Research in Vestibular Science Vol. 14, No. 4, December 2015 Original Article pissn 2092-8882, eissn 2093-5501 지속되는향지성수평반고리관양성돌발성두위현훈의임상적특성 서남대학교의과대학명지병원이비인후과 고경민, 송미현, 박진우, 이준희, 신용국, 심대보 Clinical Characteristics of Horizontal Canal Benign Paroxysmal Positional Vertigo with Persistent Geotropic Direction Changing Positional Nystagmus Kyung Min Ko, Mee Hyun Song, Jin Woo Park, Joon Hee Lee, Yong Gook Shin, Dae Bo Shim Department of Otorhinolaryngology, Myongji Hospital, Seonam University College of Medicine, Goyang, Korea Received Oct 9, 2015 Revised Oct 20, 2015 Accepted Nov 12, 2015 Corresponding Author: Dae Bo Shim Department of Otorhinolaryngology, Myongji Hospital, Seonam University College of Medicine, 55 Hwasu-ro 14beon-gil, Deokyang-gu, Goyang 10475, Korea Tel: +82-31-810-5451 Fax: +82-31-969-0500 E-mail: lovend77@gmail.com Copyright c 2015 by The Korean Balance Society. All rights reserved. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Objective: The purpose of this study was to identify the clinical characteristics of horizontal vertigo (h-bppv) with persistent geotropic direction changing positional nystagmus (DCPN). Methods: One hundred thirty two patients diagnosed as the geotropic subtype of h-bppv were analyzed retrospectively. Patients were classified into two groups: persistent h-bppv (ph-bppv) group which means h-bppv showing persistent (>1 minute) geotropic DCPN and short duration h-bppv (sh-bppv) group that means h-bppv with short duration ( 1 minute) geotropic DCPN. We compared the clinical characteristics and treatment outcomes between the two groups. Results: The study included 34 patients with ph-bppv and 98 patients with sh-bppv. There were no differences between the two groups in age, distribution of sex and the affected side. The ph-bppv group had higher secondary BPPV preponderance and dizziness handicap index (DHI) score compared to the sh-bppv group. The ph-bppv group required higher number of canalith repositioning procedures (CRPs) until resolution and higher multiple/single CRP ratio than the sh-bppv group. In addition, the ph-bppv group showed longer duration until the remission of subjective symptoms (vertigo, dizziness) compared to the sh-bppv group. Conclusion: ph-bppv was more frequently associated with secondary causes of BPPV and demonstrated higher DHI score, total number of CRP, and longer remission duration of subjective symptoms compared to sh-bppv. This information may be helpful for clinicians in counseling and managing the patients with persistent geotropic DCPN h-bppv. Res Vestib Sci 2015;14(4):117-122 Keywords: Benign paroxysmal positional vertigo; Direction-changing positional nystagmus; Geotropic nystagmus 117
Res Vestib Sci Vol. 14, No. 4, Dec. 2015 서론양성돌발성두위현훈 (benign paroxysmal positional vertigo, BPPV) 은회전성어지럼을일으키는말초성내이질환중가장높은빈도를보이는단일질환으로, BPPV는일반적으로단일반고리관을침범하며, 후반고리관, 수평반고리관, 상반고리관 BPPV로분류한다. 각반고리관에이환되는빈도는후반고리관 BPPV가 80% 90%, 수평반고리관 BPPV가 15% 20%, 상반고리관 BPPV가 1% 2% 라고알려져있다. 1 수평반고리관의 BPPV (horizontal canal BPPV, h-bppv) 는크게향지성안진을보이는경우 (geotropic subtype, h-bppv [Geo]) 와원지성안진을보이는경우 (apogeotropic subtype, h-bppv [Apo]) 로나눌수있으며, 가장흔한 h-bppv (Geo) 는수평반고리관후방부분의이석으로인하여발생하고 h-bppv (Apo) 는수평반고리관전방부분의이석이후방으로이동하면서발생하거나팽대부릉정에이석이붙어발생하게된다. 2,3 h-bppv (Geo) 는특징적으로크게피로현상이없으며안진의지속시간이짧은향지성방향전환성두위안진 (direction changing positional nystagmus, DCPN) 을동반한다. 4 그러나최근많은연구들에따르면지속적인향지성 DCPN을보이는 h-bppv (Geo) 환자들을보고하고있는데, 5-7 이러한경우를 Light cupula라고명명하고있으나, 아직까지정확한기전이나치료에대하여는더많은연구가필요한실정이다. 이에저자들은기존에보고된 h-bppv (Geo) 의전형적인형태인안진의지속시간이짧은형태의 h-bppv와의비교를통해지속적인향지성 DCPN을보이는 h-bppv의임상적인특징을알아보고자하였다. 대상및방법 2011년 1월부터 2015년 6월까지본원이비인후과로내원한 h-bppv (Geo) 환자들을대상으로후향적으로환자의과거력및의무기록을검토하였다. 모든환자에서이신경학적검사 ( 자발안진, 주시유발안진, 두부충동검사, 안구단속운동및원활추종운동등 ) 와기존신경학적검사를통해중추신경계의질환여부를확인하였으며, 모든환자들은첫방문시어지럼설문지 (dizziness handicap inventory, DHI) 를통해환자증상정도를파악했으며그밖의환자의어지럼발생시작일, 기저질환등자세한문진을하였다. 또한, 환자의문진상에서두부외상, BPPV가발생한동측의만성중이염, 동측의전정신경염, 동측의돌발성난청, 동측의메니에르병, 골다공증이있는경우이차성 BPPV로간주하였다. 8 h-bppv (Geo) 의진단은회전성현훈을주소로내원한환자들을대상으로 2008년미국이비인후과학회에서제시한진료지침에따라한명의이비인후과전문의가체위변환검사를포함한비디오안진검사를시행하였으며, 안진의확인은 video Frenzel goggle system (SLMED, Seoul, Korea) 를사용하였다. 수평면에서 Supine roll test시전형적인향지성방향의 DCPN을확인함으로써진단하였다. 병변의방향은 Supine roll test 시강한안진을나타내는방향을병변측으로진단하였고, 양측의안진세기가같은경우에는 Bow and lean test를통해병변의방향을결정하였다. 9 치료는 modified Lempert maneuver를시행하였으며, 10 1회방문시 1회의치료만을시행한환자를대상으로하였고, 재방문시안진이남아있는경우추가치료를시행하였다. 치료의성공은재방문시시행한체위성검사에서특징적인안진이관찰되지않으며체위성현훈이사라진경우로정의하였다. 모든환자에서치료후어지럼증상이호전된시점을현훈과비특이적인어지럼으로구분하여환자면담및전화설문을통해조사하였다. 총 168명의 h-bppv (Geo) 환자들중상기방법외의치료없이경과관찰한경우나다른치료를시행한경우, 외래추적관찰이이루어지지않은경우를연구대상에서제외한후, h-bppv (Geo) 환자들을다음의두군으로분류하였다. Group 1 (persistent h-bppv [Geo], ph-bppv): 안진의지속시간이 1분이상인경우, 11 Group 2 (short duration h-bppv [Geo], sh-bppv): 안진의지속시간이 1분미만인경우로분류하였다. 12 이석의이동 (canal conversion or transition) 은치료의성공을확인하기전, 다른 BPPV의아형으로바뀌는경우로정의하였다. 두그룹의임상양상을나이, 성별, 병변의방향, 기저질환, DHI, 안진의잠복기로나누어분석하였고, 어지럼발병부터 h-bppv (Geo) 진단까지의기간을알아보았다. 또한두군간총치료수기횟수및 1회치료와 1회이상치료의비율을분석하였고, 13 치료를통한어지럼증상의호전기간과치료중이석의이동을분석하였다. 두그룹의통계학적분석은 PASW ver. 18.0 (SPSS Inc., Chicago, IL, USA) 을사용하여 Independent t-test와 Pearson 118
고경민외 5 인. 비전형적수평반고리관 BPPV χ 2 test, Fisher s exact test를시행하였으며, p값이 0.05 미만일때통계적으로유의하다고판정하였다. 결과전체 h-bppv (Geo) 환자들 168명중긴안진지속시간을보인 h-bppv (Geo) 환자는 43명 (25.5%) 이었다. 본연구의대상이된 h-bppv (Geo) 환자 168명중 modified Lempert maneuver외다른치료를시행한경우와추적관찰에실패한총 36명이제외되었으며, ph-bppv 환자군이 34명, sh-bppv 환자군이 98명이었다 (Figure 1). ph-bppv 환자군 34명중남자가 6명, 여자가 28명이었고, 평균연령은 57.1± 13.1세 ( 범위, 20 89세 ) 였다. 병변부위는우측 14명, 좌측 20 명이었고, 추적관찰기간은평균 1.4±0.7일이었다. 어지럼발생후진단하기까지의기간은평균 1.8±2.3일이었고, DHI 점수는평균 23.5±19.1점, 안진의잠복기는평균 1.03± 0.76초이었다. 기저질환은원인불명이 24명, 상에서두부외상, 만성중이염, 전정신경염, 돌발성난청, 메니에르병등이차적원인을가지고있는경우가 10명으로 21.4% 를차지하였다. sh-bppv환자군 98명중남자가 20명, 여자가 78명이었고, 평균연령은 54.8±14.6세였다. 병변부위는우측 39명, 좌측 59명이었고, 추적관찰기간은평균 1.2±0.6일이었다. 어지럼발생후진단하기까지의기간은평균 2.6±4.7 일이었고, DHI는평균 16.5±10.6점, 안진의잠복기는평균 1.38±1.05초이었다. 기저질환은원인불명이 91명, 이차적원인을가지고있는경우가 7명으로 4.3% 를차지하였다. 두군의임상적특성을비교해보았을때, 나이, 연령및 병변의방향, 추적관찰기간은유의한차이를보이지않았다. 어지럼발생후진단까지의기간은통계학적유의한차이는보이지않았으나평균적으로 ph-bppv에서 sh-bppv 에비해짧은경향을보였으며, DHI점수에서는 ph-bppv에서 sh-bppv에비해통계학적으로높은점수를보였다 (p=0.050). 안진이발생하기까지의잠복기는두군에서유의한차이를보이지않았고원인불명과이차적인원인의비율의차이는 ph-bppv군에서이차적원인비율이 sh-bppv 군보다통계학적으로유의하게많았다 (p<0.001) (Table 1). 두군의치료결과를분석하였을때, 치료성공시까지시행한이석정복술의총횟수를비교해보았을때, ph-bppv 에서 2.9±2.2회 ( 최대 8회 ), sh-bppv에서 1.3±0.7회 ( 최대 4 회 ) 로유의한차이를보였으며 (p<0.001), 1회치료와 1회이상치료의비율로비교해보았을때도 ph-bppv에서 1회이상의치료가필요한경우가많았다 (p=0.001). 치료후환자의증상호전되기까지의기간에서도현훈증상은 ph-bppv 에서 4.1±3.9일 ( 최대 15일 ), sh-bppv에서 2.0±2.0일 ( 최대 12 일 ) (p=0.003), 비특이적어지럼은 ph-bppv에서 11.3±16.5 일, sh-bppv에서 4.7±6.1일로 (p=0.029), ph-bppv에서어지럼증상이없어지기까지의기간이 sh-bppv에서보다유의하게더길었다 (Table 2). 고찰향지성 DCPN을보이는수평반고리관 BPPV환자중 14% 에서지속적인향지성 DCPN을보이는수평반고리관 BPPV를보고하고있다. 7 최근많은연구들에서는이러한 Figure 1. Categorization of horizontal vertigo patients with persistent geotropic direction changing positional nystagmus. h-bppv (Geo), horizontal vertigo (geotropic direction changing positional nystagmus); ph-bppv, persistent geotropic direction changing positional change nystagmus horizontal vertigo; sh-bppv, short duration geotropic direction changing positional change nystagmus horizontal vertigo. 119
Res Vestib Sci Vol. 14, No. 4, Dec. 2015 Table 1. The comparison of clinical characteristics between persistent and short duration geotropic direction changing positional nystagmus horizontal vertigo Characteristic ph-bppv (n=34) sh-bppv (n=98) p-value Age (yr) 57.1±13.1 54.8±14.6 0.414 a) Sex (male:female) 6:28 20:78 0.727 b) Affected side (right:left) 14:20 39:59 0.785 c) Onset (day) 1.8±2.3 2.6±4.7 0.386 a) F/U interval (day) 1.4±0.7 1.2±0.6 0.287 a) Cause (idiopathic:secondary) 24:10 91:7 <0.001 c) Secondary causes Head trauma 3 2 Chronic otitis media 4 1 Labyrinthitis 1 2 Meniere s disease 0 0 Osteoporosis 3 3 Dizziness handicap index 23.5±19.1 16.5±10.6 0.050 a) Latency 1.03±0.76 1.38±1.05 0.078 a) Values are presented as mean±standard deviation or number. ph-bppv, persistent geotropic direction changing positional change nystagmus horizontal vertigo; sh-bppv, Short duration geotropic direction changing positional change nystagmus horizontal vertigo; Onset, duration from the onset until visiting the clinic; F/U, duration from the first visit until next visiting the clinic. a) Independent t-test; b) Chi-square test; c) 2 2 Fisher s exact test. 경우를 Light cupula라고명명하고있으나, 아직발병기전이명확히규명되지못하고있는실정이다. 기존의연구들에따르면이석이아닌밀도가작은조각들 (debris) 이팽대부릉정에붙게되면서기존의내림프액과비중이같아서두위변화에도움직이지않았던팽대부릉정을움직이게된다는가설이가장유력하다. 14 그밖에알코올과같은내림프액보다낮은비중을가진물질이혈액내로침투하여팽대부릉정까지퍼져팽대부릉정의비중을낮게만든다는가설, 15 두부외상, 만성중이염, 전정신경염, 돌발성난청, 메니에르병등의이차적원인으로인한내이의관류저하로혈액-미로장벽의파열이일어나게되면내림프액보다비중이높은혈액내의단백질들이내림프액으로유입되어내림프액의비중을높게만든다는가설등이있다. 16 또한최근논문에서는돌발성난청환자에서일측의 3개의반고리관들을모두침범할수있다는가설도제시하고있다. 17 본연구에서향지성 DCPN을보이는수평반고리관 BPPV환자의비율은 25.5% 로이전에연구된결과보다높았다. 아직까지지속성향지성수평반고리관 BPPV환자와 Table 2. The comparison of treatment outcome between between long duration and short duration geotropic direction changing positional nystagmus horizontal vertigo Variable ph-bppv (n=34) sh-bppv (n=98) p-value Treatment No. of CRP 2.9±2.2 1.3±0.7 <0.001 a) Single CRP:multiple CRP 15:19 76:22 0.001 b) Subjective symptom Vertigo (day) 4.1±3.9 2.0±2.0 0.003 a) Dizziness (day) 11.3±16.5 4.7±6.1 0.029 a) Transition 0 4 (4.5) 0.366 a) Values are presented as mean±standard deviation or number (%). ph-bppv, persistent geotropic direction changing positional change nystagmus horizontal vertigo; sh-bppv, short duration geotropic direction changing positional change nystagmus horizontal vertigo; CRP, mean number of canalith repositioning procedure until complete resolution of symptoms and signs; Single, treatment success with only one treatment; Multiple, two or more treatments required for resolution; Transition, a conversion into another canal type of BPPV without intervening periods of remission. a) Independent t-test; b) Chi-square test. 관련된임상연구들이많지않아정확한빈도를비교할수없으나, 본연구에서는의외로높은빈도를확인할수있었다. 이는본연구에서안진의지속시간을두군으로나누는기준이 1분으로기존의 14% 의빈도를보인연구에서정했던 2분보다짧았기때문으로추정된다. 따라서, 본연구의 ph-bppv에는 Light cupula 외에도이환된이석의수가굉장히많은경우, 환자에따른전정기관의감수성차이, 또는환자별반고리관의구조의차이등에의해안진의지속시간이길어진경우가포함되었을가능성이있을것으로생각된다. sh-bppv와비교하여 ph-bppv의임상양상을분석해보았을때, 나이, 연령과병변의방향은두군간유의한차이가없는것으로나타났고, 어지럼발병부터 BPPV 진단까지의기간의경우 ph-bppv군에서는평균 1.8±2.3일, sh-bppv 군에서는평균 2.6±4.7일로 ph-bppv군에서평균적으로진단기간이더짧은것으로나타났고, 두군간에 DHI점수또한 ph-bppv군에서평균 23.5±19.1점, sh-bppv군에서평균 16.5±10.6점으로통계적으로유의한차이를보였다. 이는 ph-bppv군에서주관적인어지럼의증상이 sh-bppv보다좀더심하였고, 그로인해병원을일찍방문하였을것으로생각된다. ph-bppv에서의안진잠복기는평균 1.03± 120
고경민외 5 인. 비전형적수평반고리관 BPPV 0.76초였고, sh-bppv의안진잠복기는평균 1.38±1.05초로두군에서의유의한차이는보이지않았다. 그러나 ph-bppv 의안진잠복기가 sh-bppv보다짧은경향성은확인할수있었고, 이는이론적으로 ph-bppv의병태생리학적인원인의일부분으로추정되는 Light cupula에서팽대부릉정의즉각적인반응으로잠복기가짧을수있으므로, ph-bppv의병태생리학적원인에 Light cupula가포함되어있을수있다는근거가될수있을것으로생각된다. 본연구에서분석한두군간의기저질환의비교에서는, ph-bppv환자군에서이차적질환비율이 sh-bppv에비해상대적으로많았다. 기존의연구에따르면전정청각기관또는뇌중추의질환이동반되는경우이차적 BPPV라고명시하고있으며, 원인불명의 BPPV보다증상이더심하며, 치료가힘들다고알려져있다. 18 또한기존연구들은골다공증을위험인자로분류하지않았으나, 최근발생및재발의원인인자로많은연구가이루어지고있다. 19 본연구에서는 ph-bppv군에서이차적 BPPV 및골다공증을가지고있는비율이 sh-bppv보다높았다. 이에대한기전은추가적인연구가더필요할것으로생각된다. 본연구에서분석한 canalith repositioning procedure (CRP) 을통한치료효과및치료중환자증상호전기간의비교에서두군간에유의한차이가확인되었다. 총 CRP 횟수는 ph-bppv군에서평균 2.9±2.2회로 sh-bppv군 ( 평균 1.3±0.7회 ) 보다유의하게많은치료가필요했으며, 최대치료횟수에서도 sh-bppv의최대 4회에비해 ph-bppv에서는최대 8회까지치료가필요한경우가있었다. 1회 CRP와 1회이상의 CRP로구분한비율에서도 ph-bppv에서 sh- BPPV보다 1회이상의 CRP가필요한경우가유의하게많았다. 이러한 ph-bppv의낮은치료효과는 ph-bppv의병리학적원인이기존의 BPPV의원인인이석의이탈현상이아닌팽대부릉정과내림프액사이의비중이상으로발생하는것일수있음을추정할수있는근거가되며, 이로인해 ph-bppv에서는 CRP의치료효과가떨어지며, 기존연구들에서보존적요법을치료방법으로제시하는이유로생각된다. 7,20 이와는반대로, ph-bppv에서도 1회의 CRP만으로도치료되는경우가 44.1% 에서있었으며, 이는 ph-bppv가 Light cupula뿐만아니라다량의이석이수평반고리관관내에서돌아다니는관내이석 (canalolithiasis) 기전도혼재되어있을수있음을추론할수있다. 치료중환자증상호전기간에대한비교에서도현훈과 비특이적어지럼증상의호전기간모두 ph-bppv 군이 sh-bppv군에비해유의하게길었다. 현훈이발생할때부터호전될때까지의기간을분석하였을때, ph-bppv군의현훈기간이평균 4.1±3.9일 ( 최대 15일 ) 로 sh-bppv군 ( 평균 2.0±2.0일, 최대 12일 ) 보다유의하게길었다. 이는앞의 DHI 결과와같이 ph-bppv군이호소하는주관적인어지럼증상이 sh-bppv군보다더심하다고생각할수있겠다. 추가적으로경과관찰중안진이사라진시점과환자의현훈증상의호전시점이 sh-bppv군에서는평균적으로비슷하였으나 ph-bppv군에서는안진이사라진시점과현훈증상의호전시점이평균적으로비슷하지않았다. 기존의 Light cupula에관한연구들은안진에대해서만서술되어있어본연구에서시행한안진과환자증상에대한연구가추후 Light cupula의연구에도움이될것으로생각된다. 결 ph-bppv환자는 sh-bppv에비해주관적인어지럼증상이심하며, CRP치료효과가낮았다. 임상적특징면에서는이차적 BPPV 및골다공증의비율이높은점을제외하고는 sh-bppv환자의임상양상과거의유사하였다. 본연구에서확인한 ph-bppv환자의임상양상및치료결과는추후지속적인향지성 DCPN을보이는 h-bppv (Geo) 환자들의연구에있어유용한정보가될수있을것으로기대된다. 중심단어 : 양성돌발성두위현훈, 방향전환성두위안진, 향지성안진 론 CONFLICT OF INTEREST No potential conflict of interest relevant to this article was reported. REFERENCES 1. Moon SY, Kim JS, Kim BK, Kim JI, Lee H, Son SI, et al. Clinical characteristics of benign paroxysmal positional vertigo in Korea: a multicenter study. J Korean Med Sci 2006;21: 539-43. 2. Casani AP, Vannucci G, Fattori B, Berrettini S. The treatment of horizontal canal positional vertigo: our experience in 66 cases. Laryngoscope 2002;112:172-8. 3. Baloh RW, Honrubia V, Jacobson K. Benign positional vertigo: 121
Res Vestib Sci Vol. 14, No. 4, Dec. 2015 clinical and oculographic features in 240 cases. Neurology 1987;37:371-8. 4. Chung WK, Lee WS, Kim MS, Lee JH, Lee SY. Direction changing positional nystagmus from canalolithiasis and cupulolithiasis of lateral semicircular canal. Korean J Otolaryngol- Head Neck Surg 1999;42:576-81. 5. Hiruma K, Numata T. Positional nystagmus showing neutral points. ORL J Otorhinolaryngol Relat Spec 2004;66:46-50. 6. Imai T, Matsuda K, Takeda N, Uno A, Kitahara T, Horii A, et al. Light cupula: the pathophysiological basis of persistent geotropic positional nystagmus. BMJ Open 2015;5:e006607. 7. Kim CH, Kim MB, Ban JH. Persistent geotropic direction-changing positional nystagmus with a null plane: the light cupula. Laryngoscope 2014;124:E15-9. 8. Shim DB, Song CE, Jung EJ, Ko KM, Park JW, Song MH. Benign paroxysmal positional vertigo with simultaneous involvement of multiple semicircular canals. Korean J Audiol 2014;18:126-30. 9. Choung YH, Shin YR, Kahng H, Park K, Choi SJ. 'Bow and lean test' to determine the affected ear of horizontal canal benign paroxysmal positional vertigo. Laryngoscope 2006;116: 1776-81. 10. Lempert T, Tiel-Wilck K. A positional maneuver for treatment of horizontal-canal benign positional vertigo. Laryngoscope 1996;106:476-8. 11. Ichijo H. Persistent direction-changing geotropic positional nystagmus. Eur Arch Otorhinolaryngol 2012;269:747-51. 12. Lechner C, Taylor RL, Todd C, Macdougall H, Yavor R, Halmagyi GM, et al. Causes and characteristics of horizontal positional nystagmus. J Neurol 2014;261:1009-17. 13. Kim JH, Jung EJ, Song CE, Song MH, Park KC, Ko KM, et al. Risk factors for treatment failure in benign paroxysmal positional vertigo. Korean J Otorhinolaryngol-Head Neck Surg 2013;56:74-8. 14. Bergenius J, Tomanovic T. Persistent geotropic nystagmus: a different kind of cupular pathology and its localizing signs. Acta Otolaryngol 2006;126:698-704. 15. Money KE, Johnson WH, Corlett BM. Role of semicircular canals in positional alcohol nystagmus. Am J Physiol 1965;208: 1065-70. 16. Kim CH, Choi JM, Jung HV, Park HJ, Shin JE. Sudden sensorineural hearing loss with simultaneous positional vertigo showing persistent geotropic direction-changing positional nystagmus. Otol Neurotol 2014;35:1626-32. 17. Kim CH, Shin JE, Shin DH, Kim YW, Ban JH. Light cupula involving all three semicircular canals: a frequently misdiagnosed disorder. Med Hypotheses 2014;83:541-4. 18. Bhattacharyya N, Baugh RF, Orvidas L, Barrs D, Bronston LJ, Cass S, et al. Clinical practice guideline: benign paroxysmal positional vertigo. Otolaryngol Head Neck Surg 2008;139: S47-81. 19. Jeong SH, Choi SH, Kim JY, Koo JW, Kim HJ, Kim JS. Osteopenia and osteoporosis in idiopathic benign positional vertigo. Neurology 2009;72:1069-76. 20. Shin JE, Kim CH. Light cupula of the horizontal semicircular canal occurring alternately on both sides: a case report. BMC Ear Nose Throat Disord 2015;15:2. 122