Ultrasonography vs computed tomography in imaging of zygomatic complex fractures

The zygoma is the principal buttress between the cranium and maxilla. The zygomatic fractures can lead to significant cosmetic and functional disorders such as enophthalmos, depression of malar eminence and parathesia due to injury of infraorbital nerve. Computed tomography (CT) was the first technology capable of allowing visualization of both hard and soft tissues of the face by image processing enhancement. It was reported that CT can achieve more accurate values in diagnosis of midface fractures. Another alternative technique is ultrasonographic examination. Ultrasonography is easy and quick to be performed; it is noninvasive and free of any risks. The possibility of ultrasonographic fracture visualization in the midface has already been described by many researchers. Objectives: the aim of this study was to compare between the ultrasonographic and the computed tomographic findings, in the diagnosis and repair of the zygomatic complex fractures. Patients and methods: Between November 2008 and December 2009, 10 consecutive patients (5 males and 5 females) who were referred to Oral and Maxillofacial Department of AL-Azhar University (Girls branch), for treatment of zygomatic complex fractures, were included in this prospective study. The mean age was 34.5 (range 16-60years). The clinical criteria for patient selection included; the presence of periorbital ecchymosis, scleral hematoma, infraorbital nerve parathesia, diplopia and/or limitation of ocular movements, as well as enophthalmos and flattening of the face. Patients who had diplopia or ocular abnormalities were examined by an ophthalmologist. With each patient an axial and coronal thin-layer CT with 3D reconstruction was done (Multislice CT). Subsequently each patient was sonographically evaluated by an experienced examiner with a linear transducer. All patients were treated under general anaesthesia via closed or open reduction according to the planned surgery. Immediately after patients’ recovery, CT and ultrasound images were taken for all patients to evaluate accuracy of the reduction. Results: The ultrasonographic findings showed clear differences in the ability to obtain a correct estimation of the selected anatomic landmarks. The zygomatic arch, the lateral wall of the orbit and the infraorbital margin can be visualized by ultrasonography very easily. The assessment of the orbital floor and the medial wall proved to be rather difficult. The ultrasound images were always concordant with the CT findings. Open reduction through extraoral and transoral accesses, was performed in 8 patients, and 2 patients were treated conservatively. The alignment of the fractured segments could be easily identified by ultrasonography in all patients. All fractured segments were adequately reduced into their normal anatomical position. The postoperative CT confirmed these results. Conclusion: CT has been recommended for preoperative evaluation of zygomatic trauma as a standard diagnostic method, especially in complicated cases with intracranial injuries or when there is a need for optic nerve evaluation, because they cannot be adequately seen by ultrasonography. While ultrasonography has proved to be a valuable tool in detecting uncomplicated fractures at the zygomaticofrontal process, the zygomatic arch and the infra orbital margin but its results for orbital floor and medial wall remain unsatisfactory. Also, ultrasound is more reliable in postoperative follow up, resulting in decreased cost and radiation exposure. [Journal of American Science 2010; 6(9):524-533]. (ISSN: 1545-1003).