聽力問題
聽覺是一個複雜的過程。聲音會從外耳經中耳傳遞至內耳，再通過神經將信息從內耳傳遞至大腦。接收到信息後，大腦會處理和詮釋信息，使人們能夠感知四周環境中的聲音。在這過程中，只要有任何一部分出現異常，都會導致不同程度的聽力障礙。於早產嬰兒中，聽力障礙通常是因內耳、神經和大腦受損而引起。[1]
懷孕週數較少和出生體重較輕的嬰兒，他們患上聽力障礙的風險較高。[2] 一項研究發現，在懷孕週數少於28週且出生體重低於1250克的嬰兒中，永久性聽力喪失的患病率為百分之3.1。[3] 除此之外，出生過程中缺氧、使用機械性輔助呼吸器、長時間吸用額外的氧氣、長期使用含耳毒性的藥物（會損害內耳/神經的藥物）和嚴重的黃疸等也是導致聽力喪失的原因。 [4],[5],[6]
出院前，醫護人員會為所有嬰兒進行聽力障礙篩查。未能通過聽力篩查的嬰兒需要進行更詳細的測試，以確認並將其損傷的程度分級。根據個別情況，嬰兒可能會被轉介至耳鼻喉專科作進一步的診斷。
有些早產嬰兒會出現遲發性的聽力障礙，並於出院後才出現徵狀。[[7]],[[8]] 隨著孩子成長，明顯的警示特徵包括：對響亮的聲音缺乏驚嚇的反應、對聲源不敏感、言語發展遲緩及學習困難等。如出現上述的情況，兒童就應接受聽力測試。此外，作為發展監測的一部分，衛生署轄下的母嬰健康院（MCHC）亦會對所有兒童進行聽力篩查。
-撰寫自劉凱盈醫生
威爾斯親王醫院兒科
駐院醫生
Hearing Problem
Hearing is a complex process that involves delivering a sound from the outer ear via the middle ear to the inner ear and transmitting signals from the inner ear to the brain through nerves. Afterwards, signals are processed and interpreted by the brain so that one could perceive the sounds in the surrounding environment. Problems can occur at any part of this process can lead to hearing impairment of different degrees. In preterm babies, this is usually caused by injury to the more central part of the pathway which includes the inner ear, nerves and the brain.[1]
The risk of hearing impairment is found to be higher in babies born at lower gestational age and of lower birth weight.[2] In one study, the prevalence of permanent hearing loss was found to be 3.1% in survivors who were born ≤ 28 weeks of gestation with a birth weight of <1250g.[3] Apart from that, factors like hypoxia during birth, mechanical ventilation, prolonged oxygen use, prolonged use of ototoxic drugs (drugs that damage the inner ear/nerves), and severe jaundice are also risk factors for hearing loss. [4],[5],[6]
All babies are screened for any hearing impairment before discharge. For those who fail hearing screening, a more detailed test would be performed to confirm and grade the level of impairment if any. Referrals to the Ear-Nose-Throat specialists may be required depending on individual condition.
Some of the preterm babies develop late-onset hearing impairment after discharge.[7],[8] Warning features includes lack of startle response to loud noises, not turning to sound source, speech delay, and learning difficulties as the child grows. A hearing test should be done if the above features are present. In addition, hearing screening is also performed at the Maternal and Child Health Centre (MCHC) of the Department of Health for all children as part of the Hong Kong government’s developmental surveillance.
Written by Dr. Sharon Lau
Resident, Department of Paediatrics
Prince of Wales Hospital
Reference:
[1] Xoinis K, Weirather Y, Mavoori H, Shaha SH, Iwamoto LM. Extremely low birth weight infants are at high risk for auditory neuropathy. J Perinatol. 2007;27:718–23.
[2] K. Wroblewska-Seniuk, et al. Hearing impairment in premature newborns-Analysis based on the national hearing screening database in Poland. PLOS One, 12 (2017), p. e0184359
[3] Robertson CM, Howarth TM, Bork DL, Dinu IA. Permanent bilateral sensory and neural hearing loss of children after neonatal intensive care because of extreme prematurity: a thirty-year study. Pediatrics 2009; 123(5): 797–807
[4] Hille E, Van Straaten HLM, Verkerk PH. Prevalence and independent risk factors fo[r hearing loss in NICU infants. Acta Pædiatrica 2007; 96(8): 1155–1158.
[5] Cristobal R and Oghalai JS. Hearing loss in children with very low birth weight: current review of epidemiology and pathophysiology. Arch Dis Child Fetal Neonatal Ed 2008; 93(6): F462–F468
[6] Marlow ES, Hunt LP, Marlow N. Sensorineural hearing loss and prematurity. Archives of Disease in Childhood - Fetal and Neonatal Edition 2000;82:F141-F144.
[7] M.E. Hutchin, C. Gilmer, W.G. Yarbrough, Delayed-onset sensorineural hearing loss in a 3-year-old survivor of persistent pulmonary hypertension of the newborn, Arch. Otolaryngol. Head Neck Surg. 126 (2000) 1014_/1017.
[8] C.M. Robertson, J.M. Tyebkhan, M.E. Hagler, P.Y. Cheung, A. Peliowski, P.C. Etches, Late-onset, progressive sensorineural hearing loss after severe neonatal respiratory failure, Otol. Neurotol. 23 (3) (2002) 353-356.