Symmetrical disease of (motor and sensory) peripheral nerves and/or the autonomic nerve system The aetiology includes an agent causing damage to the peripheral nerves. The most common causes of polyneuropathy are diabetes, alcohol, hypothyroidism and vitamin B12 deficiency. Patients in intensive care may also develop polyneuropathy. Other causes are rare. Some patients can be examined and treated in the primary care clinic; some require referral to a specialty hospital. ENMG (electroneuromyography) is an essential diagnostic tool which can also be used for monitoring disease progress. Treatment is directed at the basic cause: successful treatment of an aetiological factor may halt the progress of polyneuropathy.