RhoA activation-mediated vascular permeability in capillary malformation-arteriovenous malformation syndrome: a hypothesis

Capillary malformation-arteriovenous malformation (CM-AVM) syndrome is a class of capillary anomalies that are associated with arteriovenous malformations and arteriovenous fistulas, which carry a risk of hemorrhages. There are no broadly effective pharmacological therapies currently available. Most CM-AVMs are associated with a loss of RASA1, resulting in constitutive activation of RAS signaling. However, protein interaction analysis revealed that RASA1 forms a complex with Rho GTPase-activating protein (RhoGAP), a negative regulator of RhoA signaling. Herein, we propose that loss of RASA1 function results in constitutive activation of RhoA signaling in endothelial cells, resulting in enhanced vascular permeability. Therefore, strategies aimed at curtailing RhoA activity should be tested as an adjunctive therapeutic approach in cell culture studies and animal models of RASA1 deficiency.

High-Frequency Ultrasound Investigation of Port-Wine Stains: Hemodynamic Features Revealed By 10- and 22-MHz Transducers

OBJECTIVES

The hemodynamics of the ultrasound (US) features of port-wine stains (PWSs) have not been reported. The purpose of this study was to evaluate the high-frequency US findings of PWSs.

METHODS

We retrospectively reviewed 98 PWS cases and categorized them into 4 groups based on clinical manifestations and pathologic findings (14 nodular, 28 thickened, 52 flattened, and 4 acquired). We evaluated the US findings with 10- and 22-MHz transducers.

RESULTS

For nodular PWSs, the mean thickened skin ± SD was 0.6 ± 0.5 mm, and the nodule thickness was 5.7 ± 3.3 mm; 63.6% of skin lesions showed vessel density of 2.16 ± 0.93/cm² with venous flow of 4.6 ± 1.1 cm/s, and all nodules showed vessel density of 6.14 ± 1.92/cm² with arterial and venous flow of 26.6 ± 17.9 and 9.9 ± 5.1 cm/s, respectively. The thickened skin of the thickened type was 1.4 ± 2.7 mm; 76.5% of skin lesions showed vessel density of 3.81 ± 1.98/cm² with venous flow 4.6 ± 2.1 cm/s. The thickened skin of 36 flattened lesions was 0.1 ± 0.1 mm; 91.7% of skin lesions showed vessel density of 1.08 ± 0.28/cm² . The thickened skin of 4 acquired lesions was 0.7 ± 0.4 mm; 50% showed vessel density of 1.08 ± 0.28/cm² . The thickened skin and vessel density of nodular and thickened PWSs were thicker and higher than those of the flattened ones. The 22-MHz transducer produced clearer contrast and higher vessel density than the 10-MHz transducer.

CONCLUSIONS

These results showed differences in US findings of PWSs, which may be useful for clinical diagnosis.

Relationship between the blood perfusion values determined by laser speckle imaging and laser Doppler imaging in normal skin and port wine stains

OBJECTIVE

Laser Doppler imaging (LDI) and laser speckle imaging (LSI) are two major optical techniques aiming at non-invasively imaging the skin blood perfusion. However, the relationship between perfusion values determined by LDI and LSI has not been fully explored.

METHODS

8 healthy volunteers and 13 PWS patients were recruited. The perfusions in normal skin on the forearm of 8 healthy volunteers were simultaneously measured by both LDI and LSI during post-occlusive reactive hyperemia (PORH). Furthermore, the perfusions of port wine stains (PWS) lesions and contralateral normal skin of 10 PWS patients were also determined. In addition, the perfusions for PWS lesions from 3 PWS patients were successively monitored at 0, 10 and 20min during vascular-targeted photodynamic therapy (V-PDT). The average perfusion values determined by LSI were compared with those of LDI for each subject.

RESULTS

In the normal skin during PORH, power function provided better fits of perfusion values than linear function: powers for individual subjects go from 1.312 to 1.942 (R(2)=0.8967-0.9951). There was a linear relationship between perfusion values determined by LDI and LSI in PWS and contralateral normal skin (R(2)=0.7308-0.9623), and in PWS during V-PDT (R(2)=0.8037-0.9968).

CONCLUSION

The perfusion values determined by LDI and LSI correlate closely in normal skin and PWS over a broad range of skin perfusion. However, it still suggests that perfusion range and characteristics of the measured skin should be carefully considered if LDI and LSI measures are compared.

Focal venous hypertension as a pathophysiologic mechanism for tissue hypertrophy, port-wine stains, the Sturge-Weber syndrome, and related disorders: proof of concept with novel hypothesis for underlying etiological cause (an American Ophthalmological Society thesis)

PURPOSE

To provide an in-depth re-examination of assumed causes of tissue hypertrophy, port-wine stains, and the Sturge-Weber, Cobb, Klippel-Trénaunay, and related syndromes to support an alternative unifying pathophysiologic mechanism of venous dysplasia producing focal venous hypertension with attendant tissue responses; to provide proof of concept with new patient data; to propose a novel etiological hypothesis for the venous dysplasia in these syndromes and find supportive evidence.

METHODS

Data from 20 patients with port-wine stains and corneal pachymetry readings was collected prospectively by the author in an institutional referral-based practice. The literature was searched using MEDLINE, and articles and textbooks were obtained from the bibliographies of these publications.

RESULTS

Newly obtained dermatologic, corneal pachymetry, fundus ophthalmoscopic, ocular and orbital venous Doppler ultrasonography, and magnetic resonance imaging findings in patients with the Sturge-Weber syndrome or isolated port-wine stains, along with published data, reveal diffusely thickened tissues and neural atrophy in all areas associated with venous congestion.

CONCLUSIONS

Contrary to traditional understanding, signs and symptoms in the Sturge-Weber and related syndromes, including both congenital and acquired port-wine stains, are shown to arise from effects of localized primary venous dysplasia or acquired venous obstruction rather than neural dysfunction, differentiating these syndromes from actual phacomatoses. Effects of focal venous hypertension are transmitted to nearby areas via compensatory collateral venous channels in the above conditions, as in the Parkes Weber syndrome. A novel underlying etiology-prenatal venous thrombo-occlusion-is proposed to be responsible for the absence of veins with persistence and enlargement of collateral circulatory pathways with data in the literature backing this offshoot hypothesis. The mechanism for isolated pathologic tissue hypertrophy in these syndromes clarifies physiologic mechanisms for exercise-induced muscle hypertrophy to occur via venous compression and increased capillary transudation.

Use of reflectance spectrophotometry to predict the response of port wine stains to pulsed dye laser

Reflectance spectroscopy can be used to quantitate subtle differences in color. We applied a portable reflectance spectrometer to determine its utility in the evaluation of pulsed dye laser treatment of port wine stains (PWS) and in prediction of clinical outcome, in a prospective study. Forty-eight patients with PWS underwent one to nine pulsed dye laser treatments. Patient age and skin color as well as PWS surface area, anatomic location, and color were recorded. Pretreatment spectrophotometric measurements were performed. The subjective clinical results of treatment and the quantitative spectrophotometry results were evaluated by two independent teams, and the findings were correlated. The impact of the clinical characteristics on the response to treatment was assessed as well. Patients with excellent to good clinical results of laser treatments had pretreatment spectrophotometric measurements which differed by more than 10%, whereas patients with fair to poor results had spectrophotometric measurements with a difference of of less than 10%. The correlation between the spectrophotometric results and the clinical outcome was 73% (p < 0.01). The impact of the other clinical variables on outcome agreed with the findings in the literature. Spectrophotometry has a higher correlation with clinical outcome and a better predictive value than other nonmeasurable, nonquantitative, dependent variables.

Choosing optimal wavelength for photodynamic therapy of port wine stains by mathematic simulation

Many laser wavelengths have been used in photodynamic therapy (PDT) for port wine stains (PWS). However, how these wavelengths result in different PDT outcomes has not been clearly illuminated. This study is designed to analyze which wavelengths would be the most advantageous for use in PDT for PWS. The singlet oxygen yield in PDT-treated PWS skin under different wavelengths at the same photosensitizer dosage was simulated and the following three situations were simulated and compared: 1. PDT efficiency of 488, 532, 510, 578, and 630 nm laser irradiation at clinical dosage (100 mW∕cm(2), 40 min); 2. PDT efficiency of different wavelength for PWS with hyperpigmentation after previous PDT; 3. PDT efficiency of different wavelengths for PWS, in which only deeply located ectatic vessels remained. The results showed that singlet oxygen yield is the highest at 510 nm, it is similar at 532 nm and 488 nm, and very low at 578 nm and 630 nm. This result is identical to the state in clinic. According to this theoretical study, the optimal wavelength for PDT in the treatment of PWS should near the absorption peaks of photosensitizer and where absorption from native chromophores (haemoglobin and melanin) is diminished.

Longitudinal, multimodal functional imaging of microvascular response to photothermal therapy

Although studies have shown that photothermal therapy can coagulate selectively abnormal vasculature, the ability of this method to achieve consistent, complete removal of the vasculature is questionable. We present the use of multimodal, wide-field functional imaging to study, in greater detail, the biological response to selective laser injury. Specifically, a single-platform instrument capable of coregistered fluorescence imaging and laser speckle imaging was utilized to monitor vascular endothelial growth factor gene expression and blood flow, respectively, in a transgenic rodent model. Collectively, the longitudinal, in vivo data collected with our instrument suggest that the biological response to selective laser injury involves early-stage redistribution of blood flow, followed by increased vascular endothelial growth factor promoter activity to stimulate pro-angiogenic events.

Fast and robust extraction of optical and morphological properties of human skin using a hybrid stochastic-deterministic algorithm: Monte-Carlo simulation study

A hybrid deterministic-stochastic algorithm combining the simplex method (SM) and a genetic algorithm (GA) was applied to the problem of extracting the optical and morphological properties of human skin (HSOMPs) from visual reflectance spectroscopy data. The results using the GA-SM hybrid algorithm adopting tournament selection and selecting new sets of HSOMPs were compared with those using other conventional optimization algorithms that have generally been used for the extraction of HSOMPs. Monte-Carlo simulation showed that the suggested GA-SM hybrid algorithm enhanced the stability of the inverse solutions and computational efficiency.

Blood flow dynamics after laser therapy of port wine stain birthmarks

BACKGROUND AND OBJECTIVE

During laser therapy of port wine stain (PWS) birthmarks, regions of perfusion may persist. We hypothesize that such regions are not readily observable even when laser surgery is performed by highly experienced clinicians. The objective of this study was to use objective feedback to assess the acute vascular response to laser therapy.

STUDY DESIGN/MATERIALS AND METHODS

A clinic-friendly laser speckle imaging (LSI) instrument was developed to provide the clinician with real-time images of blood flow during laser therapy. Images were acquired from patients undergoing laser therapy of PWS birthmarks at Scripps Clinic and the Beckman Laser Institute and Medical Clinic. Blood flow maps were extracted from the acquired imaging data. Histogram-based analysis was applied in grading the degree of heterogeneity present in the blood flow maps after laser therapy.

RESULTS

Collectively, two types of patient responses were observed in response to laser exposure: (1) an immediate increase in perfusion within minutes after laser therapy; and (2) an overall decrease in blood perfusion approximately 1 hour after laser therapy, with distinct regions of persistent perfusion apparent in the majority of post-treatment blood-flow images. A comparison of blood flow in PWS and adjacent normal skin demonstrated that PWS blood flow can be greater than, or sometimes equivalent to, that of normal skin.

CONCLUSION

In general, a decrease in skin perfusion is observed during pulsed laser therapy of PWS birthmarks. However, a heterogeneous perfusion map was frequently observed. These regions of persistent perfusion may be due to incomplete photocoagulation of the targeted vessels. We hypothesize that immediate retreatment of these regions identified with LSI, will result in enhanced removal of the PWS vasculature. Lasers Surg. Med. 41:563-571, 2009. (c) 2009 Wiley-Liss, Inc.

Treatment of nodules associated with port wine stains with CO2 laser: case series and review of the literature

BACKGROUND

Port wine stains (PWS) are congenital malformations of capillaries, where with progression, blood vessels become ectatic and result in disfiguring nodules.

OBJECTIVE

To search the MEDLINE database and review literature on the treatment of PWS and present 2 cases of adults with PWS, complicated by hypertrophic and nodular lesions, treated successfully with CO2 laser.

RESULTS

Two patients with PWS, with nodular and hypertrophic areas, were treated with CO2 laser. With the first patient, improvement of 90% or greater was noted in the 14 discrete nodules present within the PWS in a V2 distribution. At baseline, ectropion of the lower eyelid was noted which resolved completely after CO2 laser. With the second patient, improvement was noted as 90% or greater in the 40 of 51 discrete nodules present within the PWS extending across the right V1-V2 distribution.

CONCLUSION

Carbon dioxide ablative laser resurfacing is safe and highly effective in the treatment of the nodular and hypertrophic components of PWS. Future treatment of PWS will likely involve a hybrid approach of utilizing nonablative lasers of varying wavelengths and pulse durations and treatment with novel laser devices, with the goal of early treatment to prevent progression of PWS to disfiguring lesions.

Hand-held pulsed photothermal radiometry system to estimate epidermal temperature rise during laser therapy

BACKGROUND/PURPOSE

During laser therapy of port wine stain (PWS) birthmarks in human skin, measurement of the epidermal temperature rise (DeltaT(epi)) is important to determine the maximal permissible light dose. In order to measure DeltaT(epi) on a specific PWS skin site, we developed an AC-coupled hand-held pulsed photothermal radiometry (PPTR) system, which overcomes the in vivo measurement limitations of bench-top systems.

METHODS

The developed hand-held PPTR system consists of an infrared (IR) lens, AC-coupled thermoelectrically cooled IR detector, laser hand-piece holder, and positioning aperture. The raw AC-coupled signal was integrated to obtain a higher signal-to-noise ratio (SNR). The experimental temperature difference (DeltaT) calibration was compared with theoretical computations. In vitro and in vivo measurements of DeltaT were performed with a tissue phantom as a function of radiant exposure and human subject as a function of melanin concentration, respectively.

RESULTS

The integrated AC-coupled signal provided higher SNR as compared with the raw AC-coupled signal. The experimental DeltaT calibration resulted in good agreements with the theoretical results. The in vitro and in vivo results also presented good agreements with theory.

CONCLUSIONS

A fiber-free, hand-held AC-coupled PPTR system is capable of accurate epidermis temperature rise (DeltaT(epi)) measurements of human skin during pulsed laser exposure.

The effect of ambient temperature on capillary vascular malformations

BACKGROUND

Following pulsed dye laser (PDL) treatment of capillary vascular malformations (CMs), the capillaries left behind tend to be smaller and deeper. The PDL is most effective against capillaries over 50 microm, suggesting that clearance of CM could be improved by inducing capillary vasodilation of the smaller remaining capillaries. However, there are reduced perivascular nerves within CMs, implying that autonomic innervation to these capillaries may be abnormal.

OBJECTIVES

To investigate whether CM capillaries will vasodilate in response to autonomic stimulation by raising ambient temperature.

METHODS

Ten patients with untreated CMs and nine with previously laser-treated CMs were studied as ambient temperature was increased from 20 degrees C to 28 degrees C. The following measurements were taken at 2 degrees C intervals: skin blood flow (SBF); capillary diameter and depth; CM colour; and skin and core temperatures.

RESULTS

All the subjects studied demonstrated superficial capillary vasodilation and increased SBF as the ambient temperature was raised from 20 degrees C to 28 degrees C. Mean+/-SEM capillary diameter increased from 66+/-7 microm to 110+/-13 microm (P<0.001) in the untreated group, compared with an increase from 28+/-5 microm to 70+/-14 microm (P<0.001) in the treated group. Mean+/-SEM SBF increased from 427.2+/-98.2 perfusion units (PU) to 580.9+/-92.7 PU (P<0.01) in the untreated group, compared with an increase from 201.3+/-28.4 PU to 458.1+/-53.7 PU (P<0.05) in the treated group.

CONCLUSIONS

Superficial capillary vasodilation within CM is achievable by raising ambient temperature, including in those patients resistant to PDL treatment, potentially allowing further clearance of these lesions.

Effects of hypobaric pressure on human skin: Implications for cryogen spray cooling (Part II)

BACKGROUND AND OBJECTIVES

Clinical results have demonstrated that dark purple port wine stain (PWS) birthmarks respond favorably to laser induced photothermolysis after the first three to five treatments. Nevertheless, complete blanching is rarely achieved and the lesions stabilize at a red-pink color. In a feasibility study (Part I), we showed that local hypobaric pressure on PWS human skin prior to laser irradiation induced significant lesion blanching. The objective of the present study (Part II) is to investigate the effects of hypobaric pressures on the efficiency of cryogen spray cooling (CSC), a technique that assists laser therapy of PWS and other dermatoses.

STUDY DESIGN/MATERIALS AND METHODS

Experiments were carried out within a suction cup and vacuum chamber to study the effect of hypobaric pressure on the: (1) interaction of cryogen sprays with human skin; (2) spray atomization; and (3) thermal response of a model skin phantom. A high-speed camera was used to acquire digital images of spray impingement on in vivo human skin and spray cones generated at different hypobaric pressures. Subsequently, liquid cryogen was sprayed onto a skin phantom at atmospheric and 17, 34, 51, and 68 kPa (5, 10, 15, and 20 in Hg) hypobaric pressures. A fast-response temperature sensor measured sub-surface phantom temperature as a function of time. Measurements were used to solve an inverse heat conduction problem to calculate surface temperatures, heat flux, and overall heat extraction at the skin phantom surface.

RESULTS

Under hypobaric pressures, cryogen spurts did not produce skin indentation and only minimal frost formation. Sprays also showed shorter jet lengths and better atomization. Lower minimum surface temperatures and higher overall heat extraction from skin phantoms were reached.

CONCLUSIONS

The combined effects of hypobaric pressure result in more efficient cryogen evaporation that enhances heat extraction and, therefore, improves the epidermal protection provided by CSC.

Thickness of Healthy and Affected Skin of Children with Port Wine Stains: Potential Repercussions on Response to Pulsed Dye Laser Treatment

BACKGROUND

Response of port wine stain to pulsed dye laser therapy is variable and dependent on treatment settings used and anatomic site as well as on size and depth of ectatic vessels.

OBJECTIVE

Our purpose was to evaluate skin thickness in different anatomic areas and in port wine stain to thus assess its possible role in the response to pulsed dye laser.

MATERIALS AND METHODS

Twenty-one children with port wine stain underwent high-frequency ultrasound evaluation (20 MHz). Eighteen unaffected areas were considered in each patient and an additional measure was taken from the symmetric affected skin when present (50 areas).

RESULTS

Skin was thicker in the centrofacial area, dermatome V1 (followed by dermatome V2, dermatome V3, and dermatomes C1-2), and with increasing age. No substantial difference between affected and symmetric nonaffected skin was found.

CONCLUSION

Thicker cutaneous areas fit with those that typically respond worse to pulsed dye laser. Differences in skin thickness related to age support the fact that better responses are achieved in younger patients.

Videomicroscopy of venular malformations (port-wine stain type): prediction of response to pulsed dye laser

Videomicroscopy has been found to be useful in determining the depth of ectasia of vascular malformations. Different patterns that hypothetically could predict the response of a vascular malformation to pulsed dye laser have been described. Our purpose was to determine if the dermoscopy pattern was able to predict the response to pulsed dye laser therapy and if it was independent of other known clinical variables. Thirty-three consecutive children presenting for evaluation or treatment of vascular malformations underwent videomicroscopy previous to pulsed dye laser therapy. Sixty-nine representative areas were evaluated before and after laser therapy. Other clinical factors, including location of the malformation, the patient's age and sex, and previous therapy, were also included in the analysis. We found that the dermoscopy pattern was differently distributed depending on the anatomic area. A superficial pattern was not present in the centrofacial area. An undefined pattern was most often present when a previously treated area was imaged. A superficial pattern independently predicted a good response to laser. The location of the lesion was another independent factor influencing the outcome. A new pattern consisting of a pale circular area surrounding a central brownish dot is described as negatively influencing the response to laser therapy. We concluded that videomicroscopy is a good tool for assessing which vascular malformations can be adequately treated with laser therapy, although other anatomic factors can influence the response. Videomicroscopy is particularly helpful in deciding when to end the treatment because it objectively shows when no further response can be expected, and is helpful for demonstrating this to patients and their parents.

Confocal Microscopy Study of Nerves and Blood Vessels in Untreated and Treated Port Wine Stains: Preliminary Observations

BACKGROUND AND OBJECTIVE

Vascular ectasia in port wine stain birthmarks (PWS) might result from reduced innervation with loss of autonomic stimulation. We investigated this theory and evaluated nerve and blood vessel density, and mean blood vessel size in untreated and treated PWS skin.

METHODS

Skin biopsy specimens were obtained from uninvolved skin, untreated PWS, PWS with a good response to laser treatment and PWS with a poor response to laser treatment. Confocal microscopy was performed to determine nerve and blood vessel density, and mean blood vessel size.

RESULTS

Nerve density was significantly decreased in all PWS sites compared to uninvolved skin. Mean blood vessel diameter was larger in untreated compared to treated PWS. PWS with a good response to treatment had decreased nerve density but blood vessel density and mean diameter was relatively normal. PWS with a poor response to treatment had decreased nerve density but increased blood vessel density and mean blood vessel diameter compared to normal skin.

CONCLUSION

Nerve density was decreased in all evaluated PWS sites and this may be a factor in lesion pathogenesis. PWS blood vessel size correlated with pulsed dye laser response and may prove to be a useful prognostic indicator of therapeutic outcome.

Computational model to evaluate port wine stain depth profiling using pulsed photothermal radiometry

We report on development of an optical-thermal model to evaluate the use of pulsed photothermal radiometry (PPTR) for depth profiling of port wine stain (PWS) skin. In the model, digitized histology sections of a PWS biopsy were used as the input skin geometry. Laser induced temperature profiles were reconstructed from simulated PPTR signals by applying an iterative, non-negatively constrained conjugate gradient algorithm. Accuracy of the following PWS skin characteristics extracted from the reconstructed profiles was determined: (1) average epidermal thickness (z(epi)), (2) maximum epidermal temperature rise (DeltaT(epi,max)), (3) depth of PWS upper boundary (z(PWS)), and (4) depth of maximum PWS temperature rise (z(PWS,max)). Comparison of the actual and reconstructed profiles from PPTR data revealed a good match for all four PWS skin characteristics. Results of this study indicate that PPTR is a viable approach for depth profiling of PWS skin.

Increase of dermal blood volume fraction reduces the threshold for laser-induced purpura: Implications for port wine stain laser treatment

BACKGROUND AND OBJECTIVES

The average success rate in achieving total blanching of port wine stain (PWS) lesions treated with laser-induced selective photothermolysis is below 25%, even after multiple treatments. This is because smaller diameter (5-20 microm) PWS blood vessels are difficult to destroy with selective photothermolysis since the volumetric heat generated by absorption of laser light is insufficient to adequately heat the entire vessel wall. The aim of this study was to investigate a potential technique for more efficient photocoagulation of small diameter PWS blood vessels in PWS that respond poorly to selective photothermolysis.

STUDY DESIGN/MATERIALS AND METHODS

The blood volume fraction (BVF) in the upper dermis of the forearm of human volunteers was increased by placing an inflated blood pressure cuff on the upper arm. Applied pressures were in the range of 80-100 mm Hg for up to 5 minutes. The increased BVF was determined by matching reflectance spectra measured with that computed using a diffusion model. The impact of increased BVF on purpura formation induced by a 0.45 milliseconds pulsed dye laser (PDL) at 585 nm wavelength was investigated in normal and in PWS skin.

RESULTS

In the presence of a 100 mm Hg pressure cuff, the BVF, as determined from the diffusion model, increased by a factor of 3 in the forearm and by 6 in the hand. Increasing BVF by a factor of 3 corresponds to an increase in blood vessel diameters by a factor of radical 3 approximately 1.7. BVF increased at 1-3 minutes after application of the pressure cuff, remained constant at 3-5 minutes, and returned to baseline values at 3 minutes after removal of the pressure cuff. Approximately 40% less radiant exposure was needed to induce the same amount of purpura after PDL irradiation when the blood pressure cuff was used. Applying an 80 mm Hg pressure cuff reduced the required radiant exposure for purpura formation by 30%. Heating of blood vessels was calculated as a function of vessel diameter and of radiant exposure (at 585 nm and at 0.5 and 1.5 milliseconds pulse duration).

CONCLUSIONS

Enlarging the vessel lumen, for example, by obstructing venous return, can significantly reduce the "small-vessel-limitation" in PDL treatment of PWS. Dilation of PWS blood vessels enables a more efficient destruction of smaller vessels without increasing the probability of epidermal damage.

Nevi flammei affecting two contralateral quadrants and nevus depigmentosus: a new type of phacomatosis pigmentovascularis?

Here, we report on a 64-year-old-woman with nevi flammei affecting two contralateral quadrants, venous insufficiency of the right leg, and asymmetry of the arms, in association with a linear nevus depigmentosus. This combination of vascular and pigmentary abnormalities may represent a novel type of phacomatosis pigmentovascularis caused by non-allelic twin-spotting.

Increased fibronectin expression in sturge-weber syndrome fibroblasts and brain tissue

Sturge-Weber syndrome (SWS) is a neurocutaneous disorder that presents with a facial port-wine stain and a leptomeningeal angioma. Fibronectin expression regulates angiogenesis and vasculogenesis and participates in brain tissue responses to ischemia and seizures. We therefore hypothesized that abnormal gene expression of fibronectin and other extracellular matrix genes would be found in SWS brain tissue and SWS port-wine skin fibroblasts. Fibronectin gene and protein expression from port-wine-derived fibroblasts were compared with that from normal skin-derived fibroblasts of four individuals with SWS using microarrays, reverse transcriptase-PCR, Western analysis, and immunocytochemistry. Fibronectin gene and/or protein expression from eight SWS surgical brain samples was compared with that in two surgical epilepsy brain samples and six postmortem brain samples using microarrays, reverse transcriptase-PCR, and Western analysis. The gene expression of fibronectin was significantly increased (p < 0.05) in the SWS port-wine-derived fibroblasts compared with that of fibroblasts from SWS normal skin. A trend for increased protein levels of fibronectin in port-wine fibroblasts was found by Western analysis. No difference in the pattern of fibronectin staining was detected. The gene expression of fibronectin was significantly increased (p < 0.05), and a trend for increased fibronectin protein expression was found in the SWS surgical brain samples compared with the postmortem controls. These results suggest a potential role for fibronectin in the pathogenesis of SWS and in the brain's response to chronic ischemic injury in SWS. The reproducible differences in fibronectin gene expression between the SWS port-wine-derived fibroblasts and the SWS normal skin-derived fibroblasts are consistent with the presence of a hypothesized somatic mutation underlying SWS.

Vascular response to laser photothermolysis as a function of pulse duration, vessel type, and diameter: implications for port wine stain laser therapy

BACKGROUND AND OBJECTIVE

Treatment of port wine stains (PWS) by photothermolysis can be improved by optimizing laser parameters on an individual patient basis. We have studied the critical role of pulse duration (t(p)) on the treatment efficacy.

STUDY DESIGN/MATERIALS AND METHODS

The V-beam laser (Candela) allowed changing t(p) over user-specified discrete values between 1.5 and 40 milliseconds by delivering a series of 100 microsecond spikes. For the 1.5 and 3 millisecond pulses, three spikes were observed at intervals t(p)/2 and for t(p)> or =6 milliseconds, four spikes separated by t(p)/3. The ScleroPlus laser (Candela) has a smooth output over its fixed 1.5 milliseconds duration. Blood vessels in the chick chorioallantoic membrane (CAM) were irradiated at fixed wavelength (595 nm), spot size (7 mm), radiant exposure (15 Jcm(-2)), and at variable t(p). The CAM contains an extensive microvascular network ranging from capillaries with diameter D<30 microm to blood vessels of D approximately 120 microm. The CAM assay allows real-time video documentation, and observation of blood flow in pre-capillary arterioles (A) and post-capillary venules (V). Vessel injury was graded from recorded videotapes. Mathematical modeling was developed to interpret results of vessel injury when varying t(p) and D. A modified thermal relaxation time was introduced to calculate vessel wall temperature following laser exposure.

RESULTS

Arterioles. For increasing t(p), overall damage was found to decrease. For fixed t(p), damage decreased with vessel size. Venules. For all D, damage was smaller than for corresponding arterioles. There was no dependence of damage on t(p). For given t(p), no variation of damage with D was observed. Photothermolysis due to spiked (V-beam) vs. smooth (Scleroplus) delivery of laser energy at fixed t(p) (1.5 milliseconds), showed similar vessel injuries for al values of D (P>0.05).

CONCLUSIONS

The difference between initial arteriole and venule damage could be explained by the threefold higher absorption coefficient at 595 nm in (oxygen-poor!) arterioles. In human patients, PWS consist of ectatic venules (characterized by higher absorption), so that these considerations favor the use of 595-nm irradiation for laser photothermolysis. For optimal treatment of PWS it is proposed that t(p) be between 0.1 and 1.5 milliseconds. This is based on a modified relaxation time tau'(d), defined as the time required for heat conduction into the full thickness of the vessel wall, which is assumed to have a thickness DeltaD approximately 0.1D. The corresponding tau'(d) will be a factor of about six smaller than given in the literature. For vessels with D between 30 and 300 mum, tau'(d) ranges from 0.1 to 1.5 milliseconds.

Bioheat transfer analysis of cryogen spray cooling during laser treatment of port wine stains

BACKGROUND AND OBJECTIVE

The thermal response of port wine stain (PWS) skin to a combined treatment of pulsed laser irradiation and cryogen spray cooling (CSC) was analyzed through a series of simulations performed with a novel optical-thermal model that incorporates realistic tissue morphology.

STUDY DESIGN/MATERIALS AND METHODS

The model consisted of (1) a three-dimensional reconstruction of a PWS biopsy, (2) a Monte Carlo optical model, (3) a finite difference heat transfer model, and (4) an Arrhenius thermal damage calculation. Simulations were performed for laser pulses of 0.5, 2, and 10 ms and a wavelength of 585 nm. Simulated cryogen precooling spurts had durations of 0, 20, or 60 ms and terminated at laser onset. Continuous spray cooling, which commenced 60 ms before laser onset and continued through the heating and relaxation phases, was also investigated.

RESULTS

The predicted response to CSC included maximal pre-irradiation temperature reductions of 27 degrees C at the superficial surface and 12 degrees C at the dermoepidermal junction. For shorter laser pulses (0.5, 2 ms), precooling significantly reduced temperatures in superficial regions, yet did not effect superficial vessel coagulation. Continuous cooling was required to reduce significantly thermal effects for the 10-ms laser pulse.

CONCLUSIONS

For the PWS morphology and treatment parameters studied, optimal damage distributions were obtained for a 2-ms laser pulse with a 60-ms precooling spurt. Epidermal and vascular morphology as well as laser pulse duration should be taken into account when planning CSC/laser treatment of PWS. Our novel, realistic-morphology modeling technique has significant potential as a tool for optimizing PWS treatment parameters.

Three-dimensional reconstruction of port wine stain vascular anatomy from serial histological sections

Port wine stains (PWSs) treated with a flashlamp-pumped pulsed dye laser show a variability in clinical response that is incompletely understood. To identify any vascular structure that might adversely affect treatment response, we obtained a three-dimensional reconstruction of the vascular anatomy of a non-responsive, light-purple superficial PWS on the forearm. The reconstructed PWS consisted of multiple clusters of small diameter (10-50 microns) blood vessels. We propose that this and similar structures, which have not been identified in the literature, have limited the efficacy of laser therapy. Further study is required to clarify the role of vessel clusters for laser treatment of PWSs, and the corresponding dosimetry necessary to clear non-responsive lesions. We expect that three-dimensional reconstruction of PWS vascular anatomy will provide the basis for (i) accurate PWS classification, (ii) guidance for selection of more effective laser dosimetry, and (iii) a standard against which to assess non-invasive diagnostic imaging techniques.

The medical necessity for treatment of port-wine stains

BACKGROUND

Port-wine stains are congenital vascular malformations that can be disfiguring and may lead to psychosocial as well as medical complications. The 585-nm pulsed dye laser is very effective in treating port-wine stains. Laser treatment is often viewed by insurance companies as a "cosmetic procedure" and not "medically necessary". Consequently many patients are denied coverage for treatment of their disfiguring birthmarks.

OBJECTIVE

To determine variability of insurance coverage for laser treatment of port-wine stains from state to state. Natural history, progression, and potential complications of port-wine stains are reviewed and rationale for consistent insurance coverage for laser treatment of port-wine stains is given.

METHODS

A questionnaire was mailed to 40 dermatologic surgeons in 22 states and the District of Columbia. We reviewed the literature regarding port-wine stains and their potential complications, and health care policy guidelines regarding "medical necessity" and "cosmetic procedures".

RESULTS

Insurance coverage for laser treatment of port-wine stains varies from state to state.

CONCLUSION

Based on current health care policy guidelines, laser treatment of port-wine stains should be regarded, and covered, as a medical necessity by all insurance providers.

Wavelengths for port wine stain laser treatment: influence of vessel radius and skin anatomy

Recent Monte Carlo computations in realistic port wine stain (PWS) models containing numerous uniformly distributed vessels suggest equal depth of vascular injury at wavelengths of 577 and 585 nm. This finding contradicts clinical experience and previous theory. From a skin model containing normal and PWS vessels in separate dermal layers, we estimate analytically the average volumetric heat production in the deepest targeted PWS vessel. The fluence rate distribution is approximated by Beer's law, which depends upon the tissue's effective attenuation coefficient, and includes a homogeneous fractional volumetric blood concentration corrected for finite-size blood vessels. The model predicts 585-587 nm wavelengths are optimal in adult PWSs containing at least one layer of small-radius blood vessels. In superficial PWSs, typically in young children with small-radius vessels, 577-580 nm wavelengths are optimal. Wavelength-independent results similar to those from Monte Carlo models are valid in single-layered PWSs of large-radius vessels. In conclusion, the volumetric heat production in the deepest targeted PWS blood vessel can be maximized on an individual patient basis. However, absorption of 585-587 nm wavelengths is sufficiently high in superficial lesions, so we hypothesize that these wavelengths may be considered adequate for the treatment of any PWS.

Possible mechanisms for an irregular vessel coagulation when long laser pulses are used in the treatment of port-wine stains

The laser treatment of port-wine stains (PWS) has as a main aim the irreversible damage of ectatic vessels. Blood content of the subcutaneous venous plexus in PWS can be increased by a factor of seven or more, compared to that of the normal skin. The venous blood velocity ranges from 0.1-1 mm/s in capillaries to approximately 22 mm/s in larger vessels of about 300 microns in diameter. A PWS, selected for study, was irradiated with a multiline argon laser 488/515 nm wavelength, 1.5 W power, 200 ms pulse duration, 0.5 mm beam diameter and repetition frequency up to 5 Hz. Laser shots were placed adjacently in an area of 1 cm2. Using these parameters, in the case of dilated PWS vessels with an optical penetration depth and thermal diffusion length less than the diameter of the vessel, together with a transit time of blood across the irradiated spot less than the pulse duration, and estimating that during a pulsed laser emission of 200 ms, the blood has travelled a distance of 3-4 mm, there is a strong indication that hemodynamics during irradiation may influence the pattern of coagulation and agglutination. Thrombosis should occur in the case of small vessels and, in larger vessels, the coagulated blood will only partly fill the lumen. The structure developed in the vessel interior may also change continuously with time, as the coagulated material is progressively replaced by fibrotic tissue and the irregular agglutination pattern may be due to inhomogeneity in the absorbed optical energy.

Evaluation of port wine stains by laser Doppler perfusion imaging and reflectance photometry before and after pulsed dye laser treatment

Treatment of choice for congenital capillary malformations of the port wine stain type is presently the pulsed dye laser. Although treatment results have usually been excellent or good, a few patients respond less well. Looking for a tool to predict and monitor the treatment we used laser Doppler perfusion imaging and reflectance photometry. Measurements with laser Doppler perfusion imaging were performed in 19 patients initially and after 1-3 treatments and with reflectance photometry initially and after 1-6 treatments. Before treatment, 15 of the patients had an increased bloodflow within the port wine stain in comparison with normal contralateral skin. After the laser treatments, 15 of 18 patients had decreased bloodflow within the lesion and all 18 had surrounding hyperemia. Reflectance photometry showed a successive increase in blanching and predicted within 6 weeks of the first treatment the eventual clinical result. The bloodflow, as measured with laser Doppler perfusion imaging, did not correlate well with the photometrically registered erythema. Reflectance photometry is a useful objective tool, which early in the treatment course indicates whether laser therapy will be successful. Laser Doppler perfusion imaging is less helpful in monitoring patients but may be of use in the study of port wine stain pathophysiology.

Dynamic epidermal cooling in conjunction with laser-induced photothermolysis of port wine stain blood vessels

When a cryogen spurt is applied to the skin surface for an appropriately short period of time (on the order of tens of milliseconds), the spatial distribution of cooling remains localized in the normal overlying epidermis, while leaving the temperature of the deeper port wine stain (PWS) blood vessels unchanged. Furthermore, cooling continues after pulsed laser exposure as cryogen remaining on the surface evaporates and removes heat deposited by light absorption in epidermal melanin. An additional advantage of dynamic cooling is a reduction in the level of pain and discomfort associated with flashlamp-pumped pulsed dye laser therapy of PWS. Preliminary clinical studies and supporting theoretical calculations demonstrate the feasibility of selective epidermal cooling while achieving photothermolysis of blood vessels during pulsed laser treatment of PWS.