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Key Features

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Essentials of Diagnosis
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  • Insidious onset of weakness and fatigability of the limbs, sometimes with pain or numbness; decreased strength and reflexes

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General Considerations
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  • Causes

    • Toxins (lead, arsenic, mercurials, vincristine, and benzene)

    • Systemic disorders (diabetes mellitus, chronic uremia, recurrent hypoglycemia, porphyria, polyarteritis nodosa, and lupus erythematosus)

    • Inflammatory states (chronic inflammatory demyelinating polyneuropathy and neuritis associated with mumps or diphtheria)

    • Hereditary, often degenerative conditions, which in some classifications include certain storage diseases, leukodystrophies, spinocerebellar degenerations with neurogenic components, and Bassen-Kornzweig syndrome

    • Hereditary sensory or combined motor and sensory neuropathies

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Clinical Findings

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  • Onset is usually insidious

  • Condition is slowly progressive

  • Disturbances of gait and easy fatigability in walking or running are presenting symptoms

  • Weakness or clumsiness of the hands is seen slightly less often

  • Pain, tenderness, or paresthesias are mentioned less frequently

  • Neurologic examination discloses muscular weakness, greatest in the distal portions of the extremities, with steppage gait and depressed or absent deep tendon reflexes

  • Cranial nerves are sometimes affected

  • Sensory deficits occur in a stocking-and-glove distribution

  • Muscles may be tender

  • Trophic changes such as glassy or parchment skin and absent sweating may occur

  • Rarely, thickening of the ulnar and peroneal nerves may be felt

  • In sensory neuropathy, the patient may not feel minor trauma or burns, and thus allows trauma to occur

  • Chronic inflammatory demyelinating neuropathy (CIDP)

    • Most common chronic motor neuropathy of insidious onset

    • Often has no identifiable cause

    • Assumed to be immunologically mediated and may have a relapsing course

    • Sometimes facial weakness occurs

    • CSF protein levels are elevated

    • Nerve conduction velocity is slowed

    • Nerve biopsy findings may show round cell infiltration

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Diagnosis

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  • Electrophysiologic testing confirms diagnosis

  • CSF protein levels are often elevated, sometimes with an increased IgG index

  • Nerve biopsy, with teasing of the fibers and staining for metachromasia, may demonstrate loss of myelin, and to a lesser degree, loss of axons and increased connective tissue or concentric lamellas (so-called onion bulb appearance) around the nerve fiber

  • Muscle biopsy may show the pattern associated with denervation

  • Screening for heavy metals as well as for metabolic, renal, or vascular disorders may need to be done

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Treatment

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  • Corticosteroid therapy is used first when the cause is unknown or neuropathy is considered to be due to chronic inflammation

  • Prednisone

    • Initiated at 2–4 mg/kg/d orally, with tapering to the lowest effective dose

    • May need to be reinstituted when symptoms recur

    • Should not be used for treatment of hereditary neuropathy

  • Immunomodulating therapy may be safer or "steroid-sparing"; options include

    • IVIg

    • Plasmapheresis

    • Mycophenolate mofetil

    • Rituximab

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Outcome

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Prognosis
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  • Varies with the cause and the ability to offer specific therapy

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References

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Eftimov  F  et al: Intravenous immunoglobulin for chronic inflammatory demyelinating polyradiculoneuropathy. Cochrane Database Syst Rev 2013 Dec ...

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