Biomedical Engineering Reference
In-Depth Information
( A )
( B )
( C )
Figure 7.11 Striae ( A ) before, ( B ) immediately after, and ( C ) 3 months after three treatments with fractional radiofrequency device (wounds are 150
μ
m in diameter,
120-
μ
m depth, and about 20% total coverage per treatment).
with ablative CO 2 laser. Each of the patients had signifi cant
improvement in the appearance of the tattoos as well as nearly
complete resolution of symptoms associated with the allergic
reaction to the tattoo ink over the course of three to four treat-
ments (30). The proposed mechanism is transepidermal elimi-
nation of the tattoo ink through damaged dermis and
epidermis. These results, although not yet carried out in a ran-
domized prospective study, suggest a new avenue for approach-
ing tattoo inks that are diffi cult to treat with currently available
Q-switched lasers.
One challenge is the patient who presents with seborrheic
keratoses. We normally treat the seborrheic keratoses at the
beginning of the session with a 1- to 3-mm spot-pulsed CO 2 laser
followed by the fractional laser.
Vitiligo
The use of lasers in vitiligo has been mostly confi ned to the
308-nm excimer laser. Other modalities to improve repigmen-
tation in vitiligo include fully ablative lasers and dermabrasion
in conjunction with ultraviolet B phototherapy (28). A small
case series of 10 patients by Shin et al. suggest a possible adjunct
role for fractional laser in increasing the rates of repigmenta-
tion of nonsegmental vitiligo in resistant location (29). Studies
on a much larger scale would need to be undertaken to confi rm
effi cacy and propose an underlying mechanism of effect if this
treatment is indeed substantiated. On the other hand, Kilmer
(personal communication) has reported the appearance of vit-
iligo 2 months after ablative fractional treatment for acne scar-
ring. In this patient, there was a family history of vitiligo and
presumably the side effect was a koebnorization phenomenon.
Surgical and Traumatic Scarring
One of the primary roles for ablative fractional technology has
been in the treatment of scars. In contrast to thinking of the
scar as being “treated,” recent work has focused on the scar as
a defect to be “rehabilitated” (Dr. Daniel Driscoll, Shriner's
Hospital, Boston, Massachusetts, USA). In military dermatol-
ogy, much work has been done in the treatment of contracture
scars among wounded veterans. Preliminary data indicate a
role for ablative lasers in improving skin pliability and increas-
ing range of motion (13). Other data suggest a role in reducing
chronic ulceration. The molecular mechanisms by which this
may occur are unclear but may be associated with the deposi-
tion of type 3 nascent collagen in conjunction with a change in
the therapeutic milieu of the scarred tissue. Clinically we usu-
ally apply two to three sessions 2-3 months apart. Regardless
of the wavelength, normal total densities in any session range
Tattoos
Traditionally, tattoo removal has been accomplished with the
use of Q-switched lasers in the visible and near-infrared spec-
trum. Ablative fractional lasers have recently been studied as
an adjunct strategy. A case report by Ibrahimi et al. describes
two cases of tattoos that resulted in an allergic reaction treated
 
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