The Nd: YAG 1064nm is a long wave infrared laser. It is commonly used for vascular conditions e.g broken veins, angiomas. The light energy needs a chromophore – pigment to be attracted to and create a thermal response. At different wavelengths different chromophores. With the verruca it is predominately the blood product found in the petechial traumatic bleeding embedded in the verruca tumour. These are the black dots, commonly thought for many years by podiatrists to be the tips of drawn up capillary loops. In a recent JAAD article: Black dots in palmoplantar warts—challenging a concept: A histopathologic study this has been revealed not to be the case. Despite this new discovery it is the blood pigment which is the main chromophore. Other chromphores are the infected cellular walls and water.
The light energy basically coagulates the blood and causes thermal cellular tissue damage. It too like the Swift can initiate heat proteins and mediate an immune response, but this would be performed with the laser set at very low fluence/ energy/ power. Generally, when treating VPs the settings are high , as much as 240 J/cm 2, so the main effect is thermal damage, The heat is allowed to build up in milliseconds in the verruca just enough to denature the tisssue proteins. The correct settings for effective verruca laser destruction were determined by the Laser Health and Academy: Treatment of warts with 1064 nm Nd:YAG.
. A podiatrist has to be skilled in analgesia techniques and post wound care. It must be remembered if infiltrating a verruca directly with Mepvicaine analgesia an additional chromphore has been added to asborb energy, so less passes are required and lower fluence to do the job. Blisters or haematomas are the outcome of a laser treatment. The tumour tissue is destroyed which needs at some point to be debrided, excised then appropriately dressed, off-loaded etc. Every result is different and I would not recommend laser treatment for all verrucae, but it is efficacious for treatment resistant and multiple singular type VPs and those stubborn ones for which patients want a quick solution.
Post treatment the discomfort caused by a laser is in my experience anecdotally less intense than that resulting from the application of strong acid keratolytics. The haematomas may look dramatic especially after debridement, but resulting ulceration is not common. Laser treatment is more controlled than acid treatments. Wounds take on average 2-4 weeks to heal depending on size, depth and position of the presenting infection.
Where we see a big role in our clinic for the laser is in treating patients who are immuno-compromised. The Swift is inappropriate for these types as a main role of the Swift is to mediate an immune response. It is hard to determine the strength and status of an individual’s immune system. A perfectly healthy individual with an HPV infection may respond to no treatments. A genome issue, but the laser can bypass these issues if all of the infected tissue is ablated, much like removing a cancerous growth. This applies also to those patients who may have their immune system suppressed for example by methotrexate. Methotrexate dampens the body’s inflammatory response. Traditional conventional verruca treatments deliberately cause inflammation as part of the healing cascade process to trigger antibody involvement. The laser is not concerned with this, but all said and done the patient has to be in good health to heal post treatment. Don’t use a laser on an ‘at risk’ patient type.
Patient selection is just as important as treatment choice for any verruca or wart.
1) Evaluating the success of Nd: YAG laser ablation in the treatment of recalcitrant verruca plantaris and a cautionary note about local anaesthesia on the plantar aspect of the foot E.A. Smith et al 2014