Augmented Hummelsheim procedure for paralytic strabismus

Purpose: To report a modification of the Hummelsheim procedure for use in the management of paralytic strabismus. Methods: Eight patients with paralytic strabismus secondary to third nerve palsy (n=1), sixth nerve palsy (n=3), combined cranial nerve palsy (n=1), or extraocular muscle damage (n=3) were treated using a modification of the Hummelsheim transposition procedure. The procedure involves half-tendon transpositions of the adjacent rectus muscles to the insertion of the paralyzed muscle, coupled with resection of the transposed halves. Further augmentation was achieved by surgical or pharmacologic weakening of the ipsilateral (n=6) or contralateral (n=1) antagonist. One patient underwent the procedure bilaterally. All patients underwent at least 6 weeks of follow-up. Results: The mean preoperative primary position deviation in the seven unilateral cases was 54 prism diopters (Δ) (range: 25-85 Δ). Preoperative forced ductions were positive in four cases. Resections varied from 4-8 mm. Ipsilateral antagonist recession varied from 0-14 mm. The mean change was 52 Δ (range: 25-85 Δ). Five cases were aligned within 15 Δ of orthotropia at 6 weeks. No cases of anterior segment ischemia or induced vertical deviation were noted. Conclusion: The modified Hummelsheim procedure appears capable of correcting large angles of strabismus associated with muscle palsy of various etiologies. It is safe, amenable to adjustable sutures, and relatively tissue- and vessel-sparing. Additional study is required to understand more fully the procedure's component effects and its interaction with ocular rotation.