Abstract
Surgical planning for a sixth nerve palsy or paresis should include an assessment of whether the deficit is complete or incomplete. In cases of incomplete paresis, a recess-resect procedure is appropriate. For small deviations, a single lateral rectus resection is effective, whereas for larger deviations, recession of the contralateral medial rectus, with or without a posterior fixation suture, may improve comitance and the field of single binocular vision. In cases of complete palsy, a superior and inferior rectus transposition procedure is advisable. Augmenting the transposition may allow two muscle surgery alone to be effective. Botulinum toxin may be useful alone, particularly in acute complete palsies, and may be used as an adjunct to transposition surgery.
Lost muscles are best addressed by relocating the lost muscle. Failure to find the muscle will necessitate a transposition procedure. If the ipsilateral antagonist is tight, requiring a recession, a vessel sparing procedure should be used for the transposition.
Type I Duane syndrome may best be addressed by incorporating a recession of the contralateral medial rectus into the surgical plan. Nevertheless, early results from an augmented transposition procedure show promise in restoring partial abduction of an affected eye.
Surgical planning should include a careful history, examination and a discussion of patient expectations.