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Gossett et al. Plast Aesthet Res 2021;8:60 https://dx.doi.org/10.20517/2347-9264.2021.69 Page 5 of 14

In the first stage of a two-stage CFNG, the donor facial nerve branch on the unaffected side of the face is
coapted to a cable graft. In the second stage, after allowing time for axonal growth, the distal end of the
cable graft is then coapted to the target for reinnervation, such as the obturator nerve of a GFMT. The most
commonly used nerve for the cable graft in a CFNG is the sural nerve [Figure 2], as its length, ease of
harvesting, and minimal donor site morbidity make it ideal for this purpose. During the first stage of the
CFNG, a suitable donor midfacial branch of the facial nerve is identified on the non-paralyzed side of the
face with satisfactory stimulation of the lip elevators. It is important to choose a donor facial nerve branch
of enough size to provide adequate axonal load. Extensive arborization of the facial nerve branches prevents
paralysis on the donor side. If concerned, the surgeon can identify redundant innervation of the lip
elevators via an adjacent facial nerve branch prior to dividing the donor nerve. Traditionally, the more distal
(closer to the ankle) end of the sural nerve is preferably used for this proximal coaptation to avoid eventual
loss of regenerated axons to the inherent branching pattern of the nerve graft. The distal end of the CFNG is
tunneled subcutaneously from the donor side of the face to the paralyzed side of the face out through a
small upper sublabial incision. The nerve is then allowed to grow through the cable graft, and the second
stage is performed when the regenerated axons have reached the distal end of the cable graft. The mean
interval between the two stages of the operation typically ranges between 8 to 12 months in adults and 6 to 9
months in children [3,4,13] . This timeline depends on the rate of facial axonal regeneration through the nerve
graft, which can be followed clinically using the progression of the Tinel sign through the length of the graft.
[21]
After the second stage has been performed, reinnervation of the GFMT commences. Faria et al. assessed
58 patients between ages 5 to 63 (mean age 28) with a GFMT innervated by a CFNG and noted first
contractions after 6 to 15 months with a mean of 11 months. With this timeline, it can be upwards of two
years between a patient’s initial stage of CFNG and experiencing the full benefits of the GFMT procedure.

Using a CFNG to innervate the GFMT has the potential advantage of restoring a smile that is spontaneous
and coordinated with the contralateral side and is considered by some as the only option that produces a
spontaneous smile in patients with complete flaccid facial paralysis [13,19,21] . As previously mentioned,
videography for the SSA found that 75% of patients with CFNG-innervated GFMT had spontaneous smiles
[14]
compared to 20% of patients with masseteric nerve-innervated GFMT . Similar differences in spontaneity
[21]
based on innervation have been identified by other groups. Faria et al. compared 58 patients with GFMT
innervated by CFNG and 22 patients innervated with masseteric nerve, and found that 34% of patients
undergoing CFNG were able to smile spontaneously compared to 0% of the masseteric nerve patients.
[13]
Similarly, Gousheh et al. reported that all 505 patients who underwent GFMT innervated by CFNG were
able to achieve a spontaneous smile post-operatively. In contrast, none of the patients in groups innervated
by other nerves (26 hypoglossal, 4 spinal accessory) were able to achieve a spontaneous smile, although the
masseteric nerve was not considered in this cohort.

One disadvantage of the CFNG is that it is less reliable when compared to other donor nerves [3,9,13] .
[18]
Bhama et al. reported on 127 GFMT for smile reanimation in patients ages 6 to 80 years old and identified
decreased oral commissure excursion with CFNG innervation compared to masseteric nerve innervation
(6.5 ± 2.9 mm vs. 8.7 ± 3.5 mm). Hontanilla and Cabello assessed 41 patients (mean age 42) with complete
[19]
facial paralysis undergoing GFMT innervated by a CFNG and found that patients regained 5.1 mm of
commissural elevation during a smile. When they compared outcomes by innervation, masseteric nerve-
innervated GFMT had 40% more oral commissure excursion than flaps innervated by the CFNG.
Ylä-Kotola et al. evaluated 27 patients aged 7 to 65 (mean age 40) undergoing a free tissue transfer
[31]
innervated by CFNG (11 underwent GFMT). The average follow-up in the study was 8.5 years. They found
that 78% of patients thought their quality of life had improved, while 22% believed the reanimation had no
effect.