By far the most common clinical disorders related to sweating arise from decreased sweating. This may be from abnormalities of the glands themselves, or more typically the nerve pathways which innervate the glands.
When the decrease in sweating is primarily in the hands and feet (distal anhidrosis), the cause is most likely to be a peripheral neuropathy such as diabetes. Amyloid is another common cause. In more advanced cases of amyloid and diabetic neuropathies, the anhidrosis may also have a preganglionic component.
When the loss of sweating is generalized, the causes may either be central (eg. MSA or multiple system atrophy or idiopathic orthostatic hypotension) or peripheral (eg. acute panautonomic neuropathy).
When the loss of sweating is throughout the body but with relative sparing of hands and feet, a central cause is most likely, such as MSA or primary autonomic failure.
A peripheral nerve abnormality may lead to abnormal sweating in the distribution of that peripheral nerve. Thus, trauma or inflammation of an isolated root, trunk, or nerve may lead to a patch of altered sweating.
The nerve pathways from the hypothalamus to the periphery travel on one side of the nervous system and therefore a lesion within this pathway will lead to hemi-anhidrosis, i.e., loss of sweating on one side of the body only. The individual nerves within this pathway do not form a tight well-defined bundle and therefore the decrease in sweating is typically patchy.
Local skin pathology may also lead to altered sweating through direct destruction of glands or blocking of their ducts. In these cases or in focal nerve lesions, there may be a compensatory increase in sweating from neighboring normal sweat glands.
|Conditions associated with decreased sweating:|
|Lambert-Eaton myasthenic syndrome|
|small fiber neuropathies|
|other parkinsonian syndromes|
|chronic idiopathic anhidrosis|
|other autonomic neuropathies|