Traction testing in superior oblique palsy.

This report describes the use of superior oblique traction testing in the evaluation of superior oblique palsy. Four consecutive children presenting with signs and symptoms of superior oblique palsy were found to have markedly abnormal tendon laxity with traction testing. Surgical exploration revealed anomalies including three with elongated lax tendons, one of which had an anomalous insertion, and one absent tendon. This tendon laxity is not typically found in acquired superior oblique palsy. It is proposed that, in addition to the well known neurogenic paresis/paralysis, a second type of "palsy" due to anatomic abnormalities of the tendon may exist and be responsible for a number of congenital superior oblique palsies. The mechanical disadvantage of these markedly long tendons may explain why inferior oblique weakening procedures alone frequently fail to correct head tilts due to superior oblique palsy in infancy.