Characteristics of sensorineural hearing loss secondary to inner ear acoustic trauma

• Published in: Srpski arhiv za celokupno lekarstvo Vol. 136; no. 5-6; pp. 221 - 225
• Main Authors: Spremo, Slobodan, Stupar, Zdenko
• Format: Journal Article
• Language: English; Serbian
• Published: Serbia Serbian Medical Society 01.05.2008
• Subjects: Adult; Aged; Audiometry; Auditory Threshold; Bosnia and Herzegovina; Explosions; hearing loss; Hearing Loss, Noise-Induced - complications; Hearing Loss, Sensorineural - diagnosis; Hearing Loss, Sensorineural - etiology; Humans; inner ear; Middle Aged; noise-induced; Warfare; Bosnia and Herzegovina
• ISSN: 0370-8179; 2406-0895
• DOI: 10.2298/SARH0806221S

INTRODUCTION Cochlear damage secondary to exposure to acoustic trauma is the consequence of the acoustic energy effects on the hearing cells in Korti's organ. OBJECTIVE The objective was to assess the correlation between the degree of sensorineural hearing loss and the type of audiogram registered in acoustic trauma exposed patients. METHOD We analyzed 262 audiograms of patients exposed to acoustic trauma in correlation to 146 audiograms of patients with cochlear damage and hearing loss not related to acoustic trauma. "A" group consisted of acoustic trauma cases, while "B" group incorporated cases with hearing loss secondary to cochlear ischaemia or degeneration. All audiograms were subdivided with regard to the mean hearing loss into three groups: mild (21-40 dB HL), moderate (41-60 dB HL) and severe (over 60 dB HL) hearing loss. Based on audiogram configuration five types of audiogram were defined: type 1 flat; type 2 hearing threshold slope at 2 kHz, type 3 hearing threshold slope at 4 kHz; type 4 hearing threshold notch at 2 kHz; type 5 notch at 4 kHz. RESULTS Mild hearing loss was recorded in 163 (62.2%) ears in the acoustic trauma group, while in 78 (29.8%) ears we established moderate hearing loss with the maximum threshold shift at frequencies ranging from 4 kHz to 8 kHz. The least frequent was profound hearing loss, obtained in 21 (8%) audiograms in the acoustic trauma group. Characteristic audiogram configurations in the acoustic trauma patient group were: type 1 (N=66; 25.2%), type 2 (N=71; 27.1%), and type 3 (N=68; 25.9%). Audiogram configurations were significanly different in the acoustic trauma group in comparison to the cochlear ischaemia group of patients (p=0.0005). CONCLUSION Cochlear damage concomitant to acoustic trauma could be assessed by the audiogram configuration. Preserved hearing acuity at low and mild frequency range indicates the limited damage to the hearing cells in Korti's organ in the apical cochlear turn. Uvod Ostecenja u kohlei posle izlozenosti akusticnoj traumi velikog intenziteta mogu nastati usled udruzenog dejstva nekoliko faktora, medju kojima poseban znacaj ima dejstvo akusticne energije na slusne celije u Kortijevom organu. Cilj rada Cilj rada je bio da se ispita korelacija izmedju stepena senzorineuralne nagluvosti i obelezja tonalnog audiograma kod ispitanika izlozenih akusticnoj traumi. Metod rada Analizirana su 262 audiograma ispitanika izlozenih akusticnoj traumi, koja su uporedjena s nalazima 146 audiograma ispitanika koji su imali kohlearno ostecenje izazvano ishemijskim, degenerativnim ili toksicnim etioloskim faktorima. Ispitanici su, prema stepenu nagluvosti, svrstani u tri grupe: prvu grupu su cinili ispitanici sa blagom senzornom nagluvoscu (21-40 dB HL), drugu ispitanici sa srednjom senzornom nagluvoscu (41-60 dB HL), a trecu ispitanici sa teskom senzornom nagluvoscu (>60 dB HL). Prema obliku i obelezjima krivulje praga sluha, definisano je pet tipova audiograma: tip 1 odnosio se na ravan audiogram, tip 2 na ostrosilazan audiogram sa padom praga sluha za 2-4 kHz, tip 3 na ostrosilazan audiogram sa padom praga sluha vecim od 4 kHz, tip 4 na audiogram sa zupcem na 2 kHz, a tip 5 na audiogram sa zupcem na 4 kHZ. Rezultati Blaga senzorna nagluvost utvrdjena je kod 163 uva ispitanika izlozenih akusticnoj traumi (62,2%), srednje teska nagluvost kod 78 ispitanih usiju (29,8%) uz najveci gubitak sluha na 4 kHz i 8 kHz, a teska nagluvost kod 21 ispitanog uveta (8%), sto se moze pripisati i udruzenom delovanju drugih etioloskih faktora koji su izazvali kohlearnu leziju. Tipicni oblici audiograma bili su: tip 1 (66 ispitanika; 25,2%), tip 2 (71 ispitanik; 27,1%) i tip 3 (68 ispitanika; 25,9%). Konfiguracija audiograma ispitanika izlozenih akusticnoj traumi statisticki se znacajno razlikovala od tipa audiograma ispitanika s kohlearnim ostecenjem ishemijskog ili degenerativnog porekla (p=0,0005). Zakljucak Na osnovu tipa audiograma i ukupnog senzornog gubitka sluha posle izlozenosti akusticnoj traumi moguce je proceniti stepen ostecenja kohlee. Smanjenje funkcije sluha u rasponu 2-4 kHz tipicno je za ostecenje kohlee akusticnom energijom.