Adjustable Bilateral Superior Oblique Tendon Advancement for Bilateral Fourth Nerve Palsy

Abstract

Purpose Bilateral fourth nerve palsy may be symmetric or asymmetric with combined vertical and excylotropic deviations and so there may be an advantage to independent adjustment of vertical and torsional components. We report a surgical technique that allows such independent adjustment. Design Retrospective interventional case series. Methods 15 patients, age 17 to 73 years, underwent adjustable bilateral superior oblique tendon advancements for bilateral fourth nerve palsy (11 symmetric (≤2 prism diopters [pd] hyperdeviation in straight ahead gaze) and 4 asymmetric). Motor alignment was assessed with double Maddox rods and prism and alternate cover tests preoperatively, pre- and post-adjustment and 6-weeks postoperatively. Results Preoperative torsion ranged from 7° to 30° excyclotropia (mean 17 ± 7 degrees) and hyperdeviation from 0 to 10pd. Preadjustment torsion ranged from 5° excyclotropia to 40° incyclotropia, and hyperdeviation from 0 to 8pd. 12 (80%) of 15 were adjusted to a target of 0pd hyperphoria and 10° incyclotropia (actual mean 9° incyclo, range 2° incyclo to 13° incyclo). At 6 weeks postoperatively there was expected excyclodrift (to mean 4° excyclo, range 0° incyclo to 15° excyclo), but 13 (87%) had 5° or less excyclotropia and 14 (93%) had 2pd or less hyperdeviation. Mean torsional correction from preoperative to pre-adjustment was 31° ± 14° (P<0.0001), and from preoperative to 6 weeks was 13° ± 6° (P<0.0001). Conclusions Adjustable bilateral superior oblique tendon advancement allows independent control of torsional and vertical components of the deviation, and therefore may be useful in cases of bilateral superior oblique palsy.

Disorders of the Fourth Cranial Nerve

“…In the absence of a vertical deviation, bilateral symmetric Harada–Ito procedures can be performed. If a vertical deviation is present, then bilateral but asymmetric Harada–Ito procedures possibly with adjustable suture techniques can be performed (68). In many patients with bilateral superior oblique palsies, there is a V-pattern esotropia and chin-up posture.…”

Adult Strabismus Preferred Practice Pattern®

“…• Inferior rectus weakening (contralateral) 256 • Superior oblique strengthening, for example, tuck (recommended for lax tendons in presumed congenital SOP 255 ), advancement for vertical and torsional deviations, 257 or a version of the Harada-Ito procedure, advancing only the anterior SO fibers that affect torsion (ipsilateral) 258,259 • Superior rectus weakening (ipsilateral) 260 Many of the above procedures may be performed using adjustable suture techniques; the target angle should be a small undercorrection because overcorrection, particularly in downgaze, is extremely poorly tolerated.…”

“…This technique may be most helpful in reoperations and unpredictable cases, such as those with restrictive or paralytic strabismus. 150,154,200,257,311,374,375…”

A simple marking system for accurate intraoperative monitoring and adjustment of cyclotorsion strabismus surgery

“…However, the resulting cyclo-alleviating effect of the same muscle procedure can vary greatly, and the outcome is often unpredictable with different etiologies and individual anatomical conformations (26,27). Surgical techniques allowing postoperative (28)(29)(30) or intraoperative adjustments under local anesthesia (31) have been proposed. However, these modified techniques can be burdensome for young children and uncooperative adult patients, rendering them occasionally unsuitable.…”