Reduced skin thickness: a new minor diagnostic criterion for the classical and hypermobility types of Ehlers-Danlos syndrome.

BACKGROUND: The diagnosis of Ehlers-Danlos syndrome (EDS) is mainly based on clinical criteria, although in some instances a sound molecular diagnosis is available. Clinical signs can be divided into two categories: one with high diagnostic specificity and the other with low specificity. Despite the fact that reduced skin thickness is one of the dermatological features in patients with EDS, this issue has not been analysed in greater detail. OBJECTIVES: To determine skin thickness in patients with the classical and the hypermobility types of EDS. METHODS: In 21 patients with classical type of EDS and in nine patients with hypermobility type of EDS, skin thickness was analysed at different body sites by cross-sectional b-mode scans obtained with a 20-MHz ultrasound system. RESULTS: We found a significant decrease in skin thickness in both types of EDS, which was highest at the chest and at the distal part of the lower leg. CONCLUSIONS: We propose that the reduced thickness of the dermis as determined by high-resolution 20-MHz ultrasound can be used as a new minor criterion in the diagnosis of the classical and the hypermobility types of EDS.

Influence of body water distribution on skin thickness: measurements using high-frequency ultrasound.

BACKGROUND: Although it is known that the skin acts as a water reservoir and participates in the fluid content of the whole body, no method has been established to quantify the fluid shifts in superficial tissue. OBJECTIVES: The aim of this study was to investigate changes in dermal and subcutis thickness and echodensity at the forehead and lower leg by high-frequency (20 MHz) ultrasound under various physiological conditions influencing water balance. METHODS: These parameters were measured in the skin of 20 healthy male volunteers at baseline and successively at 30 min after lying down, in a head-down position, after physical activity and after infusion of 10 mL kg-1 body weight of Ringer's solution. RESULTS: Dermal thickness at the forehead showed a significant increase from baseline to a horizontal position and a further increase in the head-down position. Physical activity did not lead to further changes, whereas after fluid infusion the dermal thickness also increased markedly. The echodensity showed inverse changes, with decreasing values. The thickness of the subcutis increased slightly from baseline to a lying position and decreased in the head-down position and after fluid infusion. At the lower leg, skin thickness decreased slightly in the head-down position with elevated legs, and increased after fluid infusion. CONCLUSIONS: Our results show that slight changes in the water distribution of the body influence the thickness and the echodensity of the dermis. Changes are more pronounced at the forehead than on the lower legs. Further, the fluid storage takes place mainly in the dermis and not in the subcutis. High-frequency ultrasound is able to quantify these effects and is a sensitive method for measuring fluid intake and balance during anaesthesia and therapy.

Changes of interstitial fluid volume in superficial tissues detected by a miniature ultrasound device.

We evaluated the changes of tissue layer thickness in circumscribed superficial tissue areas with a 10-MHz A-mode and a 20-MHz B-mode ultrasound device under alterations in body posture and plasma volume to detect fluid shifts between the different compartments. In 20 male volunteers, we measured tissue thickness by A mode and corium and subcutis thickness by B mode at the forehead before and 30 min after three procedures: change from upright to supine position (P1); change from upright to 30 degrees head-down-tilt position (P2); infusion of 10 ml/kg body wt of Ringer solution (P3). We found a significant correlation between baseline tissue thickness and the sum of corium and subcutis thicknesses (r = 0.75, P < 0.01). The changes of body posture and plasma volume resulted in significant increases of tissue thickness (P1, 2.9%; P2, 11.6%; P3, 5.8%) and corium thickness (P1, 4.7%; P2, 8.1%; P3, 9.1%) but not of the sum of chorium and subcutis thicknesses. We conclude that fluid shifts from the intravascular to the extravascular compartment are detectable by evaluating corium thickness with a B-mode, or more easily tissue thickness with an A-mode, ultrasound device.

The influence of female sex hormones on skin thickness: evaluation using 20 MHz sonography.

Changes in skin thickness and echodensity during the spontaneous menstrual cycle, in women taking hormonal contraceptives and pregnant women were investigated by high-frequency (20 MHz) ultrasound. Women with a spontaneous ovulatory menstrual cycle (group I), women taking one-phase contraceptives (group II), women taking three-phase contraceptives (group III) and pregnant women (group IV) were measured at the following locations: proximal and distal forearm and lower leg on both sides. The skin was investigated during three phases of the menstrual cycle: days 2-4 (phase A), days 12-14 (phase B) and days 20-22 (phase C). Oestradiol and progesterone levels were determined at each phase. The pregnant women were investigated 2 weeks prepartal and 6 weeks after delivery. Group I showed a statistically significant increase in the skin thickness from phase A to phase B, but not from phase B to phase C. Group II showed no significant changes in skin thickness, whereas the skin thickness increased from phase A to phase B in group III. In group IV, the skin was significantly thicker prepartal than after delivery. The measured echodensity showed a negative correlation with skin thickness in group III and in pregnant women. We were able to demonstrate that the status of female sex hormones influences the thickness of the skin. These results can be explained by hormone-induced water retention in the skin. Sonography at 20 MHz is able to quantify these effects, which should be considered when performing ultrasound measurement in women.