Unilateral sudden loss of hearing

Sensorineural hearing loss after cardiac surgery: a systematic review

BACKGROUND

Sensorineural hearing loss (SNHL) may occur following cardiac surgery. Although preventing post-operative complications is vitally important in cardiac surgery, there are few guidelines regarding this issue. This review aimed to characterize SNHL after cardiac surgery.

METHOD

This systematic review was registered on PROSPERO and conducted in accordance with PRISMA guidelines. A systematic search of the PubMed, Embase and Cochrane Library were conducted from inception. Eligibility determination, data extraction and methodological quality analysis were conducted in duplicate.

RESULTS

There were 23 studies included in the review. In the adult population, there were six cohort studies, which included 36 cases of hearing loss in a total of 7135 patients (5.05 cases per 1000 operations). In seven cohort studies including paediatric patients, there were 88 cases of hearing loss in a total of 1342 operations. The majority of cases of hearing loss were mild in the adult population (56.6%). In the paediatric population 59.2% of hearing loss cases had moderate or worse hearing loss. The hearing loss most often affected the higher frequencies, over 6000 Hz. There have been studies indicating an association between hearing loss and extracorporeal circulation, but cases have also occurred without this intervention.

CONCLUSION

SNHL is a rare but potentially serious complication after cardiac surgery. This hearing loss affects both paediatric and adult populations and may have significant long-term impacts. Further research is required, particularly with respect to the consideration of screening for SNHL in children after cardiac surgery.

Sensorineural Deafness After Spine Surgery: Case Series and Literature Review

BACKGROUND

Sudden sensorineural hearing loss (SNHL) after nonotologic surgery is unusual, with most occurrences reported in patients having cardiopulmonary bypass. Reports of SNHL after nonotologic noncardiac surgery are rare, particularly after spine surgery. In patients undergoing subarachnoid anesthesia or intradural surgery, loss of cerebrospinal fluid pressure can result in hearing loss and cranial nerve palsy.

METHODS

A 70-year-old male patient had ankylosing spondylitis with an Anderson lesion T11-12 with diabetes mellitus, hypertension, and American Spinal Injury Association Impairment Scale-A neurology. He underwent posterior stabilization of T10-L1 and developed a profound, painless, left-sided hearing deficit shortly afterward. An otorhinolaryngology consultation confirmed SNHL. An 82-year-old male reported claudication with L4-5 LCS and type 2 diabetes mellitus. Post L4-5 transforaminal lumbar interbody fusion, he complained of hearing loss in his left ear, confirmed by an otolaryngologist. A 72-year-old diabetic male had tuberculous spondylodiskitis of D2-3 with an epidural abscess. An emergent decompression and stabilization C7-D5 bone grafting at D2-3 was done. In the early postoperative period, the patient complained of marked hearing impairment on the right side. Audiometry indicated SNHL in his right ear.

RESULTS

A course of intravenous corticosteroids was instituted in the first and second patients for severe hearing loss. Steroids were not given to the third patient in view of his Pott spine. No improvement in hearing impairment occurred until the latest follow-up in all patients.

CONCLUSIONS

Sudden-onset hearing loss post spine surgery is disastrous with multiple etiologies and remains poorly understood. Timely evaluation by an otolaryngologist and audiologist is recommended. The role of corticosteroids in treating SNHL is still unclear.

Effects of cardiopulmonary bypass surgery on auditory function: a preliminary study

Hearing loss has been reported as a complication following cardiac surgery with extracorporeal circulation. Preoperative hearing testing is not commonly done in these procedures, so preoperative and postoperative hearing loss, if any, may occur unnoticed. 30 subjects in the age range of 50-70 with a mean age of 60.16 years with myocardial infarction and scheduled to undergo cardiopulmonary bypass surgery underwent detailed audiological assessment comprising of pure tone audiometry with extended high frequency audiometry, speech audiometry and otoacoustic emissions (OAE) testing. The audiological testing was done preoperatively and at 2 weeks after the surgery. On pure tone audiometry, the difference between pre- and postsurgery mean values for both ears at 10, 12, and 16 KHz showed highly significant differences (P < 0.0001). On OAE testing, a significant difference (P < 0.05) between pre- and postvalues of signal to noise ratio (SNR) was found. It is hypothesised that CPB surgery makes blood redistribution to other organs easy, deviating from internal ear, which is highly susceptible as it lacks collateral circulation and its cells have high energy metabolism. Epithelial damage on internal ear microcirculation causes reduction of the cochlear potentials and hence hearing loss.

Cochlear Dysfunction in Children following Cardiac Bypass Surgery

Background. Sensorineural hearing loss after procedures including extracorporeal circulation and hypothermia is greater than general population. Mild hypothermia has a protective role on cochlea; however, deep hypothermia may result in cochlear injury. This research aimed at assessing auditory function in children after open heart surgery in relation to different hypothermic techniques. Subjects and Methods. Forty children with acyanotic heart diseases who underwent open heart surgery were included: group I: twenty patients subjected to mild hypothermia (33° to 37°C), group II: twenty patients subjected to moderate hypothermia (28° to 32°C). Audiological assessment included basic evaluation and otoacoustic emissions. Results. Both groups had distortion-product otoacoustic emissions (DPOAEs) amplitude >3 dB SPL at all frequencies. However, group II showed lower amplitude at overall and at high frequencies (4.416–8.837 KHz) than group I. Transient evoked otoacoustic emissions (TEOAEs) showed partial pass in three patients of group I (15%) and in 15 patients of group II (75%). Moreover, group II showed statistical significant reduction in overall TEOAEs amplitude as well as at high frequencies (2–4 KHz). Conclusions. Patients exposed to moderate hypothermic technique had subtle cochlear dysfunction. Otoacoustic emissions should be used for early detection of subtle cochlear dysfunction in operated cardiac children.

Volumetric Imaging of Blood Flow within Cochlea in Gerbil in vivo

Changes in blood flow to the inner ear are thought to influence a number of cochlear diseases, including noise-induced hearing loss, sudden hearing loss, and Meniere's disease. Advances have been made in the areas of vital microscopic studies of micro-circulation, and the laser Doppler flowmetry. But none of these techniques can provide in vivo three-dimensional (3-D) mapping of microvascular perfusion within the cochlea. To overcome this limitation we have developed and used a method of optical microangiography (OMAG) that can generate 3-D angiograms within millimeter of tissue depths by analyzing the endogenous optical scattering signal obtained from an illuminated sample. We used OMAG to visualize the cochlear microcirculation of adult living gerbil through the intact cochlea, which would be difficult, if not impossible, by use of any other current techniques.

Effectiveness of hyperbaric oxygen therapy for hearing loss after cardiac surgery

Sudden sensorineural hearing loss is a rare complication after cardiac surgery with extracorporeal circulation. We report a case of a 60-year-old man who experienced severe sensorineural hearing loss after Bentall procedure and recovery of normal hearing after 20 days of hyperbaric oxygen therapy.

Deleterious effects of cardiopulmonary bypass in coronary artery surgery and scientific interpretation of off-pump's logic

Cardiopulmonary bypass (CPB) has been suggested to be a cause of complex systemic inflammatory response that significantly contributes to several adverse postoperative complications. In the last few years, off-pump coronary artery bypass grafting (OPCAB) has gained widespread attention as an alternative technique to conventional on-pump coronary artery bypass grafting (ONCAB). However, a degree of uncertainty regarding the relative merits of ONCAB and OPCAB continues to be a significant issue. Surgeons supporting off-pump surgery, state that the avoidance of the CPB leads to significantly reduced myocardial ischemia-reperfusion injury, postoperative systemic inflammatory response and other biological derangements, a feature that may improve the clinical outcomes. However, perfection in perioperative care, surgical technique and methods of attenuating the untoward effects of CPB has resulted in better clinical outcome of ONCAB as well. Possible reasons of these controversial opinions are that high-quality studies have not comprehensively examined relevant patient outcomes and have enrolled a limited range of patients. Some studies may have been too small to detect clinically important differences in patient outcomes between these two modalities. We present a review of the available scientific interpretation of the literature on OPCAB with regard to safety, hemodynamic changes, inflammation, myocardial preservation and oxidative stress. We also sought to determine from different reported retrospective and randomized control studies, the initial and the long-term benefits of this approach, despite the substantial learning curve associated with OPCAB.

A single-blinded case controlled study on effects of cardiopulmonary circulation on hearing during coronary artery bypass grafting

OBJECTIVES

To evaluate the effect of extra-corporeal (cardiopulmonary) bypass on hearing during coronary artery bypass grafting.

DESIGN

Prospective (single-blinded) controlled study.

SETTING

District General Hospital.

PARTICIPANTS

Fifty-two patients undergoing coronary artery bypass grafting completed this study. Comparison was made between 14 control patients undergoing off-pump coronary artery bypass grafting and 38 study patients undergoing on-pump coronary artery bypass grafting. The age range of patients was 48-81 years, with 50% between 64 and 66 years.

MAIN OUTCOME MEASURES

Pure tone audiograms were performed in all patients before and after coronary artery bypass grafting. Data were analysed for any significant difference between pre- and post-operative pure tone audiograms.

RESULTS

Mann-Whitney U-test demonstrated no difference between the area generated between mean pre- and post-operative audiograms (P = 0.754). No significant difference between off versus on pump was demonstrated for average differences at 250-500 Hz, 4 kHz, 4-8 kHz and 8 kHz. Wilcoxon matched-pairs signed-rank test demonstrated no difference between right and left ears for each individual frequency. Spearman's test to analyse the effect on vessel number or minutes on bypass pump revealed no significant difference at 4-8 kHz (P = 0.550 for number of vessels and P = 0.276 for minutes on pump.)

CONCLUSION

In this study, it was not possible to demonstrate any statistically significant deleterious effect of extra-corporeal (cardiopulmonary) bypass on hearing during coronary artery bypass grafting.

Unilateral sensorineural hearing loss after spine surgery: case report and review of the literature

BACKGROUND

Sudden sensorineural hearing loss is infrequent, with an estimated incidence of 5 to 20 cases yearly per 100,000 people. Although multiple etiologies have been identified, infection and idiopathic SNHL are most common. Sudden sensorineural hearing loss after nonotologic noncardiac surgery is highly unusual, particularly after spinal surgery.

CASE DESCRIPTION

We report a case of unilateral sudden SNHL after lumbar spinal fusion with review of the literature. Potential etiologies, treatment, and prognosis are summarized.

CONCLUSION

Multiple etiologies have been proposed for SNHL after nonotologic noncardiac surgery. Excessive positive upper airway pressure during induction of anesthesia or Valsalva maneuvers can result in SNHL from LMR. Aberrant NO accumulation in the middle ear cavity during general anesthesia with subsequent LMR is also a potential etiology, as is excessive leakage of CSF causing a form of endolymphatic hydrops. There is no definitive treatment of postoperative SNHL, although middle ear exploration may be beneficial for suspected overpressure injury to the middle ear, causing a perilymphatic fistula. Corticosteroids have been beneficial in certain cases of idiopathic SNHL; however, its effectiveness for postoperative SNHL is undocumented.

Coronary artery bypass grafting and sensorineural hearing loss, a cohort study

BACKGROUND

Sudden sensorineural hearing loss is routinely encountered by the otologist. The etiology is varied and often identifiable. One of the relatively less frequent causes is surgery. Apart from being an established entity with otological surgeries, sensorineural hearing loss has also been known to occur after non-otological procedures under general anesthesia. Commonest amongst these procedures is cardiopulmonary bypass, an association that has long been recognized. However, despite the proposition of diverse hypotheses in the past, the pathophysiology remains unclear.

METHODS

The study is a prospective matched cohort study that will be carried out in Aga Khan University Hospital, Karachi, Pakistan. Participants among exposed would include all those patients who would be undergoing coronary artery bypass surgery in the hospital who fall under the criteria for inclusion. Unexposed group would comprise of patients undergoing a non-bypass procedure of similar duration under the same type of anesthesia who meet the selection criteria. Both these groups will undergo audiometric testing at our hospital on three different occasions during the course of this study. Initially before the procedure to test the baseline hearing capacity; then one week after the procedure to assess any changes in hearing ability following the surgery; and finally a third audiogram at six weeks follow-up to assess further changes in any hearing deficits noted during the second phase of testing. Certain variables including the subjects' demographics and those concerning the procedure itself will be noted and used later for risk factors analysis. A detailed past medical and surgical history will also be obtained. Data analysis would include calculation of relative risk and significance of the results, by running the chi-square test. Other statistical tests like Fisher exact test may then be employed to facilitate data interpretation. Continuous scale may then be employed and multivariate linear regression used.

DISCUSSION

This study is planned to obtain a better understanding of the correlation between sudden sensorineural hearing loss and cardiopulmonary bypass. Being the first major cohort trial in this line of investigation, the project is designed to identify the existence of any significant relationship between cardiopulmonary bypass and sensorineural hearing deficit.

Red blood cell deformability in sudden sensorineural deafness: another aetiology?

Red blood cell deformability (RCD) was measured by a filtration technique in 12 patients with sudden sensorineural deafness. Five patients had reduced deformability, including 3 out of 4 patients with a recent upper respiratory tract infection. This may be an important factor in sudden deafness, more likely as a complicating factor of other disorders rather than as a truly primary aetiology. Factors and diseases which alter RCD are discussed and a possible link between the viral and vascular causes of idiopathic sudden deafness is suggested. While several lines of therapy seem promising there is still no clinically proved method for improving RCD. With the development of an acceptable therapeutic regimen, we feel that the possibility of reduced RCD should be considered and that a deformability test be included in the work-up of patients with a sudden sensorineural hearing loss.

Hearing loss after general anaesthesia (a case report and review of literature)

Unilateral hearing loss has been reported as an unusual complication in general anaesthesia, and so far no reports on bilateral hearing loss have been published. In this paper we present a case with bilateral sensorineural hearing impairment immediately following a minor abdominal surgical procedure. The literature is reviewed and the mechanisms causing hearing loss during anaesthesia are discussed.

Techniques for the observation and measurement of red blood cell velocity in vessels of the guinea pig cochlea

Fluorescence techniques combined with intravital microscopy provide a powerful approach to the study of cochlear blood microcirculation. In the current study, fluorescein isothiocyanate conjugated to high molecular weight dextrans was added to plasma to enhance the visual contrast of flowing blood in microscopic images from the guinea pig cochlea. Photometric signals, obtained from video pictures of the blood vessels, provided a means to continuously measure red cell velocity by using crosscorrelation algorithms to extract the time delay for moving features of the image. Alternatively, a small amount of fluorescently-labeled red blood cells (RBCs) were added to the vascular volume to serve as natural indicators of whole blood flow. The speed of these cells was measured by video photometric detection of the time required for the cells to pass between two predetermined positions in the television image. RBCs can be made fluorescent by chemical bonding of a fluorochrome to the cell membrane or by internal loading of the cell with an inert fluorochrome. Labeled RBCs provide a means to determine blood velocity in capillaries having extremely poor optical contrast, a situation which is generally the case for relatively thick tissues such as the lateral wall of the membranous labyrinth.

Sudden sensorineural hearing loss: operative complication in non-otologic surgery

Sudden sensorineural hearing loss is a well recognized phenomenon in otologic practice with both viral and vascular etiologies being supported. However, sudden hearing loss as a complication of non-otologic surgical procedure is a seldom reported and rare phenomenon. Five cases of unilateral sudden sensorineural hearing loss which are time related and probably causally related to non-otologic surgery are presented. Two cases underwent open heart surgery and support previous reports of hearing loss secondary to cardiopulmonary bypass procedures. Three noncardiac cases are also reviewed. None of these patients had prior otologic disease which would predispose to a sudden hearing loss, and no intraoperative or postoperative complication was specifically noted as a cause of the hearing loss. The literature is reviewed and attention is drawn to the problem. We wish to encourage further reports and to recommend early identification and treatment in those cases related to cardiopulmonary bypass.