Abstract
Purpose
Endoscopic sinus surgery (ESS) can manipulate sinus anatomy, but with limitations due to skull base and orbit anatomy. These anatomical structures dictate the maximal extent of ESS in the frontal recess and may limit surgical extent or operative duration. This study investigates the impact of these anatomical constraints on operative time and quality-of-life (QOL) outcomes.
Materials and methods
Patients with medically refractory chronic rhinosinusitis undergoing Draf IIa frontal sinus surgery were prospectively enrolled. Anatomic measurements of the frontal sinus anatomy were collected during computed tomography review and included: widest distance between the frontal beak and posterior table, narrowest point in the ethmoid bed, Keros height, presence of an anterior ethmoid artery on a mesentery, and presence of inter-sinus septal cells. Primary outcomes included mean operative time and improvement in SinoNasal Outcome Test (SNOT-22) survey scores.
Results
63 adult participants were enrolled and followed 13.8 (5.2) months on average. The ethmoid bed mean width was 7.2 (1.4) mm, the mean distance from frontal beak to the posterior table at widest was 9.0 (2.7) mm, and mean Keros height was 5.1 (1.8) mm. 49/63 (83.1%) of participants had inter-sinus septal cells and 30/63(50.8%) had anterior ethmoid arteries on a mesentery. Mean operative time was 121.5 (44.0) min while SNOT-22 scores significantly (p < 0.001) improved 26.1 (21.6) on average. Anatomic measurements were not predictive of operative time or mean QOL change (p > 0.050).
Conclusions
Frontal sinus surgery is an effective treatment for a range of frontal and ethmoid sinus anatomy. Further study with larger sample size and measures of more restricted anatomy might elucidate treatment limitations of ESS.
1
Introduction
Endoscopic sinus surgery is an effective means to treat chronic rhinosinusitis (CRS) and is predicated on surgically augmenting natural sinus openings . Although there is controversy over the ideal size and extent of antrostomies and sinusotomies , there is evidence that larger openings facilitate increased topical therapies and may better accommodate edema . The literature surrounding sinonasal irrigation has demonstrated that larger sinus openings facilitate greater irrigation volume and improved distribution of topical therapies. The sinuses, however, are tightly nestled between the cranial cavity and orbits which both act as strict anatomical limitations to the extent of a sinus opening during surgery. Furthermore, narrow ethmoid beds, diminutive frontal recesses and low-hanging anterior ethmoid arteries add surgical risk and challenge.
These intraoperative challenges may contribute to retained cells around anterior ethmoid arteries, predispose frontal sinus openings to swelling closed, or contribute to prolonged operative time. Retained cells and sinuses occluded by edematous mucosa may lead to diminished gains of quality of life (QOL) improvements after endoscopic sinus surgery. Given the degree to which anatomy impacts the technical challenges of surgical intervention, the present study seeks to investigate if these anatomic constraints negatively impact QOL outcomes and operative times in a surgical subpopulation requiring intervention of the frontal sinuses.
2
Materials and methods
2.1
Inclusion and exclusion criteria
All protocols and informed consent were approved by the Institutional Review Board at Oregon Health & Science University (OHSU; eIRB #7198). Adult (≥ 18 years) study participants were enrolled and followed at OHSU as part of an on-going, prospective, observational cohort study that has been previously reported . These subjects were enrolled prospectively between April, 2011 and July, 2013. All subjects had a diagnosis of CRS based on the Rhinosinusitis Task force criteria and were enrolled when the subjects elected to pursue ESS after failing either broad-spectrum or culture-directed antibiotics and a trial of oral and topical steroid therapy.
Study participants elected endoscopic sinus surgery (ESS) as the next treatment modality to assist in control of symptoms associated with CRS. Surgical extent was dictated by individual disease processes and the intraoperative clinical judgment of the enrolling physician (TLS). Participants were either primary or revision surgery cases. Surgical procedures included various combinations of the following: unilateral or bilateral maxillary anstrostomy, partial or total ethmoidectomy, sphenoidotomy, middle or inferior turbinate reduction, frontal sinus procedures (Draf I, IIa/b, or III), and septoplasty.
Only subjects undergoing ESS of the frontal sinuses were included for final study analyses. Frontal sinus surgery was defined as removal of all frontal recess cells between the lamina papyracea and the middle turbinate (Draf IIa) or between the lamina papyracea and the nasal septum (Draf IIb). This prospectively collected dataset did not originally include information regarding sinonasal anatomy associated with the frontal region; therefore, this cohort was retrospectively investigated for study participants with a preoperative computed tomography (CT) scan available for review.
Participants with at least six-month postoperative follow-up data were included for final analysis. Any participant presenting with exacerbations of recurrent acute rhinosinusitis or comorbid cystic fibrosis was excluded due to the heterogeneity of those disease processes.
2.2
QOL evaluation and objective testing
Consented participants were administered the 22-item Sinonasal Outcome Test-22 (SNOT-22) at the initial, preoperative enrollment meeting and at least 6 months post-operatively. The SNOT-22 evaluates physical, functional and emotional impact of chronic rhinosinusitis and includes all symptomatic criteria set forth by the Rhinosinusitis Task Force . Total scores range from 0 (no impact) to 110 (most severe impact). Baseline scores and mean change scores were used to evaluate post-treatment clinical improvement. Prior study has defined improvement in this population and established the minimal clinically important difference (MCID) of the SNOT-22 score as 8.9 (≥ 9.0) in a population undergoing sinonasal surgery .
Objective measures of CRS included conventional CT and visual endoscopic evaluations. Computed tomography scans were obtained preoperatively and evaluated by the enrolling surgeon (TLS) in the coronal plane using the Lund–Mackay scoring system (0–24 point scale) . Rigid sinonasal endoscopy procedures were performed preoperatively and at least 6 months postoperatively when possible. The last available endoscopic exam was used to determine for postoperative changes from baseline. Bilateral endoscopic examinations were quantified using the scoring system described by Lund and Kennedy (0–20 point scale) .
2.3
Predictive anatomic measurements
Computed tomography scans were reviewed using a triplanar view from a picture archiving and communication system (IMPAX, Agfa HealthCare Corp., Greenville, SC., USA) to identify four anatomic parameters related to the frontal recess: anterior–posterior (A–P) distance (mm), Keros height (mm) , narrowest ethmoid width (mm) and presence of either intersinus septal cells or an anterior ethmoid artery on a mesentery. A digital caliper was used for all measurements. The A–P distance was defined as the widest point of the plane at the junction of the frontal recess and the frontal sinus. This plane is defined by the line that forms a tangent simultaneously to the frontal beak and posterior table on the sagittal view ( Fig. 1 ). Keros height was measured on the coronal view from the ethmoid roof to the cribiform plate ( Fig. 2 ) . Ethmoid width was defined and measured at the narrowest distance that begins perpendicular to the lamina paparycea and ends at the lateral lamella of the cribiform plate ( Fig. 3 ). Paired measurements were averaged between both sides to generate a single reportable measure. Presence of an intersinus cell was reported as a dichotomous variable (Yes/No) if the frontal sinus beak was pneumatized ( Fig. 4 ) . If the anterior ethmoid artery was at any point distinctly inferior to and free of the ethmoid skull base, then it was defined as being on a mesentery in a binary (Yes/No) fashion ( Fig. 5 ).
2.4
Operative time
Total operative time (minutes) was collected using perioperative surgical records. The total operative time was determined from time of day of the primary surgical incision, as marked by the operative nurse, to the time of operative closure. Time associated with intubation and extubation were not included in total operative time evaluations.
2.5
Statistical analysis
De-identified study data were collected and transferred from standardized clinical research forms into a relational database (Microsoft Access; Microsoft Corp., Redmond, WA, USA). All statistical analyses were performed using a commercially available software program (SPSS v.22; IBM Corp., Armonk, NY, USA). Descriptive analytics were completed for all study subject characteristics and anatomic sinus parameters to assess distribution normality, mean, standard deviations, and data ranges. Matched pairs t-testing was used to evaluate significant improvement in SNOT-22 total scores between preoperative and postoperative assessments. Pearson’s correlation coefficients (r p ) were used to evaluate linear associations between mean improvements in SNOT-22 scores (postoperative − preoperative scores) and all continuous measurements of frontal anatomy. Independent t-testing was used to evaluate differences in improvement in SNOT-22 score measures and mean operative time across binary measures of frontal anatomy and extent of frontal surgery. Pearson’s chi-square (χ 2 ) tests and Fisher’s exact tests were also utilized to evaluate significant differences in the prevalence of improvement (one or more MCID) in SNOT-22 scores across any binary measure of frontal anatomy where appropriate. Significant associations were determined at a conventional 0.050 alpha level.
2
Materials and methods
2.1
Inclusion and exclusion criteria
All protocols and informed consent were approved by the Institutional Review Board at Oregon Health & Science University (OHSU; eIRB #7198). Adult (≥ 18 years) study participants were enrolled and followed at OHSU as part of an on-going, prospective, observational cohort study that has been previously reported . These subjects were enrolled prospectively between April, 2011 and July, 2013. All subjects had a diagnosis of CRS based on the Rhinosinusitis Task force criteria and were enrolled when the subjects elected to pursue ESS after failing either broad-spectrum or culture-directed antibiotics and a trial of oral and topical steroid therapy.
Study participants elected endoscopic sinus surgery (ESS) as the next treatment modality to assist in control of symptoms associated with CRS. Surgical extent was dictated by individual disease processes and the intraoperative clinical judgment of the enrolling physician (TLS). Participants were either primary or revision surgery cases. Surgical procedures included various combinations of the following: unilateral or bilateral maxillary anstrostomy, partial or total ethmoidectomy, sphenoidotomy, middle or inferior turbinate reduction, frontal sinus procedures (Draf I, IIa/b, or III), and septoplasty.
Only subjects undergoing ESS of the frontal sinuses were included for final study analyses. Frontal sinus surgery was defined as removal of all frontal recess cells between the lamina papyracea and the middle turbinate (Draf IIa) or between the lamina papyracea and the nasal septum (Draf IIb). This prospectively collected dataset did not originally include information regarding sinonasal anatomy associated with the frontal region; therefore, this cohort was retrospectively investigated for study participants with a preoperative computed tomography (CT) scan available for review.
Participants with at least six-month postoperative follow-up data were included for final analysis. Any participant presenting with exacerbations of recurrent acute rhinosinusitis or comorbid cystic fibrosis was excluded due to the heterogeneity of those disease processes.
2.2
QOL evaluation and objective testing
Consented participants were administered the 22-item Sinonasal Outcome Test-22 (SNOT-22) at the initial, preoperative enrollment meeting and at least 6 months post-operatively. The SNOT-22 evaluates physical, functional and emotional impact of chronic rhinosinusitis and includes all symptomatic criteria set forth by the Rhinosinusitis Task Force . Total scores range from 0 (no impact) to 110 (most severe impact). Baseline scores and mean change scores were used to evaluate post-treatment clinical improvement. Prior study has defined improvement in this population and established the minimal clinically important difference (MCID) of the SNOT-22 score as 8.9 (≥ 9.0) in a population undergoing sinonasal surgery .
Objective measures of CRS included conventional CT and visual endoscopic evaluations. Computed tomography scans were obtained preoperatively and evaluated by the enrolling surgeon (TLS) in the coronal plane using the Lund–Mackay scoring system (0–24 point scale) . Rigid sinonasal endoscopy procedures were performed preoperatively and at least 6 months postoperatively when possible. The last available endoscopic exam was used to determine for postoperative changes from baseline. Bilateral endoscopic examinations were quantified using the scoring system described by Lund and Kennedy (0–20 point scale) .
2.3
Predictive anatomic measurements
Computed tomography scans were reviewed using a triplanar view from a picture archiving and communication system (IMPAX, Agfa HealthCare Corp., Greenville, SC., USA) to identify four anatomic parameters related to the frontal recess: anterior–posterior (A–P) distance (mm), Keros height (mm) , narrowest ethmoid width (mm) and presence of either intersinus septal cells or an anterior ethmoid artery on a mesentery. A digital caliper was used for all measurements. The A–P distance was defined as the widest point of the plane at the junction of the frontal recess and the frontal sinus. This plane is defined by the line that forms a tangent simultaneously to the frontal beak and posterior table on the sagittal view ( Fig. 1 ). Keros height was measured on the coronal view from the ethmoid roof to the cribiform plate ( Fig. 2 ) . Ethmoid width was defined and measured at the narrowest distance that begins perpendicular to the lamina paparycea and ends at the lateral lamella of the cribiform plate ( Fig. 3 ). Paired measurements were averaged between both sides to generate a single reportable measure. Presence of an intersinus cell was reported as a dichotomous variable (Yes/No) if the frontal sinus beak was pneumatized ( Fig. 4 ) . If the anterior ethmoid artery was at any point distinctly inferior to and free of the ethmoid skull base, then it was defined as being on a mesentery in a binary (Yes/No) fashion ( Fig. 5 ).
