Anhidrosis, sometimes referred to as hypohidrosis, sudomotor dysfunction or sweating dysfunction, is an abnormal lack of sweat in response to heat - the person's body is unable to sweat normally.
Anhidrosis is the complete absence of sweating, while hypohidrosis is sweating less than normal.
If the human body cannot sweat properly it cannot cool itself, which is potentially harmful. Sweating allows heat to be released from the body.
If the lack of sweating affects a small area of the body, it is not usually dangerous. However, overall anhidrosis or hypohidrosis can result in overheating and eventually heatstroke, a potentially life-threatening condition.
According to the National Institute's of Health, people with anhidrosis may not know they have the condition until a significant amount of heat or exertion fails to induce proper sweating.
What are the signs and symptoms of anhidrosis?
A symptom is something the patient feels and describes to others, such as tiredness or pain. A sign, on the other hand, can be detected by others (as well as the patient), such as a rash or swelling.
The most common signs and symptoms associated with anhidrosis are:
- Abnormally poor sweating in response to heat or exertion. In some cases, no sweating (perspiration) at all.
- Dizziness - typically caused by overheating.
- A general feeling of weakness.
- Sensitivity to higher-than-normal temperatures, because the body is unable to cool down.
Anhidrosis may affect:
- Just one part of the body.
- Two or more parts of the body.
- The whole or most of the body.
Patients who are affected in just one or some parts of the body will usually find that the unaffected parts sweat more than normal in an attempt to compensate. So, the result may be one part of the body remains completely dry while another is soaking wet.
If most of the body is affected, physical exertion or hot temperatures may lead to heat cramps, heat exhaustion or heatstroke.
What are the causes of anhidrosis?
Anhidrosis occurs when the body's sweat glands do not work properly or at all.
This can occur as a result of:
A number of medical conditions, syndromes and illnesses are characterized by nerve damage, which can affect how the sweat glands work:
- Ross syndrome - a rare disorder of sweating associated with areflexia (absence of reflex) and tonic pupil (a disorder that affects the pupil of the eye). According to an article published in the journal Brain, since 1958 about 40 cases of Ross syndrome have been described.
- Amyloidosis - a group of diseases in which at least one of the organ systems in the body accumulate deposits of abnormal proteins known as amyloid. According to researchers at Shinshu University Hospital, Japan, one of the symptoms of amyloidosis may be anhidrosis.
- Parkinson's disease - a study carried out at the National Hospital for Neurology and Neurosurgery, London, England, and published in the journal Movement Disorders found that "sweating disturbances are common and distressing symptoms of PD (Parkinson's disease)."
- Multiple system atrophy (MSA) - a rare condition that causes Parkinson's-like symptoms. According to the National Library of Medicine, one of the symptoms of MSA is "loss of sweating in any part of the body."
- Diabetes - anhidrosis can be caused by diabetic autonomic neuropathy. Initially the patient may lose thermoregulatory sweating in a stocking or glove. Usually, it spreads to the rest of the body over time, especially if the patient has poor glucose control.
- Long term alcohol abuse can lead to alcoholic neuropathy, which can result in anhidrosis. Alcoholic neuropathy is damage to the nerves due to the excessive drinking of alcohol.
- Sjogren's syndrome - a chronic disorder of the immune system. People with Sjogren's syndrome have a higher risk of developing anhidrosis.
- Lung cancer - cases have been known of patients developing anhidrosis on one side of the body and excessive sweating (hyperhidrosis) on the other. Japanese researchers reported in the Journal of the American Academy of Dermatology on a lung cancer patient with "unilateral anhidrosis and contralateral hyperhidrosis as the first clinical manifestation."
- Fabry disease - Keiko Toyooka, at the National Hospital Organization Toneyama National Hospital, Toyonaka, Osaka, Japan, wrote in the Handbook of Clinical Neurology, "The main neurological presentations of Fabry disease patients are painful neuropathy, hypohidrosis, and stroke."
- Horner syndrome - a clinical syndrome caused by damage to the sympathetic nervous system. The National Library of Medicine says one of the symptoms of Horner syndrome is "decreased sweating on the affected side of the face."
Skin conditions or skin damage
- Trauma to the sweat glands
- Systemic sclerosis - also called scleroderma, refers to a group of rare chronic, progressive autoimmune diseases in which connective tissues and the skin harden and tighten. Symptoms include shiny skin, anhidrosis and deformity of fingers, according to an article published in the Journal of the Indian Academy of Clinical Medicine.
- Miliaria - also known as prickly heat or sweat rash. Often, rather than a cause of anhidrosis, the rash could be a consequence of it.
- Plugged sweat gland ducts - the sweat gland ducts can become blocked, either as a result of dead skin or bacterial infections, particularly with Staphylococcus epidermidis.
- Incontinentia pigmenti - a genetic disorder that affects the skin, hair, teeth, nails, and CNS (central nervous system).
- Severe skin burns
- Graft-versus-host disease - recipients of stem cell (bone marrow) transplants have a higher risk of developing anhidrosis. The immune cells from the donor attack the host's (recipient's) cells.
- Bazex syndrome - also known as Bazex-Dupré-Christol syndrome, is a very rare inherited condition.
- Leprosy - an early diagnosis of leprosy is to measure the patient's sweat response.
Dr William P. Cheshire Jr. and Robert D. Fealey, wrote in the journal Drug Safety that the following medications may induce hypohidrosis:
- Antimuscarinic anticholinergic agents - commonly used to control some of the side-effects of antipsychotics (neuroleptics or major tranquilizers). Examples include benzhexol, benztropine, biperidin, orphenadrine and procyclidine.
- Carbonic anhydrase inhibitors - these medications are used as antiglaucoma agents, diuretics and antiepileptics. They are also used in the management of osteoporosis, glaucoma, duodenal and gastric ulcers, mountain sickness, and some neurological disorders. Examples include acetazolamide, methazolamide, dorzolamide, and topiramate.
- Tricyclic antidepressants (TCAs) - prescribed for the treatment of clinical depression. TCAs have been around for many decades and have mostly been replaced by antidepressants with fewer side effects.
Dehydration occurs when the body sheds more fluids than it takes in. Approximately 75% of the human body is made up of water found inside cells, within blood vessels and between cells.
Dehydration is when the body loses too much water. One of the symptoms of severe dehydration is anhidrosis.
Dehydration may be the result of diarrhea, vomiting, profuse sweating, frequent urination, skin burns, being at high altitude, or endurance sports (marathons).
People with some chronic diseases have a higher risk of dehydration, examples of such diseases include adrenal gland disorders, cystic fibrosis, kidney disease and diabetes.
In most cases, dehydration can be reversed by taking in fluids. In severe cases, however, medical intervention may be necessary.
Drinking too much alcohol during one session (binge drinking), without consuming enough water, can lead to dehydration.
A good doctor will probably suspect anhidrosis after examining and interviewing the patient.
In an emergency situation, the health care team will perform measures to cool the patient and administer fluids to stabilize him or her.
In order to confirm the diagnosis and/or rule out possible conditions or illnesses, some tests may be recommended.
- Quantitative Sudomotor Axon Reflex Test (QSART) - according to The Cleveland Clinic, this test measures the autonomic nerves that regulate sweating. It is a useful test in assessing disorders of the autonomic nervous system, peripheral neuropathies, and some other types of pain disorders.
Mild electrical stimulation is applied to the skin (iontophoresis), and acetylcholine, a naturally-occurring chemical, enters the skin. Acetylcholine stimulates the sweat glands. Electrodes filled with acetylcholine are placed on the wrist and different areas of the leg. The electric stimulators are switched on and sweat responses are measured.
- Silastic sweat imprint test - in this test electrodes are also used, but pilocarpine is administered to stimulate the sweat glands. An imprint of the sweat droplets appears as indentations on silastic material (material made of silicone rubber).
- Thermoregulatory sweat test - this assesses the thermo-regulatory sudomotor pathway of the whole body. It is a useful complement to the QSART for differentiating between several disorders. The test is based on the body's proportional sweat production to an increase in core temperature.
The patient's body is coated with alizarin red powder. When moist, the powder changes color from orange to purple. To monitor core temperature, a thermal probe is inserted into the patient's mouth. To monitor for excessive surface heating a thermal device is placed on the skin.
The patient enters a chamber that is heated by infrared heating units - ambient temperature and humidity are carefully controlled.
As the patient sweats (or not) his/her whole body is photographed. With computer scanning the areas of anhidrosis are mapped.
- Biopsy - the doctor may order a biopsy in order to examine the sweat glands and skin cells.
What are the treatment options for anhidrosis?
If the cause of the anhidrosis is known, its underlying disease or condition needs to be treated.Patients with anhidrosis in only a small part of their body might not require any treatment.
Researchers at the Tokyo Metropolitan Komagome Hospital reported in The Journal of Dermatology on a 34-year-old male patient with acquired idiopathic hypohidrosis who was successfully treated with prednisolone, a corticosteroid drug. Idiopathic refers to a disease or condition for which the cause is unknown.
A team at Ajou University College of Medicine, South Korea, reported in The Korean Journal of Pain on a patient with cholinergic urticaria (hives) with acquired generalized hypohidrosis who improved after repeated bilateral stellate ganglion block (injecting local anesthetic into the sympathetic nerve tissue in the neck).
If the cause is unknown treatment options are limited. Patients should avoid activities and environments that raise their core body temperature. Exercise should be done in a cool place, and preferably under supervision.
Anhidrosis, hypohidrosis and heat stroke (sunstroke)
People who do not sweat enough (or not at all) when doing exercise or in hot environments have a serious risk of developing heat stroke.
Heat stroke is a medical emergency - it can cause brain and internal organ damage, and even death. If you suspect somebody has heatstroke get medical help immediately - call 911 and provide first aid until the paramedics arrive.
Take the person to a cool environment immediately, preferably one with air-conditioning. If that is not possible find a shady area. Apply ice packs to the their neck, back, armpits and groin.
Place the patient in a cold shower or bath. Adding ice to the bath may help.
Patients recovering from heat stroke are more sensitive to warm/hot environments and should avoid them for at least one week.