Abstract
This study aimed to investigate the effect of the maxillary line (ML)-lacrimal sac anterior border (LSA) distance on the results of endoscopic dacryocystorhinostomy (EDCR) operation. The study was designed retrospectively. The distance between LSA and ML was measured from preoperative paranasal sinus computed tomography (PNSCT) images. Nasolacrimal duct obstruction symptom score (NLDO-SS) was calculated before and after surgery. The endoscopically proven of the transition of the 2% fluorescein drop instilled into the eye to the nasal passage accepted as a surgical success. 47 patients included in the study and eight of them underwent bilateral EDCR. The average age of the patients was 50.3 ± 14.8. The LSA-ML distance was 4.2 ± 1.0 mm in all patients. The duration of surgery was found as 38.1 ± 6.1 min for each side. The preoperative NLDO-SS mean was 54.9 ± 11.7 and 22.2 ± 12.1 postoperatively (p = 0.000, CI = 28.9–36.2). Six patients (11%) required revision surgery. A statistically significant high positive correlation was found between duration of surgery and LSA-ML distance (p = 0.000, r = 0.840). There was a significant negative correlation between the duration of surgery and postoperative NLDO-SS (p = 0.041, r = −0.276). The LSA-ML distance calculated in this study was found to be significantly associated with the decrease in the duration of surgery and the NLDO-SS score obtained after surgery. However, more valid results can be obtained if similar studies are carried out in larger samples containing a sufficient number of revision cases.
Keywords: Maxillary line, Endoscopic dacryocystorhinostomy, NLDO-SS, Lacrimal sac
Introduction
The maxillary line (ML) is an important surgical guide located in the lateral nasal wall for endoscopic sinus surgery and endoscopic dacryocystorhinostomy (EDCR) surgery [1, 2]. The lacrimal sac (LS) and lacrimal canal are in a close neighborhood with the anterior and medial edge of the maxillary bone, and a bone window is created on this site for rhinostomy during EDCR [3]. EDCR surgeries have a failure rate of approximately 10% and this is due to the surgically created rhinostomy window [4]. Anatomical and radiological studies reviewed the lacrimal system and adjacent structures in the lateral nasal wall are available in the literature [5, 6]. However, the number of clinical studies examining the relationship between the lacrimal system and adjacent lateral nasal wall structures and the surgical and functional results of EDCR surgery is limited. In this study, it was aimed to investigate the effect of anatomical variations between the maxillary line and lacrimal sac.
Materials and Methods
The study was designed retrospectively. The records of patients who underwent EDCR operation in a tertiary university hospital, ear nose throat clinic in January 2014 and January 2016 were examined. The patients' age, gender, preoperative paranasal sinus computed tomography (PNSCT) images, side and duration of the operation, postoperative follow-up time, presence of an obstruction in the rhinostomy area, and revision surgery status were recorded. Nasolacrimal duct obstruction symptom score (NLDO-SS) of the patients was calculated preoperatively and in postoperative 6th month [7]. Using the data from the study by Wang et al. [3] (effect size: 0.6, α: 0.5, and 1-β: 0.95), the sample size was determined as a minimum of 32.
Inclusion and Exclusion Criteria
All patients were diagnosed with Primary Acquired Nasolacrimal Duct Obstruction (PANDO) with an ophthalmologic examination before surgery. The study group consisted of patients who underwent EDCR surgery without a stent by the same surgeon with the help of a drill (reinforced EDCR) without preserving mucosal flap and lacrimal flap. Patients under 18 years of age, patients diagnosed with neoplasia as the cause of lacrimal occlusion, patients who underwent EDCR operation in addition to another surgical procedure such as medial maxillectomy, and patients with follow-up less than one year were excluded from the study. Surgical success was defined as the endoscopic endonasal observation of 2% fluorescein drops instilled into the eye.
Radiological Examination
The midpoint between the attachment of the middle turbinate axilla on the lateral nasal wall and the end of the lacrimal canal in sagittal PNSCT images was identified. The PNSBT image in the axial plane corresponding to this point was taken as a reference and the distance between the lacrimal sac (LS) anterior edge (LSA) and ML was measured (Fig. 1, 2). All PNSCT images were acquired as standard 0.5 mm thick high-resolution sections (Toshiba, Activion16 Multislice CT, Kyoto, Japan).
Fig. 1.
Example of axial paranasal sinus CT sections for LSA-ML. *—ML: Maxillary Line, ^—LKA: Anterior edge of the lacrimal sac, LSA-ML: Lacrimal Sac Anterior-Maxillary Line Distance
Fig. 2.
Intraoperative view in left EDCR surgery. *—ML: Maxillary Line, ^—LKA: Anterior edge of the lacrimal sac
NLDO-SS Questionnaire
Based on its original form in the reference study [7], the English version of the questionnaire translated to Turkish by the authors was used. The questionnaire consists of eight questions, the answers for each question are set with 0 points in the best case, and 10 points in the worst case. In this way, the responses of the patients were summed up and the score was determined as minimum 0 and maximum 80 points.
Statistical Analysis
The relationship between LSA-ML distance with NLDO-SS and operation time was examined with the Pearson correlation. In addition, two groups were determined as below and above the mean value for LSA-ML distance, and the surgical success in these two groups was investigated with the Chi-square test. SPSS 22.0 (Statistical Package for Social Sciences, SPSS Inc., Armonk, NY) program was used for statistical analysis.
Ethics Committee Approval
The study was conducted in accordance with the 1964 Helsinki Declaration and subsequent amendments. The study was approved by the affiliated university's non-interventional researchs ethics committee (942–17/09/2020).
Results
Records of 139 patients were accessed for the study and the data of 47 patients and 55 EDCR surgeries were analyzed according to the inclusion and exclusion criteria. Eight patients underwent bilateral EDCR operation. The average age of the patients was determined as 50.3 ± 14.8. The number of female patients was 39 (71%) and the number of men was 16 (29%). EDCR operation was performed on the right side in 29 (53%) patients, and on the left side in 26 (47%) patients. The mean LSA-ML distance was found to be 4.2 ± 1.0 mm in all patients and the anterior–posterior diameter (LSD) of the lacrimal sac was 7.3 ± 1.5 mm. In 29 (53%) patients, the LSA-ML distance was above the average, and in 26 (47%) patients it was below the average. The duration of the operation was 38.1 ± 6.1 min for each side. The mean preoperative NLDO-SS was 54.9 ± 11.7 and 22.2 ± 12.1 postoperatively (p = 0.000, CI = 28.9–36.2). The mean follow-up period was 26.0 ± 16.1 months. Six patients (11%) underwent revision EDCR surgery due to recurrent lacrimal duct obstruction (Table 1).
Table 1.
Mean and standard deviation values of age, duration of surgery, LSA-ML, NLDO-SS, and follow-up time according to gender, side, and success of operation
| n (%) | Age | Duration (min) | LSA-ML (mm) | Preop. NLDO-SS | Postop. NLDO-SS | Follow-up | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| m | SD | m | SD | m | SD | m | SD | m | SD | m | SD | |||
| Gender | F | 39 (71) | 49.9 | 15.6 | 37.8 | 5.6 | 4.2 | 1.0 | 55.5 | 10.1 | 22.1 | 10.9 | 28.4 | 18.4 |
| M | 16 (29) | 51.3 | 13.3 | 38,9 | 7.0 | 4.4 | 1.1 | 53.6 | 15.3 | 22.9 | 14.9 | 20.1 | 10.4 | |
| Side | R | 29 (53) | 47.4 | 15 | 37.0 | 5.6 | 4.0 | 1.1 | 57.3 | 10.6 | 22.1 | 12.5 | 25.1 | 14,8 |
| L | 26 (47) | 53.6 | 13.6 | 39.5 | 6.3 | 4.5 | .9 | 52,2 | 12.6 | 22.5 | 11.8 | 27.0 | 19.1 | |
| Success | + | 49 (89) | 50.0 | 15.1 | 37.7 | 5.9 | 4.3 | 1.0 | 54.8 | 12.1 | 19.2 | 7.3 | 26.9 | 17.6 |
| − | 6 (11) | 53.2 | 13.2 | 41.7 | 6.5 | 4.4 | 1.4 | 56.2 | 8.6 | 47.3 | 14.3 | 19.0 | 5.3 | |
LSA-ML lacrimal sac anterior-maxillary line distance, NLDO-SS nasolacrimal duct obstruction-symptom score, min minutes, mm millimeter, F female, M male, R right, L left
The success of the operation was not affected by gender, the side of the PANDO, and the below or above average of LSA-ML distance (p = 0.229, 0.611, 0.389, respectively). A statistically significant high positive correlation was found between the operative time and the LSA-ML distance (p = 0.000, r = 0.840). Although the LSA-ML distance correlated negatively with postoperative NSDO-SS, the result was statistically insignificant (p = 0.285, r = −0.147). Consistent with these data, a significant negative correlation was found between operative time and postoperative NLDO-SS (p = 0.041, r = −0.276) (Table 2).
Table 2.
Correlation table of age, duration of surgery, LSA-ML Distance, preoperative and postoperative NLDO-SS, and NLDO-SS Gap
| Age | Duration (min) | LSA-ML (mm) | LSD (mm) | Preop. NLDO-SS | Postop. NLDO-SS | NLDO-SS fark | ||
|---|---|---|---|---|---|---|---|---|
| Age | r | 1 | .086 | .150 | .299 | − .096 | − .052 | − .037 |
| p | .533 | .275 | .026 | .485 | .704 | .790 | ||
| Duration (min) | r | .086 | 1 | .820 | .236 | − .265 | .051 | − .276 |
| p | .533 | .000 | .083 | .051 | .709 | .041 | ||
| LSA-ML (mm) | r | .150 | .820 | 1 | .300 | − .358 | − .147 | − .180 |
| p | .275 | .000 | .026 | .007 | .284 | .188 | ||
| LSD (mm) | r | .299 | .236 | .300 | 1 | − .065 | − .064 | .000 |
| p | .026 | .083 | .026 | .635 | .644 | 1.000 | ||
| Preop NLDO-SS | r | − .096 | − .265 | − .358 | − .065 | 1 | .356 | .552 |
| p | .485 | .051 | .007 | .635 | .008 | .000 | ||
| Postop NLDO-SS | r | − .052 | .051 | − .147 | − .064 | .356 | 1 | − .583 |
| p | .704 | .709 | .284 | .644 | .008 | .000 | ||
| NLDO-SS gap | r | − .037 | − .276 | − .180 | .000 | .552 | − .583 | 1 |
| p | .790 | .041 | .188 | 1.000 | .000 | .000 | ||
LSA-ML lacrimal sac anterior-maxillary line distance, NLDO-SS nasolacrimal duct obstruction-symptom score, min minutes, mm millimeter
Discussion
EDCR indication and success for nasolacrimal duct obstruction is no different from external dacryocystorhinostomy (DCR), which was previously reported as the gold standard [8]. As a surgical landmark, ML remains importance for endoscopic transnasal interventions [2, 3]. ML is a raised line formed by the frontal process of the maxillary bone, starting from the attachment site of the middle turbinate on the lateral nasal wall and extending obliquely to the lower edge of the uncinate process [9]. ML is most important landmark for the lacrimal sac and duct during EDCR surgery [1, 10].
Anatomical variations between ML and LS have been shown in previous studies [1, 3, 11]. Simmen et al. [11] determined the LSA-ML distance as 4.24 ± 2.40 mm in 100 case with PNSCT images,and they did not report any difference between the right and left sides. In the same study, this distance is divided into three groups; type 1: 0–3 mm (31.5%), type 2: > 3–7 mm (56%) and type 3: > 7 mm, (12.5%). Orhan et al. [5] detected in a cadaver study that in 46% of the specimens, ML passed through the middle of the lacrimal sac, and in 10% of the specimens, lacrimal sac consisted at completely posterior of the ML. Wang et al. classified the association of ML and lacrimal duct structures anatomically in three groups [3]. In this study, 32% of ML and lacrimal canal were determined as fusion type and 52% as completely separated (separation type), while 16% were determined as common type (mixed type). In the presented study, the LSA-ML distance was determined as 4.2 ± 1.0 mm in all patients and it is consistent with the literature. There is no study in the literature regarding LSA-ML distance and operation success or functional results in the English literature. In addition, a statistically significant positive correlation was found between the LSA-ML distance and the operation time and LSD. Also, the preoperative NLDO-SS score and the LSA-ML distance showed a significant negative correlation. These results can be interpreted as the increase in the LSA-ML distance, the worse symptom scores of the patients, and the more difficult EDCR operations. However, there was no significant relationship between the postoperative NLDO-SS and LSA-ML distance. As a better indicator of symptomatic improvement, the score gap of the NLDO-SS questionnaires before and after surgery was calculated in all patients. A significant negative correlation was found between this NLDO-SS gap and the duration of surgery in the Pearson correlation analysis. Indirectly, the effect of the LSA-ML distance on the clinical results of EDCR surgery can be interpreted significantly, but statistically, this is a poor correlation. Contrary to the findings in the presented study, this decrease of this distance and the close proximity of ML and LS have been interpreted as making the surgery difficult with extra bone resection, but it was not based on any statistical analysis [9]. Increasing the LSA-ML distance may make it difficult to demonstrate LS adequately by increasing surgical dissection. This could explain the significantly increased operative time with the LSA-ML distance. In a systematic review examining failed EDCR operations in accordance with these findings, it was found that in more than one-third of the patients, only the part of the lacrimal bone covering the anterior surface of the lacrimal sac could be removed, while the posterior part was left. In this study, leaving the posterior part of the lacrimal bone was listed as the cause of failure in EDCR surgeries [12]. Similarly, this review does not contain any scaled data regarding the LS-ML relationship [12]. In the presented study, the LSA-ML distance was 4.3 ± 1.4 mm in six patients who failed EDCR surgery, and 4.2 ± 1.0 mm in patients with surgical success, and the difference was statistically insignificant (p = 0.402, Mann-Whitney U test). Similarly, the duration of the operation does not change significantly depending on the surgical success of the surgery (p = 0.096). However, despite the weakness, a significant correlation was found between the duration of the operation and the improvement in the clinical symptom score (NLDO-SS gap, p = 0.041). This inconsistency may be due to the low number of patients in the revision patient group or the lack of validity and reliability analysis of the NLDO-SS questionnaire in Turkish. These are the main limitations of this study.
The success rate obtained in our study was determined as 89.1%, in accordance with the literature [8, 13, 14]. Failure in EDCR operations is generally related to the rhinostomy site and is listed as synechiae, residual lacrimal bone, infection, and granulation [4, 15]. Welham and Wulc showed LSD as one of the factors affecting the success of DCR surgeries [16]. A 5 mm or above of LSD indicates a successful EDCR operation [17], 18. In a similar radiological study, LSD was determined as 6.4 ± 1.8 mm in a patent nasolacrimal system [6]. In the presented study, LSD was 7.3 ± 1.5 mm on average, similar to the literature. However, the average LSD length did not statistically affect the success of EDCR surgeries. (p = 0.294). These findings contradict the literature information. However, the low number of patients who underwent revision EDCR (n = 6) reduces the validity of this result.
Conclusion
The relation of the lacrimal sac and adjacent structures have been adequately demonstrated by anatomical and radiological studies. However, the effect of these variations on the surgical and clinical success of EDCR surgeries has not been adequately elucidated. In this study, the LSA-ML distance was found to be associated with the duration of the operation and the decrease in the symptom score obtained after surgery. However, more valid results can be obtained if similar studies are conducted with larger samples containing a sufficient number of revision cases. Similar studies can be repeated with other important guiding anatomical structures (uncinate process, middle turbinate axilla) in EDCR surgeries. In addition, performing the Turkish validity and reliability analysis of the NLDO-SS questionnaire may increase the correlation between surgical success and clinical success.
Author contributions
All authors contributed equally to the design of study, data collection, writing, review of the references, critical review, and final approved version of the manuscript.
Funding
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Data Availability
Available.
Declarations
Conflicts of interest
The authors declare no conflict of interest.
Consent for publication
The authors transfer all copyrights for the article to be published in this journal.
Ethical approval
The study was approved by the affiliated university's non-interventional researchs ethics committee (942–17/09/2020).
Informed Consent
Verbal and informed consents were obtained before the study.
Footnotes
Publisher's Note
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