Scoliosis secondary to unilateral extraocular muscle paresis (ocular torticollis).

Abstract

Scoliosis as a compensatory mechanism secondary to extraocular muscle paresis was reported in the French literature as early as 1873 (3, 4). Verzella and his coworkers (15) in describing eight cases of this entity gave credit to von Graefe for being the first who, in 1864, recognized the compensatory mechanism of this type of scoliosis. Cuignet, in describing the manifestations with the cervical vertebrae, coined the term “ocular torticollis,” and this term, together with “spastic torticollis” has been used in the French (1, 3, 4, 15) and British (5, 10, 11, 13, 14) ophthalmologic literature. Cogan (2), in describing congenital palsy of the fourth nerve, emphasized the importance of compensatory head tilt due to ocular paralysis and stated that some patients are reported to have undergone tenotomy of the sternocleidomastoid muscle under the impression that the fault lay in the neck muscles. In an excellent paper Ruedemann (12) again emphasized the association of the ocular paralysis and malalignment of the spine and directed attention to the compensatory scoliosis in the dorsal and lumbar areas. In every case studied to date, bilateral leg measurements have been equal. It is the purpose of the authors to add three cases to the literature and briefly summarize the findings heretofore unreported in the radiological literature. General Features In general, ocular torticollis is due to a congenital vertical deviation and rotation of one eye, and the patient attempts to compensate for the visual disturbance by holding the head obliquely. The ocular abnormality is frequently noted shortly after birth. Because bilateral fixation develops at about five or six months of age (12), the desire for fusion usually appears before the infant can sit or walk. An adjustment is made by the infant in the muscles of the neck and back to permit bilateral fixation and subsequently to maintain vertical body posture required for normal locomotion and balance. If a vertically acting muscle paresis persists, a head tilt will develop and a compensatory scoliosis will be created through the remainder of the axial skeleton. The greater the need for ocular cyclorotation, the greater the necessary head tilt and subsequent spinal adjustment (12). Cogan explained that the head tilt tends not only to decrease diplopia and maintain fusion, but also to reconstitute a normal ophthalmological reflex and binocular alignment of the eyes. Superior oblique paresis also results in extortion of the eye and weakness of downward gaze. Although the great majority of these cases are due to superior oblique muscle paresis, some are also caused by superior rectus muscle paresis. In many instances, according to Ruedemann, two muscles are combined, representing a superior rectussuperior oblique syndrome or an inferior rectusinferior oblique syndrome.