الفهرس 
Semi-circular CanalsOnly 14 pages are availabe for public view
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Abstract
Hearing loss is categorized as conductive hearing loss, sensory neural hearing loss (SNHL)or mixed. Conductive hearing loss results from obstruction or disease of the outer or middle ear. The causes of conductive hearing loss range from cerumen impaction and otitis media to fixation of one or more of the middle-ear bones, mainly fixation of the stapes due to otosclerosis(1) The cause of SNHL remains largely unclear with approximately 90% of cases being idiopathic (2). However, the main causes of sensorineural hearing loss are degenerative processes associated with aging, genetic mutations, noise exposure, exposure to therapeutic drugs that have ototoxic side effects.(1) The primary acoustic circuit is made up of the auditory nerve, brain stem, thalamus, and auditory cortex(3)In addition to this classical auditory pathway there is link between the auditory cortex and the limbic system in the generation and maintenance of tinnitus(4) Tinnitus is the perception of sound in the absence of an external acoustic stimulus(5) Pulsatile tinnitus is often suggestive of a vascular origin and can be subjective or objective, while non-pulsatile tinnitus is almost always subjective and is the most common form of tinnitus, Sometimes there is a structural lesion (e.g. acoustic neuroma) or pathological condition (such as Meniere’s disease and multiple sclerosis) as the cause , but often, tinnitus can occur without structural lesions or other conditions, In most patients, tinnitus is associated with hearing loss, but it can also occur in people with normal hearing.