[Occupational toxic neuropathies: morphology in peripheral nerve biopsies]

G Ital Med Lav Ergon. 2012 Oct-Dec;34(4):410-9.
[Article in Italian]

Abstract

Many peripheral neuropathies are caused by the (acute or chronic) toxic action of metals, solvents, pesticides, and other occupational and environmental contaminants. These agents often reproduce the anatomoclinical pictures of hereditary (e.g., Charcot-Marie-Tooth disease), autoimmune (Guillain-Barrè syndrome), or dysmetabolic (thiamine deficiency, diabetic neuropathy) forms. Toxic peripheral neuropathies can be classified on the basis of etiology, clinical features (sensitive, motor, sensitive-motor), or histopathology: neuronopathies (uncommon, mostly secondary to retrograde axonal degeneration; e.g., arsenic, thallium), axonopathies (acrylamide, esacarbons, CS2, organophosphate-induced delayed neuropathy), myelinopathies (trichloroethylene), mixed forms (axonal and demyelinating: lead). For many substances, experimental research has led to the identification of the molecular and cellular targets of neurotoxicity. Several compounds are active by biotransformation (e.g., the esacarbons n-hexane and MnBK are neurotoxic since they are metabolized to 2,5-hexanedione), Genetic, physiological and environmental factors determine the individual metabolic set-up, and they may give origin to differences in the workers' sensitivity. Cessation of exposure is often followed by (microscopically observable) regenerative phenomena and clinical improvement. The morphology of neuropathies can be studied through peripheral nerve biopsy. Samples of sural nerve (or other nervous trunks of the limbs), adequately fixed, sectioned, and stained, allow the observation of alterations in axonal fibres (e.g., giant-axonal neuropathy, dying back neuropathy), myelin (demyelination), Schwann cells, interstitium, and blood vessels; possible inflammatory infiltrates; fibre density; regenerative phenomena (growth cone, remyelination). In occupational medicine, biopsy is indicated when the anamnestic-clinical picture, laboratory tests, and instrumental exams leave doubts about the nature, type, and entity of the neurological damage. In such cases, current optical and electron microscopy techniques can be very useful for injury evaluation, prognosis, and follow-up.

Publication types

  • English Abstract

MeSH terms

  • Axons / pathology
  • Biopsy* / methods
  • Diagnosis, Differential
  • Follow-Up Studies
  • Humans
  • Immunohistochemistry
  • Microscopy, Electron
  • Occupational Diseases / chemically induced*
  • Occupational Diseases / diagnosis
  • Occupational Diseases / pathology*
  • Peripheral Nervous System Diseases / chemically induced*
  • Peripheral Nervous System Diseases / diagnosis
  • Peripheral Nervous System Diseases / pathology*
  • Predictive Value of Tests
  • Presynaptic Terminals / pathology
  • Prognosis
  • Risk Assessment
  • Risk Factors
  • Sensitivity and Specificity
  • Sural Nerve / pathology*