Abstract
Purpose :
For rare cases of infantile nystagmus syndrome (INS) where an abnormal head position (AHP) in the vertical plane is associated with a null position in up or down-gaze, a recession-resection technique applied to vertical rectus muscles has been shown by Del Monte to be superior to recession alone. Other approaches, such as superior rectus recession with inferior oblique weakening for a chin-down AHP (Saunders), have also been proposed. We present a retrospective, descriptive case series of patients requiring surgery for a vertical AHP in INS – this accomplished via either recession-resection or weakening of both elevators.
Methods :
A retrospective review of 150 patients with nystagmus who underwent eye muscle surgery (EMS) for an AHP from 1995-2018 was conducted. Of 31 patients on whom EMS was performed for a vertical plane AHP, 27 cases with at least two months of follow-up were reviewed. The primary outcome was collapse of AHP following surgery. We considered unfavorable outcomes to include repeat surgery, induced strabismus, or lack of collapse of AHP.
Results :
Twenty-one patients had a chin-down head position with null in up-gaze, while 6 patients had a chip-up head position with null in down-gaze. Two months post-operatively, all patients had resolved AHP to within 15 degrees of primary gaze. Mean follow-up was 50 months. For patients with chin-down AHP, recession-resection (BSRc 6-9 mm; BIRs 5-9 mm) was performed in 11 cases; weakening of both elevators (BSRc 5-8 mm, BIOc or myectomy) in 10 cases. Unfavorable outcome rates were 7/11 and 2/10 respectively (p = 0.08). Reoperation was performed in 6/21 patients with chin-down AHP (5/11 recess-resect, 4/5 of these for an induced V-pattern esotropia; compared to 1/10 for weakening of both elevators; p = 0.15). For patients with chin up AHP, recession-resection (BIRc 5-8 mm; BSRs 7-8 mm) was employed in all patients; reoperation was performed in 2/6.
Conclusions :
Chin-down AHP appears to be the more common form of vertical plane AHP. For a chin-down AHP, both recession-resection and weakening of both elevators produce acceptable outcomes with regards to collapse of AHP. However, recession-resection is frequently associated with development of a V-pattern esotropia, often requiring a second surgery. In absence of other indications, weakening of both elevators appears to be the preferable procedure.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.