Superior oblique muscle dysfunction following anterior ethmoidal artery ligation for epistaxis.

Superior oblique muscle palsy is a frequently encountered acquired muscle deficit accounting for vertical and torsional diplopia. There were two cases of residual isolated superior oblique palsy following anterior ethmoidal artery ligation for epistaxis, a finding not previously reported. The mechanism is suggested to be due either to direct trochlear damage by separation from the periosteum or to localized hematoma formation beneath the periosteum with resultant fibrosis and displacement of the trochlea from its normal apposition to the frontal bone.