Botulinum Toxin A for Managing Focal Hyperhidrosis Journal review 아름다운예의원 오영상

According to the authors, Botox is a safe, rapid, and effective treatment for focal hyperhydrosis with uniformly good results, few complications, and high patient satisfaction. Studies have shown that the therapeutic effect persists for 8 to 9 months on average. Focal hyperhidrosis, characterized by excessive sweating of the forehead, axilla, palms, or soles, is believed to affect approximately 1 % of the population. This condition causes significant social discomfort, diminished function, and in severe cases can even lead to skin maceration. Hyperhidrosis is classified as primary or secondary on the basis of its causes. The cause and exact incidence of primary hyperhidrosis is undetermined but a familial predilection suggests a genetic basis. It is hypothesized that a dysfunction of the central sympathetic nervous system, specifically of the hypothalamic nuclei, causes primary hyperhidrosis.2–323

Secondary hyperhidrosis is usually caused by medications or medical conditions including endocrine and neurologic disorders, drug use, menopause, neoplastic diseases, and chronic infections. Because secondary hyperhidrosis is a side effect, it is often more diffuse and treatment may be less effective. Treatments for primary or focal hyperhidrosis have included topi cal application of metal salts, including aluminum chloride; systemic anticholinergics; tap water iontophoresis; surgical suction curettage of the axilla; axillary tissue excision; and surgical sympathectomy. R esults have varied with these methods. Recently, botulinum toxin A (Botox; Allergan Corporation, Irvine, CA) has been found to be a feasible alternative treatment.

Eccrine sweat glands, which exist in varying concentrations in diffe rent skin areas, maintain body temperature in a narrow range. They are directly stimulated by higher cortical functions, thermal stre ss, and exercise, and are most concentrated in the forehead, axilla, palms, and soles, numbering about 2 to 4 million per person. They c onsist of clear and dark cell types in a secretory coil surrounded by a capillary plexus and innervated by sympathetic post-ganglionic choli nergic fibers (Figure 1).Figure 1

Figure 2 Minor's starch-iodine test is performed on an axilla.

A more pragmatic diagnostic test and treatment adjunct is the “Mi nor's iodine test,” performed by painting the affected area with a povidone iodine solution, allowing it to dry, and then applying com mercially available corn starch (Figure 2).Figure 2 A chemical interaction between the patient's sweat, the iodine, and starch defines the affected area by turning it black.

the effectiveness of Botox in treating hyperhidrosis has been we ll documented. Botox prevents presynaptic release of acetylcholine i n sympathetic nerve endings by binding to, and cleaving, the SNAP 25 receptor on nerve endings. Botox acts on hyperhidrosis by inhibiting acetylcholine release and t hereby inhibiting sympathetic stimulation of eccrine sweat glands. Preliminary studies document anhidrosis in normal volunteers in a d ose similar to that used to treat dynamic expression lines; sweating i s arrested in 3 to 7 days. However, malodor may persist because the apocrine component of the sweat gland and normal bacterial flora are unaffected. Apocrine glands are innervated by adrenergic sympathetic nerve endings

Several studies have shown the therapeutic effect persists 4 to 22 m onths with a median duration of 8 to 9 months. This longer effect, as compared with its effect on mimetic muscles, is believed to result fro m either slower resynthesis of SNAP 25 receptors or diminished res prouting of cholinergic sympathetic nerve fibers. Although uncommon, the reported complications of this treatment i nclude discomfort from treatment, bruising, itching, muscle soreness, headache, compensatory hyperhidrosis, gastrointestinal discomfort, and subjectively diminished grip strength

Technique Topical anesthetics, ice compresses, and anxiolytics are used if indi cated. The Minor starch-iodine test is usually not required (Figure 3); however, if used, affected areas are outlined with a marker, cleaned, and injected. Alternatively, any subjectively identified areaFigure 3 can be treated empirically by placing a grid over it, marking the injection sites approximately 1 cm apart (Figure 4) and wiping the sit es dry.Figure 4 We prefer 4 mL of saline solution/100 units of Botox, a dilution of 2.5 units/0.1 mL. With a tuberculin syringe and a 30-gauge needle, 0.1 mL is injected intradermally into each site to deliver 2.5 units of Boto x/cm 2 (Figure 5). Up to 50 units of Botox can be used for each axilla.Figure 5

Figure 4 Empiric marking of axilla before Botox administration Figure 5 Intradermal injection of 2.5 units of Botox/ctn22

In the palms or soles, we recommend similar treatment beginning in the outer aspect of the palm and gradually “pinwheeling” centrally at intervals of 1 to 2 cm until the entire field is treated (Figure 6).Figure 6 We then inject each finger pad. In the palm, the needle, introduce d with minimal pressure, enters the dermis readily without pene trating more deeply and affecting intrinsic hand muscles. Conversely, the injection level in the axilla is intradermal or immediat ely subcutaneous.

Initially, we recommend treating one hand per visit to make sure that no muscle weakness results. Gentle pressure is maintained over the injection sites with a sterile gauze pad or with the patient squeezing the ice compress. Untreated or contralateral sites are injected if no effect is achieved by day 14. Patients are instructed to keep the area clean, to take over-the-counter analgesics as necessary, and to follow up with additional injections as needed. Use of Botox for hyperhidrosis has resulted in uniformly good results, few complications, and high patient satisfaction

Figure 6 Alternative injection pattern for treating palmar hyperhidrosis.