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Phototherapy
with ultra violet B light for alopecia areata
The use of phototherapy with ultraviolet B light has been explored
as a treatment option for alopecia areata and has been reported
to be useful in some patients. Ultraviolet (UV) rays of sunlight
can be helpful for certain skin conditions, but they can also
be harmful when the exposure rate is high. When sunlight penetrates
the top layers of the skin, ultraviolet radiation bombards the
genetic material (the DNA), inside the skin cells causing injury.
It also impairs immune function in the skin. Such effects are
the cause of wrinkles, aging skin disorders, and skin cancers.
These same damaging effects, however,
can be used to destroy the skin immune cells and be used for
skin therapy, by altering the amounts and kinds of chemicals the
cells make and causing the death of certain cells that are involved
in skin diseases. The use of UV light in this manner to treat
disease is called phototherapy. With phototherapy, Doctors apply
the minimum amount of UV light to gain beneficial effects in treating
skin disease while limiting the harmful effects.
Because natural sunlight exposure varies in intensity and is
not practical for a large part of the year in certain climates,
phototherapy is nearly always performed with artificial UV light.
Treatments are given in a doctor's office or in a specialized
treatment center. Depending on its wavelength, ultraviolet light,
which is invisible to the human eye, is classified as A, B, or
C. UVA or UVB is chosen based on the type and severity of the
person's disorder, while ultraviolet C is not used in phototherapy.
Ultraviolet A (UVA) penetrates deeper into the skin than ultraviolet
B (UVB) and is used in one treatment approach for alopecia areata
called “PUVA”. PUVA is a type of phototherapy used
as an immunomodulatory treatment for severe and recalcitrant skin
diseases such as psoriasis, vitiligo, atopic dermatatitis, and
pruritis (itching) as well as alopecia areata. PUVA stands for
Psoralen (P) and ultraviolet A (UVA) therapy. 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.
See the related page on PUVA treatment for alopecia areata in
this section of the web site for more details.
UVB is about 1,000 times more powerful than UVA in producing
sunburn. Mild pink skin (erythema) caused by UVB, in fact, can
be effective against psoriasis and other skin diseases. The same
skin tone caused by UVA alone, however, does little good. Overall,
UVB light poses a lower risk for skin cancers, including melanoma,
than UVA light.
Ultraviolet
B (UVB) phototherapy
Ultraviolet light B (UVB) is an effective form of ultraviolet
radiation, and is used primarily for treating skin eruptions as
in psoriasis, a non contagious inflammatory skin disease characterized
by recurring reddish patches covered with silvery scales. UVB
radiation penetrates the skin and slows the abnormally rapid growth
of skin cells associated with psoriasis. This treatment measure
involves exposing the skin to an artificial UVB light source for
a set length of time on a regular schedule, either under a doctor's
direction in a medical setting or with a home unit purchased with
a doctor's prescription. UVB is administered in a full-body cabinet
containing a bank of light tubes that expose the body to UV light
all at once, or through smaller units that treat just one part
of the body. To enhance penetration of UVB rays, an emollient
is usually applied before exposure.
There are 2 types of UVB phototherapy:
Broadband: Broad spectrum UVB is radiation measured at wavelengths
290 to 350 nm (UVB radiation below measurements of 300 nm is toxic
but not effective, while radiation above 300 nm is more therapeutic),
and has been the standard UVB phototherapy treatment for quite
a while. The biggest drawback is that broadband light does not
reach the scalp and areas where skin folds occur. Broad spectrum
UVB phototherapy may be administered as follows:
- Using UVB radiation alone
- UVB treatment with coal tar (the
Goeckerman regimen)
- UVB with anthralin (the Ingram regimen)
Narrowband: This newer form of UVB therapy is called “narrowband” because
it emits a narrower band of UVB wavelengths. Narrowband UVB therapy
is proving to be more effective than the traditional broadband
therapy. Like broadband, it is still not known if narrowband UVB
therapy poses a long-term risk for development of skin cancer,
but narrow band UVB is likely to be far safer than UVA light.
Exposure times are shorter but are of higher intensity than with
broadband UVB, with the result that the course of treatment is
also shorter. Narrow band UVB has been found to be very efficient
in reducing T-cells in the skin.
Alopecia
areata and UVB therapy
Alopecia areata has been shown to be responsive to systemic PUVA
therapy, presumably via its immunomodulatory effects. As narrow
band UVB had previously been demonstrated to be effective for
a number of other PUVA-responsive disorders including psoriasis,
parapsoriasis and vitiligo, a few research teams have endeavored
to determine the efficacy of narrow-band UVB light therapy for
extensive alopecia areata.
Thirty-two patients between the ages of 6 and 70 years with extensive
alopecia areata were treated with a Kromayer's ultraviolet lamp.
Biologically active waves were applied directly to each of the
bald patches with moderate pressure for time duration of 3 and
60 seconds, with each patient receiving enough light to cause
an erythematous reaction. Treatments were repeated weekly or every
other week. Reports indicate that 25 of the 32 patients observed
hair growth within the first 3 months of treatment and full hair
and beard re-growth occurred in 14 of 25 patients with alopecia
areata. Moreover, "almost full re-growth" was noted
in 4 patients with alopecia areata and 1 patient with alopecia
totalis. Neither of the other 2 patients with alopecia totalis
and none of the patients with alopecia universalis made further
progress after the initiation of insignificant re-growth in the
first 3 months of therapy. However, several of the patients experienced
hair loss after treatment was discontinued.
The results of these studies indicate that the use of phototherapy
with ultraviolet B light has been useful in some patients with
alopecia areata. The proposed mechanism of action is that Ultraviolet
(UV) light induces biologic reactions in the skin’s cells
that decrease the number of skin cells that grow too quickly and
kills T cells in the skin.
Side
effects of UVB light therapy
Significant side effects are uncommon with UVB therapy, but mild
sunburn should be expected. It is at its worst about 8 hours after
the treatment and fades over the next few days. Patients develop
some degree of tan. A severe blistering burn is rare when UVB
is properly administered but the possibility of it occurring cannot
be ruled out. Occasionally, after several sessions of UVB, white
and brown spots appear on the skin. A few people can get worse
or itch more from UVB. Although there is no proven link between
Narrow Band UVB phototherapy and skin cancer, it is important
to remember that excessive exposure to UV light causes premature
aging of the skin and does increase the patient’s risk of
skin cancer.
Phototherapy
with ultra violet B light for alopecia areata references
- Friedli A, Hunziker T, Finkel B, Braathen LR. Effects of acute,
low-dose UVB radiation on the induction of contact hypersensitivity
to diphenylcyclopropenone in man.
Arch Dermatol Res. 1993;285(1-2):1-5.
PMID: 7682397
- Monfrecola G, D'Anna F, Delfino M. Topical hematoporphyrin
plus UVA for treatment of alopecia areata. Photodermatol. 1987
Dec;4(6):305-6. PMID:
3444756
- Frentz G. Topical treatment of extended
alopecia. Intralesional steroid--Kromayer lamp. Dermatologica.
1977;155(3):147-54.
PMID: 892120
- Belezos NK. Local estrogen and ultraviolet
irradiation in the treatment of total alopecia (areata). Dermatologica.
1965;131(4):304-8. PMID: 5865345
- Krook G. Treatment of alopecia areata
with Kromayer's ultra-violet lamp. Acta Derm Venereol. 1961;41:178-81.
PMID: 13754514
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