Neuropathies, Toxic

Key Features

• Axonal polyneuropathy may follow exposure to

  • Industrial agents or pesticides, such as acrylamide, organophosphorus compounds, hexacarbon solvents, methyl bromide, and carbon disulfide

  • Metals, such as arsenic, thallium, mercury, and lead

  • High doses of such certain medications, such as phenytoin, amiodarone, perhexiline, isoniazid, nitrofurantoin, vincristine, and pyridoxine

• Bulbar and distal sensorimotor polyneuropathy may follow diphtheria

Clinical Findings

• Diphtheritic neuropathy

  • Results from a neurotoxin released by the causative organism and is common in many areas

  • Palatal weakness may develop 2–4 weeks after infection of the throat

  • Infection of the skin may similarly be followed by focal weakness of neighboring muscles

  • Disturbances of visual accommodation may occur about 4–5 weeks after infection

  • Distal sensorimotor demyelinating polyneuropathy may occur after 1–3 months

Diagnosis

• Detailed occupational, environmental, and medical histories and recognition of clusters of cases are important in suggesting the diagnosis

Treatment

• Prevent further exposure to the causal agent

• Isoniazid neuropathy is prevented by pyridoxine supplementation