Expanded Endonasal Approach (EEA)

In the late 1990s, Dr. Amin Kassam helped develop the Expanded Endonasal Approach (EEA) – a type of brain surgery that allows surgeons to access the skull base and upper cervical spine in a less invasive way. Today, EEA has become the standard of care for accessing a wide variety of tumors and other skull base lesions.


Before this innovative approach was developed, removing skull base tumors required a craniotomy (partial removal of the skull) and drawing back brain tissue. There are still cases in which this older approach may be necessary, but for the majority of lesions in the skull base and cervical spine, EEA can be performed. 

During endoscopic endonasal surgery, a neurosurgeon and an otolaryngologist – a head and neck surgeon – work together to enter the skull base through the nose. This minimally invasive technique eliminates the need for incisions and brain retraction. By removing the rear half of the nasal septum (the divider between the two sides of the nose) and the bone in front of the sphenoid sinus (the farthest back of the paranasal sinuses), surgeons can reach the skull base.

Tumors are then removed with the help of high-definition optics and an endoscope. Finally, the skull base is reconstructed using a flap of the septal membrane – which seals off the brain from the nose – helping prevent complications.


The Expanded Endonasal Approach allows access to skull base tumors without the complications seen with open skull base surgery, which include infections associated with large scalp incisions and the side effects seen with brain retraction. Most patients undergoing EEA spend only 1 to 2 days in the hospital, and recovery time at home is much shorter than for open skull base surgery. In addition, there are many scenarios in which EEA causes less disruption of critical nerves during skull base surgery.

Related Conditions

The Expanded Endonasal Approach is used to perform minimally invasive brain surgery and minimally invasive spine surgery for these conditions:

A Revolutionary Procedure

Dr. Amin Kassam, Aurora’s Vice President of Neurosciences, explains the Expanded Endonasal Approach.

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