Clinical localisation of a neurological lesion

The basic function of the neurological history and examination is to localise a neurological lesion.

There are several reasons why localising a lesion is helpful:

• some pathological processes occur in anatomically restricted areas e.g. syringomyelia
• some diseases present as multifocal lesions e.g. mononeuritis multiplex
• some diseases present as a diffuse lesion e.g. peripheral neuropathy
• localising a lesion permits the most effective use of special investigations
• localising lesions may affect prognosis e.g. multiple sclerosis

The localisation of a lesion in the nervous system requires some anatomical knowledge and a few simple rules.