Autonomic peripheral neuropathy. 
The autonomic neuropathies are a group of disorders in which the small, lightly myelinated and unmyelinated autonomic nerve fibres are selectively targeted.  Autonomic features, which involve the cardiovascular, gastrointestinal, urogenital, sudomotor, and pupillomotor systems, occur in varying combination in these disorders.  Diabetes is the most common cause of autonomic neuropathy in more developed countries.  Autonomic neuropathies can also occur as a result of amyloid deposition, after acute infection, as part of a paraneoplastic syndrome, and after exposure to neurotoxins including therapeutic drugs.  Certain antibodies (eg, anti-Hu and those directed against neuronal nicotinic acetylcholine receptor) are associated with autonomic signs and symptoms.  There are several familial autonomic neuropathies with autosomal dominant, autosomal recessive, or X-linked patterns of inheritance.  Autonomic dysfunction can occur in association with specific infections.  The availability of sensitive and reproducible measures of autonomic function has improved physicians' ability to diagnose these disorders.