Several different clinical syndromes have been described to include patients who seem to have partial or progressive failure of the autonomic nervous system, leading to a variety of symptoms, not the least of which is orthostatic hypotension. One condition known is “Pure Autonomic Failure,” which is most common in middle aged men. There is a gradual onset of symptoms that include orthostatic weakness, urinary incontinence or retention, sexual problems, and sometimes inability to sweat, bowel problems, and dry mouth. The disease progresses very slowly, and usually presents with a picture of lightheadedness and gradual fading to syncope, often resulting in sudden falls or “drop attacks.”
When autonomic nervous system failure also affects other parts of the brain, the condition is known as “Multiple System Atrophy.” Unlike Pure Autonomic Failure, where orthostatic hypotension predominates, patients with Multiple System Atrophy can develop muscular stiffness / rigidity (similar to Parkinson’s Disease), and other patients can become uncoordinated with difficulty standing and walking, slurred speech, and at times a tremor. This progressive neurological disease is very debilitating and can eventually lead to respiratory failure.
A rare but dramatic presentation is known as Acute Autonomic Failure or “acure panautonomic polyneuropathy.” It can affect young, healthy patients, and the orthostatic hypotension can be so severe that patients can barely sit up in bed without passing out. Near total loss of sweating along with severe bowel and bladder problems arise. Recent medical studies suggest that the problem may be related to an autoimmune process, whereby the patient’s own immune system, for some reason, has attacked the autonomic nervous system and rendered it ineffective. Luckily, many of these patients can recover, probably because of a resolution of the immune system problem.
Other cases of autonomic failure may be secondary to other illnesses, such as diabetes, kidney failure, and amyloidosis. In some cases, autonomic failure may be the presenting sign of a severe systemic illness like cancer, multiple sclerosis, or Alzheimer’s disease.