Abstract
Objective:
During the postoperative period, most patients with otosclerosis report vertigo and/or nausea caused by interventions within the inner ear. The aim of this study was to evaluate both early and late vertigo associated with hearing improvement after stapes surgery for otosclerosis.
Methods:
The analysis included 170 patients admitted to the hospital undergoing their first surgery for otosclerosis. Audiological diagnostics, surgical techniques, and symptoms reported by the patients were all analyzed.
Results:
A statistical correlation and an unfavorable influence of late, undesired symptoms, such as vertigo, nausea/vomiting, and nystagmus, on final hearing improvement after surgical treatment of otosclerosis were found. Prostheses that were too long or placed too deep within the inner ear space were the most frequent cause of both vertigo and lack of hearing improvement observed after stapedotomy.
Conclusions:
A significant negative influence on bone conduction thresholds, particularly at 2000 Hz, was associated with vestibular symptoms persisting for 7 days after the surgery. Symptoms of impaired bony labyrinth function after stapedotomy, persisting for more than 1 year, were associated with insufficient reduction of the air–bone gap and worse improvement in bone conduction thresholds at 1000 and 2000 Hz. The cause of both problems was related to a prosthesis that was too long or placed too deep in the inner ear during stapedotomy.
Introduction
Otosclerosis is a complex condition of the temporal bone, the etiology of which has not been fully elucidated. This condition involves remodeling of the bone tissue of the labyrinth, contributing to hearing loss. Otosclerosis is the cause of 5% to 9% of all cases of hearing loss and 18% to 22% of cases of conductive hearing loss. Sensorineural hearing loss develops in 30% of patients with otosclerosis. The main symptoms of the clinical form of otosclerosis include progressive hearing loss, tinnitus, and vertigo. 1,2
Operative treatment is the primary method of therapy for otosclerosis. The surgeries for otosclerosis date back to 1958 and are related to Shea performing a stapedectomy, followed by another stapedotomy in 1960. In 1994, Fish proposed reversing the order of stapedotomy stages, intending to mitigate and limit complications, such as dislocation of the incus and base fractures of the stapes. The following years brought about improvements and modernization of the procedural stages, introducing the use of microdrills and argon and carbon dioxide lasers, as well as a few new types of stapes prostheses of various sizes. All of these changes were intended to achieve the best possible results, including closing the cochlear reserve, improving speech understanding, and eliminating the risk of complications. The current operating procedure results in improved hearing and eliminates or mitigates tinnitus in 90% of cases. 3,4
During the direct postoperative period, most patients report vertigo and/or nausea caused by the intervention within the inner ear. These symptoms usually recede spontaneously or when treated pharmacologically during the first 2 to 3 days after surgery. In 5% to 8% of patients, permanent or recurring vertigo occurs after stapes surgery during the late postoperative stage. Persistent late vertigo may indicate a perilymphatic fistula or placement of the stapes prosthesis too deeply inside the vestibulum of the inner ear. 5
The aim of this study was to evaluate the impact of early and/or late vertigo on hearing improvement after stapes surgery for otosclerosis.
Materials and Methods
The analysis included 170 patients admitted to the hospital and undergoing their first surgery for otosclerosis between 2016 and 2019. Stapedotomy was performed in all included individuals.
The youngest patient was 21 years old, and the oldest patient was 63 years old. The average patient age was 39.31 years. The study group included 103 women aged 21 to 62 years (average age: 39.3 years) and 67 men aged 24 to 56 years (average age: 37.1 years). All patients were given a subjective and objective otolaryngological examination and a full set of audiological examinations, including an acoumetric examination, tuning fork tests, and tone threshold audiometry.
The stapedotomy procedure consisted of removing the suprastructure of the stapes and making a small aperture in the plate into which a piston-type prosthesis (made of a polytetrafluoroethylene piston permanently connected to a platinum element of 0.1-mm-diameter wire) is inserted and suspended on a mobile incus. The measurement of the length of the prosthesis during the operation was made using a flexible measuring rod to assess the distance between the footplate of the stapes and the lateral surface of the long process of the incus. Afterward, 0.5 mm was added to the result, so the prosthesis would enter the atrium. When adjusting the prosthesis, a block was used to cut the polymer.
A survey including the following elements was developed to obtain the data required for the analysis:
Audiological diagnostics (pure tone audiometry) before the surgery and 12 months after the surgery.
Symptoms reported by the patients within 48 to 72 hours after the surgery:
Analysis of subjective symptoms reported by the patients:
Disturbance of balance
Nausea
Vomiting
Analysis of objective signs:
nystagmus.
Symptoms reported by the patients within 7 days of the surgery:
Analysis of subjective symptoms reported by the patients:
disturbance of balance
nausea
vomiting
Analysis of objective signs:
nystagmus.
Symptoms reported by the patients after 12 months:
Analysis of subjective symptoms reported by the patients:
disturbance of balance
nausea
vomiting
Analysis of objective signs:
nystagmus.
Having collected the above data, patients included in the study are divided into the groups characterized in Table 1, according to the presence of symptoms/signs/complaints after surgery.
Characteristic of the Analyzed Groups.
A reference group (group 0) was created for the purpose of the analysis. The reference group included patients who underwent stapedotomy, and no changes in the middle ear apart from total immobilization of the base of the stapes in the oval window were observed. Another criterion for the inclusion of patients in this reference group was the lack of nystagmus, nausea, vomiting, and vertigo during the early and late postoperative stages.
Hearing loss analysis was performed, including measurements for air and bone conduction (BC), at frequencies of 500 Hz, 1 kHz, and 2 kHz, wherein changes are typical for otosclerosis. Changes in BC thresholds at 4 kHz were not defined as indicating surgical trauma to the inner ear. 6 The obtained data were used in calculations of the values of the average changes of the bone and air conduction, as well as that of the air–bone gap (ABG), both before and 12 months after the surgery.
The assessment of postoperative atrial disorders was based on the Vestibular Disorders of Daily Living (VADL) scale. 7 Tinnitus intensity was measured as recommended by Vernon and Meikle. 8
The VADL scale was used to evaluate the severity of balance disturbance. The analysis involved patients who did not complain of vertigo or balance disorders before surgical treatment and maintained the same levels over the analyzed periods of time, which was later confirmed in the VADL scale results.
The minimum score qualifying for the diagnosis of balance disorders was at least 140 points on the VADL scale in patients who did not complain about balance problems before surgery. The criteria for persistent balance disorders were based on information obtained in the VADL scale, which defines it as 2 or more episodes for several days in a row.
The patients completed the VADL questionnaire in the following specified periods of time—group A: 48 to 72 hours after surgery, group B: 7 days after surgery, and group C: 12 months after stapedotomy. Each of the groups consisted of patients who in subsequent test results scored results on the same levels as in the previous tests, which indicates the stability of symptoms in that period of time.
All patients agreed to the surgery and their participation in the study. The local bioethics committee approved the study (no. 122.6120.206.2016). Data obtained during the study were subjected to statistical analysis. Fisher test was used to analyze parametric hypotheses. The test of multiple-field contingency tables—the c2 test—was used to verify nonparametric hypotheses. Statistical significance was defined as P < .05.
Results
Stapedotomy was performed in all 170 patients included in the study. A statistical analysis of tone audiometry results was performed. The analysis of variance of BC threshold values and of changes to the average cochlear reserves in group A 12 months after the surgery compared to group 0 yielded some interesting results after surgical treatment, P < .05 (Table 2). No significant changes in the average threshold values of BC were observed at any of the analyzed frequencies between groups 0 and A. No significant differences in the changes in the average ABG were found between groups 0 and A. The observations showed that symptoms persisting 72 hours after the surgery did not influence the final stapedotomy results of decreases in the ABG or improvements in BC as compared to those in the reference group.
BC and ABG in Analyzed Groups 0 and A for Frequencies 500, 1000, 2000 Hz Before the Stapedotomy and 12 Months After the Surgery.
Abbreviations: ABG, average air–bone gap in all analyzed frequencies; BC, bone conduction thresholds; Δ, delta, changes after 12 months of follow-up; P, significance level.
The analysis of changes in the BC threshold values and the analysis of variance of changes in the ABG as a function of persisting symptoms within 7 days of the surgery (group B) as compared to those in the reference group yielded some interesting results (Table 3, P < .05). It was concluded, on the basis of the obtained values, that 12 months after the surgery, the improvement in the BC value was significantly less in group B than that in group 0 at a frequency of 2000 Hz. No significant differences were found in the BC thresholds at the other frequencies or in the changes in the average ABG. No other significantly different results were found between groups B and 0.
BC and ABG in Analyzed Groups 0 and B for Frequencies 500, 1000, 2000 Hz Before the Stapedotomy and 12 Months After the Surgery.
Abbreviations: ABG, average air–bone gap in all analyzed frequencies; BC, bone conduction thresholds; Δ, delta, changes after 12 months of follow-up; P, significance level.
The analysis of changes in the BC threshold values and of variance of changes in the average cochlear reserves as a function of persisting symptoms within 12 months of the surgery (group C) as compared to those in group 0 yielded some interesting results (Table 4, P < .05). It was concluded, on the basis of the obtained data, that 12 months after the surgery, the improvement in the BC threshold value was significantly smaller in group C than in group 0 at the frequencies of 1000 and 2000 Hz. No significant differences were found at 500 Hz. The analysis of changes in the average cochlear reserves between group C and group 0 showed a significantly worse result in group C.
BC and ABG in Analyzed Groups 0 and C for Frequencies 500, 1000, 2000 Hz Before the Stapedotomy and 12 Months After the Surgery.
Abbreviations: ABG, average air–bone gap in all analyzed frequencies; BC, bone conduction thresholds; Δ, delta, changes after 12 months of follow-up; P, significance level.
On the basis of the findings mentioned above in groups B and C, a relationship was found between balance disorders that significantly affected everyday life (evaluated using the VADL scale) and the level of hearing improvement after surgery.
Tinnitus, evaluated according to the Tinnitus Functional Index, decreased significantly or completely subsided in almost 80% of cases after stapedotomy. Only 10% of patients complained of an intensification of tinnitus after the surgery. No statistical significance was found between the persistence of balance disorders and tinnitus after the surgery.
In patients in group 0, an improvement in air conduction was observed, from a level of 58.04 dB before surgical treatment to 30.67 dB 12 months after stapedotomy was performed (as an average for 500, 1000, and 2000 Hz). The difference in average air conduction was 27.37 dB.
In group A, an improvement of 24.55 dB in the mean air conduction level was observed (as an average for 500, 1000, and 2000 Hz). The mean air conduction level before surgical treatment was 60.67 dB, whereas a value of 36.12 dB was observed 12 months after stapedotomy.
In group B, an improvement of 28.37 dB was observed in the mean air conduction level (as an average for 500, 1000, and 2000 Hz). The mean air conduction level before surgical treatment was 58.2 dB, whereas a value of 29.83 dB was observed 12 months after stapedotomy.
In group C, an improvement of 21.3 dB was observed in the mean air conduction level (as an average for 500, 1000, and 2000 Hz). The mean air conduction level before surgical treatment was 56.2 dB, whereas a value of 34.9 dB was observed 12 months after stapedotomy.
Improvement of air conduction observed 12 months after stapedotomy was comparable in all of the analyzed groups (average air conduction for 500, 1000, and 2000 Hz). No statistical significance was found between the time of onset of persistent balance disorders after stapedotomy and the level of average air conduction improvements.
The surface structure of a removed prosthesis obtained using an electron scanning microscope is presented as an example analysis in Figures 1 and 2. This analysis revealed that, in some cases, late vertigo after stapedotomy-induced damage to the prosthetic piston structure resulted in protrusion of the internal part of the piston. The damage to the piston structure was probably caused by excessive trimming of the Teflon part of the prosthesis. The above observations indicate that a prosthesis that requires fitting the piston length during stapedotomy by surgeons is a risk factor for vertigo in the postoperative period.
Prosthesis of the stapes removed from the ear because of persistent vertigo 14 months after stapedotomy. Magnification ×15 (workshop of scanning microscopy).
Prosthesis of the stapes removed from the ear because of persistent vertigo 14 months after stapedotomy. Magnification ×150 (workshop of scanning microscopy). A, Surface of the prosthesis. B, Dislocated inner element of the prosthesis.
Among the 170 analyzed patients, the surgery was repeated in 11 cases (6.47%) because of persistent vertigo or a lack of hearing improvement in pure tone audiometry. All patients who underwent revision surgery were included in group C. Among the 11 patients who underwent repeated surgery, a prosthesis located too deep within the inner ear was identified in 8 cases and was found to be caused by the following:
-Luxation in the malleus–incus joint, resulting in a decreased distance between the incus and the oval window level (found in 2 cases).
-Impaired stability of the prosthetic stem element and protrusion of the internal part of the Teflon piston into the inner ear (found in 4 cases).
-“Glue ear” type discharge, which suggested dysfunction of the Eustachian tube and depletion of the pressure inside the middle ear (found in 2 cases).
-No cause was identified during the revision surgery (found in 3 cases).
The procedure during the revision surgery depended on the individual case and involved both replacement of the prosthesis and removal of changes from the tympanic orifice area of the Eustachian tube. In 3 cases, in which no clear pathology was identified inside the middle ear, the procedure only involved sealing the opening around the prosthesis. In all patients subjected to repeated surgery, the procedure resulted in hearing improvement and mitigation or disappearance of vertigo.
Discussion
According to current knowledge, the only effective otosclerosis therapy method is stapes surgery, which aims to correct the function of the oval window, thus restoring correct mobility of the transmission system of the middle ear. The operating procedure resulted in improved hearing and eliminated or mitigated tinnitus in 90% of cases. Vestibular symptoms were observed in approximately 70% of patients during the first week following stapedotomy. 9,10 Late vertigo as a complication of stapes surgery was relatively rare (5% to 8% of cases), coinciding with our observations. Persistent vertigo, in addition to a lack of hearing improvement or further hearing loss, is one of the indications for revision of stapes surgery for otosclerosis. The revision surgery rate varies, with a range of 2.5% to 13.2% 11 -14 depending on the author.
A prosthesis with a diameter of up to 0.4 mm may be safely applied during stapedotomy at a depth of up to 0.5 mm within the vestibule. The safest location to make an opening in the plate of the stapes during stapedotomy is its central part. The shortest distance from the central part of the plate to the utriculus is 1.2 and 1.4 mm, respectively, from the saccule. The shortest distance to the cochlear duct was observed at the bottom edge of the plate of the stapes (0.2 mm). The cochlear duct is always located below the bottom edge of the plate of the stapes; thus, the risk of damage to it during a correctly performed stapedotomy in the central part of the plate is virtually nonexistent.
Early vertigo is usually caused by damage to the inner ear during surgery. It is first and foremost caused by contact between the utriculus (which is located very close to the oval window) and either the surgical tools or the prosthesis or as a consequence of perilymph aspiration. The therapy in such cases includes maintaining a bed regime and the application of appropriate pharmacotherapy.
This work did not show the negative influence of vertigo persisting up to 72 hours after stapedotomy on the final results of the surgery in terms of closing the cochlear reserve and improvement in BC. Vertigo persisting for 7 days after the surgery did not influence the closure of the cochlear reserve, according to the authors’ observations. However, it was found to lead to a significant lack of improvement in BC at a frequency of 2000 Hz. The 2000 Hz frequency is related to the Carhart notch, which is characteristic of otosclerosis.
In the analyzed group, the lack of improvement in BC at the ossicular resonant frequency of 2000 Hz indicates deficient restoration of ossicular mobility after stapedotomy, which has an influence on inner ear performance.
Vertigo persisting for many months may be caused by an excessively long stapes prosthesis, which enters the vestibule and compresses the utriculus–saccule structure. Persistent vertigo may also be caused by a perilymphatic fistula in the oval window. Thus, selection of the appropriate length of the prosthesis located inside the vestibule is extremely important. 15 -17
The work by Gierek et al showed that indications for revision surgery related to persistent vertigo in otosclerosis applied to 2.9% of patients subjected to repeated surgery. An incorrect prosthetic length in the first surgery affected 5.8% of all patients subjected to revision surgery. 18 Albera et al described patients with late vertigo after stapes surgery, ranging from 1 month to 7 years after the surgery. During repeat stapedotomy, they found symptoms of perilymph exudation in the oval window of 3 patients, and an additional seal made using fibrin glue resulted in the disappearance of vertigo in all patients. 19
Persistent late vertigo may be a result of bone fragments entering the inner ear during surgery and directly compressing the saccule. Other causes of late vertigo include intraoperative blood penetration into the labyrinth, acute postoperative labyrinthitis, incorrect prosthesis position, adhesions, scars around the prosthesis connecting the prosthesis with the ear membrane, or Eustachian tube dysfunction, as in Tullio phenomenon. 2 -4
In our observations, most cases of persistent vertigo associated with different hearing outcomes after stapedotomy were related to prostheses that were too long or placed too deep in the inner ear during stapedotomy. In 8 cases, the cause of this condition was identified as dysfunction of the malleus–incus joint, protrusion of the internal part of the prosthetic stem, or Eustachian tube dysfunction. In additional 3 cases, the cause was not found during repeat surgery, assuming the potential existence of a perilymphatic fistula without visible perilymph exudation. The area around the prosthesis was sealed during the surgery in those patients.
Conclusions
A significantly negative influence on BC thresholds, particularly at 2000 Hz, was associated with vestibular symptoms persisting for 7 days after the surgery.
Symptoms of impaired bony labyrinth function after stapedotomy, persisting for more than 1 year, were associated with insufficient reduction of the ABG and insufficient improvement in BC thresholds at 1000 and 2000 Hz. The cause of both problems was related to a prosthesis that was too long or placed too deep in the inner ear during stapedotomy.
Footnotes
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This research was supported by statutory funds of the Department of Otolaryngology of the Jagiellonian University, Krakow, Poland.
