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Autonomic Dysfunction cont'd

 

Specific syndromes

  • Pure Autonomic Failure:--

    • Symptoms

      • Postural (orthostatic) hypotension

        • "Neurogenic Orthostatic Hypotension-Medical Animation"

           

      • 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:

    • Striatonigral degeneration

    • Shy-Drager syndrome

    • Olivopontocerebellar atrophy

    • General/common --Clinical Symptoms include

      • Postural hypotension

      • Impotence

      • Bladder/bowel dysfunction

      • Defective sweating

    •  Death may occur or 7-10 years after onset

Olivopontocerebellar atrophy (OPCA):20 years old female with progressive cerebellar ataxia

Axial T2W MRI

Axial PDW MRI

Sagittal T1W MRI

  • "The T2W spin-echo axial section shows atrophy of the pons and middle cerebellar peduncles with enlargement of the prepontine and ponto-cerebellar cisterns and moderate atrophy of the cerebellar hemispheres. The PDW image shows slight signal hyperintensity of the transverse pontine fibers (arrows), sparing the pyramidal tracts. The midline sagittal T1W spin-echo image (far right) shows flattening of the pons and atrophy of the cerebellar vermis. 

    • MRI findings, combined with the clinical symptoms, are highly suggestive of olivopontocerebellar atrophy. 

      • Olivopontocerebellar atrophy (OPCA) is a degenerative disease characterized by atrophy of the pons, middle cerebellar peduncles and cerebellar hemispheres. 

        • It can exist as an inherited form, transmitted in an autosomal dominant manner or as a sporadic form.

        • Although the mean age of onset is during the fourth decade, the condition can be encountered in children.

        • Since the main clinical symptoms, ataxia, dysmetria, dysartria and ophtalmoparesis are in common with other cerebellar degenerative and non degenerative diseases, MRI is essential for diagnosis"

          • Images and commentary from: Section of Neuroradiology; Department of Radiology;University of Brescia;Policlinico Satellite; Spedali Civili; 25123 BRESCIA; ITALY--by Roberto Gasparotti, M.D.

  •  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

      •  Ahlorhydria

      •  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:  Q-T prolongation has been associated with sudden cardiac death.

  • Amyloid polyneuropathy

    • Distal painful neuropathy on presentation

    • Sensory loss

    • Cardiac/renal impairment: usual causes of death

    • Autonomic dysfunction occurs 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  (Polyradiculopathy: term used to describe processes which affect portions of many nerves and cause proximal and distal motor with or without sensory changes)  and is 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.

 

 
 
 
 

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