A. Dizziness — imprecise term used by patients to describe various sensations ranging from whirling to lightheadedness to unsteadiness B. Vertigo — illusion (sensation) of rotational movement of self or environment; described as whirling, spinning, tilting, rotating; often accompanied by nystagmus, unsteadiness, and nausea; implies abnormality of peripheral vestibular apparatus, vestibular nerve, or central nervous system (brain stem vestibular pathways) C. Syncope — loss of consciousness or fainting; often accompanied by profuse sweating (diaphoresis) and nausea; due to reduced cerebral perfusion and usually implies cardiovascular abnormality D. Dysequilibrium — unsteadiness (“drunkenness”) without vertigo; implies incongruity of sensory inputs mediating spatial orientation 1. Feeling experienced by individual who has lost proprioceptive input from legs (due to peripheral neuropathy) and cannot see foot position when attempting to walk in darkened room 2. Elderly individuals often have altered sensory input due to reduced vision (cataracts), reduced proprioception (as from diabetic peripheral polyneuropathy), or vestibular abnormalities (due to ischemia from basilar artery insufficiency) 3. Diminished sensory input causes feeling of being out of touch with environment, especially when walking or turning 4. Treatment involves supplying additional sensory cues (such as using cane when walking) E. Nystagmus - involuntary rhythmic oscillation of eye; evident as slow drift of eye in one direction followed by quick (cerebral cortex controlled) corrective jerk in opposite direction; named for direction of quick (fast) component 1. Toxic-metabolic disorders produce symmetrical horizontal nystagmus, equal in both directions of-gaze; common with large doses of phenytoin (Dilantin), benzodiazepines such as diazepam (Valiurn), or barbiturates 2. Asymmetric nystagmus -absent or reduced in one direction of gaze compared with opposite direction of gaze; usually indicates peripheral vestibular dysfunction or brain disease 3. Dysconjugate nystagmus — movements greater in one eye; always indicates brain disease 4. Upward-gaze, downward-gaze, or rotatory nystagmus — movements other than in horizontal plane suggest brain disease and are usually not associated with vertigo 5. Positional nystagmus — nystagmus (and associated vertigo) occurring with certain head positions or with head movement F. Oscillopsia — illusion that stationary objects (such as ground, buildings, or walls) are moving back and forth (oscillating); results from bilateral vestibular damage (as from vestibulotoxic drugs) or brain stem disease (as in lateral medullary infarction)