Vertigo (dizziness, giddiness, swimming in the head) 'is that condition in which a person suffers from a sense of failing equilibrium, of falling, or of rotating.' It 'may vary from a mere uncomfortable sense of oscillation, such as one feels after landing from a sea-voyage, to a condition in which the patient is quite unable to maintain his equilibrium, and either falls to the ground or is forced to support himself by clutching some fixed object.' In its most characteristic form the patient feels either as if he were being turned round or as if surrounding objects were being moved round him. Its direct cause is probably either (1) disturbance of the cerebral circulation or (2) abnormal sensory impressions from the semicircular canals (see EAR) or eyes, from which the chief sensations governing equilibration are derived. A familiar example of (1) is the dizziness often experienced on assuming or rising from a stooping posture; of (2) that following two or three quick turns of the body on its own axis, or rapid movement in a small circle.
(1) In disease vertigo is met with in faintness or loss of blood, in cerebral congestion, epilepsy, and other brain diseases. It is often met with as a symptom of disturbed digestion, probably from reflex effect upon the circulation in the brain. (2) Vertigo connected with ocular disturbance generally depends upon some abnormal condition, either spasm or paralysis of one or more of the external muscles of the eyeball. It is much more commonly met with in diseases of the ear; in the cases grouped under the name of Meniere's disease the semicircular canals are themselves the seat of disease; but frequently in disease of the middle ear, and even sometimes in disease of the external ear, vertigo is one of the symptoms complained of. The cause of vertigo, and therefore the treatment to be adopted in any particular case, must be decided by a careful study of the other symptoms with which it is associated.