Understanding the Babysitter Procedure
When the facial nerve is injured and recovery is not going to happen on its own, two problems have to be solved at once. The facial muscles need nerve input soon, before they lose the ability to respond. And the input that produces a natural, emotion-driven smile has to come from the facial nerve on the opposite side, which means a graft that takes many months to cross the face.
The babysitter procedure solves both. A nearby motor nerve is transferred to the paralyzed facial nerve to deliver input early, keeping the muscle viable. At the same operation, a cross-face nerve graft is placed so that signals from the healthy side can eventually reach the same territory. The transferred nerve babysits the muscle until the graft arrives.
The concept was introduced by Terzis in 1984, using a portion of the hypoglossal nerve as the babysitting donor.1 Dr. Panossian uses the masseter nerve instead, for the reasons below.
Why the Masseter Nerve
Several donor nerves can serve this role, including the hypoglossal nerve and the spinal accessory nerve. The masseter nerve is the most practical choice in most cases.
Proximity
The masseter nerve sits close to the facial nerve. The shorter the distance a regenerating nerve has to travel, the sooner it arrives, and in a situation where muscle viability is measured against a clock, that distance matters more than it would in most nerve reconstruction.
Analogous Function
The normal action of the masseter nerve corresponds well to certain facial nerve movements. That correspondence makes the transferred input easier for a patient to learn to use, and it is part of why the masseter has largely replaced other donors in this role.
Caliber and Power
The masseter nerve is large enough, and carries enough motor fibers, to drive multiple branches of the facial nerve rather than just one. A donor that can only supply a single branch limits what the reconstruction can restore.
Donor Site Consequences
Taking the masseter nerve produces minimal donor morbidity, and bite function is not affected. Use of the hypoglossal nerve, by contrast, can affect tongue function. For most patients that difference is decisive.
The Two Stages
Stage one. The masseter nerve is transferred to the paralyzed facial nerve, and a cross-face nerve graft is implanted at the same operation. The graft is left to grow across the face.
Stage two. After 6 to 12 months, once regenerating fibers have traveled the length of the graft, the graft is coapted to the target facial nerve branch or branches on the affected side.
By the time stage two is done, the muscle has been receiving input from the masseter nerve for most of a year and has not been sitting idle. That is the entire logic of the procedure: the long graft is worth waiting for, but the muscle cannot afford to wait for it unattended.
Where the Nerves Are Connected
Coaptation can be performed at the trunk of the facial nerve or at any of its major branches, depending on the injury. Two connection techniques are available, and the choice between them is a real tradeoff.
End-to-End Coaptation
Connecting the donor nerve directly to the cut end of the recipient gives the most complete reinnervation the donor can deliver. The cost is that it eliminates any remaining potential for recovery through a branch that is intact but currently not functioning. Where the facial nerve has been cut or removed outright, there is no such potential to preserve and this is the straightforward choice.
End-to-Side Coaptation
Connecting the donor to the side of an intact recipient nerve preserves the natural pathway and the possibility of recovery through it. The cost is that babysitter function through the masseter nerve may be weaker than it would be with an end-to-end connection. Where some native recovery is still plausible, that tradeoff is often worth making.
Timing and Candidacy
The window for reinnervating facial muscle is roughly 12 to 18 months from the onset of paralysis. Results are sometimes still achievable up to 24 months, but the probability of a good outcome diminishes substantially as that point is approached and passed.
Nerve conduction studies and electromyography can sometimes help sort out a prolonged nerve regeneration problem, but they rarely change the clinical decision. A patient can have testing that looks excellent and steadily improving while showing no real progress in facial animation, which produces a false sense of security. Serial clinical examination is what ultimately guides the timing of treatment.
Outcomes tend to be better with earlier intervention, since the less time a muscle spends denervated, the better it responds. Knowing exactly when to intervene is not always straightforward, and reasonable facial nerve specialists differ on it. Dr. Panossian gives the facial nerve a genuine chance to recover on its own when the injury is early in its course, with the threshold for intervening tightening as the 9 to 12 month mark is approached.
What to Expect
Movement driven by the masseter nerve can appear as early as 3 months after reinnervation. The cross-face nerve graft takes longer, generally 6 to 12 months, because the signal has to travel the full length of the graft before it reaches the target. The two arrive on different schedules, and that separation is deliberate rather than a shortcoming of the reconstruction.
When the Babysitter Procedure Is Not the Right Operation
Two situations rule it out.
Paralysis well past the 18 to 24 month window. In chronic facial paralysis, the potential for muscle reinnervation is considered permanently gone. Nerve transfer procedures, including both the babysitter procedure and cross-face nerve grafting on its own, are no longer options. Muscle transfer and symmetry-producing procedures become the route instead: lengthening temporalis myoplasty or gracilis free muscle transfer.
No available donor nerve. If neither the masseter nor the hypoglossal nerve is available, the procedure cannot be performed.
Why Choose Andre Panossian, MD?
The babysitter procedure is not a single operation so much as a plan that unfolds over a year. It requires judging whether a paralysis is going to recover on its own, choosing a donor nerve and a coaptation technique that fit the specific injury, and timing a second stage against the growth of a graft that cannot be hurried. The surgical technique matters, and so does the sequencing around it.
Dr. Andre Panossian trained in facial reanimation under Dr. Ronald Zuker at the Hospital for Sick Children in Toronto, one of the world's foremost centers for this surgery. His experience spans the full spectrum of facial paralysis, from congenital cases in children to complex adult reconstructions following tumor surgery, trauma, and Bell's palsy.
Patients are followed on roughly a 3-month schedule with standardized photographs and video, so that the decision to intervene rests on documented change over time rather than a single visit. From the initial consultation through the second stage and long-term follow-up, Dr. Panossian guides each patient through every phase.
Frequently Asked Questions
Why use the masseter nerve instead of the hypoglossal nerve?
The masseter nerve sits close to the facial nerve, so reinnervation happens sooner. Its normal action corresponds well to certain facial nerve movements, and it is large enough, carrying enough motor fibers, to drive multiple branches of the facial nerve rather than just one. Taking it produces minimal donor morbidity and bite function is not affected. The hypoglossal nerve and the spinal accessory nerve can also serve as donors, but use of the hypoglossal nerve can affect tongue function.
How soon will I see movement after the babysitter procedure?
Movement driven by the masseter nerve can appear as early as 3 months after reinnervation. The cross-face nerve graft takes longer, generally 6 to 12 months, because the signal has to travel the full length of the graft before it reaches the target. The two arrive on different schedules by design, which is the point of the procedure.
Do I need nerve testing before surgery?
Nerve conduction studies and electromyography can sometimes help sort out a prolonged nerve regeneration problem, but they rarely change the clinical decision. A patient can have testing that looks excellent and steadily improving while showing no real progress in facial animation, which produces a false sense of security. Serial clinical examination is what ultimately guides the timing of treatment.
What if I am past the reinnervation window?
In chronic facial paralysis, the potential for muscle reinnervation is considered permanently gone, and nerve transfer procedures including the babysitter procedure are no longer options. Muscle transfer and symmetry-producing procedures become the route instead, such as lengthening temporalis myoplasty or gracilis free muscle transfer.
1. Terzis JK, Tzafetta K. The babysitter procedure: minihypoglossal to facial nerve transfer and cross-facial nerve grafting. Plast Reconstr Surg. 2009;123(3):865-876. PubMed
Take the First Step
If you are living with facial paralysis that is not recovering on its own, timing matters. Schedule a consultation with Dr. Panossian to discuss whether the babysitter procedure fits your situation.
Request a Consultation