MAGNETIC-RESONANCE-IMAGING IN EVALUATION OF CONGENITAL AND ACQUIRED SUPERIOR OBLIQUE PALSY

Background: According to the recently popularized classification of su perior oblique (SO) palsy based on congenital variations of the tendon , the primary pathology is the abnormality of the SO tendon rather tha n an innervational problem in congenital cases. If this hypothesis is true, denervation atrophy of SO muscle should not occur in patients wi th congenital SO palsy. Methods: Eight patients with traumatic and nin e patients with definite congenital SO palsy underwent magnetic resona nce imaging (MRI) of the orbit. SO muscle width and cross-sectional ar ea measurements were taken from coronal images and compared with the c linically uninvolved superior oblique muscles. Results: Atrophy of var ying degrees was observed in the SO muscle both in congenital and acqu ired cases. No significant difference was found in the appearance of t he SO muscle between acquired and congenital SO palsy groups. Conclusi on: We have been unable to demonstrate abnormalities of the SO tendon in both groups. The MRI appearance of the SO muscle suggested that in congenital SO palsy, the pathology is not limited to the tendon; there also is an abnormality of the muscle itself.