|Year : 1991 | Volume
| Issue : 2 | Page : 65-67
Congenital nystagmus with head posture (a modified approach in surgical management).
Prem Prakash, Ramanjit Sihota, Vimla Menon
Dr. Rajendra Prasad Centre for Ophthalmic Sciences, New Delhi-110 029, India
Dr. Rajendra Prasad Centre for Ophthalmic Sciences,A.I.I.M.S. New Delhi-110 029
Source of Support: None, Conflict of Interest: None
The surgical methods for correction of an abnormal head posture in congenital nystagmus presently in use, do not correct the head posture adequately and in some cases produce a postoperative tropia. We felt that this may be related to the arbitrary quantities of surgery suggested by various workers. We have observed that surgery on the medial rectus is approximately one and a half times as effective as on the lateral. Using this ratio, excellent results have been obtained in 5 cases which are reported herein.
Keywords: Head Posture, Congenital Nystagmus Surgery, Effectivity Ratio For Horizontal Recti-Medial:Lateral rectus: 3:2.
|How to cite this article:|
Prakash P, Sihota R, Menon V. Congenital nystagmus with head posture (a modified approach in surgical management). Indian J Ophthalmol 1991;39:65-7
| Introduction|| |
Congenital nystagmus is the end product of a disturbance of oculomotor control, which may affect the afferent or efferent pathways. The aetiology is as varied as is its clinical presentation, with the characteristic rhythmic movements varying in their speed, response to the fixing eye, fatigue and position of gaze. The movement of the eyes may be decreased in a particular direction of gaze, known as the neutral zone or null point. If this is eccentric, the patient takes up a compensatory head posture to improve his vision and allow a degree of binocular vision. This posture, if exaggerated, is a cosmetic defect and may even lead to a structural torticollis.
Kestenbaum was the first to suggest surgery on all four horizontal recti, to rotate the eyes in the direction of the face turn, alleviating this abnormal head posture. He advocated the same degree of surgery on all four recti. Parks realized that the effect of surgery on the medial and lateral recti was not equal and proposed his "5-6-7-8 mm" surgery. Subsequent authors have proposed a 40% or 60% augmentation of the Parks' procedure, as further permutations based on the same premise. The result of these surgeries has been varied, ranging from a few good corrections, to a large percentage of undercorrections. A number of cases had a post-operative strabismus which later needed correction with prisms or surgery.
We do not agree with the estimation of the relationship of the medial and lateral recti, to a given amount of surgery as described above, and feel that this may have contributed to the post-operative diplopia experienced by some patients and the undercorrections in others. Our experience with thousands of strabismus surgeries suggests that the effectivity of surgery on the medial rectr is and lateral rectus approximates a ratio of 3:2. We therefore recommend surgery utilizing this ratio, the exact amount of surgery being determined by the degree of the face turn
We report our experience of 5 Patients having congenital nystagmus and an abnormal face turn.
| Case reports|| |
1. An 11-year old girl was noted to have jerky movements of the eye ball, soon after a full term normal delivery. At the age of 3 years, the parents first noticed that the child turned her face towards the left, and a slight chin elevation was noted. Her visual acuity was 6/12 with the head posture. There was orthophoria for distance, and 4/6 P.D. of exophoria for near. Fusion was present but stereopsis could not be elicited. She had a hypermetropia of 0.75 D sphere in the right eye and 0.50 D sphere in the left.
Both eyes were operated upon at the same sitting, right lateral rectus recession of 9 mm with a medical rectus resection of 6.0 mm was combined with a left medial rectus recession of 6.0 mm and a lateral rectus resection of 9 mm. There were no operative or immediate postoperative complication. Six weeks after the operation, a face turn of less than 50 to the left was seen with minimal chin elevation. The uniocular vision was 6/12 (P) in primary position was now 6/9 for distance. Exophoria of 4/6 P.D. was present for near and stereopsis was easily elicited. A follow up of 18 months has revealed no further change in the ocular position.
2. A 16-Years old boy was brought to us with a history of oscillatory movements of both eyes since an uneventful birth. The parents wire concerned about this and also complained of a face turn to the right. On examination, there was a head turn of approximately 45 0 to the right with an exophoria of 8 P.D. for near and distance. Fusion and stereopsis were both present. The retinoscopy under Cycloplegia was +1.0 D sphere in the right eye and +1.25 D sphere in the left.
Both eyes were operated upon simultaneously, the right medical rectus was recessed 6 mm and the lateral rectus resected 9 mm, while the left lateral rectus was recessed 9 mm, the medical rectus resected 6 mm.
Four weeks post-operatively the vision (Binocularly) in primary gaze was 6/5 (P) with no face turn at all. There was an asymptomatic exophoria of 4 P.D. with the presence of fusion and good stereopsis. Fourteen months later, no further change has been noted.
3. A 6-year old female patient complaining of a squint in the right eye since birth and frequent episodes of blurred vision, was seen in our squint clinic. Her parents complained of a disfiguring head posture. Vision without glasses was 6/12 and 6/18 and she had a hypermetropia of 3.25 D sphere in the right eye and 2.5 D sphere in the left.
Previous records showed that the patient originally had an intermittent divergent squint with latent nystagmus for which left lateral rectus recession 5 mm and medial rectus resection 4 mm had been done a year prior to her presentation to us.
On examination the patient was noted to have a 10 P.D.(L) esotropia for near and distance with manifest jerky horizontal nystagmus, dampened by a face turn of approximately 450 to the left. No binocular vision was present.
Further surgery was performed. In the right eye, lateral rectus recession 9 mm and medical rectus resection 6 mm, with the lateral rectus being resected 5 mm and advanced to the original insertion.
Post-operatively, there was a residual face turn of less than 50 to the right. Her vision, binocularly was 6/12 in primary gaze and there was an intermittent deviation of 4.P.D. in, for near and distance. Binocularity was easily elicited, stereopsis was good, and a follow-up of fifteen months was uneventful.
4. A 10 year old boy was brought to us with complaints of jerky movements and a face turn to the left. Examination revealed a 450 face turn to the left, a binocular visual acuity of 6/9 with the head posture, and orthophoria for distance and near. Fusion and stereopsis were present. There was a hypermetropia of +0.5 D sphere. in both eyes.
Surgery was performed on both eyes, the left lateral rectus resection 9 mm and medial rectus recession 6 mm with right medical rectus resection 6 mm and right lateral rectus recession 9 mm. At six weeks post operatively there was a minimal face turn to the left orthophoria, good binocular functions and a visual acuity of 6/9 (binocular), in primary position.
5. A 7 year old girl came with oscillatory movements of the eyes since birth. The parents complained of a face turn to the right. On examination there was a face turn of 450 to the right with exophoria of 10 P.D. for near and distance and full binocular functions. There was hypermetropia of +0.75 D sphere. in left eye.
The right medical rectus was recessed 6 mm and lateral rectus resected 9 mm while the left medical rectus was resected 6 mm and left lateral rectus recessed 9 mm. At 6 weeks the binocular visual acuity was 6/6 with no face turn, an ex ophoria of 6 P. D. and fusion and stereopsis. One year later there was no change.
| Discussion|| |
Patients with nystagmus and an eccentric null point, essentially have a gaze palsy to the opposite side which compels them to adopt a compensatory face turn. Surgery for this disorder, aims to shift the null point, so that the impulse to look in the direction of the slow phase of the nystagmus would result in the eyes looking straight ahead, in the primary position.
Various authors,,,,,, have proposed their own rationale for corrective surgery. Almost all of them are variations on Parks modification of Kestenbaum's operation. There are suggestions for a 40% or 60% augmentation , of the above which provide very precise figures, upto two decimal places, but this accuracy is not maintained during surgery or in the healing process postoperatively.
The main drawback of these surgeries lies in the fact that they are based on Park's arbitrary decision to recess/resect the lateral rectus 1 mm in excess of the medical rectus. The large individual variation in response to surgery allows some good corrections but the usual response appears to be an undercorrection with or without a significant strabismus. This iq Pxemplified by Dell' Osso and Flynn in a detailed study where a persistence of the head turn with a post-operative esotropia of 12 P.D. after Parks' procedure was reported.
We have based our surgery on our observation that the effectivity of surgery on the medial rectus is one and a half times as much, as on the lateral rectus. We advocate equal amounts of surgery on the two medial recti eg. 6 mm of recession/resection in the case report and similarly 9 mm on the two lateral recti. Recession being performed on the two muscles opposite the head turn and resection on the remaining. This is performed as a single stage surgery, though patients with a pre-operative deviation of the eyes may require a subsequent readjustment to correct the strabismus.
The good results claimed by surgeons using markedly different quantities of surgery has been explained on the phenomenon of "orthophorization of spontaneous correction, in patients with nystagmus. In a review of literature this does not seem to have been effective in a significant percentage of cases. Furthermore, we have performed the same surgery in patients adopting a head posture in conditions other than congenital nystagmus e.g musculofascial anomalies wherein orthophorization should not be effective. Our results were as effective and there were no post-operative complications.
We therefore advocate this simply calculated and executed surgery for all cases of an abnormal, head posture. This can be performed at a single sitting and does not cause a significant tropia. We have documented a total correction or a minimal undercorrection of the face turn in out patients with an associated improvement in visual acuity and binocular vision, a shift of the neutral zone and decreased intensity of the nystagmus in primary gaze.
| References|| |
Calhoun, JH, Hardey RD: Surgery for abnormal head position in congenital nystagmus. Trans. Am Ophthalmol.Soc.71:70-74,1973.
Cooper EL, Sandell CS. : Surgical treatment of congenital nystagmus. Arch.Ophthalmol. 81:473-480,1969.
Crone RA.: The operative therapy of nystagmus. Ophthalmologica 163: 15-20,1971
Delrosso LF, Flynn J.T.: Congenital nystagmus surgery. A quantitative evaluation of the effects. Arch. Ophthalmol. 97:462-469, 1979.
Kestenbaum A.: Nouvella operation de nystagmus. Bull. Soc. Ophthalmol. Fr.6:599-602, 1953.
Nelson LB, Ervin-Mulvey LD, Calhoun JH, et al.: Surgical management for abnormal head position in Nystagmus : The augmented modified Kestenbaum procedure. Br.J.Ophthalmol 68:796-799. 1984.
Parks MM.: Congenital nystagmus surgery. Am Orthopt. J 23:35-40. 1973.
Schlossman A. : Nystagmus with strabismus : Surgical management. Trans. Am. Acad. Ophthalmol. Otolaryngol. 76:1479-1486. 1972.
Spielmann A. : Congenital nystagmus: Clinical types and their surgical treatment. Ophthalmologica. 183:65-72, 1981.
Sternberg, Raab A.: Anderson -Kestenbaum operation for asymmetric gaze nystagmus. Br.J. Ophthalmol. 47:339-345. 1963.
Taylor JN.: Surgery for horizontal nystagmus Anderson - Kestenbaum operation. Aust.J.Opthalmol. 1:114-116, 1973.
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