Dual-innervated multivector muscle transfer using two superficial subslips of the serratus anterior muscle for long-standing facial paralysis

Recent reports have described several cases of double muscle transfers to restore natural, symmetrical smiles in patients with long-standing facial paralysis. However, these complex procedures sometimes result in cheek bulkiness owing to the double muscle transfer. We present the case of a 67-year-old woman with long-standing facial paralysis, who underwent two-stage facial reanimation using two superficial subslips of the serratus anterior muscle innervated by the masseteric and contralateral facial nerves via a sural nerve graft. Each muscle subslip was transferred to the upper lip and oral commissures, which were oriented in different directions. Furthermore, a horizontal fascia lata graft was added at the lower lip to prevent deformities such as lower lip elongation and deviation. Voluntary contraction was noted at roughly 4 months, and a spontaneous smile without biting was noted 8 months postoperatively. At 18 months after surgery, the patient demonstrated a spontaneous symmetrical smile with adequate excursion of the lower lip, upper lip, and oral commissure, without cheek bulkiness. Dual-innervated muscle transfer using two multivector superficial subslips of the serratus anterior muscle may be a good option for long-standing facial paralysis, as it can achieve a symmetrical smile that can be performed voluntarily and spontaneously.

Intramuscular Neural Distribution of the Serratus Anterior Muscle: Guidelines to the Injective Method for Treating Myofascial Pain Syndrome

The serratus anterior muscle is commonly involved in myofascial pain syndrome and is treated with many different injective methods. Currently, there is no definite injection point for the muscle. This study provides an ideal injection point for the serratus anterior muscle considering the intramuscular neural distribution using the whole mount staining method. A modified Sihler method was applied to the serratus anterior muscles (15 specimens). The intramuscular arborization areas were identified in terms of the anterior (100%), middle (50%), posterior axillary line (0%), and from the first to the ninth ribs. The intramuscular neural distribution for the serratus anterior muscle had the largest arborization patterns in the 5th to 9th rib portion between 50% and 70%, and the 1st to 4th rib portion had between 20% and 40%. Clinicians can administer safe and effective treatments with botulinum neurotoxin injections and other types of injections, following the methods in our study. We propose optimal injection sites in relation to the external anatomical line for the frequently injected facial muscles to facilitate the efficiency of botulinum neurotoxin injections. Lastly, these guidelines would assist practice more accurately without the harmful side effects of trigger point injections and botulinum neurotoxin injections.