Torsion in patients with superior oblique palsies: dynamic torsion during saccades and changes in Listing’s plane

Background The purpose was to assess intra- and post-saccadic torsion in superior oblique palsy (SOP) patients and the effect of surgery on torsion. Methods Eleven patients with a presumed congenital SOP and five with acquired SOP performed 10° vertical saccades over a range of ±20°. Eye movements were recorded with dual search coils. Dynamic torsion was calculated by subtracting the expected change in torsion during the saccade (based upon static torsion before and after the saccade) from the maximum intrasaccadic torsion. Eight healthy subjects were controls. We also examined the effects of surgery on dynamic torsion and the orientation of Listing’s plane in patients with congenital SOP who were operated on either by weakening of the inferior oblique muscle on the affected eye (n = 5), by recession of the inferior rectus muscle on the normal eye (n = 4) or by both procedures (n = 2). Postoperative recordings were obtained at least 1 month after surgery. Results Patients with congenital and acquired SOP showed an increased dynamic extorsion, primarily during downward saccades. Following a recession of the inferior oblique muscle in congenital SOP patients, half showed significant decreases in extorsion (up to 1.0°) during downward saccades by the affected eye. Following surgery all showed a temporal rotation of Listing’s plane (up to 15° for primary position). Conclusion Patients with a SOP show a characteristic pattern of dynamic torsion during vertical saccades differing from normals. Recession of the inferior oblique muscle leads to rotation of Listing’s plane in all congenital SOP patients and causes large changes in dynamic torsion in a subgroup of them, perhaps reflecting the heterogeneity of congenital SOP. This study was supported by the Deutsche Forschungsgemeinschaft DFG 860/2-1, Bonn Germany, Grant EYO1489, from the National Institute of Health, Bethesda, Maryland, the Abe Pollin scholarship fund, Swiss National Science Foundation Grant 3200B0-105434 and the Betty and David Koetser Foundation for Brain Research, Zurich, Switzerland.