Surgery of the frontal sinus remains the most difficult area within the management of chronic rhinosinusitis (CRS). This is evidenced by the variety of approaches to the problem, which have been proposed over the years. Endonasal approaches were originally proposed by Schaeffer, Halle, Moser, and others in the early part of the 20th century. However, these were largely blind approaches and associated with significant complications. Accordingly, for much of the 20th century, the focus was on external approaches to frontal sinus disease, such as frontal sinus collapse (Riedel procedure), osteoplastic frontal sinusotomy, and frontal sinus obliteration. With the advent of endoscopic techniques in the latter part of the 20th century, interest was renewed in endonasal approaches to frontal sinus disease and frontal sinus mucoceles. Early approaches tended to be associated with significant trauma to the frontal recess, loss of mucosa, and a significant incidence of stenosis. However, with the advent of delicate through-cutting angled instrumentation, curved microdebriders, triplanar imaging, computer-assisted surgical navigation, and delicate malleable probes for the intraoperative identification of the frontal sinus drainage pathway, very delicate atraumatic and effective frontal sinus drainage can now be achieved endoscopically with a minimally invasive (Draf 2a) procedure and a low risk of stenosis of the frontal sinus. Stammberger has called this procedure, somewhat aptly, “uncapping the egg.” The concept here is that a diseased and enlarged ethmoid infundibulum, ethmoid cell, or agger nasi cell that blocks the frontal sinus drainage pathway can be considered somewhat similar to an eggshell inside in an inverted egg cup (frontal recess). In order to reestablish drainage, it is necessary to fracture and remove the bone of the expanded cell (eggshell) away from the surrounding mucosal-covered bone (egg cup) in a minimally traumatic fashion (Fig. 17.1).

While tumors of the frontal sinus typically require an extended frontal sinus procedure, the vast majority of patients with CRS involving the frontal sinus and frontal sinus mucoceles even with extensive intraorbital and intracranial involvement, can be operated through a Draf 2a procedure (Fig. 17.2). Although when I initially suggested approaching mucoceles endoscopically with this approach it was received with significant skepticism and controversy, long-term success has now been well documented. Patients with CRS presenting for endoscopic frontal sinusotomy typically have associated disease in other sinuses, in particular the ethmoid sinus, and therefore most frequently are best addressed with a surgical approach rather than just a balloon dilatation procedure. Additionally, removal of osteitic bone fragments is an important goal in the prevention of persistent inflammation and renewed stenosis.

The success of a Draf 2a approach depends significantly upon the surgeon’s experience, the availability of appropriate minimally invasive instrumentation, and the ability of the surgeon to adequately conceptualize the 3-D anatomy of the frontal sinus drainage pathway prior to surgical intervention. It also requires endoscopic follow-up because should stenosis occur, mucocele formation often remains asymptomatic for between 15 and 20 years. Additionally, as with other surgery for CRS, the surgery itself is primarily adjunctive to medical management, and endoscopic follow-up provides the necessary basis for such therapy, which in some cases will be prolonged.