Long-term adaptation of human microneurovascular muscle flaps to the paralyzed face: An immunohistochemical study

Abstract

The purpose of this study was to characterize microneurovascular (MNV) muscle transplants immunohistochemically up to 10 years after transfer. Histological data was related to long-term functional outcome. The study comprised 17 patients with a mean age of 41 years suffering from complete unilateral long-lasting facial paralysis. A two-stage procedure was performed between 1986 and 2001. The gracilis, latissimus dorsi, and serratus muscles were used in four, eight, and five patients, respectively. Eighteen biopsy samples were taken from MNV muscle grafts during secondary refinement procedures. In one patient, the tissue samples were collected at two different time points. Immunohistochemistry testing revealed muscle fiber type distribution (anti-myosin fast), proliferating satellite cells (Ki-67), and reinnervation (S-100). Muscle atrophy was assessed histomorphometrically. In a recent study, patient characteristics and the function of the flap were evaluated. Histological data were compared with clinical data and long-term functional outcomes of the patients. In biopsy samples taken 1-10 (mean 31 months) years after MNV muscle transfer, the mean muscle fiber diameter was 38 (range 14-70) microm, indicating a 40% decrease compared with control values. Muscle atrophy was not type-specific and the mean percentage of type II fibers was not altered. Individual variation was, however, considerable. Proliferative activity of satellite cells was seen in 60% of the samples but it tended to decline with an increase in follow-up time. All samples showed intramuscular reinnervation. In statistical analysis severe atrophy correlated with prolonged intraoperative ischemia (P=0.04). The good long-term functional outcome correlated with dominance of fast fibers in muscle grafts (P=0.03). Atrophy tended to be more pronounced in the serratus than in the other muscles (ns). In summary, despite dense muscle reinnervation, morphology of the muscle is not fully restored after muscle transfer. Ischemia time affects muscle morphology. Adaptation of the graft to fast-twitch muscle activity favors better mimic function. The proliferative activity of satellite cells declines with prolonged follow-up time.

P75 Nerve Growth Factor Receptor Is Expressed in Regenerating Human Nerve Grafts

“…In our earlier studies, we evaluated characteristics of patients and muscle flaps and also the mimic function of the muscle flap [25,26]. Here, we have compared our recent results with earlier data.…”

“…Recent studies evaluated patient characteristics and the function of the muscle flap as well as the morphology of the transferred muscle [25,26]. The histological findings of the current study were compared with data gathered in the earlier studies.…”

“…In our earlier studies, we evaluated patient characteristics, the function of the muscle flap, and the morphology of the transferred muscle [25,26].…”

Sternohyoid Flap for Facial Reanimation

“…10 In many regards, the choice of the gracilis for facial reanimation is an example of using the available flap options instead of developing a specific flap for the indication from the ground up. The advances of microvascular reconstruction have revealed numerous shifts in clinical practice patterns, as new flaps have been developed to replace the available ones because they can address the limitations found in the available ones.…”

Vascular Endothelial Growth Factor and Its Receptors Are Expressed in Human Nerve Grafts

“…16 Furthermore, the histology if the innervated, target organ, the microneurovascular muscle transplant to the face, has been studied in detail. 17 In the present study, we used our extensive nerve graft sample material to characterize the vascularization of avascularized human nerve grafts and to investigate the expression of VEGF and its two receptors in human nerve tissue. A comparison of the present descriptive data and our earlier results was performed.…”