Demer JL. Miller JM. Koo EY. Rosenbaum AL.
Jules Stein Eye Institute, UCLA 90024-7002.
Quantitative magnetic resonance morphometry of extraocular muscles: a new diagnostic
tool in paralytic strabismus.
Journal of Pediatric Ophthalmology & Strabismus. 31(3):177-88, 1994 May-Jun.
Paralytic strabismus is often diagnostically ambiguous due to the similarity
of patterns of misalignment produced by different mechanisms. To address this
problem, we have developed a new technique employing high-resolution, surface
coil magnetic resonance imaging to quantify extraocular muscle size and
contractility. Adjacent coronal images are obtained spanning the
anteroposterior extent of each orbit, and repeated in multiple directions of
gaze. Contractility is evaluated from analysis of muscle cross-sectional
areas. The quantitative size and contractile characteristics of normal rectus
and superior oblique muscles are reviewed,
along with the effects of superior oblique
palsy. The morphometric features of lateral rectus
palsy are illustrated by three clinical cases exhibiting deficient contractility
and atrophy of the lateral rectus muscle. A case of superior oblique palsy is
presented illustrating atrophy and lack of contractility of the involved superior
oblique muscle. This imaging technique can be employed in any clinical center
and permits insight into extraocular muscle function in complex strabismus cases.