Endoscopic localization of the sphenopalatine foramen: do measurements matter?

Morphometric analysis of sphenopalatine foramen on computed tomography images with clinical significance

PURPOSE

This study aimed to investigate the effect of anatomical variations in the sphenopalatine foramen and the lateral nasal wall on sphenopalatine foramen-related morphometric measurements.

METHODS

Paranasal sinus multidetector computed tomography records of 153 patients were evaluated. Morphometric measurements were made between the fixed bony landmarks and the sphenopalatine foramen. Number, shape, localization variations of the sphenopalatine foramen, concha bullosa, and septum deviation were noted and the results were compared with respect to sex, age, and laterality.

RESULTS

No significant difference was detected with respect to laterality, whereas most of the measured distances were higher in males than females. There was a significant difference between the obtained morphometric data according to age groups. In our study, 91.2% single, 7.8% double, and 1% triple sphenopalatine foramen were detected and the most common irregularly shaped (37.3%). The location of sphenopalatine foramen was reported as the most common type II. Septum deviation types have no potential influence on the location of the foramen, but most of the measured parameters were found to be significantly smaller in the presence of concha bullosa, whereas the angle was found to be higher.

CONCLUSION

This study revealed a significant relationship between the morphometric measurements of the sphenopalatine foramen and concha bullosa, while septum deviation types did not affect these results. For a safer and more effective surgery with prevention of iatrogenic complications, a surgeon should be aware of this correlation, especially in endoscopic transnasal approaches.

Survey Anatomical Features and Related Factors of the Sphenopalatine Foramen on Computed Tomography

The aim of the research is to define anatomical features of the sphenopalatine foramen (SPF) and be related to the SPF on computed tomography (CT) such as shape, location, size of the SPF, the appearance of the ethmoidal crest, and the distance from SPF to some landmarks in the nasal cavity. As a result, surgeons could quickly determine the SPF location in transnasal endoscopic sphenopalatine artery ligation (TESPAL). A cross-sectional study was conducted. This study was carried out at Cho Ray hospital from August 2019 to June 2020. Image data from 55 patients who had been indicated sinuses CT. Results show that the SPF had a wide range of shapes: oval (20.9%), triangle (19.1%), circle (18.2%), racket shape (7.3%), hourglass shape (6.4%), and other shapes. In the anteroposterior dimension, the mean SPF was 5.72 ± 1.22 mm. In the craniocaudal dimension, the mean SPF measured 5.62 ± 1.99 mm. The SPF was mainly located in the superior meatus and in the transition between the middle and superior meatus. The most reliable anatomical landmark to find the SPF was the ethmoidal crest with an appearance rate of about 95.5%. The mean distances from SPF to anterior nasal spine, nasal floor, nasal septum, maxillary line, anterior head of the middle turbinate, choanal arch, and base lamella were 57.04 ± 3.11, 24.71 ± 2.90, 11.26 ± 2.09, 34.93 ± 2.07, 32.69 ± 3.30, 8.82 ± 1.65, and 8.07 ± 1.28 mm, respectively. CT scan images in this study can provide information about anatomical features of the SPF, which contribute to the quick and efficient identification of the SPF before and during TESPAL.

Measurement and implications of the distance between the sphenopalatine ganglion and nasal mucosa: a neuroimaging study

BACKGROUND

Historical reports describe the sphenopalatine ganglion (SPG) as positioned directly under the nasal mucosa. This is the basis for the topical intranasal administration of local anaesthetic (LA) towards the sphenopalatine foramen (SPF) which is hypothesized to diffuse a distance as short as 1 mm. Nonetheless, the SPG is located in the sphenopalatine fossa, encapsulated in connective tissue, surrounded by fat tissue and separated from the nasal cavity by a bony wall. The sphenopalatine fossa communicates with the nasal cavity through the SPF, which contains neurovascular structures packed with connective tissue and is covered by mucosa in the nasal cavity. Endoscopically the SPF does not appear open. It has hitherto not been demonstrated that LA reaches the SPG using this approach.

METHODS

Our group has previously identified the SPG on 3 T-MRI images merged with CT. This enabled us to measure the distance from the SPG to the nasal mucosa covering the SPF in 20 Caucasian subjects on both sides (n = 40 ganglia). This distance was measured by two physicians. Interobserver variability was evaluated using the intraclass correlation coefficient (ICC).

RESULTS

The mean distance from the SPG to the closest point of the nasal cavity directly over the mucosa covering the SPF was 6.77 mm (SD 1.75; range, 4.00-11.60). The interobserver variability was excellent (ICC 0.978; 95% CI: 0.939-0.990, p < 0.001).

CONCLUSIONS

The distance between the SPG and nasal mucosa over the SPF is longer than previously assumed. These results challenge the assumption that the intranasal topical application of LA close to the SPF can passively diffuse to the SPG.