Neurovascular anatomy of pronator quadratus for reanimation of blepharoptosis.

[PURPOSE] Pronator quadratus (PQ) is a quadrilateral muscle on a volar distal side of the forearm. The purpose of this study was to establish a novel surgical technique for reanimation of the upper eyelid for severe ptosis using PQ functional free muscle flap.

[METHODS] The current study is a cadaveric study, designed to assess a PQ free flap transfer that lies between the frontalis muscle and the upper eyelid. Fourteen PQ from fourteen embalmed cadavers were dissected, and their neurovascular pedicles were isolated. Then they were transferred to the area on the contralateral side between the frontalis muscle and upper eyelid tarsal cartilage. Measurements of the PQ flap, antebrachial region, orbitofrontal region, recipient vessels, and motor nerve were performed using a caliper. The extendibility of neurovascular pedicles was evaluated by measurements of lengths. In addition, the diameter of PQ flap vascular pedicle vessels was compared with recipient vessels.

[RESULTS] The mean width of the proximal border of PQ was 41.92 ± 2.05 mm and the distal border of the PQ was 42.84 ± 4.04 mm. The mean PQ artery (type II, Mathes-Nahai flap classification) length was found to be 117.72 ± 7.77 mm. The mean diameter of the anterior interosseous nerve was 1.89 ± 0.08 mm. The mean diameter of the uppermost branch of the frontal branch of the facial nerve was 1.18 ± 0.25 mm. The length and diameter of neurovascular pedicles of muscle flaps were adequate for microvascular anastomoses and neurorrhaphy.

[CONCLUSIONS] The results of this anatomical study demonstrate that the PQ free flap transfer has anatomical features that are suitable and compatible with the surgical treatment of blepharoptosis.