Abstract
Abstract: :
Purpose: To elucidate the cause of blepharoptosis in Jacobsen syndrome we used high resolution orbital MRI. Jacobsen syndrome is due to deletion of the terminal band 11q23, 11q24.1 and 11q24.2. Characteristic features include bilateral severe ptosis, metopic craniosynostosis, divergent strabismus, downward slanting palpebral fissures, psychomotor retardation, telecanthus, mitral valve prolapse, aortic stenosis, low set dysmorphic ears, retrognathia, carp shaped mouth, thrombocytopenia and leukopenia. Methods:A 7 year boy with cytogenetic diagnosis of Jacobsen syndrome underwent high resolution ( 2 mm. slice thickness, 390 micron pixels) surface coil, T1 weighted orbital MRI in coronal and sagittal planes. Extraocular muscle volumes were analyzed quantitatively with the NIH Image Program and compared with those of 10 matched normal volunteers. Results: In the subject with Jacobsen syndrome, there was congenital A pattern exotropia, chin up position and euryblepharon. Levator muscle function was impaired and the upper eyelid crease absent in both eyes.There was severely limited supraduction and mildly limited infraduction . Extraocular muscle volumes were normal, except for the superior rectus/ levator complex and the inferior rectus muscle, which were statistically smaller than normal (P < 0.005) . Conclusions: Hypoplasia of the superior rectus and levator muscles in Jacobsen syndrome produces clinically severe ptosis and limitation of supraduction. Early frontalis suspension is indicated in this situation to avoid deprivation amblyopia, since levator resection can be expected to fail when the levator is hypoplastic.
Keywords: genetics • eyelid • extraocular muscles: structure