objectively conrmed sinusitis whocontinue to suffer from sinonasalsymptoms following prior ESSand appropriate medical therapy.

• Certain maneuvers such as complete ethmoid dissection, middle turbinate resec-

tion, and septoplasty may lead to improved ESS outcomes and should be consid­ered during revision ESS.

• When revision ESS is appropriately selected and performed for chronic rhinosi-

Once patients meet criteria for revision ESS, surgeons must determine why the previous ESS failed, and which sinuses require revision surgery to alleviate patients’ symptoms or prevent future complications from scarringof the sinonasal cavities. The next sections will discuss reported outcomes of primary and revision ESS, as well as patient-related and technical reasons for ESS failures. These reasons for ESS failure will then be considered when performing revision ESS.

Most published ESS success rates relate to primary ESS. Multiple studies have shown improvement in cardinal sinusitis symptoms following ESS in 90–100% of chronic rhinosinusitis (CRS) cases, [2, 3] recurrent acute rhinosinusitis, [4] odonto­genic sinusitis when the dental infectious source is controlled, [5] and paranasal sinus fungal balls [6]. Most literature on long-term ESS failure rates pertains to chronic rhinosinusitis with or without nasal polyps (CRSwNP, CRSsNP), with 4–19% of primary cases requiring revision ESS [7–10]. When necessary for CRS, revision ESS is performed on average about 2–5years after primary ESS, but time to revision is shorter for patients with CRSwNP [8, 11–13]. There have been fewer publications on revision ESS outcomes, but studies to date have demonstrated simi­lar degrees of symptomatic improvement in CRS patients when comparing primary to revision ESS [14–16]. Also important, a study based on all-payer claims data­bases showed equivalent rates of major complications after revision ESS (0.46%) compared to primary ESS (0.36%) [17]. However, some minor complications may be more common after revision ESS, like synechiae [18].

Multiple studies have demonstrated that certain surgical techniques improve symp­tomatic results and prolong time to revision ESS.These studies have generally been conducted in the setting of primary ESS for CRS, but this data will be extrapolated to revision ESS for this chapter.

hypertrophy, septoplasty and/or ITR may provide additional benet when per­formed with ESS.Regardless of symptoms, these techniques may improve intraop­erative access for sinus dissection, and postoperative access for sinus disease monitoring and debridements.

One nal point to discuss is the use of image-guided surgery, which has become commonly used by many surgeons during ESS.While evidence has been mixed with regard to whether image-guided surgery improves outcomes and decreases complications, the recent international consensus on rhinosinusitis presented mul­tiple studies showing its benets, especially in advanced or revision ESS, and rec­ommended it as a viable option during ESS [1].

All patients should undergo preoperative CT evaluation to identify anatomic rea­sons for persistent disease, locations of persistent disease, and anatomy that may be high-risk for complications and for surgical failure intra-operatively [58]. Specic attention should be paid to anatomy that can contribute to persistent disease or limit access to all sinuses and ostia, areas of residual bony partitions with or without osteitis/neo-osteogenesis, lateralization of middle turbinates, and deviated nasal septum. High-risk anatomy to consider includes orbital and/or skull base dehis­cences, high maxillary:ethmoid high ratio, low-lying anterior ethmoid arteries, dehiscences of the optic nerve or carotid artery, and the presence of Onodi(spheno­ethmoid) cells.