Hyperhidrosis is a condition that causes excessive sweating beyond that which is necessary for physiological thermoregulation and homeostasis. It is a common condition that has many social, emotional, and professional consequences for clients and can adversely influence their quality of life. Hyperhidrosis is a chronic idiopathic condition that involves one or more areas of the body such as the underarm, palms, soles, face, inframammary and inguinal folds. When one area is involved, the term primary focal hyperhidrosis is used; the term primary multifocal hyperhidrosis is used if more than one area is affected. Botulinum toxins are one of the main treatments for primary focal and multifocal hyperhidrosis.
Sweating is a normal physiological response to an increase in body temperature and is an important mechanism in releasing heat produced from endogenous as well as exogenous sources. The heat regulatory centre is located within the hypothalamus. Sweating is controlled by the sympathetic nervous system.
The eccrine glands, responsible for producing sweat, are distributed around the body, with high concentrations in areas such as the palms, soles, and forehead. They are located at the junction of the dermis and subcutaneous fat and their function is to secrete water while conserving sodium chloride for electrolyte maintenance. Although they continually produce secretions, they are stimulated by heat, exercise, anxiety, and stress. Under extreme heat stress, up to 10 litres of sweat can be produced in a day; however, the normal rate is 0.5–1.0 mL/min. While rates vary greatly among individuals, men generally sweat more than women.
The apocrine glands open into the hair follicle and are located mostly in the armpits and perineum. They become functional around puberty and are not important for thermoregulation. The scant viscous secretions are thought to function as chemical attractants or signals, as an odour is produced when the secretions reach the skin surface and interact with bacteria.
The axilla is the armpit region of the human body and is the pyramidal space between the upper lateral part of the chest and the medial side of the arm.
The apex is directed up towards the root of the neck and corresponds to the interval between the outer border of the first rib, the superior border of the scapula and the posterior surface of the clavicle, and the axillary vessels and nerves pass through this.
The base is directed downwards and is broad at the chest but narrow and pointed at the arm; it is formed from the integument and a thick layer of fascia called the axillary fascia that extends between the lower border of the Pectoralis major in front, and the lower border of the Latissimus dorsi behind.
The anterior wall is formed by the Pectorales major and minor of which the former covers the whole of the wall and the latter only the central part. The space between the upper border of the Pectoralis minor and the clavicle is filled by the coracoclavicular fascia. The posterior wall extends lower than the anterior and comprises of the subscapularis, the Teres major and the Latissimus dorsi.
On the medial side are the first four ribs with their corresponding intercostals and a section of the Serratus anterior. On the lateral side where the anterior and posterior walls meet, the space is narrow and bounded by the humorous, the Coracobrachialis and the Biceps brachii.
The axillary section contains the brachial plexus of nerves, with their branches along with some of the intercostal nerves and a large number of lymph glands, alongside fat and loose areolar tissues.
The axillary artery and vein as well as the brachial plexus of nerves, extend obliquely along the lateral boundary of the axilla from its apex to the base and are placed much nearer to the anterior than to the posterior wall. The vein sits to the thoracic branches of the axillary artery and runs along the lower margin of the Pectoralis minor the lateral thoracic artery extends towards the side of the chest.
At the back section in contact with the lower margin of the Subscapularis the subscapular vessels and nerves are found; winding around the lateral border of this muscle are the scapular circumflex vessels and close to the neck of the humorous sits the posterior humeral circumflex vessels and the axillary nerve curves backwards towards the shoulder.
The line between normal sweating and hyperhidrosis is poorly defined, and objective evaluations of the disease are needed. These evaluations are based on subjective assessments and objective measurements. The iodine–starch test (Minor’s test) is the oldest method used to assess sweating. It is based on the reaction between iodine, starch, and sweat that causes a purple precipitation at the site. Minor’s test is performed after cleansing and drying of the test area. Alcoholic iodine solution is applied on the test site. After it is completely dry, corn or potato starch is dusted on the skin surface. When sweat is secreted, purple areas are formed. Due to its simplicity, the iodine–starch test has been the most commonly used in the medical profession. Its advantage in daily practice is related to its performance simplicity, but also to its ability to determine the size of the sweating area. Test results are sometimes striking in terms of side asymmetry and irregularity of the hyperhidrotic areas. Photography of the stained area and its change after treatment allows documentation of the treatment’s success.
To optimise treatment, the area should have a Minor’s iodine-starch test conducted so that the botulinum toxin can be concentrated on the affected area. Although it is true that the majority of the eccrine glands in the armpit are located in the hair-bearing area of skin, often the problematic areas can extend beyond the visible hair-bearing area and if these ectopic areas of eccrine glands are missed, the results of treatment may be suboptimal. The key to performing a high-quality iodine-starch test is to thoroughly dry the region before beginning the test. The armpit does not need to be shaved prior to performing an iodine-starch test or to injecting botulinum toxin.
Approximately 2 units of botulinum toxin into the deep dermis at the dermal subcutaneous level in doses placed 1.5–2 cm apart. Because the axillary skin is thin, a wheal should be seen with each injection. An average of 10–15 injections per armpit is required but will depend on the size of the armpit and hyperhidrotic area. In the event that an iodine-starch test cannot be performed prior to treatment or is equivocal, the aesthetician should treat the hair-bearing areas as described. Should symptoms fail to be alleviated within 2 weeks, the client can return to the clinic and an iodine-starch test performed to identify any “active” eccrine glands. The skin in these “active” areas should be injected with 3–5 units of botulinum toxin or equivalent for each 1 cm surface area identified.
Pain is minimal and the procedure is well tolerated. Side effects noted include pain, hematoma, bruising, headache, muscle soreness, increased facial sweating, perceived compensatory sweating, and axillary pruritus.
Treatment intervals are determined by the duration of the client’s treatment response but will average between 6–9 months. Some clinicians have advocated that clients use a topical therapy twice a week when the sweating starts to return to try to extend the time interval between injections and help to reduce costs.