Randomized, double-blind, placebo-controlled prospective study of the efficacy of topical anaesthesia with a eutetic mixture of lignocaine 2.5% and prilocaine 2.5% for topical 5-aminolaevulinic acid-photodynamic therapy for extensive scalp actinic keratoses.

BACKGROUND: Photodynamic therapy (PDT) is an effective treatment modality for the treatment of extensive scalp actinic keratoses (AKs), but pain is a significant drawback when treating large areas with topical PDT using 5-aminolaevulinic acid (ALA) as sensitizer. A recent study has shown that use of tetracaine gel (Ametop) did not significantly reduce pain associated with PDT.

OBJECTIVES: To assess the benefit of a eutetic mixture of lignocaine 2.5% and prilocaine 2.5% (Emla) on pain during topical ALA-PDT treatment of scalp AKs.

METHODS: Fourteen men aged 59-83 years with extensive scalp AKs were recruited into a double-blind placebo-controlled study. Two treatment fields were defined (right and left frontal scalp) and were treated 2 weeks apart. These fields were randomized to receive either Emla or Aqueous cream as first or second treatment. ALA 20% cream was applied for 4 h. Topical anaesthesia or Aqueous cream was applied for 2 h. Pain was assessed using a visual analogue scale (0-100 mm) at 3, 6, 12 and 16 min. The instrument used for this was a blinded counter with one side reading 'no pain' to 'worst pain ever' with a numerical scale (0-100) on the reverse side. Pain scores were assessed looking at median and interquartile range and confidence intervals and calculating differences between treatment groups and analysing them using a paired t-test.

RESULTS: Thirteen patients received treatment to both fields. No significant difference in mean pain scores was seen with the use of Emla cream compared with placebo during treatment of scalp AKs (P = 0.328). There was no significant difference in requirement for oral analgesia following PDT between the two groups (P = 0.06).

CONCLUSIONS: Our data do not support the routine use of topical anaesthesia with Emla for topical PDT.