ABSTRACT
Both atypical Brown syndrome (ABS) and inferior rectus restriction of double elevator palsy (DEP) are characterized by monocular limitations of upgaze in primary, abducted position as well as abducted position. Futhermore, they exhibit resistance of elevation in adduction during forced duction test and should be considered in the differential diagnosis. We gained several differential points from 6 year-old female with ABS and a 12 year-old female with DEP due to inferior rectus restriction (IRR). In forced duction test under general anesthesia, ABS exhibited resistance of elevation in adduction and IRR of DEP showed resistance of elevation in all upward direction. DEP showed an impairment of Bell`s phenomenon and mild pseudoptosis preoperatively in which ABS never showed. ABS displayed divergence in upgaze producing V-pattern, and further limitation of upgaze in adduction than DEP. Superior oblique lengthening procedure using silicone expander was performed for ABS. Ipsilateral inferior rectus and contralateral superior rectus recession were performed for IRR of DEP. The results for elevation in adduction, primary position and abduction were satisfactory in both diseases. In conclusion, the direction of resistance in forced duction test, Bell` s phenomenon, the degree of elevation in abducted and abducted position, presence of pseudoptosis and divergence in upgaze producing 3 V-pattern may be helpful to differentiate ABS from IRR of DEP.