Ultrasound-assisted lipoplasty in addition to suction-assisted lipoplasty for perforator free flap thinning.

Perforator flaps are routinely used in upper- and lower-extremity reconstruction. Increased usage of these flaps as well as their intraoperative thinning has been described; however, there are limited reports of thinning in the postoperative period. From 2005 to 2010, thinning procedures were performed on 11 patients with 11 flaps. There were six males and five females in this series. Three flaps were deep inferior epigastric artery flaps, six flaps were anterolateral thigh flaps, and two were medial thigh flaps. After the initial microvascular reconstructive procedure, the patient underwent a second procedure where ultrasound-assisted lipoplasty, suction-assisted lipoplasty, flap advancement, and excision were performed. With aggressive, staged thinning procedures, there were no cases of partial or complete flap necrosis. Given the increasing number of perforator flaps being performed for upper- and lower-extremity reconstruction, a larger number of cutaneous flaps will need postoperative thinning. Ultrasound-assisted lipoplasty has been found to be a useful modality in revision of these flaps.

Abdominoplasty with thorough concurrent circumferential abdominal tumescent liposuction.

Abdominoplasty, the removal of excess skin combined with muscle plication of a patient's abdominal region, can yield pleasing postoperative results alone, but adding significant concurrent circumferential abdominal liposuction to the procedure can dramatically improve the overall shape and contour of the final result. The perceived risk of performing this combined procedure involves potential skin necrosis resulting from devascularization of the abdominal flap, but when performed with proper technique-including thorough tumescent infiltration and vascular preservation during the liposuction portion-the procedure delivers superior results with a minimal risk of ischemia and necrosis.

Interhemispheric neuroplasticity following limb deafferentation detected by resting-state functional connectivity magnetic resonance imaging (fcMRI) and functional magnetic resonance imaging (fMRI).

Functional connectivity magnetic resonance imaging (fcMRI) studies in rat brain show brain reorganization following peripheral nerve injury. Subacute neuroplasticity was observed 2 weeks following transection of the four major nerves of the brachial plexus. Direct stimulation of the intact radial nerve reveals a functional magnetic resonance imaging (fMRI) activation pattern in the forelimb regions of the sensory and motor cortices that is significantly different from that observed in normal rats. Results of this fMRI experiment were used to determine seed voxel regions for fcMRI analysis. Intrahemispheric connectivities in the sensorimotor forelimb representations in both hemispheres are largely unaffected by deafferentation, whereas substantial disruption of interhemispheric sensorimotor cortical connectivity occurs. In addition, significant intra- and interhemispheric changes in connectivities of thalamic nuclei were found. These are the central findings of the study. They could not have been obtained from fMRI studies alone-both fMRI and fcMRI are needed. The combination provides a general marker for brain plasticity. The rat visual system was studied in the same animals as a control. No neuroplastic changes in connectivities were found in the primary visual cortex upon forelimb deafferentation. Differences were noted in regions responsible for processing multisensory visual-motor information. This incidental discovery is considered to be significant. It may provide insight into phantom limb epiphenomena.

A protocol for use of medetomidine anesthesia in rats for extended studies using task-induced BOLD contrast and resting-state functional connectivity.

The alpha-2-adrenoreceptor agonist, medetomidine, which exhibits dose-dependent sedative effects and is gaining acceptance in small-animal functional magnetic resonance imaging (fMRI), has been studied. Rats were examined on the bench using the classic tail-pinch method with three infusion sequences: 100 microg/kg/h, 300 microg/kg/h, or 100 microg/kg/h followed by 300 microg/kg/h. Stepping the infusion rate from 100 to 300 microg/kg/h after 2.5 h resulted in a prolonged period of approximately level sedation that cannot be achieved by a constant infusion of either 100 or 300 microg/kg/h. By stepping the infusion dosage, experiments as long as 6 h are possible. Functional MRI experiments were carried out on rats using a frequency dependent electrical stimulation protocol-namely, forepaw stimulation at 3, 5, 7, and 10 Hz. Each rat was studied for a four-hour period, divided into two equal portions. During the first portion, rats were started at a 100 microg/kg/h constant infusion. During the second portion, four secondary levels of infusion were used: 100, 150, 200, and 300 microg/kg/h. The fMRI response to stimulation frequency was used as an indirect measure of modulation of neuronal activity through pharmacological manipulation. The frequency response to stimulus was attenuated at the lower secondary infusion dosages 100 or 150 microg/kg/h but not at the higher secondary infusion dosages 200 or 300 microg/kg/h. Parallel experiments with the animal at rest were carried out using both electroencephalogram (EEG) and functional connectivity MRI (fcMRI) methods with consistent results. In the secondary infusion period using 300 microg/kg/h, resting-state functional connectivity is enhanced.

Hyperbaric oxygen inhibits ischemia-reperfusion-induced neutrophil CD18 polarization by a nitric oxide mechanism.

BACKGROUND: Hyperbaric oxygen decreases ischemia-reperfusion-induced neutrophil/intercellular adhesion molecule-1 adhesion by blocking CD18 polarization. The purpose of this study was to evaluate whether this hyperbaric oxygen effect is nitric oxide dependent and to determine whether nitric oxide synthase is required. METHODS: A gracilis muscle flap was raised in nine groups of male Wistar rats. Global ischemic injury was induced by clamping the gracilis muscle pedicle artery and vein for 4 hours. The hyperbaric oxygen treatment consisted of 100% oxygen at 2.5 atm absolute during the last 90 minutes of ischemia. Groups were repeated with and without various nitric oxide synthase inhibitors and carboxy-2-phenyl-4,4,5,5,-tetramethylimidazoline-1-oxyl-3-oxide (C-PTIO), a nitric oxide scavenger. Normal neutrophils were exposed to activated plasma on intercellular adhesion molecule-1-coated coverslips (percentage adherent) and labeled with fluorescein isothiocyanate/antirat-CD11b for confocal microscopy (percentage polarized). The percentage of adherent and polarized cells was reported as mean + or - SEM. Statistical analysis was by analysis of variance. A value of p < or = 0.05 was considered significant. RESULTS: C-PTIO-treated ischemia-reperfusion/hyperbaric oxygen plasma showed a significant increase in the percentage polarization of CD18 compared with ischemia-reperfusion/hyperbaric oxygen-untreated plasma from 4.1 + or - 2.5 percent to 33.7 + or - 7.7 percent (p < or = 0.05). The nitric oxide scavenger C-PTIO also increased the percentage of adherent cells from 1.6 + or - 0.4 percent to 20.3 + or - 5.9 percent (p < or = 0.05). Administration of N-nitro-L-arginine methyl ester and other nitric oxide synthase inhibitors before hyperbaric oxygen treatment restored neutrophil adhesion and CD18 polarization to ischemia-reperfusion control values, significantly greater than ischemia-reperfusion/hyperbaric oxygen alone. CONCLUSION: These results suggest that the hyperbaric oxygen reduction of ischemia-reperfusion-induced neutrophil polarization of CD18 and adherence to intercellular adhesion molecule-1 is mediated through a nitric oxide mechanism that requires nitric oxide synthase.

Evaluation of artificial dermis neovascularization in an avascular wound.

Soft tissue coverage for avascular wounds is necessary in reconstructive surgery. Several authors have demonstrated successful treatment of problem wounds using artificial dermis. This study evaluates in an animal model the potential for neovascularization of artificial dermis in devascularized and avascular wound beds. Forty rats were assigned to four groups: (1) control, full-thickness skin graft was replaced on the vascular wound bed; (2) Integra, Integra placed over the full-thickness wound; (3) fascia, the spinotrapezius fascia exposed and Integra placed over the wound; and (4) fascia/Parafilm, a Parafilm layer placed under the raised fascia with Integra over the fascia. Laser Doppler readings were taken at baseline over the intact skin and then over the created wound beds. Biopsies of the full-thickness skin graft and the neodermis were obtained on postoperative day 14 and histologically evaluated for neovascularization. The laser Doppler readings confirmed the nature of the surgically created, poorly vascularized and avascular wound beds. Subsequent biopsies of the artificial dermis in these wound beds, however, demonstrated active neovascularization. This study demonstrates that Integra artificial dermis can serve as an effective dermal substitute in avascular wounds. Lateral ingrowth of capillaries into the dermal substitute may explain the successful integration of this artificial dermis.

Resting-state functional connectivity of the rat brain.

Regional-specific average time courses of spontaneous fluctuations in blood oxygen level dependent (BOLD) MRI contrast at 9.4T in lightly anesthetized resting rat brain are formed, and correlation coefficients between time course pairs are interpreted as measures of connectivity. A hierarchy of regional pairwise correlation coefficients (RPCCs) is observed, with the highest values found in the thalamus and cortex, both intra- and interhemisphere, and lower values between the cortex and thalamus. Independent sensory networks are distinguished by two methods: data driven, where task activation defines regions of interest (ROI), and hypothesis driven, where regions are defined by the rat histological atlas. Success in these studies is attributed in part to the use of medetomidine hydrochloride (Domitor) for anesthesia. Consistent results in two different rat-brain systems, the sensorimotor and visual, strongly support the hypothesis that resting-state BOLD fluctuations are conserved across mammalian species and can be used to map brain systems.

Cortical brain mapping of peripheral nerves using functional magnetic resonance imaging in a rodent model.

The regions of the body have cortical and subcortical representation in proportion to their degree of innervation. The rat forepaw has been studied extensively in recent years using functional magnetic resonance imaging (fMRI), typically by stimulation using electrodes directly inserted into the skin of the forepaw. Here we stimulate the nerve directly using surgically implanted electrodes. A major distinction is that stimulation of the skin of the forepaw is mostly sensory, whereas direct nerve stimulation reveals not only the sensory system but also deep brain structures associated with motor activity. In this article, we seek to define both the motor and sensory cortical and subcortical representations associated with the four major nerves of the rodent upper extremity. We electrically stimulated each nerve (median, ulnar, radial, and musculocutaneous) during fMRI acquisition using a 9.4-T Bruker scanner (Bruker BioSpin, Billerica, MA). A current level of 0.5 to 1.0 mA and a frequency of 5 Hz were used while keeping the duration constant. A distinct pattern of cortical activation was found for each nerve that can be correlated with known sensorimotor afferent and efferent pathways to the rat forepaw. This direct nerve stimulation rat model can provide insight into peripheral nerve injury.