Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 24-04: Dysautonomia + Key Features Download Section PDF Listen +++ +++ Essentials of Diagnosis ++ Postural hypotension or abnormal heart rate regulation Abnormalities of sweating, intestinal motility, sexual function, or sphincter control Syncope may occur Symptoms occur in isolation or any combination +++ General Considerations ++ Primary neurodegenerative disorders with dysautonomia Pure autonomic failure Multisystem atrophy: constellation of parkinsonism, pyramidal signs, and cerebellar deficits Parkinson disease CNS lesions that may exhibit features of dysautonomias (usually postural hypotension) Spinal cord transection Other myelopathies above the T6 level (eg, due to tumor or syringomyelia) Brainstem lesions, such as syringobulbia and posterior fossa tumors Sphincter or sexual disturbances may result from cord lesions at any level Peripheral causes Guillain-Barré syndrome may have features of marked hypotension or hypertension or cardiac arrhythmias Post-viral or paraneoplastic acute autonomic neuropathy Diabetes mellitus Uremia Amyloidosis Leprosy Chagas disease Hepatic porphyria Small fiber neuropathies may underlie some cases of postural orthostatic tachycardia due to impaired contractility in denervated venules and resulting preload failure Botulism Lambert-Eaton myasthenic syndrome + Clinical Findings Download Section PDF Listen +++ +++ Symptoms and Signs ++ Syncope Postural hypotension Paroxysmal hypertension Persistent tachycardia without other cause Facial flushing, hypohidrosis, or hyperhidrosis Vomiting, constipation, diarrhea, dysphagia, abdominal distention Disturbances of micturition or defecation Erectile dysfunction Apneic episodes Declining night vision Impaired cholinergic function from botulism and the Lambert-Eaton myasthenic syndrome: constipation, urinary retention, and a sicca syndrome +++ Differential Diagnosis ++ Hypovolemia Drugs, eg, β-blockers, calcium-channel blockers, vasodilators, diuretics Situational syncope, eg, micturition, defecation, cough, swallow Postural hypotension Reduced cardiac output from volume depletion, aortic stenosis or cardiomyopathy, cardiac dysrhythmias, various medications Endocrine disorders such as diabetes, Addison disease, hypothyroidism or hyperthyroidism, pheochromocytoma, and carcinoid syndrome + Diagnosis Download Section PDF Listen +++ ++ The neurologic examination should focus on detecting signs of parkinsonism, cerebellar dysfunction, disorders of neuromuscular transmission, and peripheral neuropathy If the neurologic examination is normal, Reversible, nonneurologic causes of symptoms must be considered Isolated postural hypotension and syncope may relate to Reduced cardiac output Paroxysmal cardiac dysrhythmias Volume depletion Various medications Endocrine and metabolic disorders, such as Addison disease, hypothyroidism or hyperthyroidism, pheochromocytoma, and carcinoid syndrome For those with evidence of peripheral neuropathy, Nerve conduction studies and electromyography should be done Testing for HIV, amyloidosis, Sjögren syndrome, and Fabry disease is indicated +++ Laboratory Tests ++ Autonomic function tests Patients with acute or subacute isolated dysautonomia should undergo testing for ganglionic acetylcholine receptor, anti-Hu, voltage-gated potassium channel complex, and voltage-gated calcium channel antibodies Tests for vitamin B12 deficiency and diabetes +++ Imaging Studies ++ If there is evidence of central pathology, imaging studies will exclude a treatable structural cause +++ Diagnostic Procedures ++ Specialized tests include Cardiovascular response to the Valsalva maneuver and deep respiration Tilt-table testing Thermoregulatory sweat test Quantitative sudomotor axon reflex test Quantitative direct and indirect axon reflex test Tests of gastrointestinal motility and urodynamics may be helpful when symptoms of dysmotility, incontinence, or urinary retention are present + Treatment Download Section PDF Listen +++ +++ Medications ++ Treatment may include Wearing waist-high elastic hosiery Salt supplementation Sleeping in a semierect position (which minimizes the natriuresis and diuresis that occur during recumbency) Ingestion of 500 mL water 30 minutes before arising Fludrocortisone (0.1–0.5 mg orally once daily) Vasoconstrictor agents may be helpful and include Midodrine (2.5–10 mg orally three times daily) Droxidopa (100–600 mg orally three times daily) Ephedrine (15–30 mg orally three times daily) Less commonly used agents Dihydroergotamine Yohimbine Pyridostigmine Clonidine Refractory cases may respond to erythropoietin (epoetin alfa) or desmopressin +++ Therapeutic Procedures ++ Avoid abrupt postural change, prolonged recumbency, heavy meals, and other precipitants (eg, straining with bowel movements) Medications associated with postural hypotension should be discontinued or reduced in dose There is no satisfactory treatment for disturbances of sweating, but an air-conditioned environment is helpful in avoiding extreme swings in body temperature Postprandial hypotension is helped by caffeine + Outcome Download Section PDF Listen +++ +++ When to Refer ++ When the diagnosis is in question When symptoms do not respond to conventional therapy + References Download Section PDF Listen +++ + +Cheshire WP. Chemical pharmacotherapy for the treatment of orthostatic hypotension. Expert Opin Pharmacother. 2019 Feb;20(2):187–99. [PubMed: 30376728] + +Freeman R et al. Orthostatic hypotension: JACC State-of-the-Art Review. J Am Coll Cardiol. 2018 Sep 11;72(11):1294–1309. [PubMed: 30190008] + +Magkas N et al. Orthostatic hypotension: from pathophysiology to clinical applications and therapeutic considerations. J Clin Hypertens (Greenwich). 2019 May;21(5):546–54. [PubMed: 30900378] + +Novak P. Autonomic disorders. Am J Med. 2019 Apr;132(4):420–36. [PubMed: 30308186] + +Palma JA. Epidemiology, diagnosis, and management of neurogenic orthostatic hypotension. Mov Disord Clin Pract. 2017 May–Jun;4(3):298–308. [PubMed: 28713844] + +Pérez-Lloret S et al. Droxidopa for the treatment of neurogenic orthostatic hypotension in neurodegenerative diseases. Expert Opin Pharmacother. 2019 Apr;20(6):635–45. [PubMed: 30730771]