SURGICAL TREATMENT OF TRUE BROWN'S SYNDROME J. S. CRAWFORD, M.D. Toronto, Ontario 1
Brown was the first to describe, in 1950, a group of patients who could not actively elevate the eye above the horizontal plane when it was rotated medially. He ascribed this to a shortening of the anterior portion of the superior oblique tendon sheath which re stricted passive elevation in the fully adducted position. To correct this, he exposed the tendon, sep arated it from its sheath, cut the sheath trans versely, and then easily rotated the eye up and medially with forceps. At the same time a strengthening operation was performed on the inferior oblique muscle. Twenty-four hours later the patient was able to elevate the eye up to, but not above, the horizontal plane. Brown 1 hypothesized that the syndrome was a developmental anomaly following con genital complete paralysis of the inferior oblique muscle. Its check ligament, the sheath of the anterior segment of the superior oblique, was congenitally short because no stretching force was applied to it during de velopment. He advocated surgical correction for cosmetic reasons and to reduce the dis figuring backward head tilt. Later, Brown 2 classified the tight sheath syndrome as simulated or true. In simulated Brown's syndrome the posterior part of the superior oblique muscle and tendon is thick ened, or too firmly attached to the posterior sheath, resulting from inflammation extend ing from the ethmoid cells to the posterior sheath and tendon, from orbital floor frac ture, or from frontal sinus surgery. "True" Brown's syndrome is characterized by limitation of elevation in adduction, so From the Department of Ophthalmology, Hos pital for Sick Children, Toronto, Canada. Presented before the American Association for Pédiatrie Ophthalmology, Lake Tahoe, Nevada, February 26, 1975. Reprint requests to J. S. Crawford, M.D., 555 University Ave., Toronto, Ontario, Canada M5G 1X8.
severe that the eye cannot be raised volun tarily above the mid-horizontal plane ; little or no overaction of the homolateral superior oblique muscle, generally with slight downshoot on adduction ; widening of the palpebral fissure on adduction; and an unequivocally positive traction test on attempted elevation in adduction. As the eye is abducted from the downshoot position, elevation follows a straight line from the inner canthus to the normal limits on external rotation. There is almost normal muscle balance in the temporal field ; straight or divergent positions of the eyes in upgaze with frequent limitation of elevation of the affected eye are associated findings. Many surgeons question that true Brown's syndrome is due to a tight sheath on the an terior portion of the superior oblique tendon. Parks and M. Brown, 3 unable to substantiate Brown's theory of a primary congenital anomaly of the anterior sheath, suggested that points of adherence between the globe and other structures in the orbit existed. In 1947, Berke4 described three methods of weakening the superior oblique tendon. He found that tenotomy of the superior oblique muscle did not lead to tortional dif ficulties or to complete paralysis of the su perior oblique muscle. He showed that the amount of weakening of the superior oblique muscle could be varied by cutting or re moving part of the tendon. If a minimal effect was desired, he cut the tendon just me dial to the superior rectus muscle. If a larger effect was desired, he removed some of the tendon ; the cut end of the tendon still moved the globe because its sheath was still attached. Complete paralysis occurred if a portion of the tendon with its entire sheath, close to the pulley, was excised.
AMERICAN JOURNAL OF OPHTHALMOLOGY
Fig, 1 (Crawford). The orbit of a cadaver. The brain and orbital roof have been removed. A cord is tied around the tendon of the superior oblique muscle at the medial border of the superior rectus muscle. Top left, Orientation : a, medial orbital wall; b, belly of superior oblique; c, trochlea; d, superior oblique tendon; e, cord as a marker; and f, superior rectus muscle. Top right, The tendon is cut at the medial border of the superior rectus muscle. Note position of the cord (arrow). Left, The superior oblique muscle is drawn back by the muscle hook under its belly. Note retraction of the cut end of the tendon toward the trochlea (arrow).
roof of the orbit in cadavers (Fig. 1) several hours after death but before rigor mortis had set in, performed one of the four following procedures on the superior oblique tendon, and then applied traction to the belly of the muscle behind the trochlea (Fig. 2 ) : (1) A Z tenotomy allowed an increase in length of approximately 3 to 4 mm. (2) A split tendon lengthening allowed an increase in length of approximately 5 to 7 mm. (3) A complete tenotomy of the superior oblique tendon just medial to the superior rectus muscle allowed only an approximately 8- to 10-mm increase
in length because of Tenon's capsule and the fine attachments of tendon to the sciera ( Fig. 3). When a strong pulling force was applied to the belly of the muscle it was evident that the tendon movement was restricted by capsular attachments to the trochlea. (4) Atenectomy allowed the cut end of the tendon to re tract more than that achieved with a complete tenotomy so that the final attachment to the globe was more medial. Clinical methods—Surgery was done on 28 patients with typical true Brown's syn drome between 1960 and 1975. No tight su-
TRUE BROWN'S SYNDROME
VOL. 81, NO. 3
perior oblique tendon sheath was found in any case. This was determined by placing a hook under the superior rectus muscle and pulling the eye down and out. A retractor pulled the underside of Tenon's capsule away from the sciera and the external surface of the superior rectus muscle. In this way the sheath could be examined and was not found to be tight. A forced duction test was carried out by placing one forceps at the temporal corneoscleral limbus to displace the eye medially, a second forceps was placed at the 6 o'clock limbal position, and an attempt was made to elevate the globe. In all cases, the eye could not be elevated above the horizontal position. The forced duction test showed that after a Z tenotomy the eye elevated above the midline in adduction ; after a split tendon lengthening, the eye rotated well above the horizontal plane; and after a complete tenotomy and similarly a tenectomy, the eye rotated upward and medially normally without any restric tion (Table). In one patient the sheath was stripped, and silk sutures were placed to hold the eye up and in and were removed after ten days as described by Scott and Knapp. 5 Postoperatively the condition was unimproved.
Fig. 2 cedures.
Tendon lengthening pro
Fig. 3 (Crawford). Fine attachments of tendon to the sciera and the sheath.
Tendon lengthening procedures—TYPE 1— Nine patients underwent Z tenotomy of the superior oblique tendon. They all improved
TABLE RESULTS AFTER SURGERY
No. of Patients
Temporary suspension Scott-Knapp operation5 Z tenotomy
Split tendon lengthening Complete tenotomy
Secondary Overaction of Inferior Oblique Muscle
Final Result* E
it 5 2
6 1 1
1 2 1 2
4 4 3
* E indicates excellent, normal or almost normal ocular movement; G: good, normal head posture, eye rotates well above the horizontal but some residual limitation; I : improved, no further downshoot in medial rotation, but still has limitation of elevation ; U : unimproved, no change. t Second procedure required.
AMERICAN JOURNAL OF OPHTHALMOLOGY
Fig. 4 (Crawford). Top, Four-year-old boy has a right Brown's syndrome. Bottom, After a split tendon lengthening of the right superior oblique tendon, the right eye is elevated, better than before surgery but with limitation of elevation in adduction. to a limited degree. The eye elevated upward in adduction above the midline. T Y P E 2—I used split tendon lengthening in two cases in the way the orthopedic surgeon lengthens tendons in the leg. In both cases results were better than those obtained by Z tenotomy (Fig. 4). The eye rotated well above the horizontal plane, and the head pos ture was normal. T Y P E 3—In 16 patients, the superior oblique tendon was cut just medial to the su-
Fig. S (Crawford). A bunched up Tenon's cap sule may be mistaken for tendon.
perior rectus muscle. Fourteen of these pa tients had good binocular vision pre- and postoperatively ; the surgical results were ex cellent in nine, good in one, improved in three, and unimproved in one. Apparently in this last case the tendon was missed at op eration ; a later tenectomy gave excellent re sults. When the tendon is picked up with a muscle hook in the conventional manner, a bunched up Tenon's capsule can be mistaken for the tendon (Fig. 5). In six of the 14 pa tients, a secondary overaction of the inferior oblique muscle occurred. A myectomy of this muscle was performed in three patients and the overaction in the other three did not re quire surgery. The results were good in the two patients without binocular vision treated by complete tenotomy. One patient developed an overaction of the inferior oblique muscle that did not require further surgery (Figs. 6-9). In two patients where a secondary overaction of the inferior oblique muscle occurred, the anterior tendon of the superior oblique muscle was approximately twice its usual diameter. T Y P E 4—Excellent results were obtained in two patients who underwent tenectomy, one as a primary procedure and one after an
VOL. 81, NO. 3
TRUE BROWN'S SYNDROME
Fig. 6 (Crawford). Top, Seven-year-old girl with a left Brown's syndrome. Bottom, One week after complete tenotomy of left superior oblique tendon. unsatisfactory tenotomy in which the tendon was missed. This patient developed an overaction of the inferior oblique muscle and a myectomy of this muscle was done.
In discussing treatment in 1957, Brown 6 stated that if the surgeon cannot manually elevate the paretic eye in adduction, an opera-
Fig. 7 (Crawford). Top, Five-year-old boy with a right Brown's syndrome. Center, After complete tenotomy of right superior oblique tendon. Secondary overaction of the right inferior oblique muscle. The tendon of the superior oblique muscle was two to three times as large as normal. Bottom, After recession of the right inferior oblique muscle.
AMERICAN JOURNAL O F OPHTHALMOLOGY
Fig. 8 (Crawford). Top, Ten-year-old girl who had a right Brown's syndrome showing no improve ment after the superior oblique sheäth was stripped and the eye held up and in with silk sutures for ten days (Scott-Knapp operation). Bottom, Eight days after complete tenotomy of the right superior oblique tendon.
tion that does not relieve this restriction will also fail. Brown6 mentioned that he had cut the su perior oblique tendon in three patients with overaction of the muscle and obtained good results. Howarth 7 found that division of only the sheath of the superior oblique muscle with a resection of the inferior oblique muscle was ineffective in one patient; therefore, he cut the superior oblique tendon and sheath. Sub sequently that child developed bilateral overaction of the inferior oblique muscles but recessions of these muscles corrected the overactions.
Parks and Brown 3 performed a tenotomy in one patient with true Brown's syndrome and a tenectomy in another and reported good results. Chamberlain also has had good re sults in three cases (personal communica tion, Feb. 4, 1975). I doubt that developmental failure of the superior oblique muscle due to weakness of the inferior oblique muscle produces the syn drome because, after cutting of the superior oblique tendon, the inferior oblique muscle overacts, indicating that its action has been restricted by the tight superior oblique mus cle, and because electromyographic recordings
Fig. 9 (Crawford). Top, Eleven-year-old girl with right Brown's syndrome. Center and bottom, Two years after a complete tenotomy of the right superior oblique muscle, she has full range of motility.
VOL. 81, NO. 3
TRUE BROWN'S SYNDROME
of the inferior oblique muscle in these cases have been normal.2,s"10 In the past I found stripping the tendon1 to be unsatisfactory. Among my patients, I have not seen a true paresis of the inferior oblique muscle since there was either secon dary overaction or improved action of this muscle when the restricting antagonist was cut or lengthened. On the other hand, I found that when only the sheath was cut no per manent improvement resulted. The most common technical failure I en countered was missing the superior oblique tendon: I missed it on three occasions. McNeer 11 and Chamberlain (personal communi cation, Feb. 4, 1975) also experienced this difficulty, so a small piece of tendon may be sent for histologie examination to confirm that the tendon has indeed been cut and to compare its structure with the normal. Tenotomy of the superior oblique muscle appears to give the best results.4·11 Among my patients no permanent vertical muscle problems resulted. If secondary overaction of the inferior oblique muscle persisted, a weak ening operation was done and the end result was good. No case of underacting superior oblique muscle was found after tenotomy. When the superior oblique tendon was cut just medial to the superior rectus muscle, the eye immediately moved upward and inward, and continued to do so postoperatively. True Brown's syndrome is not due to a tight sheath on the tendon of the superior oblique muscle because cutting the sheath alone does not permanently correct the con dition, and some patients with marked downshoot on medial rotation have thick tendons. SUMMARY
In 1950 H. W. Brown reported the su perior oblique tendon sheath syndrome and cut the sheath as treatment for the condi tion. My results (as well as those of other sur geons) with similar surgery have been disap pointing. Consequently, I carried out different operations consisting of Z tenotomy of su perior oblique tendon in nine patients, split
tendon lengthening in two patients, complete tenotomy in 16 patients, and a tenectomy in two patients. One of the latter was done on a patient after an unsatisfactory tenotomy where I missed the tendon. Tenotomy of the superior oblique tendon gave the best results. Experiments with the superior oblique tendon in cadavers several hours after death showed that after cutting the tendon just me dial to the superior rectus muscle, the cut end of the tendon moved medially only about 8 to 10 mm due to restrictions of the capsular attachments to the trochlea. The cause of "true" Brown's syndrome is a tight tendon, and a safe and effective surgical treatment consists of cutting it just medial to the su perior rectus muscle. REFERENCES
1. Brown, H. W. : Congenital structural muscle anomalies. In Allen, J. H. (ed.) : Strabismus Oph thalmic Symposium. St. Louis, C. V. Mosby, 1950, p. 205. 2. : True and simulated superior oblique tendon sheath syndromes. Doc. Ophthalmol. 34: 123, 1973. 3. Parks, M. M., and Brown, M.: Superior oblique tendon sheath syndrome of Brown. Am. J. Ophthalmol. 79:82, 1975. 4. Berke, R. N. : Tenotomy of the superior oblique muscle for hypertropia. Arch. Ophthalmol. 38:605, 1947. 5. Scott, A. B., and Knapp, P.: Surgical treat ment of the superior oblique tendon sheath syn drome. Arch. Ophthalmol. 88:282, 1972. 6. Brown, H. W. : Isolated inferior oblique paral ysis. Trans. Am. Ophthalmol. Soc. 55:415, 1957. 7. Howarth, S. M.: Unusual sequelae of surgery in the superior oblique tendon sheath syndrome. Br. J. Ophthalmol. 54:675, 1970. 8. Breinin, G. M. : New aspects of ophthalmoneurologic diagnosis. Arch. Ophthalmol. 58:375, 1957. 9. Ferîc-Seinwerth, F. : Report on the 2nd Inter national Orthoptic Congress in Amsterdam, May 11, 1971. In Fells, P. (ed.) : The International Strabismological Association Newsletter, 1971, No. 10, p. 7. 10. Catford, G. V., and Dean Hart, J. C : Su perior oblique tendon sheath syndrome: An electromyographical study. Br. J. Ophthalmol. 55:155, 1971. 11. McNeer, K. W. : Untoward effects of su perior oblique tenotomy. Ann. Ophthalmol. 4:7, 1972.