A progressive disease of the central and autonomic
nervous systems in which idiopathic orthostatic hypotension is a major
Other features include bladder and bowel incontinence, anhidrosis, iris atrophy,
amyotrophy, ataxia and rigidity.
It is known as a multiple system atrophy, which helps to
distinguish it from syndromes of pure autonomic failure. More common in
Described in 1960 by G.M. Shy, an American Neurologist, and G.A.
Drager, an American physician, in Houston, Texas.
Postmortem examination demonstrates degeneration
of autonomic neurons in the intermediolateral columns, putamen, substantia
nigra, locus ceruleus, inferior olivary nuclei, and degenerative change in
peripheral ganglia. Loss of central sympathetic tone results in inability to
vasoconstrict or to mount a tachycardia in response to posture changes
causing hypotension. Involvement of the corticospinal, corticocerebellar,
and pyramidal tracts later in the disease process gives rise to symptoms of
A consensus statement generated by the American
Autonomic Society and the American Academy of Neurology, defining the various
neurogenic causes of autonomic dysfunction, suggested abandonment of the term
`Shy-Drager' syndrome in 1996. A new classification for the
autonomic disorders has been best summarized as follows: (1) primary or cause
unknown, described as pure autonomic failure (previously called idiopathic orthostatic
hypotension or the Bradbury-Eggleston syndrome) and in which no neurologic defects other
than autonomic dysfunction are present; and (2) multiple system atrophy, a sporadic,
progressive, adult-onset disorder characterized by autonomic dysfunction, parkinsonism,
and ataxia in any combination.
History, demonstration of postural hypotension, and special
investigations to demonstrate sympathetic insufficiency. Must exclude all other possible
causes of orthostatic hypotension. It usually ends in death 7 to 10 years after the onset
Symptoms include dizziness on rising, syncope,
and anhydrosis. Sexual dysfunction, urinary incontinence, fecal
incontinence, dysphagia, unequal pupils, atrophy of the iris, external
ophthalmoplegia, and wasting of distal limb muscles all reflect the
degenerative changes within the central nervous system and autonomic ganglia.
Nocturnal polyuria and natriuresis are present early in the natural history of the
Shy-Drager syndrome and cause relative hypovolemia and exacerbation of
hypotension on rising from bed. Central sleep apnea has been demonstrated on
rare occasions. Signs and symptoms of bradykinesia, rigidity, and tremor
occur following a variable interval (ranging from weeks to years) after
development of orthostatic hypotension. An abnormal response to the Valsalva
maneuver is easily demonstrated. Special investigations include stress tests
to show absent sympathetic response; demonstration of lack of response to
atropine; assessment of ability to sweat; infusion of direct-acting
sympathomimetic agents, which causes hypertension and tachycardia, in
contrast to indirect-acting agents (e.g., ephedrine) that has a limited or
no effect. The most useful treatment appears to be 9α-fludrocortisone and compression stockings along with elevation of the head
of the bed when sleeping. Amphetamines, monoamine oxidase inhibitors
(MAOIs), indomethacin, dihydroergotamine, and propranolol have all been used
with varying success.
An anesthesiology consultation is highly