Practical Hints and Comments

22.6.3.1 The Carbon Dioxide Laser Technique

The poor prognosis regarding complete healing in long-standing cases of HS and the need for prompt surgical intervention encouraged us to develop a fast and convenient surgical method suitable for an outpatient setting that was radical but at the same time tissue-sparing and that had minimally priced post-operative professional wound care. Carbon dioxide laser has previously been used in HS treatment [18, 24, 40]. Before there was access to scanner devices, we used what we called the carbon dioxide laser stripping second intention technique [38]. A carbon dioxide laser was used, operating at 30 W with a manually controlled hand piece. The beam was set to give the shortest possible exposure times with as much power as is controllable in the surgical situation, thereby causing the least lateral heat conduction and non-specific thermal injury as possible, with a narrow coagulation margin and minimal char production. If irradiation of a charred surface is continued, it will be heated to more than 400 °C, causing heat injury within the underlying tissues and margins [1, 22, 54]. Tissue vaporization by a defocused beam being moved quickly in a freehand manner in a circular motion in the "paint brush" pattern method is very dependent on the surgeon's experience.

We use a focused continuous-wave (CW) carbon dioxide laser with a rapid beam miniature microprocessor-controlled optomechanical scanner system that moves the laser spot at constant velocity in a pattern that covers the treatment site at a dwell time of less than 1 ms. This scanner uses parallel mirrors to produce a fine spiral beam. By laying down (approximately 16-18 tracks across the entire diameter of the scanner) adjacent sets of concentric spirals, a full scan is produced in 0.2 s. An ideal way to reduce the conduction of thermal injury to the skin is to combine high fluency (energy/unit area) with a very short laser exposure time, thus obtaining the ablation of tissue with minimum thermal injury. The scanners are usually used to ablate very thin layers of skin, as in the treatment of actinic keratoses or rhytides in resurfacing procedures, with short pulses (0.2 s). Used in a continuous mode, the scanned laser beam drills downwards into the tissue and removes it in a fast, even, and fully controlled way. Before 1995 a prototype named Flashscan was used. The device worked along the same principles but used a figure-of-eight scanning pattern. It was useful, but had some shortcomings with rougher tissue surfaces and gave rise to some splashing of blood and tissues; it was subsequently exchanged for the Silktouch in 1995.

In our opinion, the laser is a suitable tool for working with the contaminated and infected tissues of HS. It has the further advantages of allowing the surgeon to kill any bacteria present (through the heat applied) and to deal with the highly inflamed and purulent tissues without touching them. The carbon dioxide laser cuts and seals small blood and lymphatic vessels. It is also advantageous in that it prevents the spread of bacteria to the surrounding tissues or bloodstream, while at the same time providing a blood-free operating field with its inherent possibilities for macroscopically examining tissue pathology. Favorable effects on the healing of experimentally infected wounds after carbon dioxide laser sterilization have previously been suggested [53, 66].

We have further developed the techniques and strategies of the carbon dioxide laser to optimize its use in the different stages of HS. Instead of using the laser as a substitute for a scalpel and cutting vertically into the surface around the diseased tissue, we start from another point. Layer by layer we vaporize the tissue from inside the central surface of the diseased area downwards and outwards until all of the macroscopi-cally pathological tissue is removed and healthy tissue is reached. If we discover that the disease is more widespread than initially expected, the ablated area can be extended. The principle is to be as radical as possible and still save sufficient healthy tissue for the secondary healing process in order to obtain fast healing and to avoid unnecessary scarring and contraction. From our own experience of scalpel excisions of HS, initially there is an increased risk of removing unnecessary amounts of tissue, since we have to estimate how much tissue should be excised to give sufficient margins. Further, the surgical wound edges bleed a lot and are very hard to investigate for the presence of remnant pathologi

22.6.3.2 The Use of Scanners cal tissues, which carries the inherent risk of recurrence. The carbon dioxide laser has been applied to HS by others [24] for excision use. The excision technique is mandatory when pathological anatomical examination to exclude suspected squamous cell carcinoma is indicated. It is also reasonable sometimes to debulk heavier parts of HS lesions with wide excision, to save time and reduce the amount of fumes for the vacuum filter, but as soon as the border with healthy tissues is reached, the value of treating from the inside out, starting with pathological tissue, is obvious. Every millimeter of healthy skin tissue is valuable and should be left unless there is a reason to do otherwise. The use of a scanner makes the ablation smoother and more precise, enabling the early recognition of healthy or vascular tissue and the avoidance of unintentional damage. Special caution is recommended in patients with a low ratio of diseased skin to healthy subcutaneous tissue underlying the lesions, and in those in whom the procedure is limited by muscular fascias or vital parts other than subcutaneous fat, i.e., nerves, blood vessels. The laser optical density used for treatment is considerably higher than the threshold for vaporization without residual carbon char and it generates a clean, almost char-free crater in the tissue [64]. The scanners used with a continuous emission mode give a faster, safer and more even ablation with less bleeding and better visualization of HS macropathology during surgery compared to the freehand surgical technique. During the laser treatment the endpoint is healthy tissue in all directions. The hypothesis behind the surgical method is that, by radically removing and vaporizing the macroscopically active HS disease, tissue recurrences are avoided. Actually one is tempted to speculate that it is the cause of inflammation that is the target of laser vaporization: perhaps the cause of inflammation is destroyed along with the hypertrophi-cally deformed follicle and its content of foreign material such as keratin from corneocytes and debris from hair and bacteria. Hypothetically the sources of recurrence are the epithelial sinuses that line this debris, as they produce keratin and harbor bacteria that have the potential to be pathogenic in this environment. According to this hypothesis the surrounding inflam mation is secondary and reactive to this foreign body material and not the cause of the recurrence.

22.6.3.3 How Radical Should the Therapy Be?

The target area for surgery should be diseased and damaged skin but nothing beyond the actively diseased area [61, 72]. A study of the extent of surgery and the recurrence rate of HS by Ritz in 1998 [55] and an extensive review by Ba-nerjee in 1992 [6] give a helpful picture of the problems and complexity involved in comparative assessments of surgery in HS. The majority of patients seen in dermatology units and the majority of patients with HS have a relatively mild disease course and most often are at Hurley Stage II [29], i.e., recurrent abscesses with tract formation and cicatrization, and single or multiple widely separated lesions that have not yet turned into the more advanced stage of disease. These patients cannot be considered as candidates for advanced major plastic surgery, but still suffer from a chronic and disabling disease [35]. New abscesses outside the clinically symptomatic skin area cannot be prevented by any known surgical method and they should be regarded as an indicator of underlying disease activity rather than as a shortcoming of the surgical method [6]. Our patients are predominantly women and that may be a reflection of the fact that the disease more often presents in otherwise healthy females during their fertile years, especially the inguinal and genito-peri-neal forms [32, 45, 46, 51]. Surgery alone is only permanently curative in a select group of patients, and only temporarily in others. The results of our method accord well with results from other types of surgery [6, 25] and the need for repeated treatment sessions should be considered. This method is conveniently repeated, and as it is tissue-sparing the risk of contractures is reduced. In recurrent disease after carbon dioxide laser surgery, repeated carbon dioxide laser surgery in conjunction with supplementary medications, such as long-term immunological modulating antibiotics, e.g., tetracyclines, retinoids or cyproterone acetate combination medication, should be considered. The largest group of HS patients, i.e., the early cases or the cases of mild to moderate severity, probably suffer a lot from their disease despite their relatively limited symptoms. For both economic and practical reasons, in clinical practice there is a tendency for surgery to be withheld except for the most advanced cases. The patients we have shown to gain considerably from laser surgery in our clinic had previously been treated conservatively. There are reasons to believe that our method will prove to be an adequate surgical choice for early surgical treatment and a study of carbon dioxide laser treatment of early HS lesions is in progress.

The better safety and accuracy that come with the use of microprocessor-controlled scanners make this technique available for more general use and enable it to be used in other areas of treatment for HS patients, i.e., dermato-logic surgeons, general and plastic surgeons, and gynecologists. It will be possible to treat lesions completely and radically very early on in the course of the disease, i.e., the acute primary HS, and this could be done in outpatients with the wound left to heal by secondary intention rather than the current option of ineffective incision and subsequent expensive wound care with painful tamponade. Some of our chronic patients would be much better off under this type of regime.

wide excision and reconstructive surgery. Our impression is that the most common form of HS is Hurley Stage II and that most patients seem to stay at this stage without progressing to Hurley Stage III. When patients were thought to be suitable for surgery they were operated on at our clinic and a few were referred for wide excision surgery.

In conclusion, for patients with HS, modified minimally invasive carbon dioxide laser treatment is a safe, simple, fast and economical surgical method with satisfactory cosmetic and functional results that is suitable for the outpatient setting. The use of carbon dioxide laser microprocessor-controlled scanner devices has made the technique safer and less surgeon dependent. The technique allows early and simple treatment of HS lesions that previously perhaps tended to be left to less effective, local and conservative remedies.

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