Cranial and peripheral neuropathies.

An acute polyneuropathy developing over days to several weeks is most likely to be Guillain-Barré syndrome or a toxic neuropathy, although vasculitis can also present acutely. This presentation should be referred immediately for further investigation. A subacute to chronic (ie, developing over months) neuropathy with significant proximal weakness and prominent loss of reflexes is highly suggestive of chronic inflammatory demyelinating polyradiculoneuropathy. If there is a clear stepwise onset of symptoms, suggestive of multiple mononeuropathies, or significant asymmetry, vasculitic neuropathy should be considered, even in the absence of systemic vasculitis. Idiopathic chronic axonal neuropathy is an indolent, predominantly sensory neuropathy that typically occurs in older patients. Neuropathies occurring in young or middle age or with more subacute onset always warrant further investigation.