Autonomic Dysfunction Page 3

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  • Specific syndromes:
    • Pure Autonomic Failure:--
      • Symptoms
        • postural (orthostatic) hypotension
        • impotence
        • bladder dysfunction
        • defective sweating
      • reduction in sympathetic ganglia neuronal density
      • low supine plasma norepinephrine levels
      • reduced norepinephrine response to tyramine
      • decreased neuronal norepinephrine uptake
      • noradrenergic supersensitivity- consistent with peripheral sympathetic dysfunction
    • Multiple System Atrophy -- several, overlapping syndromes including:
      1. striatonigral degeneration
      2. Shy-Drager syndrome
      3. olivopontocerebellar atrophy
      4. General/common --Clinical Symptoms include
        • postural hypotension
        • impotence
        • bladder/bowel dysfunction
        • defective sweating
      5.  Death may occur or 7-10 years after onset
    •  Peripheral Nerve Disorders: most common cause of chronic autonomic insufficiency
      • Neuropathies -- affecting small myelinated and unmyelinated fibers of sympathetic/parasympathetic nerves occur in:
        1. diabetes mellitus
        2. amyloidosis
        3. chronic alcoholism
        4. porphyria
        5. Guillain-Barre syndrome
      • Diabetes Mellitus:
        • initial finding: often asymptomatic abnormal vagal function (reduced heart rate variation with deep breathing)
          • Loss of myelinated and non-myelinated small nerve fibers in splanchnic distribution, carotid sinus, and vagus nerve
        • Enteric neuropathy:
          • disturbances and gut motility
          • nausea/vomiting
          • achlorhydria
          • bowel incontinence
        • Other Symptoms:
          • impotence
          • urinary incontinence
          • pupillary abnormalities
          • postural hypotension
          • symptoms of hypoglycemia -- blunted or detectable because damage to sympathetic adrenal gland innervation prevents epinephrine release
          • Autonomic dysfunction may lengthen Q-T interval -- associated with sudden cardiac death
      • Amyloid polyneuropathy
        • distal painful neuropathy on presentation
        • sensory loss
        • cardiac/renal impairment: usual causes of death
        • autonomic dysfunction manicured because of:
          1. amyloid deposits at intraneural blood vessels and neurons in autonomic ganglia
          2. loss of unmyelinated and myelinated nerve fibers
      • Alcoholic neuropathy:
        • Associated with abnormal vagal and efferent sympathetic function
        • Pathologic changes found in:
          • vagus nerves
          • sympathetic fibers/ganglia
      • Porphyria
        • Acute intermittent porphyria: -- autonomic symptoms
          1. tachycardia
          2. sweating
          3. urinary retention
          4. hypertension
          5. anxiety
          6. catecholamines elevated during acute attack but abnormal autonomic functions may occur even in remission
      • Guillain-Barre syndrome:
        • Acute Inflammatory Demyelinating Polyradiculopathy-- associated with:
          • BP fluctuation
          • arrhythmias
          • abnormal sweating
          • pupillary dysfunction
          • sphincter disturbance
        • Demyelination occurs in:
          • vagus
          • glossopharyngeal
          • sympathetic chain
          • white rami communicantes
Engstrom, J, and Martin, J.B. Disorders of the Autonomic Nervous System, In Harrison's Principles of Internal Medicine 14th edition, (Isselbacher, K.J., Braunwald, E., Wilson, J.D., Martin, J.B., Fauci, A.S. and Kasper, D.L., eds) McGraw-Hill, Inc (Health Professions Division), 1998, pp 2372-2377.