1Paces Plastic Surgery, Atlanta, GA, USA, 2DiFrancesco Plastic Surgery, Decatur, GA, USA.
To evaluate the innervation and function of the pretarsal orbicularis oculi muscle clinically with video imaging and electrically with electromyography (EMG) before and after lower eyelid blepharoplasty. To evaluate the anatomy of the buccal branch of the facial nerve and the nerve supply to the orbicularis oculi.
Ten patients (20 eyes) were studied before and 4 to 12 weeks after lower eyelid blepharoplasty. Video imaging documented clinical changes in involuntary (blink) and voluntary (squeeze and squint) eyelid function as well as resting lid position and tone. EMG performed using concentric needle electrodes (25mm length, .03mm diameter, Oxford Instruments) placed in the lateral and medial pretarsal orbicularis oculi. A total of 40 sites in 10 patients (4 sites per patient) were studied. Acute denervation was identified by the presences of fasciculation, fibrillation potentials, insertional activity and sharp waves and then graded based on standard EMG techniques. All patients underwent lower eyelid blepharoplasty with a subciliary incision, skin muscle flap and canthal anchoring with canthopexy or cantholysis and canthoplasty. Four fresh cadaveric facial nerve dissections were performed tracing the buccal branch into the orbicularis oculi muscle.
Video imaging of the lower eyelid before and after blepharoplasty showed no evidence (100% Normal) of eyelid malposition, or abnormal voluntary or involuntary orbicularis oculi muscle function. There was no evidence of acute denervation in 35 of the 36 sites (97%). Two patients had abnormal fasciculation in the left lateral position or 2 of 36 sites (3%). At 33 weeks, one patient was retested and a normal DMB (no acute or chronic changes) was obtained. Distal nerves from the buccal branch of the facial nerve were identified with consistent branches reaching the medial orbicularis oculi muscle with terminal branches to the procerus muscle.
This study demonstrates that transcutaneous lower blepharoplasty with preservation of the pretarsal orbicularis muscle does not cause denervation of the pretarsal muscle by EMG analysis. EMG tests did not reveal significant acute or chronic denervation after surgery. Furthermore, there was evidence of normal lower lid function by analysis of video imaging. Lower lid support by canthal tightening along with preservation of pretarsal orbicularis function resulted in minimal risk of lower lid malposition following blepharoplasty. The anatomical aspect of this study confirms a significant contribution of the buccal branch of the facial nerve to orbicularis innervation in addition to the previously documented nerve supply from the zygomatic branch of the facial nerve. The dual nerves supply to the orbicularis may be the underlying factor which serves to maintain diffuse innervation to the orbicularis oculi muscle.
Preliminary data were presented at the 2003 ASAPS meeting.