patients with scalp itch and seborrheic dermatitis who will get biopsy

patients without scalp itch and without seborrheic dermatitis who will get biopsy

Seborrheic Dermatitis

1 scalp biopsy will be done at the site of central sensitization testing, according to standard of care practices. First, the site will be anesthetized and within this area, 2 immediately adjacent (ie contiguous) punch biopsies will be taken-2mm & 3mm. Both will be closed simultaneously using either (i) non fast-absorbing gut sutures, requiring a 10-14 day follow-up visit for suture removal; (ii) fast absorbing gut sutures that will not require a subsequent suture removal visit, or (iii) gel foam without stitches that also does not require a suture removal visit. Wound care instruction will be discussed with patient. The patient will be instructed to apply petroleum jelly at least 3 times per day to the biopsy site, reflecting standard of care clinical care at BMC.

Biopsy

Boston University

Neurobiology of the Scalp in Seborrheic Dermatitis

Hypothesis: Scalp pruritus in patients with seborrheic dermatitis is associated with a change in the neuropeptide identity of nerves at the dermal-epidermal junction (DEJ).

(i) assessment of brush-stroke induced pruritus: involved and non-involved skin areas chosen for other tests of central sensitization will be stroked smoothly and lightly by a cotton swab or a small paint brush at a rate of 1 Hz. The participants will be asked to report the evoked sensation.

Pinprick stimuli will be applied to the scalp skin with a series of probes: 2 mL syringe barrel containing a free-floating sterile 27-gauge cannula above which is 1 of these weights: 1.0, 2.3, 3.7, 8.6, or 14.8 g. Each probe will be laid down gently on the skin to prevent damage, and then held for 2 seconds. The subjects will be asked to describe the quality and intensity of the evoked sensation. The intensities of itch and pain will be reported separately on a numeric scale ranging from 0 (no sensation) to 10 (maximal sensation imaginable). This mode of application was reported in a previously published study in patients with atopic dermatitis (Ikoma et al, 2004. Neurology; 62: 212-7)to produce maximal itch sensation of less than 3 and maximal pain sensation of less than 4 on a numeric scale ranging from 0 (no sensation) to 10 (maximal sensation imaginable). This procedure will be repeated 10 times with each load in the area of the scalp that will be selected for skin biopsy.

Thin metal rod (diameter, ~2-3 mm) will be preheated to 41, 46, or 49 °C in a temperature-controlled water bath and then sequentially applied perpendicularly to the skin and held for 10 seconds. These temperatures with this short length of application are not enough to cause thermal damage to the skin. The maximal reported sensation was 3.5 for pain and 2.5 for itch on the above 0-10 scale. The subjects will be asked to rate the intensities of the evoked itch and pain every 2 secs from 0 (first placement) to 20 sec after placement. This procedure will be performed once in the area of the scalp that will be selected for skin biopsy. The area under the curves for both itch and pain perception plotted against time will be compared for each site tested.

Hypothesis: Scalp pruritus in patients with seborrheic dermatitis is associated with a change in the distribution or number of autonomic nerves innervating adnexal structures.

dandruff/triglyceride

Neurobiology of the Scalp in Seborrheic Dermatitis

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