Disabling muscle of Riolan: A novel concept of orbicularis oculi myectomy for refractory benign essential blepharospasm

Purpose: To examine the effectiveness of orbicularis oculi myectomy with disabling the muscle of Riolan in patients with benign essential blepharospasm refractory to botulinum toxin-A (BTX-A) injection. Methods: This retrospective, observational study included 25 patients. After removal of the redundant skin and underlying orbicularis oculi muscle (OOM) with or without extended OOM removal to the area of the superior orbital rim, the tarsal plate and the gray line were vertically severed at 2 points to disable the muscle of Riolan. The surgical effectiveness was evaluated using the visual analogue scale (VAS), functional disability score (FDS), and the presence or absence of necessity or enhanced effectiveness of BTX-A injection after surgery. Results: The symptoms improved in 23 patients (92.0%). The VAS and total FDS were significantly improved from 8.4 ± 1.7 to 4.0 ± 2.4 (reduction rate, 50.7 ± 35.6%) and from 74.6 ± 22.2 to 34.7 ± 25.3 (reduction rate, 53.4 ± 27.4%) after surgery, respectively (both, p < 0.001). Among the 23 patients whose symptoms improved after surgery, BTX-A injection was not required in 11 of them (47.8%). Among the remaining 12 patients (52.2%), the effectiveness of BTX-A was post-operatively enhanced in eight patients (34.8%). There were no serious complications, and none of the patients experienced madarosis. Conclusion: Disabling the muscle of Riolan is a valuable option of OOM myectomy in patients with refractory benign essential blepharospasm, without the development of serious complications, including madarosis.