Focal peripheral neuropathy

Some causes of focal peripheral nerve damage are self-evident, such as involvement at sites of trauma, tissue necrosis, infiltration by tumour, or damage by radiotherapy. Focal compressive and entrapment neuropathies are particularly valuable to identify in civilian practice, since recovery may follow relief of the compression. Leprosy is a common global cause of focal neuropathy, which involves prominent loss of pain sensation with secondary acromutilation, and requires early antibiotic treatment. Mononeuritis multiplex due to vasculitis requires prompt diagnosis and immunosuppressive treatment to limit the severity and extent of peripheral nerve damage. Various other medical conditions, both inherited and acquired, can present with focal neuropathy rather than polyneuropathy, the most common of which are diabetes mellitus and hereditary liability to pressure palsies. A purely motor focal presentation should raise the question of multifocal motor neuropathy with conduction block, which usually responds well to high-dose intravenous immunoglobulin infusions.