I. Introduction

In cases where HS is not sufficiently well controlled by medication, the added use of laser therapy in combination with medications can be helpful to better manage the disease. Especially for patients with moderate to severe HS, laser therapy may be recommended as a treatment option. Some benefits of laser therapy include its limited adverse side effects and ability to be performed in a clinic setting without the need for general anesthesia.

While LASER is popularly used as a single term, it is actually an acronym for Light Amplification by Stimulated Emission of Radiation. A laser is a medical device that uses multiple colors and wavelengths of focused light to treat various skin disorders, including HS.

Many different types of lasers have been developed. Each type of laser has unique properties and varying effects. This chapter outlines the basic principles of laser devices and how lasers and lights can benefit patients with HS. The role of the Nd:YAG laser, carbon dioxide (CO2) laser, and photodynamic therapy in the management of HS is discussed.

II. Hair Reduction (Nd:YAG Laser Treatment)

While we do not fully understand the exact cause of HS, current research indicates that HS develops when a hair follicle (which refers to the base of the hair) becomes clogged with keratin (a type of protein in the skin, hair, and nails).

Hair follicles clogged from excessive keratin, sweat, and bacterial growth lead to painful and swollen bumps. The plugged hair follicles can rupture and lead to an inflammatory response. People with HS experience this inflammation as pain and drainage. Given that hair follicles play an important role in the development of HS, lasers that reduce hair follicles may be a good treatment for select people with HS.

One of the most popular laser devices used to reduce hair follicles is the Nd:YAG laser. This type of laser can penetrate deeper into the skin than other lasers, using a beam of intense light that targets the hair follicle roots. The laser light released from the Nd:YAG device produces permanent, heat-causing damage to the follicle. Treatment with the Nd:YAG device may stop hair growth more effectively for some individuals than others.

There are many benefits to this type of treatment. These include reduction in disease severity, reduction in symptoms (e.g., less pain and/or drainage), reduction in the number of HS flareups, and decreased reliance on systemic medications. Another advantage of this type of laser treatment is its ability to be performed in a clinic without the need for general anesthesia.

It is important to note that there are factors to consider to help determine if the Nd:YAG laser is an ideal treatment option for a patient. This type of laser may not be appropriate for patients with severe HS (Hurley stage III) due to the presence of scar tissues and sinus tracts. Hair reduction laser procedures are primarily limited to patients with clinical stage I and stage II disease as a result. Additionally, because the laser works by targeting hair pigment, it is best suited for patients with fair skin and dark hair.

There are minimal risks associated with hair reduction procedures when performed by a trained dermatologist who is board-certified by the American Academy of Dermatology, but there may still be side effects. Although the treated area is numbed (with the use of a numbing medication called lidocaine), it is not uncommon for patients to experience discomfort and stinging during the procedure. Some patients have reported that the sting from a laser procedure feels similar to the sting of a rubber band snapping on the skin. However, this varies among individuals.

One of the common side effects that people may experience after hair reduction laser procedures include skin discoloration (such as brown or white discoloration at the site of treated area). Some people may also experience an increase in pain and inflammation in the first week following treatment. Please discuss with your healthcare provider if this occurs.

Additional laser devices that are less utilized for hair reduction and less studied compared to the Nd:YAG laser include the intense pulsed light (IPL) therapy, long pulsed Alexandrite laser, and non-Q switched ruby laser. Of these other lasers, the Alexandrite and IPL have the most promise, but more research needs to be done.

III. Carbon Dioxide Laser Therapy

Carbon dioxide (CO2) laser therapy is effective for the treatment of persistent HS lesions, and for locating and removing HS sinus tracts/tunnels that may not be otherwise visible. This procedure is typically used for patients with moderate to severe disease (e.g., Hurley stage II-III. A benefit of the CO2 laser procedure is that the procedure can be performed in the clinic.

CO2 laser therapy allows areas to be carefully examined after the removal of affected tissue, which facilitates the discovery and subsequent removal of hidden lesions (e.g., tunnels).

After HS lesions are treated with CO2 laser therapy, healing occurs naturally without any sutures or wound closure. This process is called secondary intention healing (SIH). Due to this process, new lesions are less likely to form in the treated areas. In fact, several studies done on the use of CO2 laser therapy for HS showed that there is around a 90% chance that lesions will not return in the area that was treated. In rare cases, CO2 laser procedures result in complications, such as bleeding, discomfort, delayed healing, and infection.

Given the high success rates, most patients with HS are satisfied with the outcome of their CO2 laser therapy. When asked about the visual appearance of the areas treated, many patients report being pleased with what they consider an aesthetically pleasing outcome. Staged CO2 laser marsupialization is discussed in Chapter 23.

IV. Post-CO2 Laser Healing and Care

As discussed, lesions treated with CO2 laser therapy will heal naturally. This is especially beneficial for lesions located in areas with high friction such as axilla (armpit) and genitalia, as this type of healing reduces the likelihood of HS lesions returning.

It is important to note that natural healing, or secondary intention healing (SIH), is gradual and may take several weeks to months. Regardless of where the treated lesion is located, SIH is often successful. While bleeding and infection are all possible, these risks are rare.

Immediately after the procedure, the wound is covered with dry or ointment-infused dressings. The ointment used is often petroleum jelly (e.g., Vaseline). In addition to the dressing, a covering bandage attached with surgical adhesive tape or gauze underwear is also used. After the procedure, patients are instructed to leave the wound dressings on for 2-3 days. After that, the wound is cleaned and rinsed with tap water. From there, the wound dressing should be changed as needed until healing is complete.

With clear instructions from their healthcare provider, patients are usually able to perform their own dressing changes with minimal discomfort. Pain can also be managed with a short course of opiates, and patients are instructed to alternate between acetaminophen/paracetamol (Tylenol®) and ibuprofen (e.g., Advil®). Reducing pain during the recovery period is essential, since changing wound dressings can be painful. Patients should follow up with the healthcare provider who performed the CO2 laser therapy one week after the procedure and again six weeks after. General principles of HS wound care and dressings are further discussed in Chapter 15.

V. Photodynamic Therapy

Photodynamic therapy (PDT) is a well-known treatment used to treat various dermatologic conditions. PDT works by selectively killing targeted cells. A topical medication (e.g., 5-aminolaevulinic acid) is applied to the lesion, which gets activated by light. This allows PDT to produce a chemical reaction that is toxic to bacteria.

Research shows that bacteria play a role in HS. Bacteria can cluster together and form a tight layer covering HS lesions called biofilm. Research shows that PDT is able to kill bacteria in the biofilm, making it a promising therapy. PDT can specifically help treat HS by reducing the amount of bacteria present in the lesions, which in turn reduces the inflammation and symptoms (i.e., drainage, odor, pain). This means that, following PDT therapy, patients will usually experience symptom relief such as less pain and less discharge.

While PDT therapy is generally safe, it is not appropriate for everyone. People who have a history of lupus, a history of porphyria, or allergies to the topical medications used in PDT are not good candidates for this form of treatment.