Bielschowsky head-tilt test alone unreliable for bilateral paresis diagnosis

This retrospective study found that the Bielschowsky head-tilt test and other commonly used criteria for identifying patients with true bilateral superior oblique paresis have poor sensitivity and none of them can be relied upon exclusively to make this diagnosis.

The study’s authors reviewed the charts of 25 patients diagnosed with acquired bilateral superior oblique paresis between 1978 and 2009. 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 downgaze than upgaze on Lancaster red-green testing, a V-pattern strabismus, and bilateral fundus extorsion.

For each patient they 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.

In making the diagnosis of true bilateral superior oblique palsy, the Bielchowsky head tilt test had a 40 percent sensitivity, the Parks 3 step test had a 24 percent sensitivity and the reversal of hypertropia a 60 percent sensitivity. 

They write that 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 the diagnosis of bilateral superior oblique paresis.

They add that part of the key to diagnosing bilateral paresis is understanding the typical pattern of the torsional misalignment. By assessing these changes in torsion and by looking for signs of reversal of the hypertropia in combination with the Bielschowsky head-tilt test, they feel they are more likely to identify the majority of cases of true bilateral superior oblique paresis, but one should not rely on the Bielschowsky head-tilt test alone to make this diagnosis.