P75 nerve growth factor receptor is expressed in regenerating human nerve grafts.

BACKGROUND: The purpose of this study was to elucidate the expression of p75 nerve growth factor receptor (p75NGFR) in human cross-facial nerve grafts and to compare the immunohistological findings with patient data and the functional outcome in facial reanimation. MATERIALS AND METHODS: The study comprised 37 sural nerve graft specimens. All of the patients had long-lasting complete facial paralysis and were operated on by the standard two-stage procedure involving cross-facial nerve grafts and microneurovascular muscle transfer. Nerve biopsies were taken 4 to 20 months (mean, 8 months) after the cross-facial nerve grafting. Immunohistochemistry for p75NGFR as well as for Schwann cells (S-100; Dako, Glostrup, Denmark) and for Neurofilament-200 (NF-200; Boehringer, Mannheim, Germany) was performed. RESULTS: In graft biopsies, the mean number of NF-200-positive axons amounted to 38% (range, 6-81%) of that in control samples. Further, regenerated axons were thinner than in control samples. Morphologically, the grafted nerves were characterized by fibrosis and invasion of inflammatory cells. A longer time between cross-facial nerve grafting and biopsy sampling correlated with a higher number of viable axons (NF-200) (P = 0.002). In all cases, expression of p75NGF receptor was clearly higher at the distal end of the grafted nerve. Expression of p75NGFR was lower in older than in younger patients (P = 0.003). A high expression of p75NGFR was often seen with better function of the transplanted muscle. CONCLUSION: Increased expression of p75NGFR in human nerve grafts was noted, especially in younger patients. We suggest that p75NGFR expression might be a contributing factor in a successful axonal regeneration and eventual recovery of muscle function.

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

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.

Facial reanimation by transplantation of a microneurovascular muscle: long-term follow-up.

The two-stage operation for reanimation of long-standing facial paralysis by cross-facial nerve grafting and later free microneurovascular muscle transfer has been the treatment of choice for nearly 25 years. However, the functional outcome may be unpredictable. We therefore need to know more about the factors that influence the final result. We have recorded the long-term results of microneurovascular surgery in facial paralysis, and evaluated which factors influenced the functional outcome. Twenty-seven of 40 patients aged 7 to 65 years (mean 40) operated on at Helsinki University Hospital between 1986 and 2000 were available for interview and video recording. The gracilis, latissimus dorsi, and serratus anterior muscles were used for microneurovascular transfer in 11, 10, and 6 cases, respectively. The outcome of microneurovascular muscle transfer was graded on House's scale 1 to 6. The mean follow-up period was 8.5 years (range 2 to 15). Sixteen patients (59%) displayed only mild or moderate dysfunction (grades 2 to 3) after reconstruction. In 8 patients (30%) dysfunction was graded as moderately severe, and in 3 (11%) as severe. There was a correlation between final functional outcome and the follow-up time after microneurovascular facial reanimation. The longer the follow-up time after muscle transplantation the poorer the functional result (p = 0.003). Twenty-one patients (78%) considered that their quality of life was better or much better after facial reanimation. Patients' satisfaction correlated with a good functional result.

Long-term morphometric and immunohistochemical findings in human free microvascular muscle flaps.

Reinnervation, muscle regeneration, density of microvessels, and muscle-type specific atrophy were studied 3-4 years after surgery in surgically nonreinnervated free microvascular muscle flaps to 13 patients transplanted to the upper or lower extremities. Routine histology and immunohistochemistry for PGP 9.5 and S-100 (neuronal markers), Ki-67 (cell proliferation), myosin (muscle fiber types), and CD-31 (endothelium) were carried out, and results were analyzed morphometrically. Three to 4 years after surgery, severe atrophy of predominantly slow-type fibers was seen in 9 cases. In 4 cases, muscle-fiber diameter and fiber-type distribution were close to normal. Long intraoperative muscle ischemia and postoperative immobilization were associated with poor muscle bulk in flaps. The density of microvessels in flaps did not differ from control muscles. PGP 9.5 and S-100 immunopositive nerve fibers were detected in 7 patients. Reinnervation was associated with good muscle bulk. In 4 patients, activation of satellite cells was evident. The results suggest that in some cases, spontaneous reinnervation may occur in free muscle flaps, and that several years after microvascular free flap transfer, the muscle still attempts to regenerate.

Salvage of major amputation stumps of the lower extremity with latissimus dorsi free flaps.

In some severe lower limb injuries, the level of bone trauma enables preservation of the knee joint or adequate length of the femoral stump only if the soft tissues can be reconstructed over the exposed bone. The options for soft-tissue reconstruction of an amputation stump are to use a flap from the amputated distal part, a local flap possibly after tissue expansion or a free flap. To preserve an adequate length of stump we reconstructed 10 stumps with latissimus dorsi free flaps: above the knee in one patient and below the knee in nine. The reconstructions were done during an acute post-traumatic phase in five and for late problems with the stump in four patients. In one patient the reconstruction was done nine weeks after a below-knee amputation for ischaemic necrosis after septicaemia. All flaps survived, but the venous anastomosis had to be revised in three patients in the early postoperative period. All patients regained adequate ambulation for their daily activities. The flap was secondarily debulked in three patients. Every effort should be made to preserve an adequate stump length, particularly in young patients with crushing injuries of the extremities and when there is severe or recurrent late stump ulceration. A latissimus dorsi musculocutaneous soft-tissue reconstruction is a reliable and durable option for stump defects.