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Evaluation of polyneuropathy
Time course
bulletAcute  & subacute:
bulletAcute: days to 4 weeks
bulletSubacute: 4 to 8 weeks
bulletSuspect
bulletGBS: Acute inflammatory demyelinating polyradiculoneuropathy
bulletPorphyria
bulletAcute toxic exposure (arsenic)
bulletMononeuritis multiplex, such as from vasculitis
bulletProximal diabetic neuropathy
bulletIdiopathic plexopathy
bulletParaneoplastic sensory neuronopathy
bulletChronic: greater than 8 weeks:
bulletStatic
bulletRelapsing: CIDP and porphyria.
bulletProgressive
Symmetric vs asymmetric polyneurpathy?
bulletSymmetric sensorimotor polyneuropathy
bulletOther polyneuropathy may have a much shorter differential:
bulletAsymmetric Polyneuropathy
bulletPolyneuropathy with specific features
bulletPainful polyneuropathy
bulletAtaxic sensory neuropathy
bulletPredominantly autonomic neuropathy
bulletTruly demyelinating neuropathy: motor NCV < 28 m/s in the legs and < 35 m/s in the arms.
Inherited or Acquired ?
      Hereditary Neuropathy:
bulletLong history (years) and symmetric symptoms since onset.
bulletPes cavus and hammer toes are signs of inherited neuropathy and should be specifically sought.
bulletA negative family history does not exclude inherited neuropathy.
bulletSymptoms may be mild and unrecognized in family members.
bulletRecessive inheritance:  implies that neither parent is affected.
bulletPaternity may not be as clear as it appears.
History
bulletMedications & toxic exposure, especially alcohol
bulletConcomitant medical problems:
bulletInfections or vaccinations
bulletConstitutional symptoms: joint pain, rash, fever, weight loss
bulletBrief occupational history
Diagnostic tests
bulletBlood test:
bulletSMAC, CBC, glycosylated hemoglobin, TSH, ESR, Rheumatoid factor, ANA, serum (and preferably urine) protein immunoelectrophoresis.
bullet

Vitamin B12 level
bullet

if the result is borderline (200-300 pg/ml) methylmalonic acid and homocysteine levels should be tested.

bullet

2 hour glucose tolerance test

bulletChest X ray: malignancy, Sarcoid
bulletElectrodiagnostic study
bullet

Special diagnostic tets:
bullet

Evidence of dry eyes or mouth
bullet

evaluation for Sjögren’s syndrome

bullet purely sensory neuropathies and gait ataxia who have markedly elevated ANA titers but few other laboratory abnormalities.
bulletLip biopsy, showing the typical inflammation of minor salivary glands, can be a useful confirmatory test.

bullet

Systemic evidence of a connective tissue disease (e.g. rash, Raynauds phemonoma, arthritis)
bullet

connective tissue disease evaluation including cryoglobulins and hepatitis C serologies.

bullet

Suspect multifocal motor neuropathy
bullet

GM1

bullet

Suspected CIDP
bullet

MAG

bulletSuspect toxic neuropathy
bulletUrine heavy metals
bullet

If EDX is negative
bullet

The most sensitive means of proving the presence of neuropathy is skin biopsy

bullet

measure intraepidermal nerve fiber density (IENF)

bullet

abnormal in approximately 90% of patients with neuropathy.

bulletMore on Autoantibody testing
Further reading
bulletChalk, CH. Neurologic Clinics. Vol 15. No 3. Aug 1997
bulletDiabetic neuropathy
bulletGuillain Barre Syndrome
bulletSearch for meaning in Monoclonal protein - Postgrad Med Aug 99

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