Pure tone audiometry and otoacoustic emissions in hypertensive subjects

Abstract

CONTACT Systemic hypertension causes changes in many target organs. The presence of stage-2 retinopathy detected by fundus examination is considered to be target organ damage. This damage occurs due to vascular physiodynamic changes (2). The cochlea is one of the target organs involved by HT due to its contents. Assessment of hearing as well as sounds induced by vibrations of the outer hair cells with OAE provides information about cochlear function. Conflicting results were reported by studies examining the effects of HT on the cochlea. Markov M et al delineated HT to be an important risk factor for the cochlea in the study of 50 patients with HT (8). Esparza et al. showed impairment in hearing thresholds in hypertensive patients with retinal vascular damage (4). However, Torre et al. reported no association between hypertension and sensorineural hearing loss in the DPOAE tests (5). Similarly, Parving et al. detected no relevant link between hypertension and hearing loss (9). In a study performed on 80 Wistar rats by Li S et al. it was shown that there were glycogenesis and an abnormal release of neurotransmitters caused by HT, resulting in aging of the cochlea (10). The result of the electrocochleographic tests was reported to be worse in rats with HT as compared with normotansive rats (11). In the literature, it was shown that glutathione, anti-oxidant enzyme, and Nacetyltransferase are found in the cochlea and these two enzymes are genetically scarce in presbyacusis (12). In this context, HT can lead to oxidative stress in the cochlea, thus, resulting in presbycusis. Our study has revealed that there was a significant increase of the subjective complaint of tinnitus in patients with HT compared to the control group. In pure tone audiological assessment, hearing thresholds were 33.08±13.09 and 40.85±19.83 dB at 4000 and 8000 Hz in the HT group, respectively, while 17.25±11.27 and 21.83±14.46 dB were measured in the control group, respectively. Audiometrically, a significant association appeared between presbycusis and HT in our study. The HT group had a statistically significant decrease in responses to DPOAE as compared with the control group at OAE tests performed especially at 6000 Hz frequencies. The results of our study, despite being different from those by Torre et al. were consistent with the ones by Esparza et al. In order to better understand the effect of HT on the cochlea, it is necessary to see the results of further studies on this issue in the literature. 5. Conclusion Systemic hypertension causes changes in a variety of target organs. Vascular physiodynamic changes have been implicated in HT induced target organ damage (2). The cochlea due to its contents vascular physiodynamic mechanisms is one of the target organs on which HT may have an effect. In studies performed so far, there have been conflicting results gained between HT and cochlear symptoms (4,5). Our results strongly suggest that HT can cause cochleopathologic changes, including dysfunction of outer hair cells, in cases with tinnitus, presbycusis and even in preclinical cases. The study was performed at the department of Ear, Nose and Throat Disorders of Umraniye Research and Training Hospital between January 2011 and December 2011. All patients gave their informed consent. The study included thirty patients with HT attending to our department for reasons other than hearing loss and ear diseases and thirty patients without HT whose ear and hearing were normal on examination. Subjects with acute or chronic middle or the external auditory canal disease, primary disorders of the inner ear or concomitant inner ear diseases (noise-induced hearing loss, inner ear damage due to ototoxicity, etc), diabetes mellitus or dyslipidemia, a neurological or renal problem, mental retardation, primary retinal damage or pregnancy were excluded. All patients underwent a thorough ENT and general systemic examination. Systemic blood pressures were measured; routine blood tests and audiological tests (pure tone audiometry and DPOAE) were performed. The HT group also underwent fundus examination; the Scheie classification of hypertensive retinopathy was also applied to the patients. 2.1. Audiology: (250-8000 Hz) pure tone audiometry was performed using a standard audiometer (Interacoustics AC40). DPOAE measurements were performed using the Otodynamics Echoport ILO292 USB-II. Stimuli were set at 75/75dB 2pts/oct. F2/f1 was set to be 1.22 and the frequency range was from 1 to 6 kHz. 2.2. Statistical investigations: Statistical analysis was performed with the use of NCSS (Number Cruncher Statistical System) 2007 & PASS (Power Analysis and Sample Size) 2008 Statistical Software (Utah, USA). Student's t-test was used in the descriptive statistics of the data (the mean and standard deviation) as well as in the comparisons. The Chi-square test and Yates Continuity Correction and Fisher’s Exact test were used for comparisons of quantitative data. P values of less than 0.05 and 0.01 were considered to indicate statistical significance. 1. Kim GH, Youn HJ, Kang S, Choi YS, Moon JI. Relation between grade II hypertensive retinopathy and coronary artery disease in treated essential hypertensives. 2010;32(7):469-73. 2. Guidelines Subcommitte of the WHO-International Society of Hypertension.Guidelines for the Management of Hypertension.J Hypertens 1999;17:151-83 3. Wong T.Y., Shankar A., Klein R. et al. Prospective cohort study of retinal vessel diameters and risk of hypertension. BMJ 2004; 329, 79–84 4. Esparza CM, Jauregui-Renaud K, Morelos CM, Muhl GE, Mendez MN, Carillo NS, Bello NS, Cardenas M. Systemic high blood pressure and inner ear dysfunction: a preliminary study. 2007; 32(3):173-8. 5. Torre P. Jr, Cruickshanks K.J., Klein R. et al. The association between cardiovascular disease and chochlear function in older adults. J. Speech. Lang. Hear. Res. 2005; 48, 473–481 6. Kemp Dt. Stimulated Acoustic Emissions from Within the Human Auditory System. Journal of Acoustic Society of America 1978; 64:1386-1391 7. Erdem T, Ozturan O, Miman Mc: Exploration of the Early Auditory Effects of Hyperlipoproteinemia and Diabetes Mellitus Using Otoacoustic Emissions. Eur Arch Otorhinolaryngol 2003; 260(2):62-6. Epub 2002 Sep 4 8. Markova M. The cochleovestibular syndrome in hypertension. Cesk. Otolaryngol. 1990; 39, 89–97 9. Parving A., Hein H.O., Suadicani P. et al. Epidemiology of hearing disorders. Some factors affecting hearing. The Copenhagen male study. Scand. Audiol. 1993; 22, 101–107 10. Li S., Gong S., Yang Y. et al. Effect of hypertension on hearing function, LDH and ChE of the cochlea in older rats. J. Huazhong. Univ. Sci. Technolog. Med. Sci. 2003; 23, 306–309 11. Tachibana M., Yamamichi I., Nakae S. et al. The site of involvement of hypertension within the cochlea. Acta. Otolaryngol. 1984; 97, 257–265 12. Bared A, Ouyang X, Angeli S, Du LL, Hoang K, Yan D, Liu xz.: Antioxidant enzymes, presbycusis, and ethnic variability. Department of Otolaryngology, University of Miami, FL 33136, USA. 2010;143(2):263-8. Mehmet Habesoglu M.D. Umraniye Education and Research Hospital, Department of Otorhinolaryngology mhabesoglu@yahoo.com Objective: To find out the effect of systemic hypertension on 1) pure tone audiometry (PTA) 2) distortion product otoacoustic emissions (DPOAE) in adults. Material and methods: A clinical controlled prospective study was conducted between January 2011 and December 2011 at Umraniye Education and Research Hospital Otolaryngology Clinic. Thirty subjects with systemic hypertension and 30 controls were included in the study. All subjects underwent a physical exam including fundus examination, PTA and DPOAE. Results: Percentage of tinnitus in subjects with hypertension and in controls was 90% and 40% respectively (p= 0.001). PTA revealed a significantly higher sensorineural hearing loss at all frequencies above 500 Hz in the hypertensive subjects (p<0.05). In the right ear, DPOAE revealed response at 4000 and 6000 Hz in 80 and 20 %of hypertensive patients as well as 96,7 and 96,7% of the controls (p=0.103) and (p=0.001), respectively. In the left ear, DPOAE revealed response at 4000 and 6000 Hz in 73.3 and 26.7% of hypertensive patients as well as 96,7 and 93.3% of the controls (p=0.026) (p=0.001) respectively. Conclusion: Isolated hypertension affects vascular physiodynamics of cochlea and results in a hearing loss at ≥ 4000 Hz at pure tone audiometry and significant loss of distortion product otoacoustic emissions at 4000 to 6000 Hz. 3. RESULTS