Wideband acoustic immitance - Absorbance measurements in ears after stapes surgery.

OBJECTIVES: The study aimed to thoroughly assess absorbance in ears after stapes surgery (stapedotomy/stapedectomy) and how stapes surgery affects wideband acoustic immittance (WAI) metrics. METHODS: Eighty-three otosclerotic ears were analyzed pre- and postoperatively. The analysis comprised: air-bone gap (ABG) and WAI which included absorbance measurements, resonance frequency assessment, low frequency tympanometry and metrics derived from these measures. RESULTS: Absorbance after stapes surgery changed considerably compared to otosclerotic ears before surgery and also differed from normal ears. Absorbance after stapes surgery revealed two significantly different plot types: single-low-frequency-peak absorbance and two-peaks absorbance. Stapes surgery reduced resonance frequency in majority of operated ears and increased static compliance in low frequency tympanometry. Static compliance difference was directly proportional to ABG improvement at low frequencies. Postoperative ABG at 250 Hz and 500 Hz was most commonly correlated with postoperative WAI parameters. ABG improvement at 3000 Hz and 4000 Hz was directly proportional to absorbance difference at ~3000 Hz and 4000 Hz. It influenced the width of the postoperative absorbance by shifting both sides of the plot (negative values shift the points of the plot toward lower frequencies) with the correlation being more pronounced in postoperative two-peaks absorbance type ears. CONCLUSIONS: Absorbance by itself is not sufficient for assessment of changes to middle function following stapes surgery, and should be complemented with other measures. WAI measurements including absorbance, resonance frequency assessment, low frequency tympanometry, and metrics derived from these measures combined with air-bone gap provide insight into mechano-acoustic changes in the middle-ear system as a result of stapes surgery.

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

<b>Background:</b> 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. <br><b>Aim:</b> 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. <br><b>Material and Methods:</b> The study group included 86 patients operated on due to vestibular schwannoma accessed via the middle cranial fossa. <br><b>Results:</b> Regarding the 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. <br><b>Conclusions:</b> Pure Tone Averages calculated according to 3 different methods (PTA1, PTA2, PTA3) may be used interchangeably in the assessment of hearing in VS patients.

Audiologic prognostic factors for hearing preservation following vestibular schwannoma surgery.

BACKGROUND: Postoperative hearing loss after vestibular schwannoma (VS) removal still remains a lifelong problem for the patients. The present study analyzes the problem of hearing preservation after VS removal from a different angle than available professional literature on this topic. OBJECTIVES: To identify audiologic factors which determine the extent of hearing loss in patients operated on for VS. MATERIAL AND METHODS: The study group included 86 patients operated on due to VS accessed via the middle cranial fossa. The analyses involved the effect on absolute hearing loss, which was calculated on the basis of the results of pure-tone audiometry performed preand postoperatively, and factors included in the preoperative audiologic tests, such as pure-tone audiometry, speech audiometry, auditory brainstem response (ABR), and impedance audiometry. RESULTS: The following parameters were demonstrated to have a prognostic value: 1. hearing thresholds at 125 Hz, 500 Hz and 1,000 Hz for the operated ear, Pure Tone Average (PTA) - calculated specifically at 500 Hz, 1,000 Hz and 2,000 Hz and at 500 Hz, 1,000 Hz, 2,000 Hz, and 4,000 Hz for the operated ear, and normal audiometric curve; 2. speech discrimination ranging from 55 dB to 75 dB for the operated ear, speech detection threshold (SDT) in the operated ear and interaural difference at 25-35 dB (non-operated vs operated ear); 3. presence of wave V, the values of I-V and III-V intervals for the operated ear, the amplitude of wave V, and the interaural ratio of wave V amplitudes; 4. intensity level for obtaining stapedial reflex or an abnormal reflex at Ipsi 500 Hz, 1,000 Hz and 2,000 Hz, and Contra 500 Hz, 1,000 Hz, 2,000 Hz, and 4,000 Hz. CONCLUSIONS: The better the preoperative hearing status, the more substantial surgery-related hearing loss was observed. A number of preoperative parameters of the basic diagnostic set of audiologic tests present a prognostic value for the degree of surgery-related hearing loss in VS patients.

Wideband tympanometry and absorbance measurements in otosclerotic ears.

OBJECTIVES: This study aimed to assess absorbance using a thorough analysis of individual points of its plot in ears with intraoperatively confirmed otosclerosis. To the best of our knowledge, until recently no analyses have been performed that concerned the shape of an absorbance plot and a detailed analysis of its individual points. This study is the first to undertake such an issue. METHODS: A total of 77 otosclerotic ears were included in the study. Pure tone audiometry, low frequency tympanometry, and wide band tympanometry including absorbance were performed preoperatively. The average patients' age in the group was 43.49 years (standard deviation = 10.44). Individual points of absorbance plot were thoroughly analyzed. Parameters were analyzed, such as resonance frequency; number of peaks; maximum absorbance (Height); and plot Width at the following Heights: 1/3, 1/2, and 2/3 (Width1/3, Width1/2, Width2/3, respectively), as well as associated absorbance parameters and frequencies. RESULTS: Data analysis revealed five different types of absorbance plots. Numerous statistically significant differences regarding the parameters of individual points of the plots were found among the distinguished types. CONCLUSIONS: There are five types of absorbance plots in otosclerotic ears: type I, characterized by two distinct peaks, closely resembling normal ear absorbance plot; type II with a single distinct peak reaching high values of absorbance; type III with reduced absorbance for frequencies <2000 Hz; type IV with reduced absorbance for all frequencies; and type V with reduced absorbance for frequencies >2000 Hz. Absorbance measurements may play an important role in the diagnostics of otosclerosis; however, further research is necessary in this area. LEVELS OF EVIDENCE: 4 Laryngoscope, 129:E365-E376, 2019.