Temporary Arterial Obstruction: Effect on Perilymph Oxygen and Microphonics

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Abstract
The principal source of oxygen to the cochlea is the arterial blood supply. When blood flow (oxygen delivery) is stopped the reserves of oxygen in the cochlea are very limited and begin to fall in a few seconds. The oxygen reserves drop in a linear fashion and are exhausted in about 100 seconds. The oxygen reserve in the cochlea can maintain normal cochlear function (microphonic output) for only a few seconds after blood flow stops. After this cochlear function drops reaching a 50% level in 40 seconds. With return of blood flow cochlear oxygen tension recovers in a linear manner while cochlear function recovers more rapidly. Full recovery of normal blood flow, normal oxygen reserves and cochlear function can be obtained even after 6 minutes of obstruction of the internal auditory artery. When blood flow resumes the initial velocity may be two to three times normal. In a short period (i.e. 100 seconds) depending on the duration of the obstruction, blood flow velocity returns to normal. This is an indication of the capacity of this vascular bed for autoregulation.