Post operative sensorineural hearing loss after middle ear surgery

Mild Sensorineural hearing loss subsequent to middle ear surgery has till today been an important complication to middle ear surgery inspite of advances in surgical techniques, operative instruments, monitoring devices and better treatment options. Lack of proper knowledge about this problem is because of under reporting of exact magnitude of hearing loss on account of difficulty in measuring hearing threshold of patients in immediate postoperative period as it may lead to post operative infection and discomfort to the patient. In our study of 80 cases carried out at ENT department, Baroda Medical College and S.S.G Hospital, Baroda, we have utilized weber’s lateralisation principle and measured bone conduction thresholds of patients undergoing middle ear surgery for evaluation of postoperative Sensorineural loss as a result of middle ear surgery. Probable causes of post operative hearing loss in a patient undergoing middle ear surgery are, noise due to drills, continuous suction irrigation, vibrations, inner ear injury, manipulation of ossicles and a few unknown reasons.     

伴有骨导下降的中耳疾病手术效果分析

目的探讨慢性中耳炎（胆脂瘤）伴有骨导下降患者经手术治疗后骨导听力的改善及其生理基础，并与耳硬化症术后“卡哈氏”切迹的变化进行对比分析。方法病例分二组，一是本院耳硬化症手术有一年以上完整听力随访资料的42例（57耳），平均年龄46．74岁（15～71岁），男8例（12耳），女34例（45耳）。二是同期中耳炎（含鼓室硬化、胆脂瘤、粘连性中耳炎）行听力重建并有一年以上随访资料者182例（200耳），平均年龄43．92岁（15～72岁），男79例（83耳），女103例（117耳）。统计二组术后骨导听力改善（至少一个频率减少10dB以上）的耳数和百分比，进行卡方统计分析。结果镫骨手术组57耳术后有13耳（22％）、中耳炎组200耳中有51耳（25．5％）符合条件。卡方检验，x^2=0．172〈x^2 0.005=3．8416，故P〉0．05，2组差异没有显示显著性意义。2个典型病例术后骨导明显改善。结论耳病变由于改变了振动频率，或增加了质量负荷，都可以影响骨导；中耳炎毒素也可以使内耳水肿，细胞变性甚至坏死。前者随着中耳病变解除，骨导可以恢复；后者需要尽早治疗，部分可能挽救。     

Bone conduction improvement after surgery for conductive hearing loss

The objective is to evaluate change in post-operative bone conduction in patients who underwent surgery for conductive/mixed hearing loss due to various reasons. The study design is of retrospective case review and tertiary referral center setting. Five-hundred patients with unilateral conductive/mixed hearing loss were divided into five equal groups (each representing different causes for pre-operative hearing loss), who underwent appropriate surgical correction and had a follow-up audiogram available. The intervention comprises surgery (like myringoplasty and ossiculoplasty with closed or open cavity mastoidectomy for chronic otitis media, stapes mobilization for tympanosclerosis and stapedotomy for otosclerosis) for conductive/mixed hearing loss. Significant improvement or worsening in bone conduction was defined as 15?dB or more improvement or worsening of bone conduction threshold at least in two frequencies between 500 and 4000?Hz. All the other groups also showed a consistent pre-operative bone conduction reduction with an equally consistent improvement in post-operative bone conduction improvement to a varying degree with otosclerosis group having maximum percentage of patients with post-operative bone conduction improvement (60%). The measurement of bone conduction is not necessarily a true reflection of the function of the inner ear. Middle ear makes a contribution to bone conduction and correction of a middle ear conductive lesion causes an apparent improvement in inner ear function. The apparent inner ear hearing loss caused in this way may be reversible to some extent.     

A new implantable middle ear hearing device for mixed hearing loss: A feasibility study in human temporal bones.

HYPOTHESIS: To assess the feasibility of a new, active middle ear device in temporal bones (TB). BACKGROUND: This device is designed for patients with mixed hearing loss subsequent to chronic middle ear infection, surgery, or trauma. This Bell-Vibroplasty is built from a VIBRANT MED-EL Vibrant Soundbridge and a Kurz Bell titanium partial ossicular replacement prosthesis. METHODS: In three fresh TBs, healthy and reconstructed middle ears were analyzed by means of laser Doppler interferometry. The sound transmission properties of a partial ossicular replacement prosthesis and a passive and an active Bell-Vibroplasty were compared with healthy middle ear function. RESULTS: The measurements provided reliable results with small standard deviations and good signal-to-noise ratios. The performance levels of the partial ossicular replacement prosthesis and of the passive Bell-Vibroplasty were comparable with that of healthy middle ear function. The activated Bell-Vibroplasty provided linear function and a flat frequency response within the measured frequency range (500 Hz-8 kHz), with peak deviations of less than 10 dB. The maximum output of the Bell-Vibroplasty was equivalent to 125-dB sound pressure level. CONCLUSION: Bell-Vibroplasty is feasible in TBs. Bell-Vibroplasty performance in TBs is sufficient to allow for a clinical trial as a next step.     

Efficacy of middle ear surgery for patients with hearing aids and middle ear disease

Of 356 cases that underwent middle ear surgery for hearing improvement, 30 (8.4%) with air conduction hearing aids and middle ear disease were evaluated pre- and postoperatively. All surgeries were performed by the same surgeon. Diagnoses included 22 chronic otitis media, 5 chronic otitis media with cholesteatoma, 1 otosclerosis and 2 ossicular anomaly. Chief complaints at the first visit to Fukui Medical University Hospital were otorrhea (17 cases), hard of hearing (28 cases), dizziness (2 cases) and tinnitus (2 cases). Nineteen patients underwent surgery on both ears and eleven on one ear including five ears that showed better hearing preoperatively. Surgical procedures were tympanoplasty type I (15 cases), modified type III (8 cases), modified type IV (3 cases), stapedotomy (2 cases) and implantable hearing device (2 cases). After surgery, 16 patients (group 1) did not need hearing aids, while 14 (group 2) still needed hearing aids. Preoperative hearing was 64.1dB (n = 30) on average and average hearing one year after surgery in group 1 (35.4 +/- 14.1dB) was significantly better than in group 2 (58.1 +/- 18.4dB). After surgery, otorrhea stopped in all cases (100%), subjective hearing loss improved in 82% of the patients, vertigo improved in 100% and tinnitus improved in 50%. These results emphasize the benefits of surgical therapy, and the reasons why it should be recommended to patients with hearing aids and middle ear disease, such as to improve hearing disorders, to stop otorrhea and to prevent progressive sensorineural hearing loss.     

Effects of packing on the postoperative hearing after middle ear surgery

CONCLUSION: The changes of hearing by packing after middle ear surgery should be anticipated and carefully interpreted. OBJECTIVES: To evaluate the amount and patterns of hearing loss resulting from packing in middle ear cavity (MEC) and external auditory canal (EAC) after middle ear surgery. METHOD: We obtained pure tone thresholds by bone (BC) and air conduction (AC) up to 12 weeks after middle ear surgery in 17 patients who had minimal middle ear pathology. To observe the effects of packing only in the EAC as in cases of explorative tympanotomy or stapes surgery, BC and AC threshold were obtained after packing only in the EAC in 18 volunteers. The changes of BC and AC thresholds in terms of pure tone average (PTA) and high frequency PTA were analyzed. RESULTS: PTA by AC increased significantly by a maximal value of 38.7 dB at the second postoperative day, by 35.0 dB at 1 week after middle ear surgery. PTA by BC also increased maximally at the second postoperative day by 4.8 dB. The elevation of BC threshold at high frequencies (2, 3, 4 kHz) was more pronounced. Packing of EAC without MEC packing resulted in elevation of AC threshold by 43.0 dB, with similar patterns of BC threshold changes as MEC and EAC packing.     

Semi-implantable electromagnetic middle ear hearing device for moderate to severe sensorineural hearing loss

Despite the many improvements in hearing aid technology, conventional hearing aids continue to have significant limitations, which has led to increased interest in implantable hearing devices. The SOUNDTEC Direct Drive Hearing System for moderate to moderately severe sensorineural hearing loss is one such device. In this article the authors present results on five individuals enrolled in a Food And Drug Administration Phase I feasibility study.     

Ten years of active middle ear implantation for sensorineural hearing loss

Objectives: To evaluate long-term benefits of a totally implantable active middle ear implant (AMEI) that has been used in a single implanting center for over 10 years.

Methods: Forty-one subjects who underwent implantation with an Esteem^® AMEI during a 10-years period were evaluated on the auditory benefits, as derived from pure tone and speech audiometry tests. The analysis included a comparison with a conventional hearing aid, the problematics related to the battery duration and surgical replacement and, finally, the complication rate.

Results: Over 80% of the implanted subjects maintained over time a satisfactory auditory gain, ranging from 10 to over 30?dB in respect to the unaided situation, as mean at 0.5, 1, 2 and 4?kHz. In more than 60% of them, an improvement has also been found at 4 and 8?kHz. Battery duration varied according to the severity of the hearing loss and to the daily use of the device. No major post-operative complications were recorded, whilst explantation was necessary in five subjects, although none for device failure.

Conclusions: The Esteem^® can be considered a reliable device for rehabilitation of sensorineural hearing loss in alternative to conventional hearing aids.     

Sensorineural hearing loss after vibration: an animal model for evaluating prevention and treatment of inner ear hearing loss

Sensorineural hearing loss following a variety of acoustic trauma, including middle ear surgery, is well known. Current literature, which points to the deleterious influence of noise on the inner ear during surgery, has yet to assess the influence of vibration generated by the burr. The purpose of the study reported here was to establish an animal model that mimics drilling and can be used to explore methods of hearing loss prevention and treatment. A specially developed electromagnetic vibrator was calibrated and used in 59 guinea pigs to induce hearing loss. Both young and old guinea pigs were used. The bony external ear canal of guinea pigs were exposed to vibration or sound of varying duration and intensity. The vibration of the temporal bone and noise level in the middle ear were measured. Electrocochleography was recorded to evaluate the hearing loss. Among the young animals, 90% developed a significant threshold shift (TS > 20 dB), when vibrated with 250 Hz at an intensity of 6.2 m/s2 for 15 min. An average of 42 dB TS was observed. With 10 min exposure 63% showed a TS. The older animals vibrated for 5 min developed the same TS (mean TS 34 dB) as the young animals when vibrated for 10 min. The vibration-induced TS showed no recovery within 3 days of observation. In the contralateral ear 4 out of 5 animals showed TS > 20 dB. When exposed to sound levels exceeding the vibration-generated sound in the middle ear (119 dB at 250 Hz) only 2 out of II animals (18%) showed TS. The frequency of TS and level of TS were significantly greater in the vibrated animals than in sound-only exposed animals (p < 0.01). The degree of vibration-induced TS in the present animal model could be controlled by vibration intensity and duration. The older animals were more susceptible to vibration-induced inner-ear damage than younger animals. This model will be used in further studies to find methods for prevention and treatment of hearing loss during ear surgery.     

Lyophilized homologous bone grafts in middle ear surgery: new perspectives

The authors share their experience of the use of allografts in the reconstruction of the tympano-ossicular chain. The implants were cut from the cortical substance of the long bone in patients deceased for a maximum of six hours; the donors were tested for syphilis, hepatitis, AIDS, systemic diseases or a neoplasm. These bone allografts were cut to size, degreased, demineralized, frozen and then lyophilized in order to be presented to the surgeon in a sterile container (Bone Bank). The implants were all tolerated well. The anatomical results were satisfactory. Optical microscopic studies showed that the implant was: a) covered with mucosa, b) full of osteoblasts and c) the site of a bone neoformation. Experimental research is currently underway in order to perfect the implant preparation methodology.     

Binaural hearing after middle ear surgery. Masking-level difference for interaural time and amplitude cues

Previous investigations have shown that binaural hearing is often abnormal in patients having conductive hearing losses, and even in patients who have had hearing thresholds corrected by middle ear surgery. The present study assessed further the masking-level difference (MLD) in patients who had previously undergone middle ear surgery. The stimuli were chosen such that the sensitivity to interaural time difference cues and to interaural amplitude difference cues could be assessed independently. Results indicated that the MLD is abnormal in more than a third of 15 patients, even after surgery has restored normal hearing at the frequency of the test. The MLD is more likely to be reduced for the cue of interaural time difference than for interaural amplitude difference. Subjects who had lesions of long duration, early onset, and large asymmetry were particularly likely to have reduced MLDs.     

Improvement of bone conduction after stapes surgery in otosclerosis patients with mixed hearing loss depending from surgical technique

This study investigate the effect of stapes surgery on bone conduction (BC) improvement in otosclerotic patients with mixed hearing loss and also compare the effect of three different types of surgery (complete stapedectomy, partial stapedectomy and microfenestration stapedotomy) on this improvement. We retrospectively reviewed surgical database of 84 otosclerotic patients with mixed hearing loss. Sixty-two patients (75%) had significant improvement in BC after surgery (P = 0.03). In 85% of patients with follow-up time longer than 1 year, this improvement had remained. Improvement in BC after surgery was better in partial stapedectomy group (82.6%) and complete stapedectomy group (80.8%) in comparison with microfenestration stapedotomy group (63%) (P = 0.052).     

Results of bone conduction following surgery for chronic ear disease

Preoperative and postoperative bone conduction thresholds were compared in 181 chronic ears operated on over a 5-year period between 1990 to 1994. In the majority (92%) of cases the bone conduction thresholds remained unchanged (± 10 dB). Nine ears (5%) showed better thresholds after surgery, with improvements ranging from 11 dB to 25 dB. This improvement was especially noted in ears with severe tympanic pathology. One ear with a large labyrinthine fistula became totally deaf after surgery. In 5 ears (3%) bone-conduction thresholds deteriorated, but remained measurable at all frequencies tested. In these latter cases this impairment ranged from 11 dB to 27 dB. Cholesteatomatous ears having intact ossicular chains were found to be at the highest risk of inner ear damage when canal wall-down mastoidectomies were performed. Methods for prevention of sensorineural hearing loss following chronic ear surgery are discussed.     

Preoperative swabs for the treatment of draining ears after middle ear surgery

The value of a preoperative swab for the treatment of postoperative infection after middle ear surgery was investigated. In a selected group of 80 patients with postoperative infection a preoperative swab was available, and the variability was analysed for each species. The well-known pathogens Pseudomonas aeruginosa, Staphylococcus aureus, Proteus and Escherichia coli showed good correlation between pre- and postoperative swabs. In contrast to this all other species found in preoperative swabs were of little value postoperatively. This observation is important for the treatment of infection after middle ear surgery, and should be considered if prophylactic antibiotics are planned.     

The middle ear bioelectronic microphone for a totally implantable cochlear hearing device for profound and total hearing loss.

BACKGROUND: A bioelectronic middle ear microphone (BMEM) has been developed in a laboratory bench model and successfully tested in fresh human temporal bones. A transducer actually has been bench-tested in our laboratory; it was implanted in chronic animal experiments (cats) as well as in humans for a period of 1 year as a driver of a semi-implantable electromagnetic middle ear hearing device (IDE, FDA approved). This BMEM is the result of the use of this same electromagnetic transducer used in a reverse mode. The applicability of the BMEM is for the development of a totally implantable cochlear implant using the eardrum as a diaphragm that transmits vibrations to a magnet cemented to the ossicles. This BMEM is to be powered by a lithium-ion implantable, rechargeable battery. MATERIALS AND METHODS: To test the efficacy of this BMEM, the experiment was divided into two parts: (1) bench model, and (2) fresh human temporal bones, using an air-core electromagnetic (EM) coil and a ferrite core EM coil for comparison. RESULTS: In the bench model, the average displacement at 3 kHz was 0.95 microns (peak) for 4 V p-p and 1.65 microns (peak) for 10 V p-p. At 5 kHz, the measurements were somewhat higher. In fresh human temporal bones, with sound source in the ear canal (60 dB HL and 90 dB HL), the result was better with the magnet implanted on the head of the malleus with the incus removed. The ferrite core EM coil with the magnet implanted on the malleus with the incus removed was compared with the air-core EM coil. At 60 dB HL, the ferrite core EM coil yielded more than four times the amplitude of the EM coil. At 90 dB HL, the ferrite core EM coil produced more than five times the amplitude compared with the air-core coil. CONCLUSION: This BMEM using an EM ferrite coil and a permanent magnet on the head of the malleus is more efficient when compared with an EM air-core coil. This BMEM may be applicable to the construction of a totally implantable cochlear implant. Further research is necessary to integrate this BMEM with the other components of the design concept of the totally implantable cochlear implant.     

Unpredictable hearing loss after intratympanic gentamicin treatment for vertigo. A new theory

A new hypothesis is advanced suggesting that unpredictable cases of profound hearing loss after intratympanic gentamicin treatment (IGT) may be caused by decreased patency of the communication routes between the inner ear and the cerebrospinal fluid, primarily of the cochlear aqueduct. A tympanic displacement analyzer, which can indirectly analyze inner ear and intracranial pressure changes and can also evaluate the efficiency of communication between these two compartments, was used. Two cases are presented: in the first, a patient who became deaf after IGT showed signs of decreased patency of the communication routes with the tympanic membrane displacement (TMD) test; in the second, a patient without hearing damage after IGT had efficient communication evaluated by the TMD test. These preliminary findings are in accordance with the proposed pathophysiology. If future clinical studies confirm the present theory and findings, it may prove possible to predict and prevent deafness after IGT and possibly also after systemic aminoglycoside treatment.