When perception of orientation in space becomes disturbed, the resulting sensation may be described by sufferers as ‘dizziness’. However, the technical term used by medical practitioners for an illusory perception of orientation and movement is ‘vertigo’ (not to be confused with the lay usage of the term to refer to a fear of heights). The sensations that characterize vertigo range from vague giddiness or unsteadiness to a feeling that oneself or the environment is tilting or spinning, accompanied by partial loss of postural control and a range of autonomic symptoms such as pallor, cold sweating, nausea and vomiting (see also ‘Nausea and vomiting’).

Dizziness is extremely common: around one in four people have experienced recent dizziness, one in ten people of working age report some degree of handicap due to current dizziness, and 2% of the working age population experience chronic, frequent, substantially handicapping episodes (Kroenke et al., 2000; Yardley et al., 1998a). The most common cause of dizziness and vertigo is disorder of the vestibular organ in the inner ear, which senses head position and motion, but dizziness can result from dysfunction of any part of the complex balance system, which integrates information from the vestibular, visual and proprioceptive senses (see also ‘Tinnitus’).