The Sensitivity of the Bielschowsky Head Tilt Test in Diagnosing Acquired Bilateral Superior Oblique Paresis – Accepted Manuscript

Abstract: Purpose: To determine the sensitivity of the Bielschowsky head-tilt test and other commonly used criteria in identifying patients with true bilateral superior oblique paresis.Design: A retrospective chart review was performed to identify patients seen between 1978 and 2009 who were diagnosed with acquired bilateral superior oblique paresis.Methods: All patients had a confirmed history of head trauma or brain surgery with altered consciousness followed by symptomatic diplopia. Bilateral superior oblique paresis was defined and diagnosed by the above history including the presence of greater extorsion in down gaze than upgaze on Lancaster red-green testing, a V-pattern strabismus, and bilateral fundus extorsion. We analyzed findings of the Bielschowsky head-tilt test, the Parks 3-step test, and reversal of the hypertropia from straight-ahead gaze to the other eight diagnostic positions of gaze to determine these tests’ sensitivity in identifying true bilateral superior oblique paresis.Results: Twenty-five patients were identified with the diagnosis of “true” bilateral superior oblique paresis. The Bielschowsky head-tilt test had a 40% sensitivity, the Parks 3-Step test a 24% sensitivity, and reversal of the hypertropia a 60% sensitivity in making the diagnosis of true bilateral superior oblique paresis.Conclusions: What has previously been described as masked bilateral superior oblique paresis may simply be a reflection of inherent poor sensitivity of the Bielschowsky head-tilt test, the Parks 3-step test, and reversal of the hypertropia in diagnosing bilateral superior oblique paresis. Hence, none of these tests should be relied upon exclusively to make this diagnosis.