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Long-term results of single intradermal 1 % methylene blue injection for intractable idiopathic pruritus ani: a
N E Samalavicius1, T Poskus, R K Gupta
1Clinic of Internal, Family Medicine and Oncology, Faculty of Medicine, Oncology Institute, Vilnius University, 1 Santariskiu str., 08406, Vilnius, Lithuania.
Background:
The aim of this study was to assess the effectiveness and side effects of methylene blue injection into the perianal skin of patients with chronic refractory idiopathic pruritus ani (IPA).
Methods:
Patients with IPA who failed to respond to standard perianal skin care advice and treatment of associated pathologies were included. One per cent methylene blue solution was injected intradermally into the itching perianal area up to the level of the dentate line, with a 10-ml syringe with a 22-gauge needle, using a total of 15 ml. A patient symptom score from 1 to 5 was used (1 = worst). The study was designed as a single-centre, prospective, non-randomized trial.
Results:
Between September 2004 and November 2008, 10 patients with IPA were included in the study. Symptoms resolved within 4 weeks in all cases. Numbness of the perianal area and tattooing disappeared within the period of 3-4 weeks. There was no skin necrosis or anaphylaxis. The median follow-up was 47 months, range 29-60 months. Anal itching recurred in 8 patients. Four of those 8 patients noted that anal itching was less severe when it recurred, and it was unchanged in the other 4 patients. Six out of 10 patients felt much better or reported the resolution of pruritus ani.
Conclusions:
An intradermal application of 1 % methylene blue solution is associated with a positive effect on IPA with mild side effects related to sensory cutaneous innervation in all patients within the first 4 weeks following the procedure and a 20 % success rate within 60 months.
