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Medical Rounds

Surgery: Something to Smile About

For people with one-sided facial muscle paralysis due to birth defects, stroke, tumors or Bell’s palsy, the ability to show expressions of joy through wide smiles has been elusive.

“People are judged to be angry when they can’t smile,” says Kofi Boahene, associate professor of otolaryngology–head and neck surgery and of dermatology. “Previously, the best we could hope for most of the time with surgery was a smirk like the one Mona Lisa has in DaVinci’s famous painting. But that isn’t a joyful, expressive smile where the lips move up, teeth show and eyes narrow.”

Now Boahene and his colleagues have been able to achieve a “true smile” by modifying a muscle transplant operation. The team published its findings involving 12 adult patients—along with measurements of improvement—online in JAMA Facial Plastic Surgery.

Until now, standard surgical fixes for people with one-sided facial paralysis involved transplanting muscle tissue from a person’s thigh that pulled up on the paralyzed side of the mouth.

Boahene explains that his modified procedure uses gracilis muscles from the thigh placed in two directions—and sometimes three—placed at the corner of the mouth or the upper lip to the cheek and eyelid to recreate an authentic smile that shows teeth and gum on both sides of the face.

During surgery, the surgeons positioned the new muscles so that they pulled the lips up to match the nonparalyzed half-smile when contracted. Then, the surgeons rerouted blood vessels and one or more types of nerves to the transplanted tissue from the nonparalyzed side of the face. The idea was that when the nerves on the nonparalyzed side send a signal for the muscle to contract, forming a smile, they do so for the paralyzed side of the face too, Boahene says. By four months after the procedure, all participants had function in the transplanted muscle.

On average, each person showed an extra three teeth when smiling on the newly functional side of their face. The amount of gum exposed during smiling increased from an average of 31.5 millimeters before surgery to 43.7 millimeters after surgery. Wrinkling around the eyes when smiling was observed in four of the 12 people after surgery. The surgeons also said asymmetry, or differences between the corners of each side of the mouth, was reduced from an average of 9.1 millimeters to 4.5 millimeters after surgery in the patients, making their smiles more even.

“For me, joy is to see a child who has never smiled or someone who has lost their smile to paralysis be able to smile; you just see people transform,” says Boahene. “In the past, we were restoring fake smiles, and now our patients’ new smiles are so contagious that you can’t help but smile back.” 

Watch a Video Kofi Boahene shares the story of a patient whose smile has been restored.