Abstract
Purpose :
Complicated strabismus includes many types of diseases. Most of these diseases are rare and complex conditions. The unknown varieties of disease types from complicated cases pose a major diagnostic challenge, and traditional clinical examinations have been unsuccessful to distinguish those diagnoses.
Methods :
In this study, we propose to employ the MRI technique to examine cranial nerves and extraocular muscles abnormal activity for complicated strabismus. Among the patients who visited the Beijing Tongren hospital in China between 2006 to 2016, 1113 strabismus patients were identified with unusual ocular motility disorders after clinical examinations. These patients were further evaluated using several types of high-resolution MRI techniques, including the imaging of the ocular motor nerves at the brainstem using 0.8-mm thickness image planes and the heavily T2-weighted FIESTA sequence. Nerves in the cavernous sinus were imaged with a head coil, and the FSE/T2WI was obtained in sagittal and coronal planes. Nerves to extraocular muscles (EOMs), the EOMs and their associated connective tissues were imaged with T1 weighting in triplanar scans with dual-phased coils and 2.0-mm thick planes.
Results :
Among 1113 patients, 26.5% were identified with normal conditions. Nine different disease types are identified, accounting for more than half of the studied populations (57.1%), which include 23.1% of patients with Congenital Cranial Dysinnervation Disorders (CCDDS); 18.8% with thyroid associated ophthalmopathy; and 15.2% with abnormalities of the extraocular muscles. Other diseases include tumors (2%); orbital fractures (3.3%); lesions of cavernous sinus (2.3%); intraorbital inflammations (2.7%); and injuries of medial rectus muscle after endoscopic sinus surgery (1.2%). An additional 5% of patients were identified as other unknown conditions.
Conclusions :
MRI of the oculomotor nerves in the brainstem, cavernous sinus, and the orbits provide unique information unavailable from the standard clinical examination. Thus, we are not only able to distinguish CCDDs condition from normal conditions, but also identify other complex diseases representing various cranial nerves and extraocular muscles abnormal statuses. Further study with molecular diagnostic tools such as genetic testing combined with these MRI findings could be conducted to examine the potential causes of these disease and associated treatment strategies.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.