Polyneuropathy

Typically polyneuropathy will cause the combination of distal limb muscle weakness, loss of tendon reflexes, and reduced distal limb sensation. There is variable involvement of the autonomic innervation, damage to which causes a dry, vasodilated foot or hand. Loss of tendon reflexes is a cardinal sign of polyneuropathy, often restricted to the ankle jerks in axonal degeneration, but involving more proximal reflexes in acquired demyelinating neuropathies which may involve more proximal segments or the nerve roots. Clinical features suggestive of demyelinating or conduction block polyneuropathy include: a relative lack of muscle wasting in relation to the degree of weakness because no denervation has occurred; weakness of proximal muscles as well as distal, because of nerve root involvement; and disproportionate loss of joint position and vibration sensations compared to relative preservation of pain and temperature sensations which are carried by unmyelinated fibres.