Another inherited form of peripheral dysautonomia is characterized by severe pain in the feet on exercise and an autosomal dominant pattern of inheritance (Robinson et al). Bending, crouching, and kneeling increase stabbing pains in the feet. There is no sweat response to intradermal injection of 1 percent ACh and no autonomic fibers were found in punch biopsies of the skin. Systemic amyloidosis is the other type of peripheral neuropathy that has prominent features of autonomic failure.
Autonomic Failure in the Elderly (See Also
Chap. 28)
Orthostatic hypotension, a marker of autonomic sympathetic failure, is defined for research purposes as a reduction of systolic blood pressure of 20 mm Hg or more, or a drop in diastolic blood pressure of 10 mm Hg or more at the third minute of standing. Orthostatic hypotension is typically due to baroreflex failure. In the elderly, orthostatic hypotension commonly results from the use of medications. Neurogenic orthostatic hypotension results from a lesion in autonomic nervous system and is frequently seen in multiple system atrophy, Parkinson’s disease or diabetes.
It should be emphasized how prevalent orthostatic hypotension is in the elderly. Caird and coworkers reported that among individuals who were older than 65 years of age and living at home, 24 percent had a fall of systolic blood pressure on standing of 20 mm Hg; 9 percent had a fall of 30 mm Hg; and 5 percent had a fall of 40 mm Hg. An increased frequency of thermoregulatory impairment also has been documented. The elderly are also more liable to develop hypothermia and, when exposed to high ambient temperature, to hyperthermia. Loss of sweating of the lower parts of the body and increased sweating of the head and arms probably reflect a neuropathy or neuronopathy. The number of sensory ganglion cells decreases with age (de Castro). Erectile dysfunction and incontinence also increase with age, but these, of course, may be the result of a number of processes besides autonomic failure and many of the medications used to treat ailments that come with aging, such as hypertension, prostatic hypertrophy, depression, and impotence, have autonomic effects and can cause orthostatic hypotension.
It is of interest that an idiopathic type of small fiber neuropathy that occurs predominantly in elderly women (“burning hands and feet” syndrome) has no associated autonomic features (see Chap. 43).
Horner (Oculosympathetic) and Stellate Ganglion Syndromes (See Also Chap. 13)