Cadaver dissection and CT correlation of lacrimal sac and nasolacrimal duct: a prelude to endoscopic dacryocystorhinostomy.

Amit Kumar, Tyagi (2012) Cadaver dissection and CT correlation of lacrimal sac and nasolacrimal duct: a prelude to endoscopic dacryocystorhinostomy. Masters thesis, Christian Medical College, Vellore.

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Abstract

Objectives and aims of study: To measure the distances of surgically important landmarks from relevant structures by cadaveric dissection and CT scan, as a means for assisting the surgeon to grasp three- dimensional anatomy and as a prelude to endoscopic dacryocystorhinostomy. Design: This was a descriptive study (Cadaver dissection/case series) in which data collection was done by measurement of anatomical landmarks in CT scan and cadaver sagittal head sections. Participants: Ten adult cadaver’s head sections (10 right and 10 left sagittally sectioned specimens) fixed with 10% formaldehyde solution Setting: Anatomy, ENT and Radiodiagnosis department of a tertiary hospital. Results: Maxillary line was clearly identified in 15 (75%) and not clear in five (25%) cadavers. The distance between the anterior nasal spine to axilla and anterior nasal spine to genu was noted as an average of 34.89 mm (23.64-44.40) and of 28.15 mm (19.98-37.21) respectively and these measurements also showed positive correlation with corresponding CT measurements. The lacrimomaxillary suture was seen posterior to maxillary line in nine (45%); at maxillary line in eight (40%) and anterior to maxillary line in three (15%) of the cadavers. Maxillary line overlapped the lacrimal sac in 95% cadavers. Thickness of lacrimal bone was found to be an average of 0.25 mm. The distance between the inferior edge of lacrimal sac and inferior turbinate was an average of 7.90 mm. The anteroposterior diameter of lacrimal sac was an average of 7.35 mm. The length of lacrimal sac was an average of 11.72 mm and showed positive correlation with CT scan measurements. The distance between fornix (superior end) of lacrimal sac and axilla of middle turbinate was of 8.88 mm and showed positive correlation with CT scan measurements. More than half of the lacrimal sac was above the axilla in 60% and less than half above the axilla in 40 % of cadavers in our study (seen both in dissection and CT scans). The length of nasolacrimal duct (NLD) was an average of 10.27 mm in length and showed positive correlation with CT scan measurements. NLD was about 4.04 mm anterior to maxillary sinus ostium. Agger nasi was noted in 16 cases (80%). Conclusions Incision performed anterior to the maxillary line and anterior to genu of middle turbinate with 8-9 mm above axilla could be sufficient to expose the lacrimal sac. Maxillary line, Mpoint and axilla are three important landmarks in localization of sac. M point can be used as an inferior limit of surgical exposure of lacrimal sac. Preoperative endoscopic evaluation for the presence of aggar nasi is mandatory in all cases prior to endoscopic dacryocystorhinostomy. CT scan appears to be also useful in measuring length of lacrimal sac and nasolacrimal duct.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Cadaver dissection; CT correlation; lacrimal sac; nasolacrimal duct; endoscopic dacryocystorhinostomy
Subjects: MEDICAL > Otolaryngology
Depositing User: Devi S
Date Deposited: 12 Jul 2017 11:56
Last Modified: 12 Jul 2017 11:56
URI: http://repository-tnmgrmu.ac.in/id/eprint/1543

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