At the bedside, the most convenient ones are measurement of orthostatic heart rate and blood pressure changes, blood pressure response to the Valsalva maneuver, estimation of heart-rate changes with deep breathing, pupillary responses to light and dark, and a rough estimate of sweating of the palms and soles and with lesions of the spinal cord, on the trunk. The results of these tests and the clinical situation will determine whether further testing is needed.
Since this condition was first reported by Young and colleagues in 1975, many more cases in both adults and children have been placed on record. Over a period of a week or a few weeks with or without a preceding systemic or respiratory infection, the patient develops some combination of anhidrosis, orthostatic hypotension, paralysis of pupillary reflexes, loss of lacrimation and salivation, erectile dysfunction, impaired bladder and bowel function (urinary retention, postprandial bloating, and ileus or constipation), and loss of certain pilomotor and vasomotor responses in the skin (flushing and heat intolerance). Fatigue, sometimes severe, is a prominent complaint in most patients, and abdominal pain and vomiting in others. A few develop sleep apnea or the syndrome of inappropriate secretion of antidiuretic hormone (SIADH), leading to hyponatremia. The cerebrospinal fluid (CSF) protein is normal or slightly increased.
Clinical and laboratory findings indicate that both the sympathetic and parasympathetic parts of the autonomic nervous system are affected, mainly at the postganglionic level. Somatosensory and motor nerve fibers appear to be spared or are affected to only a slight extent, although many patients complain of paresthesias, and tendon reflexes are frequently lost. In one of the patients described by Low and colleagues, there was physiologic and morphologic (sural biopsy) evidence of loss of small myelinated and unmyelinated somatic fibers and foci of epineurial mononuclear cells; in other cases, sural nerve fiber counts have been normal; and in an autopsied case, in which there had also been sensory loss, there was lymphocytic infiltration in sensory and autonomic nerves (Fagius et al). The original patient described by Young and colleagues and most of the other patients reported with pure dysautonomia are said to have recovered completely or almost so within several months, but many of our patients have been left with disordered gastrointestinal and sexual functions. In addition to an idiopathic form of autonomic paralysis, some cases are postinfectious, and there is a similar but rare paraneoplastic form (see Chap. 30 under “Paraneoplastic Sensory Neuronopathy”). Antibodies against ganglionic acetylcholine receptors have been found in half of idiopathic cases and one-quarter of paraneoplastic ones (Vernino et al).
Some children with this disease and a few adults have had a syndrome of predominantly cholinergic dysautonomia with pain and dysesthesias (Kirby et al); there is little or no postural hypotension and the course has been more chronic than that in cases of complete dysautonomia described earlier.
In view of the identical autonomic disturbances in the Guillain-Barré syndrome and the high incidence of minor degrees of weakness, reflex loss, CSF protein elevation, and especially paresthesias, it is likely that pure pandysautonomia is also an immune-mediated polyneuropathy affecting the autonomic fibers within peripheral nerves, in most ways comparable to the Guillain-Barré syndrome. The aforementioned autopsy findings reported by Fagius and coworkers support such a relationship. In animals, autonomic paralysis has been produced by injection of extracts of sympathetic ganglia and Freund’s adjuvant (Appenzeller et al), similar to the experimental immune neuritis that is considered as an animal model of the Guillain-Barré syndrome.