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Psoralen
and ultraviolet A radiation (PUVA) for alopecia areata
Although research over the last few years has yielded valuable
data on the etiology and pathogenesis of the insidious form of
hair loss in alopecia areata, there are still many grey areas,
and the answers of many unfathomable questions continue to elude
scientists and medical experts. With an enigmatic etiology, there
is neither a permanent cure for alopecia areata nor a universally
proven therapy for inducing remission. Early intervention is crucial,
and most patients can be offered hope and support to help them
cope with the months of treatment usually needed to achieve reduction
in disease symptoms.
PUVA has been used with variable success in the treatment of
alopecia areata. PUVA is a type of ultraviolet radiation treatment
(phototherapy) used as an immunomodulatory treatment for severe
skin diseases. PUVA stands for Psoralen (P) and ultraviolet A
(UVA) therapy. Ultraviolet (UV) light therapy has been use for
many years to treat varied recalcitrant skin conditions as psoriasis,
vitiligo, atopic dermatatitis, and pruritis (itching). In PUVA
therapy, the patient is exposed first to Psoralens (drugs containing
chemicals that react with ultraviolet light) and then to UVA light.
This combination treatment is also called Psoralen photo chemotherapy.
Psoralens are compounds found in many plants which make the skin
temporarily sensitive to UVA. In fact, ancient Egyptians were
the first to use Psoralens for the treatment of skin diseases
thousands of years ago. As a drug, the chemical 8-methoxypsoralen
(8-MOP) in the form of capsules is taken by mouth about two hours
prior to radiation, which allows the deeply penetrating UVA band
of light to work on the skin. Psoralen acts as a photosensitizer
by enhancing the biological effects of the broad-spectrum, high
intensity, artificial source of long-wave UV radiation. The effectiveness
of PUVA has been widely documented and has been widely accepted
for providing the best therapy for progressive skin disorders.
A typical PUVA session consists of coming into a dermatology
office, removing clothes from the affected body areas and standing
in a five foot square by seven foot high light box. The UV lights
are then turned on for 1-10 minutes. The length of each session
is increased marginally over the previous session. Patients must
wear groin protection while in the light box.
Success
rate of psoralen and ultraviolet A radiation (PUVA) in
alopecia areata treatment
In any dermatological condition, the ideal treatment would be
one that is effective, easy to apply, painless, free of side effects,
and inexpensive - therapy should always be commenced with the
treatment module that fulfills as many of these criteria as possible.
Moreover, therapeutic management should always be undertaken by
dermatologist or a physician with experience in the treatment
of hair diseases.
PUVA has been used with variable success in the treatment of
alopecia areata. PUVA may be an effective treatment through its
photo-immunologic effect on T cells. The immunosuppression induced
by PUVA therapy in the treatment of alopecia areata can be attributed
to different mechanisms:
- The disappearance of epidermal Langerhans cells and their
decreased antigen-presenting capacity after PUVA treatment have
been suggested to play a crucial role in the immunosuppression
induced by PUVA treatment.
- PUVA treatment induces apoptosis(programmed
self death) in T-lymphocytes
- PUVA treatment has also been shown
to influence the release of cytokines (Chemical messengers
which play a role in regulating
the body's immune response).
- Because dendrite cells are thought
to play an important role in the initiation of Alopecia areata by antigen-presentation
and
co-stimulation, PUVA treatment might exert an inhibitory effect
on the development of this form of hair loss.
- PUVA has been
shown to stimulate the Dopa-negative melanocytes in the outer
root sheath to divide and proliferate. As melanocytes
appear to be playing an important role in alopecia areata,
this interplay during PUVA therapy may be important to a successful
clinical response.
Various experimental studies have been carried out on alopecia
totalis, alopecia universalis and alopecia areata patients who
have been treated with photo chemotherapy, combining topical 8-methoxypsoralen
(8-MOP) with UV irradiation of the scalp at a phototoxic dose.
Both topical and oral Psoralen combined with exposure to ultraviolet
light A (UVA) has shown variable results in the treatment of alopecia
areata.
Some studies show good results with cosmetically acceptable hair
re-growth in 40% to 55% of treated patients, but there are no
controls in any of the studies and, therefore, the claimed response-rate
includes an unknown number of cases showing spontaneous re-growth.
For limited, patchy alopecia areata there have been claimed success
rates of up to 56%, but the treatment required was extensive and
included whole body irradiation. Some reports indicate that PUVA
is not an effective treatment, but in other clinics, PUVA for
alopecia areata is still used. Overall the use of PUVA for alopecia
areata is limited, and often it is only considered after other
treatments such as corticosteroids have failed.
Moreover, there are a high number of relapses (between 30% and
50% of successfully treated patients) after initial hair re-growth,
which strongly decreases the efficacy of PUVA treatment of alopecia
areata. This high number of relapses is most likely due to the
fact that re-grown hair prevents the UVA light from reaching the
skin. Technical improvement such as a comb emitting UVA light
has been tried, but so far no quantifiable results have been reported.
Unfortunately, a continuous hair re-growth after the initial response
has to be actively maintained for several years in most cases.
Precautions
and side effects of psoralen and ultraviolet A radiation
(PUVA) treatment
Although PUVA is recognized as the treatment of choice for various
dermatic dermatoses, PUVA has been associated with health hazards
in humans. The greatest hazard is that it increases the risk for
cancer of the skin, a risk that includes melanoma, a highly malignant
and sometimes fatal form of skin cancer. Patients who receive
long-term PUVA treatment should therefore be carefully monitored
throughout their lives. These patients should also report to their
healthcare practitioners any peculiar skin abnormalities, including
abnormally pigmented areas and skin that is changing color or
size, itching, or painful. Other side effects caused by PUVA therapy
include:
-
Headache and dizziness.
- An overdose of PUVA can result in a
sunburn-like reaction called phototoxic erythema which is more
likely in fair skinned patients
who sunburn easily. A burn is most likely 48 to 72 hours after
the first two or three treatments.
- Nausea is not uncommon.
- Redness of the skin.
- Temporary mild pricking or itching of
the skin is common after treatment as the skin is often rather
dry.
- Stinging sensation.
- Tan or darkening of the skin which lasts
several months. Although the skin appears brown it may still
burn easily on sun exposure.
- Skin aging
Because of the increased risk of squamous cell carcinoma, basal
cell carcinoma and malignant melanoma post long-term PUVA therapy,
PUVA therapy is not recommended for Alopecia areata by many authors
even if technical improvement likes a UVA-comb should ultimately
prove to be effective. Although PUVA therapy may play a role in
the management of alopecia areata, these concerns combined with
the need for long-term therapy, make this treatment modality less
than satisfactory. Narrow-band UVB has the potential to play a
more pro-active role in the treatment of alopecia areata than
PUVA. However, clinical research studies to confirm the efficacy
of this treatment modality remain to be completed.
Psoralen
and ultraviolet A radiation (PUVA) for alopecia areata
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