الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
The peripheral vestibular system consists of three semicircular canals and two otoliths organs. It is responsible for sensing and control of motion. Vestibular nerve afferents innervating individual semicircular canal respond to angular acceleration in the plane of the canal and send a signal to the brain stem vestibular nuclei. Affrents that innervating the otolith organs respond to linear acceleration and tilt of head relative to gravity. The most common disorders that affect the peripheral vestibular end organs are Benign paroxysmal positional vertigo, Vestibular neuronitis and Meniere?s disease. Many other disorders either peripheral or combined peripheral and central may affect the labyrinth but with less frequancy of incidence. Patient with vertigo should be evaluated in a systematic manner including a careful history, thorough otologic and neurotologic evaluation including cranial nerves assessment, search for spontaneous, gazeevoked, positional and Hallpikeinduced nystagmus. Bed side evaluation should also include cerebellar limb tests, gait observation, pursuit and saccadic eye movements examination, and the three specific tests for labyrinthine dysfunction posthead shake nystagmus, head thrust test and dynamic visual acuity test. These together with laboratory tests, radiologic and audiologic studies contribute for a major part of the evaluation workup. Vestibular function tests in the form of the electronystagmography (ENG), Videonystagmography (VNG), rotational chair and computerized dynamic posturography are the cornor stone in the diagnosis of vertigo of peripheral aetiology. Electrooculogrpahy and Videooculography are used to document central oculomotor function and record the response to caloric stimulation. Rotational chair tests explore the vestibuloocular reflexes and visual vestibular interaction throughout a broad frequency and velocity range. The computerized dynamic posturography is used in cases of postural instability to document the patterns of sensory organization and motor control during various visual and support surface challenges.