Vertical transposition of the horizontal rectus muscles to correct head tilt because of infantile nystagmus syndrome - A case series

Abstract

Purpose: Head tilt associated with infantile nystagmus syndrome (INS) can be corrected by (a) operating the oblique muscles, (b) horizontally transposing the vertical rectus muscles, or (c) vertically transposing the horizontal rectus muscles. We report three cases of INS with head tilt corrected by vertically transposing the horizontal rectus muscles in both the eyes.

Methods: Three cases of head tilt with INS from an institutional practice operated by a single surgeon were retrospectively reviewed and analyzed. The intervention included full tendon width transposition (upward or downward) of all four horizontal rectus muscles to induce cyclotorsion in the direction of head tilt. The primary outcome measure was the correction of head tilt in the primary position.

Results: Three patients (boys) of ages ranging from 4 to 7 years with a pre-operative head tilt of 30° were operated upon. Although one patient's oblique muscles had been operated on to correct head tilt, another patient had an unmasked face turn after the surgery, which was corrected with a modified Anderson's procedure. Post-operatively, all patients had a reduction of head tilt to a range of 0-10°.

Conclusion: Vertical transposition of horizontal rectus muscles is a simple surgical option to correct head tilt in INS. However, the results may vary based on individual cases.

Keywords: Head tilt; INS; nystagmus; surgical outcomes.

Figure 1

Pre-operative and post-operative head posture of all three cases. Case 1 as seen pre-operatively with the right head tilt of 30° (1A) and small residual tilt after a year of surgery (1B). Case 2 with a persistent left tilt of 25° after oblique muscle surgery (2A) and after 3 months of surgery with no residual AHP (2B). Pre-operative right head tilt of 30° in case 3 (3A) and after 7 months of surgery (3B) with a residual head tilt of 10° and minimal face turn

Figure 2

(a) In this scenario, the patient had a right head tilt. (b) Both the eyes have been surgically rotated in the direction of head tilt – to correct right head tilt, the right eye is excyclo-rotated and the left eye is incyclo-rotated. (c) The head tilt was corrected after the induced rotation in both the eyes

Figure 3

Methods of correcting the right head tilt. (a) Surgery on oblique muscles: The right eye superior oblique can be weakened with inferior oblique muscle strengthening. The left eye superior oblique muscle can be strengthened with inferior oblique muscle weakening. The procedure can be performed in each eye on a single oblique muscle to correct different angles of tilt. (b) Surgery on vertical rectus muscles: Nasal shifting of the superior rectus muscle with the temporal shifting of the inferior rectus muscle in the right eye and temporal shifting of the superior rectus muscle with the nasal shifting of the inferior rectus muscle to correct right head tilt. (c) Surgery on the horizontal rectus muscle: Superior shifting of the lateral rectus muscle along with an inferior shift of the medial rectus muscle is performed in the right eye. Similarly, superior shifting of the medial rectus muscle and inferior shifting of the lateral rectus muscle are performed in the left eye to correct the right head tilt