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A verruca is a wart on the foot, and like warts affecting other areas of the body it is caused by the skin becoming infected with the Human Papilloma Virus (HPV). There are hundreds of different types of HPV and several can cause Verrucae/Wart infections.
Infection occurs via direct contact with the virus mainly as a result of walking barefoot on contaminated floor surfaces such as communal showers, saunas, hotel bathrooms, swimming baths, gymnasia, etc. Although verrucae can infect any area of the foot it is these areas of the skin that make contact with the ground (weight bearing areas), that are therefore more vulnerable.
Areas of broken skin such as cuts, graze, open blisters, and cracks (often present with eczema / dermatitis / psoriasis / athletes foot) are particularly vulnerable to verrucae infection. If the skin is healthy and intact then risk of infection is minimal, wearing ‘flip flops’ in communal areas would reduce the risk of infection.
Initially the verruca will be small and go un-noticed. Eventually you may become aware of a small area of thickened skin developing. At this stage the verruca will be painless and if ignored may not necessarily increase in size. If the verrucae does increase in size to the point at which it becomes symptomatic (eg painful to walk on) then treatment can be considered.
We would advise patients that if verrucae are asymptomatic (do not cause discomfort), and if the verrucae have not proliferated dramatically, then patients should ignore them.
Providing a patient is not immuno-compromised then verrucae will eventually clear without treatment. This form of spontaneous cell mediated immunity occurs faster in young children than in adults. Approximately 60% of children’s warts & verrucae clear spontaneously within 2 years. For this reason we would urge parents of particularly young children to ignore verrucae unless they become symptomatic. This advice is now widely accepted within Dermatology and Podiatric Medicine as standard.
The most common cause of verrucae increasing in size and proliferating is un-necessary self treatment using over the counter caustics/acids particularly in combination with regular debridement with a pumice/files. The vast majority of patients who use these treatments will only succeed in making their verrucae worse!
There is a huge assortment of ‘weird and wonderful’ suggestions, potions, and treatments that are often mentioned by patients with regard to verruca treatments. Unfortunately there is no ‘magic bullet’ as no treatment can offer a simple, quick, and painless cure.
Cryotherapy involves the application of a very cold substance onto an affected lesion in order to create a form of controlled burn. Liquid nitrogen at -195°C is the substance used for treatment of hand warts and verrucae at this practice.
Liquid nitrogen is our preferred choice of substance as it is far colder than other substances available (nitrous oxide & ethers, acquired at pharmacies for self treatment). Since liquid nitrogen is much colder (at least x3 colder), it delivers a quicker and more effective burn, and consequently will provide higher rates of cure than commercially available products (when used by an experienced practitioner).
Cryotherapy is simple and quick to undertake and as it does not break the surface of the skin, the affected area does not require dressing, and does not have to be kept dry directly following the treatment. Since liquid nitrogen is not toxic or poisonous, it is a perfectly safe medium with which to deliver a therapeutic burn (79% of the air you inhale is nitrogen gas!)
If after three treatments the wart/verruca had failed to clear, then cryotherapy would normally be discontinued and an alternative form of treatment considered.
Is cryotherapy painful?
The majority of patients who receive cryotherapy on weight bearing verrucae will experience discomfort/pain during treatment, and some level of discomfort that will normally last for 1-4 days (possibly sufficient to cause a modest limp).
Hand warts are tolerated much better and will rarely cause any significant pain beyond 24 hours.
The level of discomfort experienced, during and after cryotherapy, varies depending on the following factors:
SIZE OF AREA TREATED - the larger the surface area treated, the greater the levels of discomfort.
PRESSURE APPLIED AT TIP OF PROBE – the more that pressure is applied onto the skin via the tip during the treatment, the greater the levels of discomfort.
DURATION OF FREEZE – the longer the ‘freeze’, the greater the levels of discomfort. Average duration of freeze is between 10-30 seconds.
SITE – verrucae frozen on weight bearing areas can be painful for several days if treated aggressively. Cryotherapy is generally used less aggressively on non weight bearing warts (where the skin is thinner) and therefore the duration and intensity of any pain is less pronounced and well tolerated in comparison to that on weight bearing areas.
How effective is cryotherapy?
It is important to consider that a ‘one off’ painless cure for verrucae does not exist, and although some verrucae will clear with one treatment of cryotherapy, some (mainly weight bearing verrucae) can prove very difficult to clear even after aggressive and painful cryotherapy treatments.
Cure rates for cryotherapy are maximised when liquid nitrogen is used (it is much colder than other substances available). Children demonstrate higher rates of cure than adults, and the longer the wart/verruca has been present the more resistant to treatment it can become. The more aggressive the liquid nitrogen is applied the higher the cure rate.
For warts anywhere other than on the weight bearing areas of the feet cryotherapy can prove very effective. We can offer over 90% cure rates for warts on hands. However warts on the sole of the foot (verrucae) are by far more difficult to clear with cure rates of 50-60% after three treatments.
The use of strong acids in Podiatry is mainly used for the treatment of Verrucae. The treatment can also be used to produce tissue destruction where a foreign body (usually animal hairs / splinters / fibres etc) are suspected to be present within the dermis of the skin.
For treatment on suspected foreign bodies the two caustics used at this Practice are
1 Monoclhoroacetic Acid (100% saturated crystals)
2 Salicylic Acid (70% paste)
3 Silver Nitrate (95%)
The principle of the treatment is to produce tissue destruction down to the level of the suspected foreign body. Once sufficient tissue destruction has been achieved the necrotic tissue (dead skin) that the acids have produced, is removed exposing a small ulcer, the ulcer will then heal uneventfully over the next week or two. Hence the treatment is intended to ‘burn a hole in the skin’.
Although the treatment is painless when the acids are applied to the skin, patients will feel discomfort two days later as the caustics begin to affect the dermis. Discomfort varies significantly depending on how much acid has been applied, however it is common for the discomfort to be enough to cause patients to limp for at least two days.
If the levels of discomfort become intolerable then the cover and strapping should be removed and the foot soaked in warm salt water. Patients should then contact the surgery.