Practice Essentials
Primary syndromes of generalized autonomic failure include the following:
Idiopathic orthostatic hypotension and other forms of pure autonomic failure (PAF)
Autoimmune autonomic neuropathy (AAN)
Multiple system atrophy (MSA)
Unlike the above disorders, which each affect sympathetic and parasympathetic function, the autonomic condition postural orthostatic tachycardia syndrome (POTS) affects only sympathetic function.
Signs and symptoms
Symptoms of decreased sympathetic function may include the following:
Orthostatic hypotension
Decreased sweating
Ejaculatory dysfunction
Ptosis associated with Horner syndrome
Symptoms of decreased parasympathetic function may include the following:
Constipation
Nausea
Urinary retention
Erectile dysfunction
Pure autonomic failure
More specifically, symptoms of PAF include the following:
Orthostatic hypotension: With an inappropriate lack of compensatory increase in heart rate with standing
Gastroparesis: Associated with nausea or constipation
Urinary retention: May cause bladder distention
Decreased sweating: Manifesting as heat or exercise intolerance
Ophthalmologic manifestations: Including ptosis, anisocoria, Horner syndrome, and tonic pupils
Failure of either erection or ejaculation
Autoimmune autonomic neuropathy
The overall physical findings are similar to those observed in PAF. Patients may have additional findings of sensory abnormalities, pain, or loss of deep tendon reflexes.
Multiple system atrophy
Autonomic manifestations are similar to those observed in AAN and PAF. The following neurologic features may also be present:
Pyramidal or cerebellar abnormalities: Weakness, ataxia, incoordination, and eye-movement abnormalities may precede the autonomic features by as long as 2 years
Variable parkinsonian findings: Found in MSA parkinsonian variant; are unresponsive to levodopa; include rigidity, bradykinesia, tremor, and truncal instability
Evidence of cerebellar dysfunction: Found in MSA cerebellar variant; includes ataxia, dysmetria, dysdiadochokinesia, and incoordination; eye-movement abnormalities are frequently present
Postural orthostatic tachycardia syndrome
A greater than 30-bpm increase in heart rate on standing, without a clinically significant decrease in blood pressure, is diagnostic.
See Clinical Presentation for more detail.
Diagnosis
Lab studies
Evaluation for acute inflammatory demyelinating polyneuropathy (AIDP): Prompted by an acute onset of autonomic symptoms without other neurologic problems or with features such as subtle weakness or numbness
Measurement of ganglionic AChR antibody: A subacute onset without other neurologic or systemic findings may indicate AAN
Evaluation for Parkinson’s disease and MSA: Should be performed in patients with a chronic onset
Drug or toxin exposure may cause generalized or organ-specific acute autonomic dysfunction. The predominant abnormality (ie, increased or decreased sympathetic or parasympathetic activity) should be identified. The patient’s medications should be reviewed carefully.
Tests for systemic disorders causing secondary pandysautonomia, including the following, may be ordered according to clues from the patient’s history:
Glycosylated hemoglobin or glucose tolerance test: To test for diabetes
Anti-Hu antibody titers: If the patient has associated sensory neuropathy or cognitive changes.
Anti-calcium channel antibody titers: For Lambert-Eaton myasthenic syndrome (LEMS)
Stool screen for botulinum by culture and detection of toxin: In cases of suspected poisoning by food or wound contamination
Serum and urine protein electrophoresis: To evaluate myeloma with amyloidosis
Genetic testing: To evaluate for familial amyloidosis
Rapid plasma reagent (RPR) or Venereal Disease Research Laboratory test (VDRL): To test for syphilis
Human immunodeficiency virus (HIV) testing
Autoimmune screening: To evaluate for collagen-vascular disease; may include antinuclear antibody levels, erythrocyte sedimentation rate, and other autoimmune tests (eg, rheumatoid factor, SS-A and SS-B antibodies)
Assessment of the urinary porphyrins and erythrocyte porphobilinogen deaminase levels: If the clinical history suggests the possibility of porphyria
Imaging studies
Brain magnetic resonance imaging (MRI): Particularly in cases of centrally mediated dysautonomia
In MSA, brainstem or cerebellar atrophy may be seen, with T2 hyperintensity of the pons (the hot-crossed bun sign); these findings differentiate MSA from other types of primary autonomic dysfunction.
See Workup for more detail.
Management
Treatment strategies for autonomic disorders include the following:
AAN: Treatment is based on anecdotal evidence
Chronic PAF syndromes: Treatment is symptomatic only
POTS: Can be treated with low doses of beta blockers, as patients are normally sensitive to their adverse effects
Nonpharmacologic measures are useful for all patients with autonomic dysfunction.
They include the following:
Antihypertensive medications and other medications known to lower blood pressure should be discontinued, if feasible
Fluid and salt intake should be increased
Equipment aids may be helpful; these include tight support stockings, abdominal binders, or antigravity suits for symptomatic hypotension and bladder catheterization for urinary retention
Dietary fiber and enemas may help to improve bowel motility and decrease straining during defecation
Patients with decreased sweating should limit their physical activity, particularly in hot weather; sponging with water during activity may help to prevent overheating
Large meals may exacerbate hypotension and should be avoided
Positional changes, such as standing up, should be performed slowly and gradually
The head of the bed should be elevated, and prolonged recumbency should be avoided
See Treatment and Medication for more detail.