on the exact position of the lesion, its relationship to the optic nerves and arteries, and what the surgery needs to achieve. That decision belongs to an experienced skull base team that has reviewed your scans.
What Is Endoscopic Endonasal Skull Base Surgery?
The skull base is the floor of the skull. The brain sits on top of it, and the nose, sinuses, eye sockets, and throat lie below it. Many important structures pass through this area, including the optic nerves, the carotid arteries, the pituitary gland, and the cranial nerves that control eye movement, facial sensation, and swallowing.
In an endoscopic endonasal operation, the surgeon passes a rigid endoscope with a camera and light through one or both nostrils. The sphenoid sinus, at the back of the nose, is opened to expose the bone of the skull base. Bone is then removed over the lesion, and the tumour is removed with fine instruments while the surgeon watches a high-definition screen. Neurosurgeons and ear, nose, and throat (ENT) surgeons often work together, with two surgeons operating through both nostrils at the same time.
Standard endoscopic transsphenoidal surgery stays within the sella, the bony pocket that holds the pituitary gland. The expanded endonasal approach goes further. Surgeons at the University of Pittsburgh described it as a series of modules along the midline of the skull base, from the crista galli at the front, through the sella, down to the clivus and the foramen magnum. Each module opens a different corridor, which is why the term covers a family of operations rather than one procedure.
Which Conditions Can Be Treated Through the Nose?
The endonasal route works best for lesions that sit in the midline and grow towards the nose, so that the surgeon can reach them without crossing nerves or major arteries. Common examples include:
- Pituitary adenomas, including large and invasive tumours, and hormone-secreting tumours such as those causing Cushing disease or acromegaly
- Craniopharyngiomas, especially tumours below or behind the optic chiasm
- Clival chordomas and chondrosarcomas, which arise in the bone behind the nose
- Selected midline meningiomas, such as some tuberculum sellae and planum meningiomas
- Rathke cleft cysts, epidermoid tumours, and other cysts reaching the skull base
- Spontaneous or post-traumatic cerebrospinal fluid (CSF) leaks and encephaloceles
- Sinonasal tumours that have grown through the skull base, such as esthesioneuroblastoma
Prof. Guive Sharifi's own published work reflects this range. His team has reported endoscopic endonasal removal of a large petrous apex epidermoid tumour with clival and intradural extension, five years of experience using image guidance in endonasal sinus and skull base surgery, and a pure endoscopic endonasal approach for Cushing disease.
Endonasal or Open Surgery: How Is the Approach Chosen?
No single approach is best for every skull base tumour. A systematic review comparing endoscopic and open transcranial surgery found that, for craniopharyngiomas, clival chordomas, esthesioneuroblastomas, and giant pituitary adenomas, the endonasal route could achieve equal or higher rates of complete removal. For meningiomas, open approaches still achieved complete removal more often, and CSF leaks were more common after endoscopic surgery for meningiomas and craniopharyngiomas. A later meta-analysis of olfactory groove and tuberculum sellae meningiomas found a similar balance of benefits and trade-offs.
In practice, the team looks at several questions before recommending a route:
- Where is the tumour centred, and does it extend sideways beyond the carotid arteries or optic nerves?
- Which way did the tumour push the optic nerves and the pituitary gland as it grew?
- Is the tumour encasing arteries or nerves, and how firm is it likely to be?
- Has the patient had previous surgery or radiotherapy in the same area?
- What is the goal: complete removal, decompression of the optic nerves, a biopsy, or hormone control?
Sometimes the best plan combines both: an endonasal stage for the midline part of a tumour and a transcranial stage for the part that extends sideways. A second opinion from a team that performs both endoscopic and open skull base surgery helps avoid choosing a route only because it is the one a surgeon prefers.
How Is the Skull Base Repaired After Surgery?
Removing a tumour through the skull base leaves an opening between the nose and the fluid around the brain. If it is not sealed well, CSF can leak through the nose, and a leak can lead to meningitis. Reconstruction is therefore as important as tumour removal.
The most important advance in this area was the vascularised nasoseptal flap, a strip of lining from the nasal septum that keeps its own blood supply and is rotated to cover the defect. In the original 2006 series of 43 patients, two had a postoperative CSF leak. A systematic review of large skull base defects later found a leak rate of 6.7% when vascularised tissue was used, compared with 15.6% with free grafts. Leak rates in an individual series depend on the type of tumour, the size of the defect, and the patient, so your surgeon should explain the risk for your specific operation.
What Are the Risks?
Endoscopic endonasal surgery avoids some risks of open surgery, such as brain retraction and a large scalp wound, but it has its own risks. These are discussed in detail before consent. The main ones are:
- CSF leak, which may need a return to theatre or a lumbar drain
- Meningitis, usually linked to a CSF leak
- Hormone problems, including temporary or permanent diabetes insipidus and pituitary hormone deficiency, especially for tumours near the pituitary stalk
- Changes in vision, although many patients with optic nerve compression see improvement
- Injury to the carotid artery or other blood vessels, which is rare but serious
- Nasal crusting, a reduced sense of smell, and sinus symptoms during healing
The general benefits and risks of brain and spine operations are covered in our guide to neurosurgery risks and benefits.
What Is Recovery Like?
Most patients wake up with a blocked nose rather than a painful head wound. The hospital stay depends on the size of the operation. After a standard pituitary operation, many people go home within a few days. After an extended approach with a large reconstruction, the stay is often longer, and some teams recommend bed rest or a lumbar drain for a short time to protect the repair.
During the first weeks, patients are usually asked to avoid blowing the nose, straining, heavy lifting, and drinking through a straw. Saline rinses and clinic visits help clear crusts as the nose heals. Hormone levels and sodium are monitored closely, particularly when the tumour was close to the pituitary gland. A detailed, week-by-week timeline is in our article on recovery after endoscopic transsphenoidal surgery.
Call your team the same day if you notice clear watery fluid dripping from the nose, especially when leaning forward, a worsening headache, fever, neck stiffness, a change in vision, or extreme thirst with large volumes of urine.
The Role of Experience
Endonasal skull base surgery depends on a team, not a single instrument. Good results need a surgeon who knows the anatomy from both the endoscopic and the open side, an ENT partner for access and reconstruction, an endocrinologist for hormone care, and imaging and navigation that help the surgeon locate the tumour. In a series published by Prof. Sharifi's team, 134 patients with Cushing disease underwent endoscopic endonasal transsphenoidal surgery by a single surgeon, including 15 patients whose tumours could not be seen on MRI. Work like this shows why a multidisciplinary skull base team matters for complex pituitary and skull base cases.
Prof. Guive Sharifi is a Professor of Neurosurgery and skull base surgeon. You can read more about endoscopic pituitary surgery, how pituitary tumours affect vision, and his research on the publications page.