Authors
Helveston EM. Krach D. Plager DA. Ellis FD.
Institution
Department of Ophthalmology, Indiana University School of Medicine, Indianapolis.
Title
A new classification of superior oblique
palsy based on congenital variations in the tendon.
Source
Ophthalmology. 99(10):1609-15, 1992 Oct.
Abstract
BACKGROUND: Superior oblique
palsy is the most frequent isolated cranial nerve
palsy seen in strabismus practice. It is traditionally
diagnosed according to etiology as acquired, congenital, or idiopathic, but
surgical treatment is based on deviation not etiology. Observations at
surgery led to speculation that the superior
oblique tendon is different in congenital compared with
acquired superior oblique
palsy and that this difference should be considered in
surgical treatment. METHODS: The authors reviewed the charts of 82 patients
(89 eyes) undergoing surgery on the superior
oblique tendon for superior
oblique palsy. In each case, the
palsy had been diagnosed preoperatively as acquired,
congenital, or idiopathic, and, at surgery, characteristics of the tendon
anatomy were described. RESULTS: Thirty-eight superior
oblique tendons (36 patients), diagnosed as congenital
superior oblique palsy,
included 33 abnormal tendons and 5 normal tendons. Twenty-four tendons (21
patients), diagnosed as traumatic superior
oblique palsy, included 22 normal and 2
abnormal tendons. Twenty-seven tendons (25 patients), diagnosed as
idiopathic, included 19 normal and 8 abnormal tendons. Abnormal tendons were
divided into 4 categories: (1) redundant, (2) misdirected, (3) inserted in
posterior Tenon's capsule, and (4) absent. CONCLUSIONS: The authors conclude
that congenital superior oblique
palsy is usually associated with a structural abnormality of
the superior oblique tendon (87%). Whereas
acquired superior oblique
palsy usually has a normal tendon (92%).
Superior oblique underaction in acquired
superior oblique palsy
results from a neural deficit. Potential variance in anatomy of the
superior oblique tendon should be
considered when undertaking surgery for superior
oblique palsy.