Surgical trainees and powered-drill use do not affect type I tympanoplasty hearing outcomes.
The purposes of this study were to determine if use of a powered drill or trainee involvement during tympanoplasty is associated with a decline in sensorineural hearing, as well as to examine whether trainee involvement affected tympanic membrane (TM) closure rates. This study was a chart review (February 2006 to October 2011) of 172 pediatric otolaryngology patients undergoing type I tympanoplasty for TM perforation of any etiology at a tertiary-care pediatric otolaryngology practice. Data collected included air conduction (AC) at 250 to 8,000 Hz, speech reception thresholds, bone conduction (BC) at 500 to 4,000 Hz, and air-bone gap (ABG) at 500 to 4,000 Hz. Rates of surgical success did not change significantly if a trainee assisted during surgery (69.6% with an assistant vs. 77.4% without; p = 0.297). AC hearing was not found to be significantly different between the two groups preoperatively or postoperatively at 250, 500, 1,000, 2,000, 4,000, or 8,000 Hz (p > 0.05). There were no significant differences in AC hearing outcomes between patients in whom a surgical drill was used and those in whom no drill was used (p > 0.05). BC and ABG did not change significantly at any frequency (p > 0.05). In conclusion, no correlation between high-frequency hearing loss and use of a powered drill for canalplasty during type I tympanoplasty was found in this pediatric population. No significant difference was found in surgical success rates or AC hearing outcomes when a surgical trainee was present.
Myringotomy with tympanostomy tube insertion is the most commonly performed pediatric surgery. (1) Approximately 1 to 4% of patients will have persistent tympanic membrane (TM) perforation after spontaneous tube extrusion. (2-4) Children with persistent perforation and hearing loss are known to have impaired social interactions and academic performance, as well as inhibited language and cognitive development. (5)
More than half of children with chronic otitis media suffer from mild to moderate conductive hearing loss, and TM perforation alone caries a theoretical risk of up to a 40-dB loss in conductive hearing. (6,7) Frequency-specific hearing studies are important because the average pure-tone threshold does not directly correlate with patterns of hearing perception. (8) Our group has previously shown that type I tympanoplasty improves conductive hearing loss between 250 and 2,000 Hz but with a simultaneous decrease in bone conduction (BC) thresholds at 4,000 Hz. (9)
A decrease in BC thresholds at 4,000 Hz suggests that previously unrecognized perioperative factors may influence sensorineural hearing in this pediatric population. In a review of our surgical cases, the participation of trainee surgeons during tympanoplasty, as well as the use of a powered bone drill, were identified as potential intraoperative sources of iatrogenic injury.
The evidence for surgical trainee impact on hearing outcomes after tympanoplasty is scant. Liu et al found that operative time improved as trainees progressed, but they did not find any difference in surgical outcomes or complications. (10) They did not examine hearing results. Charlett et al examined the differences in audiometric outcomes between trainees and attending surgeons after tympanoplasty with hydroxylapatite prostheses and found a significant improvement in air-bone gap (ABG) outcomes in favor of attending surgeons. However, sensorineural hearing outcomes were not examined individually. (11)
Evidence regarding sensorineural hearing loss after use of a powered drill in otologic surgery is inconclusive. Prior measurements have found that noise levels up to 125 dB are generated during drilling in mastoid surgery, raising the concern for possible noise-induced sensorineural hearing loss. (12) Domenech et al reported that 37.5% of patients had a measurable sensorineural hearing loss at 8,000 Hz and above after use of a powered drill during tympanoplasty. (13) In contrast, Urquhart et al found no difference in sensorineural hearing after mastoid surgery, but they only measured frequencies between 500 to 4,000 Hz. (14)
The purpose of this study was to ascertain whether surgical trainee participation affects hearing or anatomic outcomes in type I tympanoplasty, and to characterize the effect of a powered drill on hearing outcomes.
Patients and methods
This study was approved by the Institutional Review Board of the Children's Hospital of the University of Pittsburgh Medical Center. It was designed as a retrospective medical chart review of 172 patients who underwent type I tympanoplasty between February 2006 and October 2011, previously collected by our group for a related study. (9)
A total of 492 patients were initially reviewed as having undergone type I tympanoplasty. Study exclusion criteria included a history of congenital hearing loss, identification of cholesteatoma or other middle ear mass lesions, identification of ossicular chain discontinuity or destruction, and missing pre- or postoperative audiometric testing. A total of 320 patients were ultimately excluded, largely due to missing pre- or postoperative audiometric data. Therefore, 172 patients (95 male and 77 female) were included in analyses of surgical success and failure.
A powered surgical drill was used in 41 patients, but complete audiometric data were missing in 7. Frequency-specific analyses were therefore completed on 34. Surgery was performed by 11 attending surgeons, individually and with assistance from otolaryngology second post-graduate year residents (PGY2), fourth post-graduate year residents (PGY4), or fellows. Surgical success was defined as an intact TM on clinical examination and by tympanometry testing at the time of the final postoperative assessment.
Demographic data collected included age, sex, assistance of a trainee during surgery, and surgical technique, including the use of a powered drill. The decision for lateral or medial graft tympanoplasty technique was at the discretion of the attending surgeon.
Pure-tone audiometry was conducted in a double-walled sound room using standard procedures. Audiometric testing of the air conduction (AC) threshold was performed at 250, 500, 1,000, 2,000, 4,000, and 8,000 Hz. BC thresholds were recorded at 500, 1,000, 2,000, and 4,000 Hz if AC was greater than 20 dB at the corresponding frequency, with appropriate masking of the opposite ear. AC testing at 250 Hz was not recorded in 64.7% of preoperative audiograms and 35.3% of postoperative audiograms; at 8,000 Hz, AC testing was not completed in 29.4% of preoperative audiograms and 14.7% of postoperative audiograms.
The median time from preoperative audiometric testing to surgery was 75 days (range: 6 to 753), and the median time to postoperative audiometric testing from surgery was 93 days (range: 36 to 239).
A chi-square test was used to compare surgical outcomes between cases in which a surgical trainee was or was not present. Mann-Whitney U testing was used to compare AC hearing results between these two groups. It was also used to compare AC postoperative hearing outcomes between patients undergoing surgery in whom a drill was used against those undergoing surgery in whom no drill was used. Preoperative and postoperative AC, BC, and ABG values were compared in patients in whom a drill was used with the Wilcoxon signed-rank test.
The age range of the 172 patients was 3 to 17 years (mean: 8.9). Some 55.2% were male and 44.8% were female. On average, surgery was successful in 73.8% of patients in this series. (9) Rates of surgical success did not change significantly when a trainee assisted during surgery (69.6% with an assistant vs. 77.4% without; p = 0.297).
Surgical assistants were present for 45.9% of cases (table). The ratios of PGY2 residents, PGY4 residents, and fellows did not vary significantly with use of a powered drill ([chi square] [5, N= 79] = 0.791, p = 0.673).
AC values were not found to be significantly different between the two cohorts preoperatively or postoperatively at 250, 500, 1,000, 2,000,4,000, or 8,000 Hz (p > 0.05) (figure 1).
In the 34 patients in whom a powered drill was used, AC improved at 250,500, and 1,000 Hz (p [less than or equal to] 0.05,0.001, and 0.014, respectively). A trend toward decreased AC hearing was observed at 8,000 Hz (p = 0.095) that was not significant. BC and ABG did not change significantly at any frequency (p > 0.05) (figure 2). No significant differences in AC hearing outcomes were found between patients in whom a surgical drill was used and those in whom no drill was used (p > 0.05) (figure 3).
Many attending surgeons experience some degree of concern when less experienced surgical trainees assist with their cases. However, the data from our pediatric population of 172 cases showed no significant difference in frequency-specific AC hearing outcomes or surgical success rates when a trainee assisted with surgery.
The 34 patients in whom a powered drill was used during surgery showed significant improvements in low and mid-range frequencies (250, 500, and 1,000 Hz), with a trend toward worsening of high-frequency hearing at 8,000 Hz that did not reach significance. Importantly, no significant difference was observed in BC hearing results pre- and postoperatively between 500 and 4,000 Hz, which would suggest that use of a powered drill during canalplasty is safe.
In contrast to prior findings, no significant improvements in ABG were noted at any frequency in the group in whom a surgical drill was used. (9) The necessity of a powered surgical drill may indicate that visualization of the tympanomeatal angle, particularly anteriorly or inferiorly, was reduced in these cases with subsequent suboptimal TM graft placement. Poor surgical technique may result in TM graft lateralization and fibrous adhesion formation at the tympanomeatal angle, also increasing TM impedance. TM shape and thickness are also known to affect sound transmission as they affect impedance. (15)
Despite the lack of improvement in ABG, no differences were observed in AC hearing outcomes between patients in whom a surgical drill was used compared with those in whom no drill was used. The lack of significant changes in ABG values pre- to postoperatively may therefore indicate that any impact of a powered drill on them is relatively small and clinically insignificant.
This study is limited by significant variation in the timing and reporting of clinical examinations and interventions. Additionally, a wide range of surgical trainees (ranging from the second to the seventh post-graduate year) assisted in surgery, and this study was not sufficiently powered to stratify surgical outcomes by year of training. Stratifying by trainee experience may yield differences in surgical outcomes not seen here. Further study would benefit from a larger sample size and standardization of examination timing.
No correlation between high-frequency hearing loss and use of a powered drill during type I tympanoplasty was found in this pediatric population. No significant difference was found in surgical success rates or AC hearing outcomes when a surgical trainee was present. Based on these results, use of a powered bone drill and the assistance of surgical trainees are not contraindicated during type I tympanoplasty.
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(8.) Choi HG, Lee DH, Chang KH, et al. Frequency-specific hearing results after surgery for chronic ear diseases. Clin Exp Otorhinolaryngol 2011;4(3):126-30.
(9.) Kent DT, Kitsko DJ, Wine T, Chi DH. Frequency-specific hearing outcomes in pediatric type I tympanoplasty. JAMA Otolaryngol Head Neck Surg 2014;140(2):106-11.
(10.) Liu CY, Yu EC, Shiao AS, Wang MC. Learning curve of tympanoplasty type I. Auris Nasus Larynx 2009;36(l):26-9.
(11.) Charlett SD, Scott AR, Richardson H, et al. Audiometric outcomes of tympanoplasty with hydroxylapatite prosthesis: Consultant versus trainees. Otol Neurotol 2007; 28(5):678-81.
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(13.) Domenech J, Carulla M, Traserra J. Sensorineural high-frequency hearing loss after drill-generated acoustic trauma in tympanoplasty. Arch Otorhinolaryngol 1989;246(5):280-2.
(14.) Urquhart AC, Mcintosh WA, Bodenstein NP. Drill-generated sensorineural hearing loss following mastoid surgery. Laryngoscope 1992; 102(6):689-92.
(15.) Williams KR, Lesser TH. A finite element analysis of the natural frequencies of vibration of the human tympanic membrane. Part I. Br J Audiol 1990;24(5):319-27.
David T. Kent, MD; David H. Chi, MD; Dennis J. Kitsko, DO
From the Department of Otolaryngology, University of Pittsburgh School of Medicine (Dr. Kent, Dr. Chi, and Dr. Kitsko); and the Division of Pediatric Otolaryngology, Children's Hospital of Pittsburgh of UPMC, Pittsburgh (Dr. Chi and Dr. Kitsko).
Corresponding author: Dennis Kitsko, DO, Division of Pediatric Otolaryngology, Children's Hospital of Pittsburgh of UPMC, 4401 Penn Ave., Floor 3, Pittsburgh, PA 15224. Email: Dennis. Kitsko@chp.edu
Caption: Figure 1. Graphs show the preoperative and postoperative air-conduction results.
Caption: Figure 2. Graphs demonstrate the frequency-specific air-conduction, bone-conduction, and air-bone gap hearing changes after type I tympanoplasty with use of a powered drill.
Caption: Figure 3. Graph shows the frequency-specific air-conduction hearing outcomes between patients in whom a surgical drill was used vs. patients in whom no drill was used.
Table. Distribution of otolaryngology resident and fellow surgical assistants during type 1 tympanoplasty Surgical Use of powered No drill use, Total, assistant drill, n (%) n (%) n (%) Fellow 11 (32.4) 46 (33.3) 57 (33.1) PGY4 3 (8.8) 10 (7.2) 13 (7.6) PGY2 1 (2.9) 8 (5.8) 9 (5.2) No assistant 19 (55.9) 74 (53.6) 93 (54.1) Key: PGY4 = fourth post-graduate year resident trainee: PGY2 = second post-graduate year resident trainee.
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|Title Annotation:||ORIGINAL ARTICLE|
|Author:||Kent, David T.; Chi, David H.; Kitsko, Dennis J.|
|Publication:||Ear, Nose and Throat Journal|
|Date:||Sep 1, 2017|
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