In-Vivo Histological Analysis of a Fractional CO2 Laser System Intended for Treatment of Soft Tissue.

BACKGROUND: Fractional ablative lasers have been shown to be safe and effective for improving wrinkles, scars, skin texture, and dyspigmentation. However, the exact effects of this technology in vivo on epidermal and dermal skin constituents have not been delineated. This study evaluated the in vivo histological effects over time of treatment with a fractional ablative CO2 system, using different treatment parameters. MATERIALS AND METHODS: Healthy adult volunteers were enrolled in this multicenter clinical study. Study participants, previously scheduled for abdominoplasty, received fractional CO2 laser treatment on the abdomen at a predetermined time prior to surgery. Biopsies were taken at baseline and after CO2 treatment. Morphological and morphometric analyses were performed in the ablated and coagulated tissue areas. RESULTS: Nine healthy adult volunteers were treated. Histologic evaluation showed 800-900 micron diameter zones of ablation and coagulation confined to the upper most layer of the skin in the mode with the greatest fractional skin coverage using Light Mode 30 - 50% (spot diameter of 150 microns, 30-60 millijoules fluence), while ablation to levels of up to 900 microns in depth using the Deep Mode (spot diameter 150 microns, 50-80 millijoules). Healing times of treated tissue varied from 1-day post-treatment with the Light Mode, and up to 10 days post-treatment with the Deep Mode. No remnants of ablation or coagulation were seen after 30 days post CO2 treatment with either mode. There were no adverse events associated with treatments. CONCLUSION: Treatment of the skin using the fractional CO2 device leads to skin resurfacing via ablation and coagulation of the treated area at a depth proportional to the delivered energy. The higher the energy used, the greater the degree of ablation and coagulation in tissue, which can lead to a greater tissue response in terms of fibroblast activity, collagen remodeling, and new collagen formation.

J Drugs Dermatol. 2017;16(11):1085-1090.

Bilateral pupil-sparing third nerve palsies as the presenting sign of multiple sclerosis.

We report the case of a young man who presented with bilateral third nerve palsies without pupillary involvement. Brain MRI demonstrated lesions in the region of the oculomotor nerves, and further evaluation led to the diagnosis of multiple sclerosis. Our case documents a rare initial clinical presentation of this demyelinating disease.

Comparison of Neurovascular Characteristics of Facial Skin in Patients After Primary and Revision Rhytidectomies.

IMPORTANCE: Wound healing influences both the cosmetic and functional outcomes of facial surgery. Study of cutaneous innervation may afford insight into patients' preoperative wound healing potential and aid in their selection of appropriate surgical procedures. OBJECTIVE: To present the quantitative and qualitative differences of epidermal nerve fibers (ENFs), neurotransmitters, vasculature, and mast cells in facial skin among patients after primary and revision rhytidectomies. DESIGN, SETTING, AND PARTICIPANTS: This pilot study collected cutaneous specimens from 8 female patients aged 42 to 66 years who underwent primary rhytidectomy (n = 5) and revision rhytidectomy (n = 3) at Centennial Lakes Surgery Center, Edina, Minnesota, from July 2010 to March 2014. Tissue was processed for confocal/epifluorescence microscopy and indirect immunofluorescent localization of several neural and tissue antigens as well as basement membrane and mast cell markers. INTERVENTION: Primary rhytidectomy vs revision rhytidectomy with selection of a small area of redundant, otherwise disposed of tissue anterior to the tragus for ENF study. MAIN OUTCOMES AND MEASURES: Demographic characteristics included smoking status; 10-point rating scales for facial sensation, pain, and paresthesias; and confocal/epifluorescence microscopy to quantify ENFs, neurotransmitters, vasculature, and mast cells. RESULTS: Patients in the primary rhytidectomy group had a mean (SD) of 54.4 (31.6) ENFs/mm (range, 14.2-99.2 ENFs/mm), and those in the revision rhytidectomy group had a mean (SD) of 18.6 (5.8) ENFs/mm (range, 13.8-25.0 ENFs/mm). A patient in the primary rhytidectomy group was a 25-pack-year smoker and had 14.2 ENFs/mm, the lowest in both groups. In addition to these structural neural changes, functional neural changes in revision rhytidectomy samples included qualitative changes in normal neural antigen prevalence (substance P, calcitonin gene-related peptide, and vasoactive intestinal peptide). Capillary loops appeared less robust and were less common in dermal papilla among samples from both the primary and revision groups, and mast cells were more degranulated. No differences were found in subjective, self-reported postoperative facial sensation. CONCLUSIONS AND RELEVANCE: Previous skin elevation was associated with decreased epidermal nerve fiber density and qualitative changes in dermal nerves, capillaries, and mast cells in a clinical sample of patients undergoing rhytidectomy. Future research is needed to determine whether histological findings predict wound healing and to better understand the effects of surgery on regenerative capacity of epidermal nerve fibers. LEVEL OF EVIDENCE: NA.

Double dissociation of exteroceptive and interoceptive feedback systems in the orbital and ventromedial prefrontal cortex of humans.

The primate ventral prefrontal cortex contains two densely interconnected subregions: a lateral/orbital cortex processing primarily sensory/exteroceptive information, and a ventromedial cortex processing primarily visceroappetitive/interoceptive information. These regions have major afferents from and efferents to other associative cortices. The organization of these structures leads to an hypothesized role in feedback processing. We use neuroimaging to test this model, defined so far mostly through anatomical studies. Healthy volunteers were trained operantly on a transitive inference task (A>B, B>C ==> A>C) requiring flexible manipulation of feedback to solve. Two groups of subjects learned an arbitrary face hierarchy, one adjacent face pair at a time; each group received either visual/exteroceptive ("XXXX") or visceroappetitive/interoceptive (fruit juice) feedback for correct responses to adjacent face pairs. After task acquisition, the subjects were tested on novel stimulus pairs (i.e., nonadjacent, TEST) derived from the acquired hierarchy. The TEST condition required transitive inference. No feedback was provided during TEST. Brain activity during TEST in the group trained with visual/exteroceptive feedback increased in the orbital prefrontal cortex and decreased in the ventromedial prefrontal cortex. In contrast, brain activity during TEST in the group trained with visceroappetitive/interoceptive feedback decreased in the orbital prefrontal cortex and increased in the ventromedial prefrontal cortex. These results provide functional evidence, consistent with previous anatomical studies, for two major feedback systems in human ventral prefrontal cortex: a lateral system specialized for exteroceptive information and a medial system specialized for interoceptive information. Although highly interconnected, there is a double dissociation of function between these networks in healthy humans.

CO(2) hypersensitivity in recently abstinent alcohol dependent individuals:; A possible mechanism underlying the high risk for anxiety disorder among alcoholics.

Alcohol, administered acutely, is known to cause CO(2) hyposensitivity. CO(2) hypersensitivity associated with anxiogenic hyperventilation (HV) could reasonably be expected to emerge as an opponent process upon withdrawal from chronic alcohol use. To test this hypothesis, we applied two well-known methods to quantify CO(2) sensitivity in recently detoxified alcohol-dependent individuals and never alcohol-disordered individuals who are social drinkers. We found that the alcoholic group exhibited significantly greater CO(2) sensitivity than did controls in response to both challenges. Indirect evidence of chronic HV was also obtained. These findings implicate the effect of chronic alcohol use on CNS-based CO(2) sensitivity in heightening the vulnerability to disturbing anxiety symptoms and syndromes exhibited by alcoholic individuals. Future work must verify that pathological drinking actually causes the dysregulated respiratory responding observed in this study as is inferred in our conclusions.