Importance of sagittal orbital imaging in evaluating extraocular muscle trauma following endoscopic sinus surgery

Orbital trauma may result in severe restrictive, paralytic, or combined strabismus. Clinical diagnosis may be extremely challenging. Orbital imaging is helpful in determining the exact site of injury, functionality, and integrity of the extraocular muscles. A typical study now includes coronal and axial views of the muscles. This study aimed to emphasise the importance of sagittal imaging of the orbit when evaluating extraocular muscle injury or entrapment.

A retrospective review of two subjects who underwent endoscopic sinus surgery procedures that resulted in trauma to the medial rectus muscle. High resolution orbital imaging studies were performed.

High resolution magnetic resonance imaging (MRI) scans with coronal and axial views suggested a large section of the muscle was not present and was probably destroyed. In both cases there was a displacement of the mid-portion of the medial rectus muscle into an area of bony defect not seen on the axial and coronal views. Sagittal images demonstrated continuity between the anterior and posterior segments of the medial rectus muscle in each case.

Surgical strategies are dependent on accurate interpretation of MRI scans. Muscle displacement may result in axial and coronal orbital imaging misinterpretation. Sagittal views were essential to determine muscle integrity.