Inhibition of inducible nitric oxide synthase reduces an acute peripheral motor neuropathy produced by dermal burn injury in mice.

The systemic inflammatory response produced by a full-thickness dermal burn injury is associated with a peripheral motor neuropathy. We previously reported that a 20% body surface area (BSA) full-thickness dermal burn in C57BL6 mice produced structural and functional deficits in motor axons at a distance from the burn site. The etiology of the neuropathy, however, is not well characterized. Burn injury leads to an increase in production of a number of proinflammatory mediators, including nitric oxide (NO). We tested the hypothesis that dermal burn-induced motor neuropathy is mediated by increased production of NO. NO synthase (NOS) activity was inhibited following a 20% BSA full-thickness burn by injection of non-specific NOS inhibitor, nitro-L-arginine methyl ester or inducible NOS (iNOS) inhibitors, L-N6-(1-iminoethyl) lysine, and aminoguanidine. NOS inhibitors also prevented the reduction in ventral roots mean axon caliber and the decrease in a motor nerve conduction velocity (MCV) following burn. iNOS knockout mice prevented MCV decrease in the first 3 days post-burn, but iNOS knockout MCV was significantly reduced at 7-14 days post-burn. These results suggest that an increase in NO production generated by systemic inflammatory response pathways after burn injury contributes to the development of structural and functional deficits in peripheral motor axons.

Early excision of a full-thickness burn prevents peripheral nerve conduction deficits in mice.

BACKGROUND: A full-thickness 20 percent body surface area burn in mice produces a significant decrease in tibial motor nerve conduction velocity within 6 hours of the burn and in sensory conduction velocity within 7 days. This suggests that cutaneous burn injury produces a systemic response that affects peripheral motor and sensory nerve function at a distance from the burn site. The authors tested the hypothesis that burn wound excision either 30 minutes or 3 hours after burn would prevent neuropathy. METHODS: A 20 percent body surface area third-degree burn was applied to the backs of anesthetized mice using procedures that followed National Institutes of Health guidelines. Motor nerve conduction velocity and sensory conduction velocity were determined in intact, anesthetized mice by percutaneous nerve stimulation. Burn wounds were excised and closed at 30 minutes or 3 hours after burn. Motor nerve conduction velocity and sensory conduction velocity were measured before burn and 1, 3, 7, 14, and 21 days after a burn or sham procedure. The number of circulating neutrophils and serum concentrations of tumor necrosis factor-alpha, nitrite, and electrolytes were also determined in each group. RESULTS: Motor nerve conduction velocity and sensory conduction velocity in the 30-minute excision (n = 10) and sham group (n = 5) were not significantly different. Motor nerve conduction velocity and sensory conduction velocity in the nonexcised group (n = 10) and 3-hour excision group (n = 10) were significantly decreased. Serum tumor necrosis factor-alpha concentration was elevated 6 hours after burn in nonexcised animals (n = 9) and in 3-hour excision mice (n = 8) but was not significantly different in the sham (n = 8) and the 30-minute excision group (n = 7). CONCLUSION: The authors conclude that burn wound excision at 30 minutes but not at 3 hours prevents the nerve conduction deficits measured in mice with 20 percent body surface area burns. The cellular basis of burn-induced neuropathy is unknown, but nitric oxide and tumor necrosis factor alpha-alpha appear to play a role.

Peripheral axon caliber and conduction velocity are decreased after burn injury in mice.

Peripheral neuropathies are reported to arise as a result of the systemic inflammatory response produced by a full-thickness cutaneous burn injury. This study was designed to characterize the magnitude and time course of functional and morphological changes in peripheral axons that arise after a full-thickness dermal burn injury in an animal model. A 20% body surface area (20% BSA) full-thickness dermal burn was applied to the back of C57BL6 female mice. Longitudinal H- and M-wave recordings were used to determine the conduction velocities (CV) of large myelinated motor and sensory axons in the tibial nerve of sham control and burn-injured mice. Motor CVs were significantly reduced from 6 h to 28 days after the burn, and sensory CVs were significantly reduced from 7 to 14 days after the burn. Morphological evaluation also showed that the mean caliber of large axons in tibial nerves and L5 ventral and dorsal roots in burned mice was significantly decreased. The results demonstrate that both functional and morphological deficits may be produced in peripheral nerve axons at sites well removed from a full-thickness dermal burn injury. The neural deficits may contribute to changes in neuromuscular transmission and the development of limb and respiratory muscle weakness that also accompany burn injury.

Immediate breast reconstruction after mastectomy increases wound complications: however, initiation of adjuvant chemotherapy is not delayed.

BACKGROUND: Immediate breast reconstruction is being increasingly used after mastectomy, although it may increase the incidence of wound complications. The indications for chemotherapy in breast cancer are expanding and wound complications following mastectomy may delay the initiation of adjuvant chemotherapy. HYPOTHESIS: Immediate breast reconstruction after mastectomy for breast cancer does not lead to an increased incidence of wound complications nor delay the initiation of systemic chemotherapy. DESIGN AND SETTING: Retrospective medical record review at a tertiary care center. PATIENTS: One hundred twenty-eight women treated with a mastectomy for breast cancer over an 8-year period (January 1, 1995, through December 31, 2002). MAIN OUTCOME MEASURES: Surgical site complications (infectious and noninfectious) and time to initiation of postoperative chemotherapy. RESULTS: One hundred forty-eight mastectomy procedures in 128 women with breast cancer were evaluated. We analyzed 4 subgroups according to whether or not immediate breast reconstruction was part of the surgical procedure (76 or 72 procedures, respectively) and whether or not postoperative adjuvant chemotherapy was administered (81 or 47 patients, respectively). There was an increased incidence of wound complications in patients who underwent immediate breast reconstruction compared with those who did not (6/72 [8.3%] vs 17/76 [22.3%]; P = .02). However, these complications did not delay initiation of postoperative chemotherapy. CONCLUSIONS: Although we observed an increased incidence of wound complications when immediate breast reconstruction was combined with mastectomy, there was no delay in the initiation of adjuvant therapy. Immediate breast reconstruction should remain an important treatment option after mastectomy even when postoperative chemotherapy is anticipated.

The infected median sternotomy wound: management with the rectus abdominis musculocutaneous flap.

Treatment of patients with infected median sternotomy wounds includes debridement and closure using vascularized tissue, most often the pectoralis major muscle. However, occasionally, surgeons use other flaps to close sternotomy wounds. The purpose of this study is to review 1 center's experience with infected median sternotomy wounds utilizing a less common technique, the rectus abdominis musculocutaneous flap.