Clinical Trial: Neurobiology of the Scalp in Seborrheic Dermatitis

Study Status: Completed
Recruit Status: Completed
Study Type: Observational

Official Title: Neurobiology of the Scalp in Seborrheic Dermatitis

Brief Summary: Seborrheic dermatitis is a common, inflammatory skin condition that causes flaky, white to yellowish scales to form on oily areas such as the scalp or inside the ear. These scales can occur with or without underlying reddened skin. In addition to causing psychological distress, low self esteem, and embarrassment, seborrheic dermatitis is associated with scalp pruritus (itch). Treatment modalities exist to control scalp flaking and itch associated with seborrheic dermatitis, although such therapies often lose efficacy over time. As seborrheic dermatitis is a chronic (life-long) condition, better treatments are needed. The investigators propose to better characterize in subjects with seborrheic dermatitis involving the scalp versus normal scalp controls: (a) the clinical characteristics of the associated itch and (b) the pattern of nerve innervation to the scalp. In this way, the investigators hope to get a comprehensive understanding of the factors causing scalp itch with the aim that this information will create new candidates to which treatment modalities can be designed. At least 12 (up to 20) subjects and similar number of control subjects without disease will have one clinic visit including questionnaires, testing of sensation on the scalp, and biopsy of the scalp.

Detailed Summary:

Seborrheic dermatitis (SD) is a common skin disorder that mainly affects the scalp, causing scale, itch, and red skin. Dandruff, a subset of SD, shows scale and itch in the absence of associated red skin. Seborrheic dermatitis can occur on many different body areas, including the scalp, eyebrows, eyelids, creases of the nose, lips, behind the ears, in the outer ear, and middle of the chest. On the scalp, SD is commonly associated with pruritus (itch). Multifactorial theories have been proposed regarding the pathogenesis of SD, and these include irritation from a skin-based yeast called malessizia, overproduction of sebum by sebaceous glands in the affected skin areas, and individual variability. Specifically, malassezia produce free fatty acids from sebaceous gland-produced triglycerides, and these free fatty acids have an "irritant" (ie, non-immunologic) effect in those patients with a "susceptible predisposition." Other factors associated with flares of SD include stress, fatigue, weather extremes, infrequent shampoos or skin cleaning, use of lotions that contain alcohol, skin disorders (such as acne), obesity, neurologic conditions (including Parkinson's disease, stroke, and head injury), and HIV infection. What role, if any, such factors play in the etiology of scalp pruritus in patients with SD is not known. Furthermore, itch is signaled by specific subsets of nerves in the skin and whether pruritus of SD results from alteration of these nerves by the underlying inflammatory state is unknown. Moreover, pruritus from the skin can be a result of peripheral sensitization, where skin-derived signals activate nerves in the skin to send increased nerve signals into the central nervous system. Pruritus sensed in the skin can also be a result of altered central-nervous system processing of skin-derived nerve signals, such as when skin-derived touch or pain is misperceived as itch by the central nervous s
Sponsor: Boston University

Current Primary Outcome: Percentage of vasodilatory peptidergic nerve fibers in the papillary dermis versus total nerves in the papillary dermis in control versus diseased scalp [ Time Frame: one year ]

Original Primary Outcome: Same as current

Current Secondary Outcome:

• Presence or absence of brush-stoke induced pruritus in disease versus control skin [ Time Frame: one year ]
  (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.
• Duration (minutes) of cowhage-spicule induced pruritus in diseases versus control skin [ Time Frame: 1 year ]
  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.
• Amount of pin-pressure induced pruritus in diseased versus control skin [ Time Frame: one year ]
  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.
• Amount of thermal (sensation of mildly painful and non-damaging heat)-induced itch in diseased versus control skin [ Time Frame: one year ]
  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.
• Percent of autonomic nerves to total nerves innervating adnexal structures in diseased versus control skin [ Time Frame: one year ]
  Hypothesis: Scalp pruritus in patients with seborrheic dermatitis is associated with a change in the distribution or number of autonomic nerves innervating adnexal structures.

Original Secondary Outcome: Same as current

Information By: Boston University

Dates:
Date Received: January 26, 2015
Date Started: February 2013
Date Completion:
Last Updated: March 23, 2017
Last Verified: March 2017