Abstract
Purpose
To present the outcomes of two patients (three ears) with hyperacusis treated with round and oval window reinforcement.
Materials and methods
Transcanal placement of temporalis fascia on the round window membrane and stapes footplate was performed. Loudness discomfort level testing was performed. Results of pre and post-operative hyperacusis questionnaires and audiometric testing were reviewed.
Results
Two patients (three ears) underwent surgery. Results from the hyperacusis questionnaire improved by 21 and 13 points, respectively. Except for a mild loss in the high frequencies, no change in hearing was noted post-operatively. Both patients reported no negative effects from surgery, marked improvement in ability to tolerate noise, and would recommend the procedure to others. There were no complications.
Conclusions
Round and oval window reinforcement is a minimally invasive option for treating hyperacusis when usual medical therapies fail. Further studies are needed to evaluate the effectiveness of the procedure in reducing noise intolerance.
1
Introduction
Hyperacusis, defined as noise intolerance to ordinary sounds, is a challenging problem encountered by otolaryngologists. Patients often present with emotional (anxiety, stress, depression), social (isolation, limitation in activities), and physical (pain, discomfort) symptoms. Individuals with hyperacusis suffer from a reduced quality of life, due to anxiety and noise-related avoidance in daily activities . Although individuals with hyperacusis report varying degrees of intolerance to sound, the primary complaint is a physical and/or psychological reaction to sound. The physical properties of certain sounds elicit negative reactions in patients with hyperacusis which do not evoke an adverse reaction in an average listener . The reported prevalence of hyperacusis ranges from 5.9% to 17.2%, depending on the definition of hyperacusis used and whether individuals with hearing loss are excluded in various studies .
The mechanism of hyperacusis is not completely understood, but has been related to acoustic overexposure resulting in increased gain within the central auditory pathways . Contributing factors include a history of head trauma or acoustic trauma, hearing loss, and aging . Hyperacusis is often accompanied by tinnitus and vice versa . While tinnitus may arise from failure of the brain to adapt to deprived peripheral input, hyperacusis is thought to be related to an “over-adaptive” increase in response gain, as a result of afferent neuronal degeneration of auditory fibers .
Current commonly used treatment options for hyperacusis include avoidance of provocative stimuli, cognitive behavioral therapy, tinnitus retraining therapy, hearing amplification devices, and gradual sound exposure using wideband noise generators, with varied rates of success . Although no surgical technique exists specifically for the treatment of hyperacusis, surgical intervention has been found to improve hyperacusis in patients with superior semicircular canal dehiscence (SSCD). Silverstein et al. found round window reinforcement to be an effective and minimally invasive surgical option for reducing the symptoms of SSCD . Nikkar-Esfahani et al. noted an improvement in noise tolerance in patients with SSCD chiefly complaining of hyperacusis who underwent complete surgical occlusion of the round window . Complete resolution of hyperacusis has also been reported in a case of unilateral posterior and superior canal dehiscence treated with transmastoid plugging of both defects .
The success of round window reinforcement in improving hyperacusis in patients with SSCD led the senior author to realize the potential benefits of performing a similar procedure in patients with a chief complaint of hyperacusis without evidence of SSCD. This paper reports the outcomes of two patients (three ears) with no evidence of SSCD, who underwent transcanal round and oval window reinforcement for the treatment of hyperacusis.
2
Methods
2.1
Loudness discomfort level testing
Loudness discomfort level (LDL) testing was performed after establishing pure tone thresholds at 250, 500, 1000, 2000, 3000, 4000, and 8000 Hz. Sound stimuli was presented starting at 60 dB HL and increased in increments of 5 dB HL. As the tone approaches the uncomfortable loud level, the step size is decreased in order to determine the LDL with a 1 dB resolution. This process is performed twice at each frequency, and the average of the two LDLs is recorded. The normal reference level for the LDL is traditionally accepted to be at 100 dB HL, although normal hearing individuals have been found to have LDLs between 86 and 98 dB HL .
The patients completed a validated hyperacusis questionnaire to rate the severity of their pre-operative and post-operative symptoms ( Fig. 1 ) .
2.2
Surgical technique
Under general anesthesia, transcanal round window niche and oval window reinforcement was performed using a traditional transcanal tympanomeatal flap approach. If needed, the bony posterior canal was enlarged using a high-speed drill or curette to allow visualization of the ossicular chain, round window niche, chorda tympani, horizontal facial nerve, and hypotympanum. The bony lip overlying the round window niche was also removed with a one millimeter diamond drill for further exposure of the round window membrane. Temporalis fascia was obtained through a 2 cm incision above the auricle and small pieces were gently placed against the round window membrane and the stapes footplate ( Figs. 2 and 3 ), and held in place with gelatin foam (Gelfoam). A 3 mm biopsy punch can be used to cut the fascia for the round window niche, and a 2 mm biopsy punch can be used to cut the fascia for placing over the stapes footplate. Following reinforcement, the tympanomeatal flap was repositioned and the external auditory canal was packed for one week with polyester packing strips and a small sponge.
2.3
Patient 1
A 64-year old male presented with a several-week history of positional vertigo consistent with benign paroxysmal positional vertigo. He was successfully treated with an Epley maneuver. On further questioning, he also reported an 18-year history of noise intolerance and tinnitus after noise exposure from a tank explosion. He had undergone right tympanoplasty for a tympanic membrane perforation a few months after his acoustic trauma. Otoscopic examination was remarkable for a left positive Tullio phenomenon. CT of the temporal bones showed normal superior semicircular canals bilaterally and no other pathologic findings. Pre-operative audiogram showed bilateral mild to moderate high-frequency sensorineural hearing loss with normal tympanograms. Pre-operative vestibular evoked myogenic potential (VEMP) was normal on the left side and absent on the right side, and electronystagmography (ENG) revealed intact and normal bilateral vestibular function. After informed consent was obtained, left round and oval window reinforcement was performed for a suspected perilymph fistula. Post-operatively, hearing remained unchanged except for mild loss in the high frequencies ( Fig. 4 ). The patient did not notice any hearing loss after surgery. Post-operative LDLs were above 90 dB HL in all frequencies except at 2000 and 8000 Hz in the left ear ( Fig. 4 ). Pre-operative LDLs were not routinely obtained at the time of the patient’s initial presentation and are not available for comparison. Hyperacusis survey results improved from 33 points pre-operatively to 12 points post-operatively. Post-operatively, the patient no longer exhibited a left positive Tullio phenomenon. He reports continued marked improvement of his hyperacusis and tinnitus, as well as quality of life, at 4 years after surgery.
2.4
Patient 2
A 75-year old female presented with a 15-year history of noise intolerance with associated tinnitus that was worse in the right ear. Otoscopic examination was unremarkable bilaterally, but sensitivity and wince aversion to 512 Hz tuning fork testing was noted. CT of the temporal bones showed thinning of the roofs of the superior semicircular canals bilaterally, but no frank dehiscence. There were no other pathologic findings noted on CT imaging. Pre-operative audiogram showed bilateral moderate to moderately severe high-frequency sensorineural hearing loss with normal tympanograms. VEMPs were normal on the left side, while showing reduced thresholds on the right side. After informed consent was obtained, right round and oval window reinforcement was performed. One week after surgery, the patient noted a marked improvement in the ability to tolerate noise in the right ear. Post-operative right LDLs remained under 90 dB HL in all frequencies but improved by an average of 8.67 dB ( Fig. 5 ). As a result of her improved noise tolerance, the patient subsequently elected to have the same procedure in the left ear, which was performed two months later. Post-operative left LDLs improved by an average of 7.14 in the left ear, and improved above 90 dB HL in four frequencies ( Fig. 6 ).
