The Location Of The Palatovaginal Canal And The Anotomic And Clinical Applicational Study Of Its Surrounding Skull Base

Objective Palatovaginal canal and vomerovaginal canal are two important structures in pterygopalatine fossa that can be useful in the clinical management. But these two structures are difficulty to be identified in CT transverse images and sometimes they are mislabeled by investigators.The major aim of the article is to discuss whther the two canals can be observed and distinguished in transverse CT images.The second aim is to measure the length of the palatovaginal canal.,the angle between the palatovaginal canal and the pterygoid canal was measured and compared with previous reports.Furthermore,we try to established methods which could be used to identify palatovaginal canal in CT transverse images.Methods We used a probe guide method in 20 skull specimens to establish the CT imaging features of palatovaginal canal and vomerovaginal canal. We also used endoscopy to deeply looked at the inside structure of palatovaginal canal and vomerovaginal canal.Finally,70 patients CT images were also used to confirm our findings.The transverse CT images were analyzed, and the data were used to distinguish the palatovaginal canal and vomerovaginal canal.Results In skull specimens and patient CT, the frequency of simultaneous observation of palatovaginal and vomerovaginal canals,the angle from PV canal pterygoid canal,the angle from palatovaginal canal to to palatal plane,the length of palatovaginal canal, the angle of posterior groove to palatal plane, the angle of posterior groove to sagittal were 72.50%、(43.78±4.62)°、(53.14±5.48)°、 (4.29±0.56)mm、(20.93±6.28)°、(2.85±3.46)°and 70.71%、(43.81±5.19)°、 (53.19±6.87)°、(4.34±0.68)mm、(20.31±5.54)°、(2.21±4.16)°respectively, which were no significant difference (tvalue:-0.042、-0.041、-0.382、0.610、0.892, P>0.05).In axial CT images, the palatovaginal canal was in the shape of short sections,The posterior groove was in the shape of a long tube parallel to the medial sagittal plane, the vomerovaginal canal was also in the shape of a long tube canal and running posteromedially.Under endoscopy, the pterygoid canal, palatovaginal canal, and vomerovaginal canal appear differently. The pterygoid canal is almost parallel to the sagittal plane and faces the posterior direction. Compared to the pterygoid canal, the palatovaginal canal goes down and is located in the posterior and interior direction. Its back opening is linked to the posterior groove, which often presents as a deeper pressure trace than the palatovaginal canal on the vaginal process. The vomerovaginal canal goes down and is in the inner-posterior direction. The front part shows a big angle with the midline. After the nasopharynx, it goes between the vaginalis and vomer. In this area, its angle to the midline is small. There is a bone interval between the palatovaginal canal and vomerovaginal canal. In the two sides, there is only a bony prominence between them in their anterior parts. The interval between the back opening of the palatovaginal canal and vomerovaginal canal is wide.Conclusion We find that the two canals can be observed and distinguishedin transverse CT images Simultaneously.Based on our results regarding 20 skull specimens and 70 patients, we established a simple method which could be used to identify palatovaginal canal between pterygoid canal and vomerovaginal canal in CT transverse images. Furthermore, we think the groove behind the palatovaginal canal is a good landmark that could be used to distinguish palatovaginal canal and vomerovaginal canal.Our finding has great impact not only for accurately identification of pterygoid canal, but also for early detection of tumor metastasis and palatine artery embolization.Objective The major aim of the article is to explore the groove behind the palatovaginal canal (PVC) is a critical landmark for safe identification of the PVC during endoscopic endonasal transpterygoid approaches and transfer CT scan of the pterygopalatine fossa.The second aim is to show that the rencently known palatosphenoidal canal is a misnomer and should be renamed back to palatovaginal canal.Methods Probes were inserted thorough the PVC of 20 dry skulls. The PVC and the groove behind it were proved on MSCT, meanwhile a comparative study was also carried out by the traditional method to identificate the PVC. Dissection of two skulls and cadaveric heads was performed to demonstrate the endoscopic anatomy of the PV canal and tbe groove, as well as to verify the structures involved in the formation of the palatovaginal canal.Results The grooves can be found in all 20 dry skulls and appeared as a narrow groove near the posterior opening of PV canal.26 sids were deep while 14 sides were dimple. Mainly appeared as tube-shaped (24 sides) or ovoid dimple-shaped (16 sides).In CT scan, the average angle between PVC and the hard palate was 53.14±5.48°, while between the groove and the hard palate was 20.93±6.28°. There was also statistical difference for identification of the PVC in transfer CT between the traditional method and the method assisting with the groove. Anatomic steps and foundations for dissection of the PVC while using the groove as a landmark were described. The dissection also showed the front and root wall of the sphenoid sinus did not contribute to the formation of the PV canal but the vaginal process of the sphenoid bone.All of the groove were under the surface of the vaginal process.Conclusion Anatomic investigation, radiologic studies and comparison between the methods for identification of the PVC demonstrate the important anatomic relationship of the PVC with the groove, and reveal the groove as a landmark in endoscopic endonasal transpterygoid approaches and transfer CT scan of the pterygopalatine fossa. Anatomically, the PV canal was consisted by the vaginal process of the sphenoid bone and sphenoidal process of palatine bone.The PV canal should not be replaced with palatosphenoidal canal.Objective To investigate use of posterior groove of palatovaginal canal(PVC) as an anatomic landmark in determining the location of PVC in axial computed tomography (CT) images of pterygopalatine fossa (PPF) in patients. Furthermore,we hope to supply the anotomic datas of the PVC and its surrounding skull base for the radiologist,otolaryngologist and neurosurgeon.we also mesure the distance form the PVC to the pterygoid canal and VVC as well as the positional relationships between the three canals.Methods A total of 20 sw kull specimens were examined in this analysis. Each skull was scanned by CT with and without a probe inserted through PVC to measure the anatomic structures. CT images of 70 patients were used for comparing the rate of correct location of PVC between the conventional method (using the pterygoid canal as a landmark) and the method of using the posterior groove as a landmark. In coronal CT,both in the anterior opening and posterior opening of thepvc, we mesure the distance form the PVC to the pterygoid canal and VVC, as well as the positional relationships between the three canals.Results In all 20 skull specimens, the groove behind the PVC showed the morphology of a narrow groove and elliptical fossa in 24 and 16 sides. In CT images, the angle frompvc 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 PVC 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 PVC were described. In Coronal MPR,a septum can be found both at the segment of the anterior and the posterior opening of thepvc. The distance form the palatovaginal (PV) canal to the pterygoid canal was significantly different between anterior opening and posterior opening of the PVC,as well as to vomerovaginal canal. A total of 7.89% of sides,PVC was observed superior to the pterygoid canal in anterior opening segment,while all sides inferior to the pterygoid canal in posterior opening; 1.32% of sides, PVC was observed superior to the VVC in posterior opening segment; 9.21% of sides, VVC was observed superior to the pterygoid canal in anterior opening,while in posterior opening,all of VVC was observed inferior to the pterygoid canal.Conclusion The posterior groove can be used as an anatomic landmark in correctly locating PVC in the axial CT image of the Patients. The anotomic datas of the PVC and its surrounding skull base described the different trace of the three canal. Radiologist and surgeons should distinguish them in clinical dignosis and operation in PPF of the skull base.