Endoscopic endonasal approach (EEA)
History
Types
Indications
Advantages
see Endoscopic skull base surgery advantages. The major potential advantage of the endoscopic endonasal approach to the skull base is that it provides a direct anatomical route to the lesion without traversing any major neurovascular structures, obviating brain retraction. Many tumors grow in a medial-to-lateral direction, displacing structures laterally as they expand, creating natural corridors for their resection via an anteromedial approach.
Refinements in approach and closure techniques have reduced the risk of Cerebrospinal fluid fistula and infection. This has allowed surgeons to more aggressively treat a variety of pathologies. Now its a safe and effective procedure for various parasellar lesions. Selection of patients who are unlikely to develop complications seems to be an important factor for procedure efficacy and good outcome 1).
Disadvantages
Potential disadvantages of this procedure include the relatively restricted working space and the danger of an inadequate dural repair with Cerebrospinal fluid fistula and potential for meningitis resulting. These approaches often require a large opening of the dura mater over the tuberculum sellae and posterior planum sphenoidale, or retroclival space. In addition, they typically involve large intraoperative Cerebrospinal fluid fistulas, which necessitate precise and effective dural closure 2).
Sinus opacity is still present after one year of advance endoscopic skull base surgery but symptoms seems to return to basal after 12months of follow-up 3).
Requirements
Technique
Supine position with the trunk raised 10º and the head in neutral position rotated 10º towards the surgeon. The head is secured in a Horseshoe Headrest without rigid three-pin fixation. The nose is prepared by placing pledgets soaked with 0.02% of Oxymetazoline into each nostril, followed by Povidone Iodine solution applied over the nose and upper lip as well as into the nares with cotton tip applicators.
Pediatric population
Endonasal endoscopic skull base approaches are viable in the pediatric population, they are not impeded by sphenoid sinus aeration, and they have minimal risk of Cerebrospinal fluid fistula and meningitis. Outcomes and complications can be predicted based on specific radio anatomical skull base measurements rather than age 4).
Challenges
One challenge performing endoscopic endonasal approaches is the surgical conflict that occurs between the surgical instruments and endoscope in the crowded nasal corridor. This conflict decreases surgical freedom, increases surgeon frustration, and lengthens the learning curve for trainees.
The application of a malleable endoscope to transsphenoidal approaches to the parasellar region decreases instrument-endoscope conflict and improves surgical freedom 5).
Endoscopic endonasal surgery (EES) of the skull base often requires extensive bone work in proximity to critical neurovascular structures.
In selected EES, the ultrasonic bone curette was successfully used to remove loose pieces of bone in narrow corridors, adjacent to neurovascular structures, and it has advantages to high-speed drills in these specific situations 6).
Complications
Outcome
Quality-of-life instruments
see Shukla A, Ahmed OG, Orlov CP, Price C, Mukherjee D, Choby G, Rowan NR. Quality-of-life instruments in endoscopic endonasal skull base surgery-A practical systematic review. Int Forum Allergy Rhinol. 2021 Feb 21. doi: 10.1002/alr.22783. Epub ahead of print. PMID: 33611853.
The Endoscopic Endonasal Sinus and Skull Base Surgery Questionnaire (EES-Q), is a comprehensive, multidimensional, disease-specific instrument. A distinguishing characteristic is that, apart from the physical and psychological domains, the EES-Q also encompasses a social domain. Understanding different HRQoL aspects in patients undergoing EES may help caregivers restore, improve, or preserve the patient's health through individualized care, which depends on identifying their specific needs 7).