신생아난청과신생아청각선별검사 박수경 http://dx.doi.org/10.7599/hmr.2015.35.2.72 pissn 1738-429X eissn 2234-4446 한림대학교강남성심병원이비인후과 Newborn Hearing Loss and Newborn Hearing Screening Su-Kyoung Park Department of Otorhinolaryngology-Head and Neck Surgery, Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea The incidence of bilateral profound hearing loss of newborns is 1 to 2 per 1,000 newborns. It is higher in infants with risk factors for hearing loss. Congenital hearing loss can cause many problems in language, learning, speech development and educational and occupational performance. Most developed countries have conducted the Universal Newborn Hearing Screening (UNHS) with automated otoacoustic emissions (AOAE) or automated auditory brainstem response (AABR). UNHS reduced the average age of identification of permanent hearing loss in infants 6 months or less after birth. This early identification and intervention of hearing loss with amplification and speech therapy optimizes communication during the early critical period of language acquisition and can improve language outcomes in children between 2 and 5 years of age. The aims of this paper are to explain the incidence of newborn hearing loss, the importance of early detection of hearing loss and intervention and newborn hearing screening methods. Key Words: Hearing Loss; Infant, Newborn; Neonatal Screening; Transient Evoked otoacoustic Emissions; Evoked Potentials, Auditory, Brain Stem Correspondence to: Su-Kyoung Park 우 150-950, 서울시영등포구신길로 1, 한림대학교강남성심병원이비인후과 Department of Otorhinolaryngology-Head and Neck Surgery, Kangnam Sacred Heart Hospital, Hallym University College of Medicine, 1 Singil-ro, Yeongdeungpo-gu, Seoul 150-950, Korea Tel: +82-2-829-5217 Fax: +82-2-842-5217 E-mail: ashock@daum.net Received 9 March 2015 Revised 20 March 2015 Accepted 27 March 2015 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 서론양측중등도이상의선천성난청은신생아 1,000명당 3-5명, 고도난청은신생아 1,000명당 1-2명에서발생하며이는국내모든신생아들이국가지원하에실시하는선천성대사이상질환보다높은발생률을가지고있다 [1-4]. 유소아의정상적인언어적인발달을위해서는소리자극이중요한데, 난청으로인해뇌에소리자극이전달되지않으면정상적인언어습득이이루어지지않아언어장애를초래할뿐만아니라행동장애와학습장애로정상적인사회생활과직장생활이어렵다 [4,5]. 선진국에서는난청을가진유소아들이정상적인언어발달을할수있도록모든신생아를대상으로신생아청각선별검사를시행하고있으며, 2008년미국예방보건당국 (US Preventive Services Task Force) 에서는신생아청각선별검사를모든신생아를대상으로반드시시행해야할선별검사인 Grade B 로 권고하고있다 [6,7]. 미국영유아청각협회 (Joint Committee on Infant Hearing, JCIH) 에서는생후 1개월이내신생아청각선별검사를시행하고, 선별검사에서어느한쪽귀라도재검 (refer) 판정을받은경우생후 3개월이내난청확진을위한정밀청력검사를시행하고, 최종난청을진단받은경우생후 6개월이내보청기등의청각재활치료를시행하도록하는 1-3-6 원칙 을제시하고있다 [3]. 국내의신생아청각선별검사는 2000년대초에분만산부인과를중심으로도입되었으며 2003년도부터는대한청각학회주도로정착을위해다양한활동이시행되었다. 보건복지부에서는 2007년과 2008 년에지역별신생아난청조기진단시범사업을시행하고현재까지저소득층을중심으로신생아청각선별검사와난청확진검사를지원하고있으나아직전신생아를대상으로하지않으며또한추적관리시스템은없는실정이다. 72 2015 Hanyang University College of Medicine Institute of Medical Science http://www.e-hmr.org
박수경 신생아난청과신생아청각선별검사 신생아난청의조기진단이언어발달에미치는영향유소아가성장하면서언어를효과적으로배울수있는민감한시기가있다. 이시기에소리자극이뇌에전달되면뇌의형태학적, 기능적발달을일으켜서언어청각이정상적으로발달하게되는데이를뇌의가소성 (plasticity) 이라고한다. 이시기가지나면뇌의가소성이감소하여언어와청각재활치료를하여도언어발달의한계를초래한다 [8]. 난청의발견시기와언어발달과의관계를연구한논문들을분석한 2012년문헌에서는정상적인언어발달을위해서는생후 6개월에서 9개월이전에난청을발견하여청각재활치료를시작하는것이좋으며난청의조기진단후조기재활의효과를볼수있는최대연령이생후 1세이전이었다 [9]. 난청의조기진단과조기재활의중요성에대해임상자료를제시한중요한전향적연구가미국콜로라도대학의 Yoshinaga-Itano 의연구진에의해보고되었다. 난청발견후 2개월이내청각재활치료를시작한청각장애 150명을대상으로청각장애의발견시점을생후 6개월을기준으로언어발달을비교한연구에서, 생후 6개월이전에난청이발견된유소아들의언어발달지수는그이후에발견된소아들에비해의미있게우수하였다. 이는효과적인청각발달과재활을위해서는초기영아기에난청이진단되고늦어도생후 6개월이전에청각장애치료가시작되어야한다는중요한전향적인연구이다 [4]. 모든신생아들이청각선별검사를받아야하는근거신생아청각선별검사는초기에는난청위험요소를가진난청고위험군에서만시행되었으나, 난청을진단받은영유아중난청위험요소를가진경우는약 50% 정도에불과하며, 나머지 50% 는위험요소가없는영유아에게서발생하였다는사실이밝혀지면서현재대부분의선진국에서는모든신생아를대상으로신생아청각선별검사를실시하게되었다 [3,6]. 신생아청각선별검사 1. 신생아청각선별검사의종류와특징신생아청각선별검사는자동이음향방사검사 (automated otoacoustic emissions, AOAE) 와자동청성뇌간유발반응검사 (automated auditory brainstem response, AABR) 가있으며, 두가지검사를모두한기기에서시행할수있는기기들도상품화되어있다. 자동청각선별검사는기기자체의알고리즘에의하여통과 (pass) 또는재검을판별하도록되어있기때문에청각사가아닌일반인들도간단한훈련에의해판독에큰어려움이없고검사방법이간단하여쉽게시행할수있다. 청각선별검사는선진국에서는 1990년도부터도입되어신생아난청의조기진단을위해이용하고있으며, 국 내에는 2000년대부터도입되었다 [10-12]. 자동이음향방사검사의민감도는 50-100%, 특이도는 13-91% 까지보고되고있으며, 자동청성뇌간반응검사의민감도는 96%, 특이도는 98% 로자동청성뇌간반응검사의민감도와특이도가더높다 [13]. 자동청성뇌간반응검사는임신 34주에서생후 6개월정상청력뇌파가기기에원형 (template) 으로저장되어있어연령제한이있는반면, 자동이음향방사검사는연령의제한이없다. 검사비는일반적으로인정비급여로국내에서시행되고있으며자동청성뇌간반응검사가자동이음향방사검사에비해 2배이상검사비가높다. 신생아가자연수면을하는동안검사가시행되며자동청성뇌간반응검사는이어폰모양의 ear tip과양측유양동과이마에붙이는전극을추가로장치하고양측양측검사에약 20분이소요되며, 자동이음향방사검사의경우 ear tip만필요하고약 10분정도검사시간이소요된다. 1회선별검사시재검률 (referral rate) 은자동청성뇌간반응검사가 4% 내외, 자동이음향방사검사가 7-8% 정도이다. 자동청성뇌간반응검사의경우달팽이관의이상또는청각신경의병변에이상이있는경우재검으로판정하며, 중이의영향을적게받으나주변소음과전극의상태에영향을받는단점이있다. 자동이음향방사검사의경우전극등의소모품이없고, 검사비가저렴하고검사시간도짧게걸리는장점이있으나달팽이관까지의이상만측정이가능하고청각신경의이상을판정할수없어중환자실신생아의뇌손상으로인한청각신경병증 (auditory neuropathy) 등의청각신경이상을발견할수없는단점이있다. 이로인해신생아중환자실의신생아들은자동청성뇌간반응검사를이용하여청각선별검사를시행하여야한다 [2,3]. 두신생아청각선별검사에대한장단점을표로정리하였다 (Table 1). 2. 신생아청각선별검사의시기와결과청각선별검사는생후 1개월전 ( 미숙아또는중환자실신생아의경우본래예정일을기준으로하여태생 34주에서생후 1개월전 ) 에시행한다. 조용한환경에서시행하는것이좋으며자동청성뇌간반응의경우자연수면중에검사를시행하도록하고, 자동이음향방사검사의경우아기가깨어있어도울지않으면검사가가능하다. 출생직후에는외이도에태지나중이내삼출액이있어선별검사에서위양성을보일수있으므로이를방지하기위해적어도생후 12 시간은지난후에검사를시행하는것이바람직하다 [3,13,14]. 신생아청각선별검사의결과 1. 통과 (pass) 아기의양측귀에서모두통과결과가나온경우검사당시신생아가정상청력을가지고있음을의미한다. http://www.e-hmr.org 73
Su-Kyoung Park Newborn Hearing Loss and Newborn Hearing Screening Table 1. Characteristics of newborn hearing screening system Automated auditory brainstem response Automated otoacoustic emissions Screening result Pass or refer Pass or refer Sensitivity 96% 50-100% Specificity 98% 13-91% Age for test 34 weeks gestation-6 months after birth All age Cost High Low Time for test About 20 minutes About 10 minutes Referral rate 7-8% 4% Lesion side Retrocochlear lesion Cochlear lesion Result of auditory neuropathy Proper subject for test Refer Well baby or Intensive care unit baby Pass (False negative result) Well baby 2. 재검 (refer) 어느한귀라도재검결과가나온경우다시한번청각선별검사를받거나정밀청력검사를받아야한다. 즉, 검사시점에서결과가불분명하기때문에재선별검사나정밀청력검사를시행한다고보호자에게설명하며, 첫번째청각선별검사에서재검결과가나왔다고하여난청이있음을의미하지않기때문에아이가난청이라고보호자에게설명하지않도록주의한다. 3. 청각선별검사의한계간혹난청이있어도청각선별검사에서통과로나타날수있다. 저주파수나고주파수에국한하여난청이있는경우, 중간주파수난청 (0.5-2 khz) 이있는아기에게자동청성뇌간반응으로검사한경우, 전정도수관확장증이나중이염의경우처럼변동형의난청을보이는경우, 청각신경병증이나거대세포바이러스간염등의진행성난청인경우, 선별검사를반복하여여러번시행한경우에위음성이나타날수있으므로주의해야한다. 실제청력은정상이나재검결과가나올수있는경우로는소음이있는곳에서자동이음향방사로검사하는경우, 출생직후외이도에태지나삼출물이있는상태에서검사를시행한경우이다 [3]. 신생아청각선별검사프로토콜 Fig. 1. Well baby newborn hearing screening protocol of newborn nursery unit. 1. 건강신생아프로토콜 정상분만으로출생한건강한신생아나신생아중환자실에서 4 일미만입원하고신생아실에옮겨져퇴원예정인신생아에게실시 하는프로토콜이다. 자동청성뇌간반응또는자동이음향방사검사 를 1 단계검사로시행한다. 두번의청각선별검사를시행하는 2 단 계프로토콜을이용할수도있으며, 이때에는 1 단계검사로자동이 음향방사를초기선별검사로시행하고재검판정을받은경우 2 단 계로자동청성뇌간반응검사를시행한다. 청각신경병증등의이상 을놓칠수있기때문에청성뇌간반응검사후청성이음향검사를 시행하지않는다 (Fig. 1)[10]. 또한같은검사방법으로 3 번이상검 사를반복하지않는다. 이는검사를반복함에따라우연히통과가 나와위음성을초래하는것을막기위함이다. 일반적으로 2 단계프 로토콜로청각선별검사를시행할경우재검률을 1-2% 정도줄일 수있다 [15-18]. 양측모두통과로판정된경우라도난청고위험군 에해당할경우초등학교에입학하기전까지 6 개월 -1 년마다정밀청 력검사를실시한다 [10]. 국내신생아청각선별검사임상진료지침은 2010년대한이과학회와대한청각학회주관하에제작되었으며청각선별검사프로토콜은신생아가출생후입원기간동안실시되는건강신생아프로토콜과신생아중환자실프로토콜, 퇴원후외래에서실시하는프로토콜이있다 [10]. 2. 신생아중환자실프로토콜중환자실신생아의연령은항상교정연령을기준으로하며가능한교정연령 1개월이내에검사를시행한다. 또한중환자실치료가모두끝나고전신상태가양호할때시행하며퇴원하루또는이틀전에시행하는것이바람직하다. 교정연령이재태 34주이내인경우는기다렸다가선별검사를재태 34주이후가될때청각선별검 74 http://www.e-hmr.org
박수경 신생아난청과신생아청각선별검사 Fig. 3. Newborn hearing screening protocol in the outpatient clinics. Fig. 2. Neonatal intensive care unit (NICU) newborn hearing screening protocol. 사를시행한다. 대상으로는신생아집중치료실또는신생아중환자 실에서 5 일이상입원하여치료를받은신생아, 중환자실신생아중 명백한일측성혹은양측성외이기형이있는신생아또는뇌막염 으로확진되었거나뇌막염의증을앓고난후회복된신생아, 이전 청각선별검사에서 통과 로판정받은건강신생아가뇌막염을앓게 되어신생아중환자실에재입원하게된경우, 선별검사에서 통과 로판정받아퇴원하고출생 4 주이내에교환수혈이필요할정도의 고빌리루빈혈증이나세균이배양된패혈증등난청의위험이있는 질병을앓게되어병원에재입원하게된경우이다. 신생아중환자실 신생아는자동청성뇌간반응검사를우선적으로실시한다. 간혹자 동청성뇌간반응과자동이음향방사검사를동시에시행할수있으 나검사결과는청성뇌간반응검사에기준하여판정하고자동이음 향방사검사는참고로한다 (Fig. 2)[10]. 중환자실에 5 일이상입원한 신생아는청각선별검사에서양쪽귀에서두가지검사모두이상이 없어도학령전까지매 6 개월또는 1 년마다정기적인청각검진을 위해이비인후과로의뢰하는것이권장된다. 이는선별검사로진단 하지못하는경도의난청이나특정주파수대역의난청, 지연성난 청 (delayed hearing loss), 진행성난청 (progressive hearing loss) 또 는후천성난청등을염두에두고학령전까지매 6 개월또는 1 년마 다언어발달사항, 고막진찰, 정밀청력검사 ( 만 3 세이전에는청성뇌 간반응검사를, 만 3 세이후에는순음청력검사를우선으로실시 ) 등을시행하기위함이다 [13]. 두가지검사중어느한쪽귀에서한 가지검사라도 재검 이나온경우에는바로이비인후과로의뢰하 여정밀청력검사를받도록한다. 3. 외래에서의신생아청각선별검사프로토콜 신생아가입원중청각선별검사를시행하지못하였거나, 1 차청 각선별검사후하나의측또는양측에서 재검 으로판정받거나, 이전에청각선별검사에서 통과 판정하였으나난청위험요소에새로이해당하게되어이비인후과외래로방문한경우에해당하는프로토콜이다. 내원한신생아가정상분만신생아또는신생아중환자실에 4일이하로입원한신생아이면서선별검사를시행하지못한경우는 건강신생아프로토콜 을, 신생아중환자실에 5일이상입원한신생아인경우 신생아중환자실프로토콜 에준하여실시한다 (Fig. 3)[10]. 이전에 1단계로청각선별검사를시행한경우자동청성뇌간반응으로다시청각선별검사를시행하거나, 청성뇌간반응역치검사를비롯한정밀청력검사를고려한다 [19]. 4. 난청고위험군미국에서는신생아난청의조기발견을위하여 1969년영유아청각협회 (JCIH) 를설립하고 1973 년조기청각검사가필요한난청고위험군을정의하였고, 또한영유아청각협회지침을 1982, 1990, 1994, 2000, 2007에걸쳐고위험군의내용을보강하였다. 2007년지침에서제시한고위험군은유전성소아난청의가족력, 5일이상신생아집중치료를받거나, 5일이내라도체외막형산소섭취나인공호흡기를사용한경우, 이뇨제또는이독성약제사용등이있다 (Table 2) [3]. 난청위험요소를가진유소아에서지연성난청의발생률은위험요소가없는유소아에비해 10배이상 ( 중환자실입원아 100명당 1-2명정도 ) 임이보고되고있으며이러한지연성또는진행성난청의발생은위험요소의폭로시기와무관하게발생한다 [6]. 고위험군의지연성난청을발견하기위해미국에서는생후 3년까지적어도 1회의청성뇌간반응을실시하나, 해당환아의개별적인언어발달과고위험요소의임상양상을고려하여전문의의판단에의해추가적인정밀청력검사를시행할수있도록하였다 [3]. 영국에서는국가적으로신생아청각선별검사를관리하고있으며, 병원기반의형식과지역사회방문간호형식을통해관리하고있다. 영국의고위 http://www.e-hmr.org 75
Su-Kyoung Park Newborn Hearing Loss and Newborn Hearing Screening Table 2. Risk factors associated with permanent hearing loss in childhood Family history of permanent childhood hearing loss Neonatal intensive care of more than 5 days Syndrome known to include a sensorineural or conductive hearing loss or Eustachian tube dysfunction Exposure to ototoxic medications such as gentamycin and tobramycin or loop diuretics (furosemide) Craniofacial anomalies, including those that involve pinna, ear canal, ear tags, ear pits, and temporal bone anomalies Culture-positive postnatal infections associated with sensorineural hearing loss including bacterial or viral meningitis (especially herpes viruses and varicella) In utero infections such as cytomegalovirus, herpes, rubella, syphilis, and toxoplasmosis Heperbilirubinemia at a serum level requiring exchange transfusion Persistent pulmonary hypertension of newborn associated with mechanical ventilation, and Conditions requiring the use of extracorporal membrane oxygenation Syndromes associated with progressive or late-onset hearing loss such as neurofibromatosis, osteopetrosis, and Usher syndrome Neurodegenerative disorders, such as Hunter syndrome, or sensory motor neuropathies, such as Friedreich s ataxia and Charcot-Marie-Tooth disease Head trauma, especially basal skull or temporal bone fracture that requires hospitalization Chemotherapy Recurrent or persistent otitis media with effusion for at least 3 months 험군의대상은미국의고위험군과거의동일하며고위험군의경우 생후 7-12 개월에행동반응청력검사를시행하도록하고있으며, 영 유아시기의건강검진을통해지속적인관리가이루어지고있다 [20]. 중환자실에입원중실시한신생아청각선별검사에서 통과 판정을받은고위험군신생아 111 명중 14 명 (12.5%) 에서지연성난 청이발생되어위험요소에노출된시기와난청발생시기는통계적 으로연관성이없었다. 따라서저자들은고위험군신생아들이생 후 12 개월, 18 개월, 30 개월, 42 개월에정기적인청력검사를실시하 도록권고하고있다 [21]. 결론 신생아난청은국내전신생아를대상으로하는대사이상질환 보다더흔한발생률을가지고있음에도불구하고아직모든신생 아들이청각선별검사를받지못하고있는실정이다. 또한민감도와 특이도가높은선별검사방법을가지고있어, 이미대부분의선진 국에서는모든신생아들이청각선별검사를받고있다. 신생아청각 선별검사와프로토콜을올바르게이해하여보다많은신생아들이 검사를받도록함으로써, 난청을조기에발견하여청각장애를극 복하고정상적인언어발달을도모할수있도록해야할것이다. REFERENCES 1. Thompson DC, McPhillips H, Davis RL, Lieu TL, Homer CJ, Helfand M. Universal newborn hearing screening: summary of evidence. JAMA 2001; 286:2000-10. 2. Norton SJ, Gorga MP, Widen JE, Folsom RC, Sininger Y, Cone-Wesson B, et al. Identification of neonatal hearing impairment: evaluation of transient evoked otoacoustic emission, distortion product otoacoustic emission, and auditory brain stem response test performance. Ear Hear 2000; 21:508-28. 3. American Academy of Pediatrics, Joint Committee on Infant Hearing. Year 2007 position statement: principles and guidelines for early hearing detection and intervention programs. Pediatrics 2007;120:898-921. 4. Yoshinaga-Itano C, Sedey AL, Coulter DK, Mehl AL. Language of earlyand later-identified children with hearing loss. Pediatrics 1998;102:1161-71. 5. Yoshinaga-Itano C, Gravel JS. The evidence for universal newborn hearing screening. Am J Audiol 2001;10:62-4. 6. Universal screening for hearing loss in newborns: US Preventive Services Task Force recommendation statement. Pediatrics 2008;122:143-8. 7. Nelson HD, Bougatsos C, Nygren P. Universal newborn hearing screening: systematic review to update the 2001 US Preventive Services Task Force Recommendation. Pediatrics 2008;122:e266-76. 8. Yoshinaga-Itano C. Levels of evidence: universal newborn hearing screening (UNHS) and early hearing detection and intervention systems (EHDI). J Commun Disord 2004;37:451-65. 9. Pimperton H, Kennedy CR. The impact of early identification of permanent childhood hearing impairment on speech and language outcomes. Arch Dis Child 2012;97:648-53. 10. The Korean Audiological Society and the Korean Otologic Society. Korean Clinical Practice Guildline: newborn Hearing Screening 2010. Seoul: ML Communications; 2011:1-80. 11. Watkin PM. Outcomes of neonatal screening for hearing loss by otoacoustic emission. Arch Dis Child Fetal Neonatal Ed 1996;75:F158-68. 12. Mason JA, Herrmann KR. Universal infant hearing screening by automated auditory brainstem response measurement. Pediatrics 1998;101:221-8. 13. Oh SH. Newborn hearing screening. In The Korean Audiological Society, ed. Practical manual of hearing tests. 1st ed; 2008:247-68. 14. Finitzo T, Albright K, O Neal J. The newborn with hearing loss: detection in the nursery. Pediatrics 1998;102:1452-60. 15. Johnson JL, White KR, Widen JE, Gravel JS, James M, Kennalley T, et al. A multicenter evaluation of how many infants with permanent hearing loss pass a two-stage otoacoustic emissions/automated auditory brainstem response newborn hearing screening protocol. Pediatrics 2005;116:663-72. 16. Norton SJ, Gorga MP, Widen JE, Folsom RC, Sininger Y, Cone-Wesson B, et al. Identification of neonatal hearing impairment: a multicenter investigation. Ear Hear 2000;21:348-56. 17. White KR, Vohr BR, Meyer S, Widen JE, Johnson JL, Gravel JS, et al. A multisite study to examine the efficacy of the otoacoustic emission/auto- 76 http://www.e-hmr.org
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