|Year : 1962 | Volume
| Issue : 4 | Page : 103-106
Superior oblique sheath syndrome
Institute of Ophthalmology, Calcutta, India
I S Roy
Institute of Ophthalmology, Calcutta
|How to cite this article:|
Roy I S. Superior oblique sheath syndrome. Indian J Ophthalmol 1962;10:103-6
The purpose of this paper is to reveal the nature of a type of vertical squint due to congenital abnormality of the sheath of the superior oblique muscle which prevents the active and passive elevation of the eye in adducted position.
It was first reported by H. W. Brown (1949). So far no such case has yet been reported from India and so the following two cases are reported in this country for the first time.
A short description of the sheath and tendon of the superior oblique muscle is necessary to understand the mechanism of the syndrome. The strong fibrous sheath of superior oblique tendon has two attachments, one in front to the outer margin of the pulley and the other behind on the postero-superior quadrant of the eye ball along with the tendon of insertion of the superior oblique muscle. The linear distance from the pulley to the insertion of the muscle decreases on adduction and increases on adduction of the eye. [Figure - 1]. Normally this sheath acts as the check ligament of the inferior oblique muscle. If however, the sheath is taut in the primary position adduction will not be possible unless the eye is depressed. [Figure - 2].
The superior oblique sheath syndrome is a structural anomaly of the anterior tendon sheath apparently associated with congenital paralysis of the inferior oblique muscle. The anterior tendon sheath of superior oblique is congenitally short and so it is quite natural that the action of the inferior oblique gets restricted. This restriction is only manifested when the sheath is taut due to increase in the linear distance from the pulley to the insertion during the adduction of the affected eye. This abnormal shortening of the sheath will also restrict any passive elevation of the affected eye in the adducted position. In the true sense the inferior oblique could elevate or a passive elevation would have been possible had the tightness of the sheath been relaxed. Brown has shown that transverse section of the sheath makes the passive elevation possible and there is some improvement in the action of inferior oblique too. There is considerable improvement in the head tilt as well. Johnson (1950), Lyle (1953), Nutt (1954) have shown that severance or partial excision of the sheath makes the passive elevation possible with some improvement of the action of inferior oblique action. Duke-Elder has labelled these rather rare cases under the heading of "Insufficiency of the Inferior Oblique". He thinks its occurrence may be due to its late developmental separation from the inferior rectus. The restricted active and passive elevation of the eye in adducted position give support to Brown's view of a short superior oblique sheath.
Following clinical characteristics are noted :
1. Failure of the elevation movement of the affected eye beyond the horizontal plane when it is fully adducted This paralysis of inferior oblique is apparent.
2 As the affected eye is made to follow a finger from the abducted and elevated position to one of adduction and elevation the limit of elevation will be parallel to a straight line joining the inner canthus to nearly normal limit of elevation in the midline.
3. When the affected eye is abducted, there will be nearly normal muscle equilibrium.
4. There is sometimes widening of the palpebral fissure on adduction.
5. Traction test is positive i.e. the passive elevation of the eye in adducted position will be restricted. Surgical treatment like cutting the sheath of superior oblique and strengthening of the inferior oblique is only advocated when there is a disfiguring backward head tilt.
Case 1. G. R., Muslim, 23 years of age, of average health who was a sea-man by profession had a vertical squint in the upward gaze to the left for as long as he could remember and was not bothered by it. For his dimness of vision he attended the ophthalmic department of Medical College Hospital on 12-10-60. Right vision improved to 6/6 with-0.25D sph. -1.50D cyl. 125' and left vision improved to 6/6 with -0.50D sph. -1.75D cyl. 55◦ . The extra ocular movements revealed the following features. In the primary position there was slight narrowing of the palpebral fissure of the right eye and eyes were almost straight. In the upward gaze to the left the elevation of the right eye was limited to the horizontal plane and during adduction there was some amount of widening of the right palpebral fissure. Cover test revealed left hyperphoria in the upward gaze to the right. Muscle balance was normal in the downward gaze to the left or right. The right eye could not be elevated above the horizontal plane with a pair of forceps under anaesthesia. Hess chart revealed an under acting inferior oblique on the right and an overacting superior rectus on the left. As there was no subjective symptom, operative treatment was not advised.
Case 2. F. S. Christian, 5 years of age, was brought to the ophthalmic department, Medical College Hospital, by her mother for the investigation of the peculiar vertical squint. She had a backward head tilt with a slight turn to the left since age 6 months. In the primary position the eyes were straight. In the upward gaze to the left there was marked limitation of elevation of the right eye. There was normal muscle balance in all other positions of gaze. Traction test could not be performed as the mother did not allow a general anaesthetic.
Acknowledgement:- Thanks are due to Prof. K. L. Sen and Prof. M. Sengupta for their kind permission to publish these cases.
| References|| |
|1.||Allen, J. H. (1958), Strbismus Ophthalmic Symposium II, C. V. Mosby Company, St. Louis p. 410 |
|2.||Brown, II. W. (1950). |
|3.||Duke-Elder, W. S. (1949), Text book of Ophthalmology, Henry Kimpton, London, Vol. IV, p. 4087. |
[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4]