Significance of Cochlear Dose in the Radiosurgical Treatment of Vestibular Schwannoma

Neurosurgery ◽  
2014 ◽  
Vol 74 (5) ◽  
pp. 466-474 ◽  
Author(s):  
Jeffrey T. Jacob ◽  
Matthew L. Carlson ◽  
Terry K. Schiefer ◽  
Bruce E. Pollock ◽  
Colin L. Driscoll ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Vestibular Schwannoma ◽  
Pure Tone ◽  
Interobserver Reliability ◽  
Univariate Analysis ◽  
Hearing Preservation ◽  
Neck Surgery ◽  
Tumor Control ◽  
Speech Discrimination ◽  
Pure Tone Average

Abstract BACKGROUND: Cochlear dose has been identified as a potentially modifiable contributor to hearing loss after stereotactic radiosurgery (SRS) for vestibular schwannoma (VS). OBJECTIVE: To evaluate the association between computed tomography-based volumetric cochlear dose and loss of serviceable hearing after SRS, to assess intraobserver and interobserver reliability when determining modiolar point dose with the use of magnetic resonance imaging and computed tomography, and to discuss the clinical significance of the cochlear dose with regard to radiosurgical planning strategy. METHODS: Patients with serviceable pretreatment hearing who underwent SRS for sporadic VS between the use of Gamma Knife Perfexion were studied. Univariate and multivariate associations with the primary outcome of time to nonserviceable hearing were evaluated. RESULTS: A total of 105 patients underwent SRS for VS during the study period, and 59 (56%) met study criteria and were analyzed. Twenty-one subjects (36%) developed nonserviceable hearing at a mean of 2.2 years after SRS (SD, 1.0 years; median, 2.1 years; range 0.6-3.8 years). On univariate analysis, pretreatment pure tone average, speech discrimination score, American Academy of Otolaryngology-Head and Neck Surgery hearing class, marginal dose, and mean dose to the cochlear volume were statistically significantly associated with time to nonserviceable hearing. However, after adjustment for baseline differences, only pretreatment pure tone average was statistically significantly associated with time to nonserviceable hearing in a multivariable model. CONCLUSION: Cochlear dose is one of many variables associated with hearing preservation after SRS for VS. Until further studies demonstrate durable tumor arrest with reduced dose protocols, routine tumor dose planning should not be modified to limit cochlear dose at the expense of tumor control.

scholarly journals Hearing subclassification may predict long-term auditory outcomes after radiosurgery for vestibular schwannoma patients with good hearing

2016 ◽  
Vol 125 (4) ◽  
pp. 845-852 ◽  
Author(s):  
Seyed H. Mousavi ◽  
Ajay Niranjan ◽  
Berkcan Akpinar ◽  
Marshall Huang ◽  
Hideyuki Kano ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Stereotactic Radiosurgery ◽  
Vestibular Schwannoma ◽  
Pure Tone ◽  
Hearing Preservation ◽  
Class I ◽  
Tumor Control ◽  
Speech Discrimination ◽  
Pure Tone Average

OBJECTIVE In the era of MRI, vestibular schwannomas are often recognized when patients still have excellent hearing. Besides success in tumor control rate, hearing preservation is a main goal in any procedure for management of this population. The authors evaluated whether modified auditory subclassification prior to radiosurgery could predict long-term hearing outcome in this population. METHODS The authors reviewed a quality assessment registry that included the records of 1134 vestibular schwannoma patients who had undergone stereotactic radiosurgery during a 15-year period (1997–2011). The authors identified 166 patients who had Gardner-Robertson Class I hearing prior to stereotactic radiosurgery. Fifty-three patients were classified as having Class I-A (no subjective hearing loss) and 113 patients as Class I-B (subjective hearing loss). Class I-B patients were further stratified into Class I-B1 (pure tone average ≤ 10 dB in comparison with the contralateral ear; 56 patients), and I-B2 (> 10 dB compared with the normal ear; 57 patients). At a median follow-up of 65 months, the authors evaluated patients' hearing outcomes and tumor control. RESULTS The median pure tone average elevations after stereotactic radiosurgery were 5 dB, 13.5 dB, and 28 dB in Classes I-A, I-B1, and I-B2, respectively. The median declines in speech discrimination scores after stereotactic radiosurgery were 0% for Class I-A (p = 0.33), 8% for Class I-B1 (p < 0.0001), and 40% for Class I-B2 (p < 0.0001). Serviceable hearing preservation rates were 98%, 73%, and 33% for Classes I-A, I-B1, and I-B2, respectively. Gardner-Robertson Class I hearing was preserved in 87%, 43%, and 5% of patients in Classes I-A, I-B1, and I-B2, respectively. CONCLUSIONS Long-term hearing preservation was significantly better if radiosurgery was performed prior to subjective hearing loss. In patients with subjective hearing loss, the difference in pure tone average between the affected ear and the unaffected ear was an important factor in long-term hearing preservation.

Hearing preservation in surgery for large vestibular schwannomas

2009 ◽  
Vol 111 (4) ◽  
pp. 845-854 ◽  
Author(s):  
Masahiko Wanibuchi ◽  
Takanori Fukushima ◽  
John T. McElveen ◽  
Allan H. Friedman
Keyword(s):  
Pure Tone ◽  
Hearing Preservation ◽  
Hearing Level ◽  
Discrimination Score ◽  
Speech Discrimination ◽  
Pure Tone Average ◽  
Speech Discrimination Score ◽  
Class A ◽  
Abducent Nerve Palsy ◽  
Hearing Preservation Surgery

Object Hearing preservation remains a challenging problem in vestibular schwannoma (VS) surgery. The ability to preserve hearing in patients with large tumors is subject to particular difficulty. In this study, the authors focus on hearing preservation in patients harboring large VSs. Methods A total of 344 consecutive patients underwent surgical removal of VSs over the past 9 years. Of these 344 cases, 195 VSs were > 20 mm in maximum cisternal diameter. Of the 195 cases, hearing preservation surgery was attempted for 54 patients who had a Class A, B, C, or D preoperative hearing level; that is, a pure tone average ≤ 60 dB and speech discrimination score ≥ 50% according to the Sanna/Fukushima classification. The tumors were classified as moderately large (21–30 mm based on the largest extrameatal diameter), large (31–40 mm), and giant (≥ 41 mm) according to the international criteria. The authors categorized patients with Class A, B, C, D, or E hearing (pure tone average ≤ 80 dB and speech discrimination score ≥ 40%) as having preserved hearing postoperatively. Results Forty-one tumors (75.9%) were totally removed and 13 (24.1%) had near-total removal. Of the 54 patients, 29 maintained their hearing postoperatively; the overall hearing preservation rate was 53.7%. Analysis based on the preoperative hearing level showed that hearing was preserved in 14 (77.8%) of 18 cases for Class A; in 8 (47.1%) of 17 cases for Class B; in 4 (57.1%) of 7 cases for Class C; and in 3 (25.0%) of 12 cases for Class D. In addition, according to the analysis based on the tumor size, 20 (52.6%) of 38 patients with moderately large tumors retained their hearing, as did 5 (50.0%) of 10 patients with large tumors and 4 (66.7%) of 6 patients with giant tumors. Complications included 2 cases of bacterial meningitis that were cured by intravenous injection of antibiotics, 3 cases of subcutaneous CSF leakage that resolved without any surgical repair, and 1 case of temporary abducent nerve palsy. There were no deaths in this series. Conclusions The results indicate that successful hearing preservation surgery in large VSs is possible with meticulous technique and attention to adhesions between the tumor and the cochlear nerves.

scholarly journals Usefull Hearing Preservation Is Improved in Vestibular Schwannoma Patients Who Undergo Stereotactic Radiosurgery Before Further Hearing Deterioration Ensures

2021 ◽  
Author(s):  
Hideyuki Kano ◽  
Akiyoshi Ogino ◽  
Hao Long ◽  
Stephen Johnson ◽  
Andrew Faramand ◽  
...  
Keyword(s):  
Stereotactic Radiosurgery ◽  
Vestibular Schwannoma ◽  
Hearing Preservation ◽  
Initial Diagnosis ◽  
Speech Discrimination ◽  
Pure Tone Average ◽  
Younger Age ◽  
Grade Ii ◽  
Preservation Rate

Abstract IntroductionThe present study evaluates whether hearing deterioration during observation reduces serviceable hearing preservation rates after stereotactic radiosurgery (SRS) in vestibular schwannoma (VS) patients with useful hearing.MethodsWe retrospectively analyzed 1447 VS patients who underwent SRS between 1992 to 2017. We identified 100 VS patients who had Grade I Gardner- Robertson (GR) hearing at initial diagnosis but were observed without surgery or SRS. We compared hearing after SRS in 67 patients who retained GR Grade I hearing from initial diagnosis to SRS (the hearing maintenance or HM group) to 33 patients whose hearing worsened from GR grade I to grade II (the hearing deterioration or HD group). We also investigated whether a decline in pure tone average (PTA) or speech discrimination score (SDS) before SRS affected hearing preservation after SRS.ResultsThe serviceable hearing (GR I and II) preservation in HM patients was 80%s, 63%, and 51% at 3, 5, and 10 years, respectively. The serviceable hearing preservation in HD patients was 40%, 33%, and 20% at 3, 5, and 10 years, respectively. In multivariate analysis, younger age (<55 years, p=0.012) and HM during observation (p<0.001) improved serviceable hearing preservation rates. Patients whose PTA increased >15 dB (p=0.011) or whose SDS declined >10% (p=0.024) had reduced serviceable hearing preservation rates.ConclusionsHearing deterioration during observation before SRS reduced long term hearing preservation rate in VS patients with GR grade I hearing at initial diagnosis. SRS before hearing deterioration was recommended for hearing preservation.

HEARING PRESERVATION AFTER INTRACANALICULAR VESTIBULAR SCHWANNOMA RADIOSURGERY

Neurosurgery ◽  
2008 ◽  
Vol 63 (6) ◽  
pp. 1054-1063 ◽  
Author(s):  
Ajay Niranjan ◽  
David Mathieu ◽  
John C. Flickinger ◽  
Douglas Kondziolka ◽  
L. Dade Lunsford
Keyword(s):  
American Academy ◽  
Head And Neck ◽  
Vestibular Schwannoma ◽  
Tumor Resection ◽  
Hearing Preservation ◽  
Neck Surgery ◽  
Head And Neck Surgery ◽  
Tumor Control ◽  
Gamma Knife Stereotactic Radiosurgery

Abstract OBJECTIVE Tumor control, facial function preservation, and hearing preservation are important criteria for successful management of intracanalicular vestibular schwannomas, whether observation, microsurgery, or radiosurgery is chosen. We collected data prospectively to assess hearing preservation after intracanalicular vestibular schwannoma radiosurgery. METHODS Between 1987 and 2003, 96 patients (65 men and 31 women) underwent gamma knife stereotactic radiosurgery (SRS) for intracanalicular tumors. The median patient age was 54 years (range, 22–80 years). Hearing was graded using the Gardner-Robertson (GR) and the American Academy of Otolaryngology–Head and Neck Surgery classifications. Dose planning was performed on intraoperative stereotactic images using multiple 4-mm isocenters. The median tumor volume was 0.112 mm3 (range, 0.05–0.447 mm3), and the median margin dose was 13 Gy (range, 10–18 Gy). RESULTS The mean and median audiologic follow-up periods were 42 months and 28 months (range, 12–144 months), respectively. Serviceable hearing was preserved in 31 of 40 (77.5%) patients with initial American Academy of Otolaryngology–Head and Neck Surgery Class A hearing. Serviceable hearing was preserved in 40 of 79 (64.5%) patients with GR Grade I or II pre-SRS hearing. Ninety-two patients had GR Grade I, II, or III hearing before SRS, and GR Grade I, II, or III hearing was maintained in 78 patients (85%). Hearing grades improved in 7 patients. Facial and trigeminal nerve function was preserved in all patients. The tumor control rate (freedom from additional intervention) was 99.0% (95 of 96) at a median follow-up of 28 months (range, 12–144 months). One patient underwent tumor resection 18 months after radiosurgery. CONCLUSION SRS is a minimally invasive first-line management option for patients with intracanalicular tumors and provides high rates of hearing preservation with minimal morbidity.

Stereotactic radiosurgery as the first-line treatment for intracanalicular vestibular schwannomas

2021 ◽  
pp. 1-7
Author(s):  
Akiyoshi Ogino ◽  
L. Dade Lunsford ◽  
Hao Long ◽  
Stephen Johnson ◽  
Andrew Faramand ◽  
...  
Keyword(s):  
Stereotactic Radiosurgery ◽  
Observation Interval ◽  
Univariate Analysis ◽  
Hearing Preservation ◽  
Vestibular Schwannomas ◽  
Tumor Control ◽  
Line Treatment ◽  
First Line ◽  
Additional Intervention ◽  
First Line Treatment

OBJECTIVEThis report evaluates the outcomes of stereotactic radiosurgery (SRS) as the first-line treatment of intracanalicular vestibular schwannomas (VSs).METHODSBetween 1987 and 2017, the authors identified 209 patients who underwent SRS as the primary intervention for a unilateral intracanalicular VS. The median patient age was 54 years (range 22–85 years); 94 patients were male and 115 were female. Three patients had facial neuropathy at the time of SRS. One hundred fifty-five patients (74%) had serviceable hearing (Gardner-Robertson [GR] grades I and II) at the time of SRS. The median tumor volume was 0.17 cm3 (range 0.015–0.63 cm3). The median margin dose was 12.5 Gy (range 11.0–25.0 Gy). The median maximum dose was 24.0 Gy (range 15.7–50.0 Gy).RESULTSThe progression-free survival rates of all patients with intracanalicular VS were 97.5% at 3 years, 95.6% at 5 years, and 92.1% at 10 years. The rates of freedom from the need for any additional intervention were 99.4% at 3 years, 98.3% at 5 years, and 98.3% at 10 years. The serviceable hearing preservation rates in GR grade I and II patients at the time of SRS were 76.6% at 3 years, 63.5% at 5 years, and 27.3% at 10 years. In univariate analysis, younger age (< 55 years, p = 0.011), better initial hearing (GR grade I, p < 0.001), and smaller tumor volumes (< 0.14 cm3, p = 0.016) were significantly associated with improved hearing preservation. In multivariate analysis, better hearing (GR grade I, p = 0.001, HR 2.869, 95% CI 1.569–5.248) and smaller tumor volumes (< 0.14 cm3, p = 0.033, HR 2.071, 95% CI 1.059–4.047) at the time of SRS were significantly associated with improved hearing preservation. The hearing preservation rates of patients with GR grade I VS were 88.1% at 3 years, 77.9% at 5 years, and 38.1% at 10 years. The hearing preservation rates of patients with VSs smaller than 0.14 cm3 were 85.5% at 3 years, 77.7% at 5 years, and 42.6% at 10 years. Facial neuropathy developed in 1.4% from 6 to 156 months after SRS.CONCLUSIONSSRS provided sustained tumor control in more than 90% of patients with intracanalicular VS at 10 years and freedom from the need for additional intervention in more than 98% at 10 years. Patients with initially better hearing and smaller VSs had enhanced serviceable hearing preservation during an observation interval up to 10 years after SRS.

Criteria for hearing preservation in acoustic schwannoma surgery: The concept of useful hearing

1992 ◽  
Vol 106 (6) ◽  
pp. 500-503 ◽  
Author(s):  
A. E. Hinton ◽  
R. T. Ramsden ◽  
R. H. Lye ◽  
J. E. M. Dutton
Keyword(s):  
Pure Tone ◽  
Tumour Size ◽  
Hearing Preservation ◽  
Discrimination Score ◽  
Speech Discrimination ◽  
Average Difference ◽  
Pure Tone Audiogram ◽  
Speech Discrimination Score ◽  
Acoustic Schwannoma

AbstractIn the quest for hearing preservation in patients with acoustic schwannomas it is essential that surgeons do not lose sight of the concept of ‘useful’ hearing. There is an important difference between hearing preservation which pleases the surgeon and that which will be appreciated by the patient.Tumour size, pure tone audiogram average differences between ears and speech discrimination scores have been recorded in a series of 114 patients with unilateral acoustic schwannomas. Criteria for useful hearing are presented in terms of pure tone audiogram average difference and speech discrimination scores.There were 11 patients (10 per cent) with a speech discrimination score of 50 per cent or more, a pure tone audiogram average difference of 30 dB or better and a tumour size of no more than 2 cm. Only one patient (0.9 per cent) had a speech discrimination score of 50 per cent or more, a pure tone audiogram average difference of 20 dB or better and a tumour size of no more than 1 cm.It is concluded that hearing preservation techniques may be applicable to between 1 and 10 per cent of patients with unilateral acoustic schwannomas.

Hearing preservation in patients with vestibular schwannoma treated with Gamma Knife surgery

2013 ◽  
Vol 118 (3) ◽  
pp. 571-578 ◽  
Author(s):  
Andrew M. Baschnagel ◽  
Peter Y. Chen ◽  
Dennis Bojrab ◽  
Daniel Pieper ◽  
Jack Kartush ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Gamma Knife ◽  
Vestibular Schwannoma ◽  
Hearing Preservation ◽  
Gamma Knife Surgery ◽  
Speech Discrimination ◽  
Before And After ◽  
Nerve Dysfunction ◽  
Preservation Rate

Object Hearing loss after Gamma Knife surgery (GKS) in patients with vestibular schwannoma has been associated with radiation dose to the cochlea. The purpose of this study was to evaluate serviceable hearing preservation in patients with VS who were treated with GKS and to determine if serviceable hearing loss can be correlated with the dose to the cochlea. Methods Forty patients with vestibular schwannoma with serviceable hearing were treated using GKS with a median marginal dose of 12.5 Gy (range 12.5–13 Gy) to the 50% isodose volume. Audiometry was performed prospectively before and after GKS at 1, 3, and 6 months, and then every 6 months thereafter. Hearing preservation was based on pure tone average (PTA) and speech discrimination (SD). Serviceable hearing was defined as PTA less than 50 dB and SD greater than 50%. Results The median cochlear maximum and mean doses were 6.9 Gy (range 1.6–16 Gy) and 2.7 Gy (range 0.7–5.0 Gy), respectively. With a median audiological follow-up of 35 months (range 6–58 months), the 1-, 2-, and 3-year actuarial rates of maintaining serviceable hearing were 93%, 77%, and 74%, respectively. No patient who received a mean cochlear dose less than 2 Gy experienced serviceable hearing loss (p = 0.035). Patients who received a mean cochlear dose less than 3 Gy had a 2-year hearing preservation rate of 91% compared with 59% in those who received a mean cochlear dose of 3 Gy or greater (p = 0.029). Those who had more than 25% of their cochlea receiving 3 Gy or greater had a higher rate of hearing loss (p = 0.030). There was no statistically significant correlation between serviceable hearing loss and age, tumor size, pre-GKS PTA, pre-GKS SD, pre-GKS Gardner-Robertson class, maximum cochlear dose, or the percentage of cochlear volume receiving 5 Gy. On multivariate analysis there was a trend toward significance for serviceable hearing loss with a mean cochlear dose of 3 Gy or greater (p = 0.074). Local control was 100% at 24 months. No patient developed facial or trigeminal nerve dysfunction. Conclusions With a median mean cochlear dose of 2.7 Gy, the majority of patients with serviceable hearing retained serviceable hearing 3 years after GKS. A mean cochlear dose less than 3 Gy was associated with higher serviceable hearing preservation.

Immediate and 1-Year Outcomes with a Slim Modiolar Cochlear Implant Electrode Array

2020 ◽  
Vol 162 (5) ◽  
pp. 731-736
Author(s):  
Nedim Durakovic ◽  
Dorina Kallogjeri ◽  
Cameron C. Wick ◽  
Jonathan L. McJunkin ◽  
Craig A. Buchman ◽  
...  
Keyword(s):  
Pure Tone ◽  
Signal To Noise Ratio ◽  
Case Series ◽  
Low Frequency ◽  
Electrode Array ◽  
Hearing Preservation ◽  
X Rays ◽  
Case Volume ◽  
Pure Tone Average ◽  
Academic Center

Objective To explore the immediate and 1-year outcomes of patients who underwent implantation with the slim modiolar electrode (SME). Study Design Consecutive case series with chart review. Setting Tertiary referral academic center. Subject and Methods Between May 2016 and August 2018, a total of 326 cochlear implantations (CIs) were performed. Intraoperative x-rays were performed in all cases to identify tip rollovers. Scalar location was identified for 76 CIs that had postoperative computed tomography reconstructions. Speech outcomes were measured at 3, 6, and 12 months with consonant-nucleus-consonant word and AzBio sentences in quiet and noise (+10-dB signal-to-noise ratio). Preservation of hearing was defined as maintaining a low-frequency pure tone average ≤80 dB at 250 and 500 Hz. Results Among 326 CIs, 23 (7%) had tip rollovers. Postoperative reconstructions revealed 5 of 76 (6.6%) scalar translocations. A subset of 177 cases met criteria for evaluation of speech perception scores. The marginal mean differences between presurgery and 12 months for speech tests were as follows: consonant-nucleus-consonant, 43.7 (95% CI, 39.8-47.6); AzBio in quiet, 49.7 (95% CI, 44.9-54.4); and AzBio in noise, 29.9 (95% CI, 25.2-34.7). Sixty-one patients were identified with preservable hearing (low-frequency pure tone average ≤80 dB), and 12 of 61 (20%) preserved hearing at 1 year. Conclusion CI with SME provides reliable scala tympani insertion in a consistent perimodiolar position. An initially increased tip rollover rate improved with case volume and sheath design improvement. For long-term outcomes, speech performance was comparable to that of other cochlear implants. While hearing preservation for the SME may be better than prior perimodiolar electrodes, consistent outcomes are unlikely.

Hearing outcomes of vestibular schwannoma patients managed with ‘wait and scan’: predictive value of hearing level at diagnosis

2010 ◽  
Vol 124 (5) ◽  
pp. 490-494 ◽  
Author(s):  
S-E Stangerup ◽  
M Tos ◽  
J Thomsen ◽  
P Caye-Thomasen
Keyword(s):  
Vestibular Schwannoma ◽  
Predictive Value ◽  
High Frequency ◽  
Pure Tone ◽  
Hearing Level ◽  
Speech Discrimination ◽  
Resonance Imaging ◽  
Hearing Outcome ◽  
Hearing Outcomes ◽  
Better Than

AbstractAims:This study aimed to evaluate the predictive value of both hearing level (at various frequencies) and speech discrimination for forecasting hearing outcome after a period of observation, in patients with vestibular schwannoma.Subjects:Over a 33-year period, 1144 patients with vestibular schwannoma were allocated to ‘wait and scan’ management, with annual magnetic resonance imaging and audiological examination. Two complete pure tone and speech discrimination audiograms were available for 932 patients.Results:The predictive value of initial hearing level better than 10 dB for forecasting hearing outcome after observation increased from 59 per cent at 250 Hz to 94 percent at 4000 Hz. At diagnosis, hearing level of 10 dB or better at 4000 Hz was found in only 18 of the 932 VS ears, while good speech discrimination was found in 159 patients (17 per cent). Of the latter patients, 138 maintained good hearing after observation.Conclusion:In vestibular schwannoma patients, good high frequency hearing and good speech discrimination at diagnosis are useful tools in predicting good hearing after observation.

Interchangeability of three different methods of calculating Pure Tone Average in patients with vestibular schwannoma to assess the risk of surgery-related hearing loss

2020 ◽  
Vol 74 (4) ◽  
pp. 1-5
Author(s):  
Aleksandra Ochal-Choińska ◽  
Magdalena Lachowska ◽  
Katarzyna Kurczak ◽  
Kazimierz Niemczyk
Keyword(s):  
Hearing Loss ◽  
Vestibular Schwannoma ◽  
Pure Tone ◽  
Hearing Threshold ◽  
Middle Cranial Fossa ◽  
High Frequencies ◽  
Pure Tone Average ◽  
Hearing Status ◽  
Status Assessment ◽  
Cranial Fossa

Background: Patients with vestibular schwannoma (VS) most commonly present with hearing threshold reduction for high frequencies and a falling type of audiometric curve. However, it is doubtful whether all Pure Tone Averages described in the literature characterize patients with VS correctly, as the type of PTA which comprises higher frequencies may be more appropriate for hearing status assessment in those patients. Aim: The aim of this study was to analyze 3 common methods of calculating Pure Tone Averages (PTA1 - 500, 1000, 2000 and 3000 Hz; PTA2 - 500, 1000, 2000 and 4000 Hz; PTA3 – 500, 1000 and 2000 Hz) and to determine which of them is the most reliable for the assessment of VS patients. Material and Methods: The study group included 86 patients operated due to vestibular schwannoma accessed via the middle cranial fossa. Results: Regarding method of calculating Pure Tone Averages (PTA1, PTA2 and PTA3) identical or similar correlations were found between the preoperative values of Pure Tone Averages (PTA1, PTA2 and PTA3) and surgery-related hearing loss, as well as individual parameters of audiologic tests. Conclusions: Pure Tone Averages calculated according to 3 different methods (PTA1, PTA2, PTA3) may be used interchangeably in the assessment of hearing in VS patients.

Sign in / Sign up

Export Citation Format

Share Document