Local muscle transfer for long-standing facial palsy

Abstract

Although there is no accurate time line definition for chronic or long-standing facial paralysis, most authors would agree that in cases of complete facial palsy with duration of 12-18 months, recruitment of neuromuscular units to produce sufficient excursion is unlikely. In cases of partial facial palsy of such duration certain authors suggest the possibility of upgrading function via CFNG while others do not consider this a viable option. For the purpose of this discussion we consider 18 months of partial or complete palsy as long-standing palsy and the likelihood of spontaneous facial nerve recovery is very low during this stage. Nerve repairs or transfers are ineffective based on critical depletion of motor end plates rendering the muscles permanently nonfunctional. Dynamic treatment options thus center on recreating a functional neuromuscular unit either by free tissue transfer or via local muscle transfer. For details on free functional muscle flaps refer to the previous chapter. This approach has many advantages. In two stage procedures spontaneity may be achieved since neurotization occurs from the contralateral facial nerve. This approach may suffer from shorter excursions and may not be the best option in older populations. In one stage procedures excursion may be improved often at the expense of spontaneity. Free functional muscle transfers are useful in previously operated or radiated patients where gliding surfaces may not exist and also enable good control over the smile vector. Among the limitations are a more prolonged surgery, need for microsurgery skills, and some risk for total flap loss. Local muscle flaps have been described for decades. These include masseteric muscle advancement, and temporalis muscle slings. The lengthening temporalis myoplasty is a relatively recent modification of the temporalis sling myoplasty. Since first described by Labbe in 1997, it has shown promising results for dynamic reconstruction. The ability to transpose the temporalis insertion in a deep plane avoids cheek deformation and bulkiness as seen with free muscle transfers. Although some authors contend that spontaneity does not occur, results have demonstrated that in many cases patients have undergone cortical adaptation and show spontaneity. Potential advantages include shorter surgeries, quick recovery to motion, and no need for microsurgery expertise. Potential drawbacks may include weaker excursion, possible limitations in scarred or previously radiated tissue, and slight temporal hollowing.