Evaluating the Prevalence of Nasolacrimal Canal Injury in Midfacial Fractures: A Retrospective CT-Based Study.

INTRODUCTION

Midface injuries, which are most common, can result in affectations to adjacent structures, including the nasolacrimal apparatus (NLA), which consists of the lacrimal sac, canaliculi, and nasolacrimal duct.

OBJECTIVES

The objectives of this study were to visualise the radiographic patency of the nasolacrimal canal in a computed tomography (CT) scan and assess the type of injury.

METHODOLOGY: This was a retrospective study wherein 322 CT scans of facial bones were analysed of patients who presented with midface fractures to the Department of Oral and Maxillofacial Surgery. The bony nasolacrimal canal was visualised on axial and coronal sections and confirmed on sagittal sections. The collapse of the bony nasolacrimal canal was measured using the advanced tools setting in the RadiAnt DICOM Viewer (Medixant, Poznań, Poland). The values were tabulated and statistically analysed.

RESULTS

The incidence of NLA involvement in midface fractures was 37.6% (121 out of 322 fractures). The maximal involvement was seen in zygomaticomaxillary complex (ZMC) fractures. The visualisation of the fractures in the CT scan revealed that avulsion of the fossa was seen in 2.5% (eight out of 322 fractures), communication of the fossa or canal in 2.8% (nine out of 322 fractures), and linear fracture of the canal in 32.0% (103 out of 322 fractures). When measured in axial section, the Le Fort III fractures presented with a median of 2.15 mm, naso-orbito-ethmoid (NOE) fractures with a median of 0.90 mm, and fronto-naso-orbito-ethmoid (FNOE) fractures with a median of 1.15 mm. In the coronal section, the type of injuries that showed avulsion of the fossa had a median of 9.00 mm, communication of the fossa or canal showed 6.52 mm and linear fracture of the canal showed a median of 7.00 mm.

CONCLUSION

Many a time, the NLA is often neglected during a routine radiographic assessment of a CT scan in patients presenting with maxillofacial injuries. These injuries may not be clinically evident during examination. This might lead to postoperative clinical presentations in a patient. This study shows the various types of injuries to the NLA and its appearance on a CT scan. It also explains the requirement of soft tissue management and the clinical co-relationship of these injuries.