Acute rectus muscle palsy in children as a result of orbital myositis.

OBJECTIVE

Acute rectus muscle palsy caused by orbital myositis is often confused with infectious orbital cellulitis. The purpose of this article is to clarify the former condition by explaining how it is manifested and treated.

METHODS

The seven children less than age 11 years in this study were examined after having an acute onset of ocular pain. Physical examination indicated a loss of motility in the field of action of the involved extraocular rectus muscle. Computed tomographic examination confirmed the existence of orbital myositis. Treatment consisted of intravenous or oral administration of corticosteroids.

RESULTS

In all the initial evaluations, computed tomography showed the isolated rectus muscle to be enlarged. In four of the patients in whom the lateral rectus was involved, esotropia was present in the primary position. In the fifth patient with lateral rectus involvement, esotropia was seen only in the field of gaze of the involved lateral rectus muscle. The patient with medial rectus involvement had exotropia, and the patient with superior rectus involvement had hypotropia on the involved side. Each had injection and chemosis of the conjunctiva and Tenon fascia only in the quadrant overlying the involved rectus muscle.

CONCLUSIONS

Children with orbital myositis can have an acute rectus muscle palsy. The inflammation and strabismus are exquisitely sensitive to systemic corticosteroid therapy, which produces a rapid resolution of symptoms. If the steroid therapy is discontinued abruptly, the myositis can recur.