Can palatovaginal canal be the site of origin of juvenile nasopharyngeal angiofibroma?

Juvenile nasopharyngeal angiofibroma (JNA) is the most common benign tumor of the nasopharynx. For reasons unknown, this tumor is found almost always in male population. However, site of origin of JNA is still an enigma. Previously, JNA was considered to arise from the superior aspect of sphenopalatine foramen. Over last decade, the vidian canal was considered to be the more specific and likely site of origin. However, based on our observations, we believe this hypothesis to be anomalous as it does not explain major blood supply, pattern of skull base erosion in early stage of tumor and newer studies on electron microscopic and immunopathological findings. To explain these anomalies, we hypothesize the site of origin to be palato-vaginal canal.

Incidence of anomalous canals in the base of the skull: a retrospective radio-anatomical study using cone-beam computed tomography

PURPOSE

Several skull-base foramina including foramen meningo-orbitale, craniopharyngeal canals, canaliculus innominatus, foramen vesalius, palatovaginal canals, and canalis basalis medianus are visible on cone-beam computed tomographs. A good understanding of the anatomical variants of these foramina is important to accurately diagnose fractures, understand the paths that infections may take, and identify associated anomalies. We used cone-beam computed tomography to measure the incidences of skull-base foramen variants in a normal population.

METHODS

A total of 350 subjects (200 females, 150 males, 6-30 years of age) were included. The prevalences of foramen meningo-orbitale, craniopharyngeal canals, canaliculus innominatus, foramina vesalius, palatovaginal canals, and canalis basalis medianus were evaluated by age and gender.

RESULTS

Subject age ranged from 6 to 30 years (mean age ± SD = 15.1 ± 4.08). Foramen meningo-orbitale, craniopharyngeal canals, canaliculus innominatus, foramen vesalius, palatovaginal canal, and canalis basalis medianus were observed in 51 (14.6%), 19 (5.4%), 60 (17.1%), 145 (41.1%), 34 (9.7%), and 15 (4.3%) patients, respectively.

CONCLUSIONS

Skull-base foramina are important clinically and radiologically. Imaging of such variants via cone-beam computed tomography is valuable for both physicians and patients. Few studies of skull-base foramina have used cone-beam computed tomography. Additional research is required for a fuller understanding of this phenomenon.

The posterior groove as a landmark for location of the palatovaginal canal in axial computed tomography

PURPOSE

To investigate use of posterior groove of palatovaginal (PV) canal as an anatomic landmark in determining the location of PV canal in axial computed tomography (CT) images of pterygopalatine fossa (PPF).

METHODS

A total of 20 skull specimens were examined in this analysis. Each skull was scanned by CT with and without a probe inserted through PV canal to measure the anatomic structures. CT images of 70 patients were used for comparing the rate of correct location of PV canal between the conventional method (using the vidian canal as a landmark) and the method of using the posterior groove as a landmark. Two skulls were dissected using endoscopy to further reveal the advantage of the posterior groove as a landmark.

RESULTS

In all 20 skull specimens, the groove showed the morphology of a narrow groove and elliptical fossa in 24 and 16 sides, respectively. In CT images, the angle from PV canal and the posterior groove to the hard palate was 53.14° ± 5.48° and 20.93° ± 6.28°, respectively, which was significantly different (P ≤ 0.05). The rate of correct location of PV canal was statistically significantly higher with the method of posterior groove as a landmark than the conventional method (70.7 vs 49.3 %, P < 0.05). The endoscopic anatomy of the posterior groove and its use in locating the PV canal were described.

CONCLUSION

The posterior groove can be used as an anatomic landmark in correctly locating PV canal in the axial CT image of the PPF.

Anatomical study of pterygoid canal (PC) and palatovaginal canal (PVC) in endoscopic trans-sphenoidal approach

PURPOSE

The primary purpose of our work was to make anatomical measurements of pterygoid canal (PC) and palatovaginal canal (PVC). The secondary goal was to locate the two structures based on the landmarks in the trans-sphenoidal surgery and draw a safe corridor of fenestration in the bottom of sphenoid sinus during surgical procedure to sphenopalatine region.

MATERIALS AND METHODS

Computed tomographic angiography (CTA) images of PC, PVC and sphenoid sinus in 200 adults were reviewed. Multiplanar reconstruction of the CT images was performed, and the anatomical features of the PC and PVC were studied in the coronal, sagittal, and axial planes. The length, diameter and direction of PC and PVC were measured in the plane through or perpendicular to them. The anterior and posterior opening of PC and PVC were identified by the surgical landmarks such as the middle lowest point of sellar floor, the sagittal midline and the bottom of the sphenoid sinus.

RESULT

Both PC and PVC can be found and identified easily on CTA image, the shape and size of the PC and PVC were in agreement with those retrieved from previous literatures, the position of them can be located by the anatomical landmarks in sphenoid sinus.

CONCLUSION

Knowing the anatomical features of PC and PVC and their location based on the anatomical landmarks are helpful to the endoscopic trans-sphenoidal surgery. These data in our study will provide surgeons a better understanding of PC and PVC and their relationship to sphenoid sinus. Notably, it will not help the surgeons to avoid injuring neurovascular structures as well as provided supportive information for the choice of the appropriate endoscopic equipment.

Simultaneous observation and discrimination of palatovaginal and vomerovaginal canals by transverse CT

This study is to palatovaginal canal and vomerovaginal canal identify by computed tomography (CT) transverse imaging and are often mislabeled by investigators. We used a probe guide method in skull specimens to establish the CT imaging features of the two canals. We also used endoscopy to look deeply into the inside structure of them. Finally, CT images of patients were used to confirm our findings. Based on our results using 20 skull specimens and 70 patients, we established a simple method that can be used to identify the two canals on CT transverse imaging. In the transverse images of skull specimens and of patients, the frequency of simultaneous observation of the two canals was 72.5% and 70.71%. We also identified several mislabeled images of the palatovaginal and vomerovaginal canals in published papers. In summary, we found that the two canals could be observed and distinguished by transverse CT imaging. Furthermore, we established a method that could distinguish them. In conclusion, our findings will have a great impact not only on the accurate identification of the pterygoid canals but also on the early detection of tumor metastasis and palatine artery embolization.