97th DOG Annual Meeting 1999

K477

THE INVERSE BIELSCHOWSKY HEAD-TILT PHENOMENON

W. Happe, H. Mühlendyck

The Bielschowsky head-tilt phenomenon (BHP) consists in an increase of a positive vertical divergence (+VD) when the head is tilted to the right or an increase of a negative vertical divergence (-VD) when the head is tilted to the left. Against this in an inverse BHP it comes to a -VD when tilting the head to the right or a +VD when tilting the head to the other side. We report about 5 otherwise healthy patients with uniform typical findings.

Patients: All 5 patients showed a sursoadduction on one side, which let the suspicion on a superior oblique underfunction and an inferior oblique overfunction arise. In contrast to patients with strabismus sursoadductorius or a fourth nerve palsy, however, an inverse BHP was present. The largest increase of the vertical deviation was found when the head was tilted to the contralateral side. The intraoperative findings and postsurgical results confirm largely the following explanation: Causally there is mostly an insertion anomaly of the contralateral superior oblique muscle. The superior oblique insertion extends to far in direction to the limbus. This leads to an incyclorotatoric overfunction. When tilting the head with provocating an incylorotation an increased compensatory innervation of the homolateral inferior rectus muscle leads to the inverse BHP. The sursoadduction of the other eye can be interpreted as an already present BHP at a straight head position and the fact that the overacting rotatoric function of the oblique muscle is mostly present in abduction. The anomalous head posture consists in a head-tilt to the contralateral side to reduce the vertical deviation to the smallest degree.

Conclusion: Patients with a marked inverse BHP cause diagnostic problems. The clinical phenomenons can be explained by an insertion anomaly of the superior oblique muscle mostly of one side, sometimes of both sides. Adequate surgery with retroposition of the anterior part of the superior oblique tendon and sometimes additional anteroposition of the anterior part of the inferior oblique muscle can correct the disturbance.

Dept. of Strabismology and Neuroophthalmology, Univ.-Eye Clinic, Robert-Koch-Str. 40, D-37075 Göttingen

Back