Neurobiology of the Scalp in Seborrheic Dermatitis

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 system. Whether itch in
patients with SD is a result of peripheral and/or central sensitization is also not unknown.
Understanding this distinction has therapeutic implications, in that itch that is a result
of misprocessing by the central nervous system will not be adequately treated, in the short
term, by skin-administered topical therapies.

To better understand the etiology of scalp pruritus in subjects with SD, we will determine
the clinical characteristics of scalp pruritus in subjects with SD compared with normal
controls, as well as to determine the relationship between scalp pruritus and changes in
cutaneous innervation.

METHODS:

This exploratory and pilot study has only a single planned visit to the outpatient
Dermatology clinic in Shapiro center.

Subjects who carry the diagnosis of seborrheic dermatitis and scalp itch, or controls who
don't, (either internally referred through routine visits to outpatient Dermatology clinics
at BMC or externally referred from outside providers or who respond to recruitment
techniques) will undergo an initial phone screening to review inclusion and exclusion
criteria. This screening will involve anonymous screening questions without collection of
personal health information. Subjects/controls that meet the criteria to be eligible for the
study will then be asked if they are willing to come to BMC for the single study visit.
Those subjects/controls that then agree to be scheduled will next be told that we are
seeking informed consent by phone for the following minimal risk procedures in preparation
for the study visit:

1. to place a unique patient code identifier on the screening form and

2. if they are willing to stop using any topical scalp treatments for seborrheic
dermatitis/dandruff as well as (c) to stop any prn or elective use of prescribed or
over-the counter antihistamines for at least 3 weeks before their scheduled visit.

(d) if they are willing not to wash their hair for at least 48 hours prior to the visit.

The consent process will include highlighting that the individual can stop the "washout" at
anytime. Those subjects/controls, after undergoing informed consent process read to them
over the phone, that agree to (a) and (b) and (c) above, will then be scheduled for a one
hour visit at the outpatient Dermatology floor during a non-clinic time.

At this visit, all subjects/controls will first undergo the following:

1. Visual and non-invasive inspection of the scalp

2. Completion by the patient of a visual analogue scale (VAS) score to measure degree of
scalp pruritus over the past week. This VAS form will have no identifiable health
information.

3. Review of the inclusion/exclusion criteria answers they provided over the phone, that
after informed consent by phone at the time they gave those answers, they agreed to
allow us to store with a unique subject/control identifying code.

The above 3 minimal risk procedures (one of which the patients have already provided
informed consent for), will happen before "study visit screening" (described in detail in
Screening Section 20.0 below) and the second informed consent process is performed. This
order is to respect the patient's time. If they no longer meet inclusion/exclusion criteria
based on the above minimal risk screening, they will not be eligible for the study and so
would then have unnecessarily undergone additional screening as well as an informed consent
process.

After obtaining written informed consent to participate in the study, the following will
occur:

1. Female subjects of child-bearing potential will take a urine pregnancy test.

2. Subjects/controls will fill-out a questionnaire for pruritus and a questionnaire that
contains additional targeted questions related to their scalp itch and hair care
practices

3. Investigators will assess scalp to identify involved, pruritic sites along EEG lead
axis T3-O1 or, secondarily, along EEG lead axis C3 to Pz. EEG testing is a standard
non-invasive neurologic test in which scalp electrodes are placed in well-defined and
specified positions on the scalp. We will not be doing an EEG or using electrodes. We
are simply using the anatomic landmarks specified for EEG placement to allow uniform
selection of scalp areas to test and biopsy.

4. Digital photographs of the patient's head, focusing on the scalp will be taken.

5. At the selected scalp site, an investigator will perform the following tests for
central sensitization, at the selected scalp site (see below for methods for these
tests):

- Warm heat (methods section below explains this procedure) to assess it is or is
not felt as itch using 3 mm diameter metal probe

- Alloknesis (brush to itch: if possible on scalp with hair)

- Hyperknesis (enhanced sensation of itch to pinprick)

- Duration of itch elicited by insertion of a cowhage spicule into the scalp (if
possible on scalp with hair). This procedure is described in detail below.

6. The investigator will then perform a single scalp biopsy procedure at the site of
central sensitization testing, according to standard of care practices. The 2mm
specimen will be placed into formalin for routine paraffin-embedding. The 3mm specimen
will be placed into a special fixative that optimizes immunohistochemistry on frozen
sections to detect antigens expressed by nerves. These specimens will be labeled with
the subjects/control's unique identifying code only and without personal health
information.

This one visit completes the subjects/control's entire participation in the study. No
additional visits will be scheduled (unless the individual has opted for suture option and
removal of these sutures at BMC) but the subject/control will be provided the contact
information of the investigator in the rare event that the subject/control requires further
care as a complication of the biopsy procedure, such as bleeding, persistent pain,
infection, and/or failure to heal.

In all biopsies, the density and distribution of different subsets of cutaneous nerve fibers
will be determined by immunohistochemistry in the frozen-fixed tissue and the presence or
absence of histopathologic features of seborrheic dermatitis will be evaluated in the
paraffin-embedded tissue. Left over tissue from either the frozen and/or the
paraffin-embedded tissue will be saved in a repository if the individual consents, and the
storage of these tissues and safeguards are described in detail in the tissue banking
section of the BMC approved IRB protocol.

Estimated Duration of Enrollment (how long will it take to recruit the required sample
size): One year.

Estimated Duration of Entire Study (estimated duration from initial IRB approval through
data analysis to close of study): Two years Sample Size- Total=60 patients with scalp itch
and seborrheic dermatitis =30

- consent and/or fully participate in study = 20

- expected drop outs withdrawal and terminations = 5

- screened and not enrolled = 5 patients without scalp itch and without seborrheic
dermatitis =30

- consent and/or fully participate in study = 20

- expected drop outs withdrawal and terminations = 5

- screened and not enrolled = 5

Sample Size Justification:

Although the proposed study is exploratory in intent and does not require a formal power
statement, we can nonetheless estimate power for the primary outcome of no central
sensitization in patients with seborrheic dermatitis versus controls for the planned sample
size of 20 subjects. The expected average mean score for a patient with central
sensitization is 3 out of 10 and for a control patient 1 out of 10 with a standard deviation
of 1. Therefore, for there to be no difference between both groups, we would expect both
groups to have a mean score of 1 with a standard deviation of 1. In this case, if there is
truly no difference between the control and experimental group (ie, no central
sensitization), then 36 total patients (18 per group) are required to be 80% sure, 40 total
patients (20 per group) are required to be 85% sure, and 44 total patients (22 per group)
are required to be 90% sure, that the 90% two-sided confidence interval will exclude a
difference in means of more than 1. We feel that in this instance, certainty over 80% will
be clinically meaningful and have opted for 40 instead of 36 to better ensure the date
achieves at least 80% certainty.

For the total number per cohort, some number of patients will contact us and undergo
anonymous screening questions without collection of personal health information. This number
is difficult to predict, and those patients that do not meet eligibility criteria based on
the answers to these anonymous screening questions, are not included in either cohort as
there is no risk to them, again because no personal health information is being collected.

Data Analysis:

The proposed study design is one in which for each one of the three specific aims described
above, there is one dependent variable (outcome) and 1 independent variable (2 independent
populations: subjects with seborrheic dermatitis and scalp itch and controls without scalp
itch or seborrheic dermatitis). For non-normal data, we intend to use a non-parametric test,
such as the Mann Whitney or Wilcoxon rank sum test to assess for statistical differences
between the medians between these populations. In addition, we will use non-parametric
analysis, such as the Spearman correlation to correlate results of the skin testing with
results of the immunohistochemical counts of nerves. If in fact distributional assumptions
are met to allow parameteric analysis, we will use a 2 independent sample t-test to assess
for statistical differences between the means.

Inclusion Criteria:

Study Subjects

- Individuals 18 years or older

- Pruritus measured by VAS score for scalp itch greater than or equal to 30 in past
week and "dandruff" without skin changes or erythema but with histologic evidence of
at least focal or mild epidermal spongiosis

- Pruritus measured by VAS score for scalp itch greater than or equal to 30 in past
week and seborrheic dermatitis, including histologic evidence of at least focal or
mild epidermal spongiosis

- No topical anti-pruritic treatments and no prescribed or over-the-counter topical
seborrheic dermatitis treatments for at least 3 weeks before initiation of study,
including antifungal shampoos, tar or urea-containing shampoos, selenium sulfide or
zinc-containing shampoos, or topical steroids

- Willingness to forgo elective (ie PRN) use of systemic over-the-counter or prescribed
antihistamines to treat conditions other than chronic pruritic skin diseases (for
example, seasonal allergies) for at least 3 weeks before initiation of the study

Control Subjects

- Individuals 18 years or older

- No pruritus of the scalp as measured by VAS score for scalp itch less than 30 in past
week and no "dandruff" or scalp skin changes or erythema and no histologic evidence
of at least focal or mild epidermal spongiosis

- No pruritus of the scalp as measured by VAS score for scalp itch less than 30 in past
week and no seborrheic dermatitis, including no histologic evidence of at least focal
or mild epidermal spongiosis

- No topical anti-pruritic treatments and no prescribed or over-the-counter topical
seborrheic dermatitis treatments for at least 3 weeks before initiation of study,
including antifungal shampoos, tar or urea-containing shampoos, selenium sulfide or
zinc-containing shampoos, or topical steroids

- Willingness to forgo elective (ie PRN) use of systemic over-the-counter or prescribed
antihistamines to treat conditions other than chronic pruritic skin diseases (for
example, seasonal allergies) for at least 3 weeks before initiation of the study

Exclusion Criteria:

- Individuals with the diagnosis of psoriasis or evidence of psoriasis in other
non-scalp body areas

- Individuals with evidence of any primary scarring alopecia (active or inactive).

- Individuals with non-dermatologic scalp itch, including scalp itch with no scale (ie
dandruff) or erythema, individuals with senile pruritus of the scalp, or scalp
dysthesias (such as in the setting of anxiety/mood disorders).

- Individuals on anti-depressant medication specifically to treat pruritus. (Patients
on anti-depressants for non-pruritus reasons and that meet the VAS criteria for itch
will be included).

- Individuals with known psychiatric or substance abuse disorders that would interfere
with cooperation with the requirements of the trial

- Individuals unable to read and/or comprehend the questionnaires utilized in this
study

- Individuals that present with haircare practices associated with scarring alopecias,
such as but not limited to, hot combing, chemical relaxers/straighteners, and tight
braiding

- Individuals with an allergy and/or history of adverse reaction to lidocaine used for
the scalp biopsy

- Any use of systemic anti-pruritic or anti-fungal treatments in the 3 weeks prior to
initiation of the study, including systemic corticosteroids, immunosuppressive
agents, phototherapy, or antihistamines (in the setting of chronic use for
anti-pruritic therapy, such as chronic urticaria)

- Women who are pregnant