準分子雷射矯正疤痕與白紋色素過低現象安全有效


  Aug. 17, 2004 - 一項發表於8月號皮膚學學誌(Archives of Dermatology)的隨機分派控制試驗結果顯示,以308奈米的準分子雷射治療,對於矯正疤痕與白紋色素過低現象是安全且有效的方法。
  
  紐約市紐約雷射與皮膚手術中心Macrene R Alexiades—Amenakas醫師與他的同事表示,由於缺乏一種高度有效的、低風險的療法,長久以來,疤痕與白紋色素過低現象的治療一直被認為是個挑戰;這項308奈米的準分子雷射已經被用於白斑與換膚後白斑加深色素用。
  
  為了評估308奈米準分子雷射療法,31位成人,包括22位疤痕色素過低、9位白紋色素過低,與正常控制組區域一起被隨機分派接受治療或沒有接受治療;色素矯正是主要的試驗終點,以目視及色度計測量。
  
  雷射治療受影響區域起始劑量為病患個體造成紅腫的劑量減去50 mJ/cm2;每2個星期治療一次,直到50%—75%的色素過低被矯正後,才改為2個月治療一次;最多治療10次、以色度計測量增加了75%深度、或是目視100%矯正。
  
  試驗結果顯示,以上述兩種方法評估,色素矯正百分比與治療次數成正比上升,此外,沒有發生水泡或不當的色素沉積。
  
  經過9次治療後,相較於控制區域,不論是目視(平均61%﹕95%信賴區間,55%—67%)或色度計測量(平均102%﹔95%信賴區間,99%—104%),疤痕色素深度明顯地被矯正。
  
  而白紋在接受9次治療後,相較於控制區域,最可能顯著地矯正色素過低的現象,不論是以目視(平均,68%﹕95%信賴區間,62%—74%)或色度計(平均,102%﹕95%信賴區間,99%—104%)測量。
  
  治療後,研究人員針對受試者追蹤6個月,結果發現,矯正值逐漸回到基本值,暗示可能需要維持性治療。
  
  研究人員指出,這項新的治療發明的主要限制,為疤痕與白紋的色素矯正需要維持性治療,研究人員進一步指出,膚色較淺的病患可能比膚色較深的患者需要更頻繁的維持性治療(每1到2個月1次)。
  
  研究人員表示,以紫外線B為主的皮下雷射治療可能與癌症發生率的增加有關;曾經有報導指出,使用紫外線B治療的病患可能與扁平細胞瘤或非黑色素瘤的發生有關,但是這些結果不是一致的;儘管如此,計算出增加的風險顯然是很低的。
  
  研究人員總結指出,以308奈米準分子雷射治療疤痕與白紋的色素過低現象是安全且有效的;此外,治療執行者應該告知病患為了要達到長期效果,必須接受維持性治療。
  
  其中一位研究人員接受Photomedex的資助,這家公司是這項試驗中Xtrac氯化氙準分子雷射製造廠商。

Excimer Laser Corrects Hypopig

By Yael Waknine
Medscape Medical News

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Aug. 17, 2004 — Therapy with the 308-nm excimer laser is a safe and effective method of correcting hypopigmentation in scars and striae alba, according to the results of a randomized controlled trial published in the August issue of the Archives of Dermatology.

"Hypopigmented scars and striae alba have long been a therapeutic challenge for which a highly effective, low-risk treatment modality has been lacking," write Macrene R. Alexiades-Armenakas, MD, PhD, and colleagues, from the Laser & Skin Surgery Center of New York in New York City. "The 308-nm excimer laser has been used in the repigmentation of vitiligo and postresurfacing leukoderma."

To assess effects of 308-nm excimer laser therapy, lesions in 31 adult subjects with hypopigmented scars (22 patients) and striae alba (nine patients) were site-matched with normal control areas and randomized to receive treatment or no treatment. Pigment correction was the primary end point of treatment and assessed both visually and by colorimetric measurements.

Laser treatment of affected areas was initiated using a patient's individual erythema dose minus 50 mJ/cm2. Biweekly treatments were administered until 50% to 75% pigment correction was achieved and then reduced to a bimonthly schedule to a maximum of 10 treatments, 75% increase in colorimetric measurements, or 100% visual pigment correction.

Results showed that the percentage of pigment correction, as assessed by both methods, increased in direct proportion to the number of treatments. No incidences of blistering or dyspigmentation were reported.

After nine treatments, scars achieved significant pigment correction compared with control areas, as assessed visually (mean, 61%; 95% confidence interval [CI], 55% - 67%) and by colorimetric measurement (mean, 101%; 95% CI, 99% - 103%).

Significant pigment correction was likewise achieved after nine treatments in striae alba compared with control areas, as assessed visually (mean, 68%; 95% CI, 62% - 74%) and by colorimetric measurement (mean, 102%; 95% CI, 99% - 104%).

Values gradually declined toward baseline during a six-month follow-up, suggesting the need for maintenance treatments.

"A major limitation of this new therapeutic intervention for pigment correction of scars and striae alba is the need for maintenance treatments," the authors write, noting that patients with lighter skin types would likely require maintenance treatment more frequently (every one to two months) than patients with darker skin types.

Increased risk of carcinogenesis may also be associated with cutaneous use of the UV-B–based laser therapy. "Inconsistent results regarding squamous cell carcinoma and other non-melanoma skin cancer rates in UV-B–treated patients have been reported; nevertheless, the calculated increased risk appears to be low," the authors write.

"Treatment with the 308-nm excimer laser is safe and effective in pigment correction of scars and striae alba," the authors conclude. "The practitioner should inform patients of the need for maintenance treatments for durable results."

One of the authors received funding from Photomedex, the maker of the Xtrac xenon chloride excimer laser used in this study.

Arch Dermatol. 2004;140:955-960

Reviewed by Gary D. Vogin, MD

    
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