Any lesion along the auditory nerve can result in a focal demyelination (small lesion in the insulating layer around the nerve).

We can verify the effect it has by a functional test, auditory evoked brainstem potentials. Conduction of sound in the auditory nerve is seen as a curve consisting of six peaks. Slowing down in conduction velocity between peak I and III or a decrease in positivity of peak II or a difference between the pathological and the normal side are arguments in favour of a lesion on the auditory nerve itself. The lesion can be a benign tumor of the auditory or vestibular nerve or a bloodvessel compressing the auditory nerve.

If for example a bloodvessel continues to hammer on the auditory nerve, this can result in auditory nerve damage with the formation of a scar in the auditory nerve as a consequence, leading to irreversibility of the tinnitus.

The focal demyelination creates an ectopic exatation (short circuit) resulting in a less functional auditory nerve. When the brainstem and brain receive abnormal auditory information, both the brainstem and auditory cortex and the brain will adjust to this change.

If the adjustment is maladaptive it results in tinnitus.

As a conclusion we can state that a lesion or compression of the auditory nerve creates a focal lesion in this nerve resulting in a short circuit. Brainstem and brain will adapt to this altering auditory information and this adaptation is what we here as tinnitus. As such we can consider tinnitus as phantom pain of the auditory tract. In this sense tinnitus is almost identical to phantom pain patients suffer after an amputation. Tinnitus can thus be considered a phantom phenomenon.

The explanation given above for cochlear nerve mediated tinnitus probably also holds for other causes of tinnitus. The final common pathway is the change occurring in the auditory cortex when temporarily of definitively a part of the auditory tract becomes un- or less functional. Braincells genetically coded for a very specific function become activated by sensory information not destined for them, resulting in the perception of tinnitus.