Answer
Although tinnitus is not a surgical disease for the most part, tinnitus due to a surgical lesion in the ear usually responds to treatment of that lesion. Typical lesions amenable to surgery include those caused by glomus tumors, sigmoid sinus diverticulum, arteriovenous malformation, and conductive hearing loss.
The examiner should suspect glomus tumors in any case of pulsatile tinnitus that corresponds to heartbeat. Pulsatile tinnitus resolves once the tumor is removed. However, the patient may still have a hum or other vascular symptom due to the surgery.
Similarly, most patients with acoustic tumors present with tinnitus. Once the tumor is removed, 50% find the tinnitus improved, and 50% find it to be unchanged. Additionally, dural arteriovenous fistulas can be embolized, and aneurysms can be clipped. When a jugular venous hum is diagnosed, the optimum therapy may be counseling and reassurance. Ligation of the vein or other arteriovenous malformation may resolve the symptom, but it frequently returns after a number of years.
A study by Wang et al indicated that in patients with pulsatile tinnitus caused by sigmoid sinus diverticulum (SSD), surgical correction of the SSD and of any accompanying sigmoid sinus wall dehiscence (SSWD) can effectively eliminate the tinnitus. The study involved 25 patients with SSD, most of whom also had SSWD, who underwent sigmoid sinus wall reconstruction. The investigators found that pulsatile tinnitus completely resolved in 17 patients and partially resolved in three of them. [13]
Tinnitus is organic to Ménière syndrome. Thus, treatment of the syndrome may help resolve tinnitus. In more severe cases, tinnitus may remain despite best efforts at treatment. Surgical intervention with an endolymphatic shunt, nerve section, or labyrinthectomy and ototoxic antibiotic injection provides relief for 40-80% of such patients. Interestingly, the recent advent of gentamicin or corticosteroids has resulted in a higher percentage of patients describing either temporary or permanent relief from tinnitus. The exact mechanism of relief is unknown, but relief is greatly appreciated by patients.
As discussed in the Philosophy section, the problem with the therapy of tinnitus is its unpredictability. Although the successful ablation of the identifiable problem in many of these cases should eliminate the problem, often only 50% of patients describe complete relief from the difficulty. The explanation seems to rest with some type of sensitization to the function of the inner ear, auditory nervous system, and the brain, with the resultant head noise, or tinnitus.
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Tinnitus model. Two phenomena in the auditory cortex are associated with peripheral deafferentation: 1) hyperactivity in the lesion projection zone and 2) increased cortical representation of the lesion-edge frequencies (here, C6) in the lesion projection zone. These two phenomena are presumed to be the neurophysiological correlates of tinnitus. The red letters correspond to octave intervals of a fundamental frequency.
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Masking. In this graphic, masking sounds are applied at C6, the tinnitus frequency. The result is that the sensation of tinnitus is reduced. In the auditory cortex, this corresponds to decreased spontaneous firing rates.
