World Neurosurgery
Expanded Endonasal Approach
A differentiated paradigm for removing complex skull base lesions without external incisions.
Medically Reviewed
This page was reviewed for medical accuracy by Amin B. Kassam, MD, FRCSC on June 25, 2026.
A Paradigm Shift in Skull Base Surgery
The Expanded Endonasal Approach (EEA) represents one of the most significant advances in skull base surgery over the past two decades. Developed at the University of Pittsburgh by Dr. Kassam and his otolaryngology colleagues, the EEA uses the natural nasal corridor to access and remove complex lesions of the skull base and brain, without an external incision.
The technique was defined through sentinel publications outlining the rostrocaudal axis: Part I covering the crista galli to the sella turcica, and Part II covering the posterior clinoids to the foramen magnum. These publications have become among the most cited in the field of skull base surgery.
Before this approach was developed, removing skull base tumors typically required a craniotomy, partial removal of the skull, and retraction of brain tissue to reach the tumor from above. The EEA upends this paradigm, approaching the pathology from below through the natural nasal corridor, eliminating the need for brain retraction in most cases.
How It Works
Using high-definition endoscopes inserted through the nostrils, surgeons can visualize and access the ventral skull base, from the frontal sinus to the upper cervical spine. The approach eliminates the need for external incisions, brain retraction, or craniotomy in many cases, resulting in reduced surgical trauma, shorter hospital stays, and faster recovery compared to traditional open approaches.
What This Means for You
No External Incisions
The entire procedure is performed through the nose. There are no scalp cuts, no facial incisions, and no visible scars.
Faster Recovery
Most patients spend only one to two days in the hospital, compared to the weeks of recovery that can come with traditional open skull base surgery.
No Brain Retraction
Unlike traditional approaches that required lifting brain tissue to reach the tumor, the EEA works from below the skull base, avoiding direct manipulation of the brain.
Earlier Access to Follow-Up Treatment
Patients with malignant tumors can begin chemotherapy or radiation almost immediately, without waiting for surgical incisions to heal.
Reduced Nerve Disruption
The approach causes less disruption to critical cranial nerves compared to traditional craniotomy in many skull base cases.
Conditions Treated
- Pituitary tumors and adenomas
- Craniopharyngiomas
- Meningiomas of the skull base
- Chordomas and chondrosarcomas
- Cerebrospinal fluid (CSF) leak repair
- Sinonasal tumors with intracranial extension
- Clival lesions
- Encephaloceles
Defining the Framework
Dr. Kassam defined the anatomic framework that organizes the EEA — the rostrocaudal corridors set out in his 2005 Neurosurgical Focus series — and contributed to the technology, instrumentation, and operative technique the approach depends on. A 2023 bibliometric analysis of the field’s 100 most-cited articles lists him as first author of six of the top ten, and coauthor of the most-cited. Under his leadership the Minimally Invasive Neurosurgery Center at the University of Pittsburgh became a global training destination, and he continues to teach and refine the approach.
Related Publications
Endoscopic Endonasal Approaches to the Skull Base and Paranasal Sinuses
Endoscopic endonasal technique: Treatment of paranasal and anterior skull base malignancies
Journal of Neurological Surgery Part B: Skull Base
Microsurgical anatomy of the anterior skull base as seen through the endonasal endoscopic view
Is This Procedure Right for You?
Every patient's condition is unique. Dr. Kassam and his multidisciplinary team evaluate each case individually to determine the most appropriate surgical approach.
This information is for educational purposes only and does not constitute medical advice. Treatment decisions should be made in consultation with your physician.