Bilateral Hearing Loss Following Unilateral Stapes SurgeryFarhad Mokhtarinejad, Navid Ahmady Roozbahany, Maryam Ajami
Hearing Disorders Research Center, Shahid Beheshti University of Medical Sciences, Tehran, IranCorresponding Author: Navid Ahmady Roozbahany, MD, Hearing Disorders Research Center, Shahid Beheshti
University of Medical Sciences, Tehran, Iran: Email: [email protected]
ABSTRACT
Otosclerosis is a common cause of conductive hearing loss. It is surgically treated with stapedectomy orstapedotomy. Sensory-neural hearing loss is an uncommon but known complication of this surgery. A 25-year-oldIranian female with bilateral otosclerosis underwent right stapedotomy and developed bilateral sensorineuralhearing loss a few days after the surgery, which recovered with appropriate treatment. The possible causes andtheir clinical courses are discussed in this study. Sensorineural hearing loss after stapedotomy has many differentetiologies. Generally, the causes which are not directly related to the surgery should also be considered.Keywords: Otosclerosis, Hearing loss, Trauma.Please cite as: Mokhtarinejad F, Ahmady Roozbahany N, Ajami M. Bilateral Hearing Loss Following Unilateral StapesSurgery. 2015; 1(1):25-28.
INTRODUCTIONOtosclerosis is one of the most common causesof conductive hearing loss in people 15-50 yearsof age. The disease now refers to the bony earcapsule and may result in progressive andconductive hearing loss, mixed hearing loss andalso absolute sensorineural hearing loss in somerare cases. Otosclerosis is a hereditary diseasewhich is transmitted, in an autosomal dominantform with incomplete penetrance (1).Bilateral otosclerosis has been observed in 60%of patients. Otosclerosis occurs most commonlyamong Caucasians with an incidence of 1%followed by Asians at 0.5% (1). Progressive andconductive hearing loss particularly in lowfrequencies (500-2000 Hz) which maysometimes occur with sensorineural hearing losshas been identified as the main clinical findingof otosclerosis (1). The diagnosis is made basedon the clinical history, the physical examination,and tests such as pure tone audiometry, voiceaudiometry and immitance testing. Imaging mayalso provide relevant diagnostic information.Computed tomography (CT) is the method ofchoice (1). The treatment may be medical (oralanti bone remodeling drugs) or surgical(stapedotomy or stapedectomy). Personal soundamplification devices (PSAD) are a furtheroption, particularly in patients with surgicalcontraindications (2). The most bothersomecomplication of stapes surgery is sensorineuralhearing loss that occurs in less than 1% of cases
and the pathogeneses are varied. Usually, thepathogenesis of sensory-neural hearing loss(SNHL) can be evaluated by clinicalexaminations and imaging (3-5). The aim of thisstudy is to report a rare case of bilateral hearingloss following unilateral stapedotomy and toreview the literature on this theme.
Case ReportA white Iranian female, aged 25 years,presented to otolaryngology department ofLoghman Hakim hospital with complaining ofbilateral progressive hearing loss for 2 years;there were no vestibular or tinnitus symptoms.The patient reported no episodes of otitis duringthe past years. The patient had no family historyof otosclerosis. The otologic exam revealed anormal tympanic membrane at both sides. Inpure tone audiometry, air-bone gap was 40 dBon the right side, and 30 dB on the left. Averagehearing level of the right ear was 46 dB and theleft ear was 43dB. Immitance testing revealeddecreased bilateral tympanic membranecomplacency and bilateral absence of thestapedial reflex. CT scan before the surgeryshowed no significant abnormalities (Fig1, 2).Stapedotomy of the right ear was performedand Teflon prosthesis inserted. Surgicalfindings included a restricted movement of
Figure 1. Post-operative high resolution CT scan.Top: Coronal, bottom: Axial. Note the normal
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26 Bilateral Hearing Loss Following Unilateral Stapes Surgery
anatomy in both ears and the appropriate position ofthe prosthesis in the right ear.
Figure 2. Post-operative T2 MRI. Note the normalanatomy of bilateral inner ear structures and nervebundles.
stapes. Surgical findings included a restrictedmovement of stapes. The patient felt significanthearing improvement after the surgery. She hadno complaint of vertigo or other complicationsand was discharged the day after the surgery.After 5 days she experienced a sudden bilateralhearing loss and intermittent non-pulsatiletinnitus, with no vertigo. She was admitted tothe hospital and pure tone audiometry wasperformed. She also underwent temporal highresolution CT and brain and temporal MRI,
which revealed no significant findings (Figures1 and 2).The patient underwent treatment withintravenous Methyl Prednisolone (500mg/daily)for 3 days and intra tympanic injection ofDexamethasone in both ears every other day forthree times. This treatment was successful andthe hearing thresholds ret (urned to the initiallevels one week after the initiation of thetreatment (Figure 3).
Figure 3. Consecutive audiograms of the patient. A:Pre-operative, B: Two days after surgery, C: Sixdays after surgery, D: twelve days after surgery.
DISCUSSIONSensorineural hearing loss (SNHL) occurs inless than 1% of stapedectomized ears. It mayarise because of many reasons. This lowpercentage remains as an irreducible minimumeven among the most experienced andcompetent surgeons. The etiology has beenhypothesized; however, the actual causeremains unknown. The pathogeneses are varied.Bulging of the prosthesis into the
26 Bilateral Hearing Loss Following Unilateral Stapes Surgery
anatomy in both ears and the appropriate position ofthe prosthesis in the right ear.
Figure 2. Post-operative T2 MRI. Note the normalanatomy of bilateral inner ear structures and nervebundles.
stapes. Surgical findings included a restrictedmovement of stapes. The patient felt significanthearing improvement after the surgery. She hadno complaint of vertigo or other complicationsand was discharged the day after the surgery.After 5 days she experienced a sudden bilateralhearing loss and intermittent non-pulsatiletinnitus, with no vertigo. She was admitted tothe hospital and pure tone audiometry wasperformed. She also underwent temporal highresolution CT and brain and temporal MRI,
which revealed no significant findings (Figures1 and 2).The patient underwent treatment withintravenous Methyl Prednisolone (500mg/daily)for 3 days and intra tympanic injection ofDexamethasone in both ears every other day forthree times. This treatment was successful andthe hearing thresholds ret (urned to the initiallevels one week after the initiation of thetreatment (Figure 3).
Figure 3. Consecutive audiograms of the patient. A:Pre-operative, B: Two days after surgery, C: Sixdays after surgery, D: twelve days after surgery.
DISCUSSIONSensorineural hearing loss (SNHL) occurs inless than 1% of stapedectomized ears. It mayarise because of many reasons. This lowpercentage remains as an irreducible minimumeven among the most experienced andcompetent surgeons. The etiology has beenhypothesized; however, the actual causeremains unknown. The pathogeneses are varied.Bulging of the prosthesis into the
26 Bilateral Hearing Loss Following Unilateral Stapes Surgery
anatomy in both ears and the appropriate position ofthe prosthesis in the right ear.
Figure 2. Post-operative T2 MRI. Note the normalanatomy of bilateral inner ear structures and nervebundles.
stapes. Surgical findings included a restrictedmovement of stapes. The patient felt significanthearing improvement after the surgery. She hadno complaint of vertigo or other complicationsand was discharged the day after the surgery.After 5 days she experienced a sudden bilateralhearing loss and intermittent non-pulsatiletinnitus, with no vertigo. She was admitted tothe hospital and pure tone audiometry wasperformed. She also underwent temporal highresolution CT and brain and temporal MRI,
which revealed no significant findings (Figures1 and 2).The patient underwent treatment withintravenous Methyl Prednisolone (500mg/daily)for 3 days and intra tympanic injection ofDexamethasone in both ears every other day forthree times. This treatment was successful andthe hearing thresholds ret (urned to the initiallevels one week after the initiation of thetreatment (Figure 3).
Figure 3. Consecutive audiograms of the patient. A:Pre-operative, B: Two days after surgery, C: Sixdays after surgery, D: twelve days after surgery.
DISCUSSIONSensorineural hearing loss (SNHL) occurs inless than 1% of stapedectomized ears. It mayarise because of many reasons. This lowpercentage remains as an irreducible minimumeven among the most experienced andcompetent surgeons. The etiology has beenhypothesized; however, the actual causeremains unknown. The pathogeneses are varied.Bulging of the prosthesis into the
vestibule, trauma to the membranous labyrinth,postoperative granuloma, oval window fistula,labyrinthitis, and endolymphatic hydrops are theprimary known etiopathogenic factors (2, 8).Systematic surgical revision is the method ofchoice for identifying some of these underlyingcauses of SNHL. High resolution CT can depicta malpositioned prosthesis, postoperativemiddle ear granuloma, perilymphatic fistula,and inner ear malformations. Nonsuppurativelabyrinthitis is relatively common in theimmediate postoperative period, and may causetransient SNHL, (7). As mentioned before,HRCT and MRI were performed in this caseand no abnormality was detected.Endolymphatic hydrops may occur due tootosclerosis or as two separate disease entities.Stapedectomy in the presence of uncontrolledMénière’s disease can potentially result in adead ear and should be avoided (9).Our patienthad no history of Ménière’s disease and therewere no signs or symptoms in favor of thedisease in the past few years.Perilymphatic fistula is a rare complication afterstapes surgery with an incidence ranging from 3to 10% (7). Patients complain of a mixedconductive sensorineural hearing loss with somevague unsteadiness and, rarely vertigo. It mayoccur between weeks to years following surgeryand persist until an endosteal membrane formsat the oval window. CT scan studies may showfluid in the middle ear, depending on thepressure of the vestibule. This finding maysuggest perilymphatic fistula if associated witha pneumolabyrinth which, is the presence of airbubbles on the tip of the prosthesis (2, 7).Ourpatient had no vestibular complaint and hernormal CT excluded perilymphatic fistula.Serous labyrinthitis is common afterstapedectomy due to inner ear inflammation.Patients may exhibit mild unsteadiness,positional vertigo, and/or a slight decrease inhigh-frequency hearing. The above symptomstypically fade within several days to weeks (9).Our patient had neither the clinical finding northe clinical course compatible with a serouslabyrinthitis.Postoperative reparative granuloma has beenrecognized as a cause of sensorineural hearingloss after stapedectomy (2). Patients presentwith initial improvement in hearing followed bya gradual or sudden deterioration 1 to 6 weekspostoperatively. Vertigo can also occur and areddish discoloration in the postero-superiorquadrant of the tympanic membrane is
sometimes evident (2, 9). None of these signsand symptoms matches the present reportedcase.Suppurative labyrinthitis is a severecomplication of stapes surgery. It occurs withindays after the surgery or even after a long delay(2, 7). The clinical manifestation of our patientwas not consistent with the ones of suppurativelabyrinthitis.There are several possibilities to explain thecontralateral hearing loss after stapedectomy. Itcould be secondary to idiopathic suddensensorineural hearing loss. This disease has anannual incidence of approximately 0.001% (10).Progressive cochlear otosclerosis in thecontralateral ear is also a possibility (10) .Willis studied 300 stapedectomy patients andfound that over a minimum of 10 years,sensorineural hearing loss developed in theoperated ear in 19%. In 5 of the 300 patients(1.6%), sensorineural hearing loss developed inthe contralateral ear in the same time period(11). Another study demonstrated a similardecline in bone conduction in the non-operativeear after stapedectomy with at least a 5-yearfollow up. The contralateral ear showed asignificantly greater annual decline in boneconduction thresholds than the ear thatunderwent stapedectomy (10).Sympathetic cochleolabyrinthitis (SC) is a veryuncommon occurrence after stapedectomy. SCdevelops from an activation of immuneresponse to exposed inner ear antigens as aresult of trauma or surgery (10, 12 , 13).Richards ML et al., have proposed thatrevision stapedectomy rarely is associated ithearing loss in the contralateral ear and that maybe due to sympathetic cochleolabyrinthitis(10). There is no report of SE happened afterprimary non-complicated stapedectomy.Furthermore, the reported course of thispotential immunologic process is not compatiblewith one of our patient.Any asymmetric progression of a sensorineuralloss after stapes surgery should provokesuspicion of a pathologic process. These includeperilymphatic fistula, labyrinthine otosclerosisor ischemia and acoustic neurinoma. Incoexistence of an acoustic neurinoma withotosclerosis, the diagnosis of acoustic neuromais usually delayed because more commoncauses of sensorineural hearing loss associatedwith otosclerosis or its surgery are usuallyconsidered (3, 13).
28 Bilateral Hearing Loss Following Unilateral Stapes Surgery
Our patient did not have the characteristics ofany previous mentioned complications. Theonly matched scenario is occurrence of abilateral idiopathic sensorineural hearing loss.The absences of the concomitant clinical andimaging finding as well as the dramaticresponse to steroid are in favor of this diagnosis.
CONCLUSIONSensorineural hearing loss after stapedectomymay have many potential causes. Nonetheless,in rare cases, which cannot be matched with thefirst line possible etiologies, the other causes ofSNHL, which may not necessarily be directlyrelated to the surgery, must be taken intoaccount. This is important because a prompt andurgent treatment is often necessary to achieve abetter clinical outcome.
ACKNOWLEDGEMENTSWe would like to thank all patients whoparticipated in this study. We also would like toappreciate the support of clinical researchdevelopment center of Loghman Hakimhospital.
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