**3. Patient selection, radiographic evaluation, and statistical analyses**

We reviewed the medical records of 243 patients who received bilateral FESS in our department by the same senior surgeon of a tertiary referral hospital from September 2010 to August 2011. Computed tomography (CT) of paranasal sinuses was performed in all patients at most 2 months prior to surgery. Other preoperative evaluations included hematologic examination the day before surgery. Patients with known systemic diseases or malignancies were excluded, such as diabetes mellitus, asthma, or other immunocompromised diseases. Forty-eight CRS patients who received revised sinus surgery during this period were recruited; 21 of these patients received surgery by the same surgeon, and the other 27 patients received surgery from different surgeons. Among the 21 patients, patients with no previous

sinus CT scan available for comparison were excluded. Among the 27 patients, we excluded the patients who received previous Caldwell-Luc procedures. Nine patients were assigned to Group A (primary and revised surgery by the same senior surgeon), 17 patients were assigned to Group B (previously operated on by other surgeons), and 30 control patients were assigned to Group C who received primary FESS surgery during the same period and were followed up for at least 3 years without revision surgery. Group D included 30 control patients with head and neck CT scan from parotid surgery without notified sinonasal problems. Hematologic examination was evaluated for Group D patients 1 day prior to surgery. The flow chart of patient selection is shown in **Figure 1**. The clinical information including the result of bacterial culture and pathology to evaluate eosinophilic rhinosinusitis, with or without asthma and ImmunoCAP Specific IgE blood test, were also collected for further analysis.

The extent of paranasal sinus mucosal disease was evaluated by using the L-M staging system [7]. Sinus wall thickness was measured in coronal view of the sinus CT. The posterolateral wall of maxillary sinus, para-crista galli level (around the lateral lamella) of the ethmoid sinus, and the anterior clinoid level of sphenoid sinus were measured as the representative thickness of each sinus wall (**Figure 2**). All CT studies were performed by 64 multidetector-row CTs (LightSpeed VCT, GE Medical Systems). Contiguous axial 1.2-mm-thick slices were obtained through the maxillofacial bones, and images were reconstructed with soft tissue and bone reconstruction algorithms; 3.0-mm-thick coronal and sagittal reformatted images were obtained per our institutional protocol. All CT measurements were made on bone algorithm reconstructed and bone-windowed images (W:2000, L:500) using an independent workstation. The measurements were repeated by two independent otolaryngologists. In detail, maxillary sinus wall thickness is measured at the posterolateral region where the first cut is shown when the zygoma is separated from the maxillary sinus wall, measuring the thickest part. The ethmoid sinus wall thickness is measured at the para-crista galli region around the lateral lamella, also the thickest part. The sphenoid

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population.

*clinoid, the thickest part (white arrow).*

**Figure 2.**

*Refractory Rhinosinusitis*

*DOI: http://dx.doi.org/10.5772/intechopen.84714*

sinus wall thickness is measured at the first cut showing the anterior clinoid, the thickest part. At the lateral sphenoid wall, the carotid canal and optic nerve may introduce measurement confusion, and it is the reason why we choose the anterior clinoid level instead of the lateral sphenoid wall for wall thickness measurement where more constant sinus wall thickness could be measured. Frontal sinus wall was excluded due to its high variation of pneumatization in normal

*Representative sinus CT scan to measure sinus wall thickness. A 61-year-old male patient with recurrent CRS and status post two times of FESS; the figure shows the preoperative sinus CT image of the first FESS. (A) Maxillary sinus wall thickness is measured at the posterolateral region. The first cut is shown when the zygoma (white arrow) is separated from the maxillary sinus wall, measuring the thickest part. (B) Ethmoid sinus wall thickness is measured at the para-crista galli region around the lateral lamella, the thickest part (white arrow). (C) The sphenoid sinus wall thickness is measured at the first cut showing the anterior* 

We assessed gender, age, hemoglobin (Hb) levels, white blood cell (WBC) count, eosinophilic count, L-M score, bony wall thickness of maxillary/ethmoid/ sphenoid sinus, and mean recurrence time of CRS. Comparisons between groups were performed by analysis of variance (ANOVA) tests for normally distributed variables and Kruskal-Wallis test for nonparametric variables, as required. Chisquare tests for categorical variables. Multiple logistic regression analysis was performed between Groups A and C against various parameters including age, gender and maxillary sinus wall thickness, LM score, Hb, and eosinophil count. Receiver-operating characteristic (ROC) curves were constructed to define cutoff value for potential refractory CRS. Linear regression was used to determine the relationship between scalar variables. All statistical analyses were performed using

SPSS software. *p* < 0.05 was considered to be statistically significant.

**Figure 1.** *Flow chart of patient selection.*

*Refractory Rhinosinusitis DOI: http://dx.doi.org/10.5772/intechopen.84714*

#### **Figure 2.**

*Rhinosinusitis*

lected for further analysis.

sinus CT scan available for comparison were excluded. Among the 27 patients, we excluded the patients who received previous Caldwell-Luc procedures. Nine patients were assigned to Group A (primary and revised surgery by the same senior surgeon), 17 patients were assigned to Group B (previously operated on by other surgeons), and 30 control patients were assigned to Group C who received primary FESS surgery during the same period and were followed up for at least 3 years without revision surgery. Group D included 30 control patients with head and neck CT scan from parotid surgery without notified sinonasal problems. Hematologic examination was evaluated for Group D patients 1 day prior to surgery. The flow chart of patient selection is shown in **Figure 1**. The clinical information including the result of bacterial culture and pathology to evaluate eosinophilic rhinosinusitis, with or without asthma and ImmunoCAP Specific IgE blood test, were also col-

The extent of paranasal sinus mucosal disease was evaluated by using the L-M staging system [7]. Sinus wall thickness was measured in coronal view of the sinus CT. The posterolateral wall of maxillary sinus, para-crista galli level (around the lateral lamella) of the ethmoid sinus, and the anterior clinoid level of sphenoid sinus were measured as the representative thickness of each sinus wall (**Figure 2**). All CT studies were performed by 64 multidetector-row CTs (LightSpeed VCT, GE Medical Systems). Contiguous axial 1.2-mm-thick slices were obtained through the maxillofacial bones, and images were reconstructed with soft tissue and bone reconstruction algorithms; 3.0-mm-thick coronal and sagittal reformatted images were obtained per our institutional protocol. All CT measurements were made on bone algorithm reconstructed and bone-windowed images (W:2000, L:500) using an independent workstation. The measurements were repeated by two independent otolaryngologists. In detail, maxillary sinus wall thickness is measured at the posterolateral region where the first cut is shown when the zygoma is separated from the maxillary sinus wall, measuring the thickest part. The ethmoid sinus wall thickness is measured at the para-crista galli region around the lateral lamella, also the thickest part. The sphenoid

**76**

**Figure 1.**

*Flow chart of patient selection.*

*Representative sinus CT scan to measure sinus wall thickness. A 61-year-old male patient with recurrent CRS and status post two times of FESS; the figure shows the preoperative sinus CT image of the first FESS. (A) Maxillary sinus wall thickness is measured at the posterolateral region. The first cut is shown when the zygoma (white arrow) is separated from the maxillary sinus wall, measuring the thickest part. (B) Ethmoid sinus wall thickness is measured at the para-crista galli region around the lateral lamella, the thickest part (white arrow). (C) The sphenoid sinus wall thickness is measured at the first cut showing the anterior clinoid, the thickest part (white arrow).*

sinus wall thickness is measured at the first cut showing the anterior clinoid, the thickest part. At the lateral sphenoid wall, the carotid canal and optic nerve may introduce measurement confusion, and it is the reason why we choose the anterior clinoid level instead of the lateral sphenoid wall for wall thickness measurement where more constant sinus wall thickness could be measured. Frontal sinus wall was excluded due to its high variation of pneumatization in normal population.

We assessed gender, age, hemoglobin (Hb) levels, white blood cell (WBC) count, eosinophilic count, L-M score, bony wall thickness of maxillary/ethmoid/ sphenoid sinus, and mean recurrence time of CRS. Comparisons between groups were performed by analysis of variance (ANOVA) tests for normally distributed variables and Kruskal-Wallis test for nonparametric variables, as required. Chisquare tests for categorical variables. Multiple logistic regression analysis was performed between Groups A and C against various parameters including age, gender and maxillary sinus wall thickness, LM score, Hb, and eosinophil count. Receiver-operating characteristic (ROC) curves were constructed to define cutoff value for potential refractory CRS. Linear regression was used to determine the relationship between scalar variables. All statistical analyses were performed using SPSS software. *p* < 0.05 was considered to be statistically significant.
