REVIEW online ML Comm J Neurocrit Care 2008;1:128-133 ISSN 2005-0348 말초성으로오인되기쉬운중추성현훈 서울대학교의과대학분당서울대학교병원신경과학교실 김선혜 김지수 Central Vertigo Mimicking Acute Peripheral Vestibular Disorder Seonhye Kim, MD and Ji Soo Kim, MD, PhD Department of Neurology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Korea Acute vestibular syndrome of severe vertigo, nausea/vomiting, spontaneous nystagmus and postural imbalance is commonly due to viral or post-viral inflammation of the vestibular nerve or labyrinth. However, similar symptoms and signs may occur in cerebellar or brainstem stroke in which vertigo may be an isolated or initial symptom without other focal neurologic deficits. Since cerebellar or brainstem strokes may be fatal, it is important to recognize acute vestibular syndrome of vascular etiologies. In general, central origin should be suspected in isolated vertigo when the patients show 1) central type nystagmus, 2) horizontal nystagmus with normal head impulse test, 3) skew deviation, 4) impaired smooth pursuit, 5) severe imbalance, 6) persistent dizziness in association with vascular risk factors, and 7) no improvement of vertigo and nystagmus in 48 hours. J Neurocrit Care 2008;1:128-133 KEY WORDS: Central origin vertigo Cerebellar stroke Lateral medullary syndrome. 서 론 어지럼 (dizziness) 은환자들이가장흔하게호소하는증상의하나로일반인구의 20~30% 가어지럼을경험한다. 1,2 회전성어지럼인현훈 (vertigo) 은전정계이상을의미하며, 현훈의평생유병률은 7.8%, 1년유병률은 5.2% 이고, 3 응급실을방문하는환자의 1% 를차지한다. 4 현훈, 오심, 구토, 자발안진과자세불안정을특징으로하는급성정전증후군 (acute vestibular syndrome) 은말초혹은중추전정계의편측손상으로유발되는데, 전정신경염 (vestibular neuritis) 의경우수시간에걸쳐서서히증상이발생하고하루내에최고조에달했다가수일에걸쳐줄어든다. 5 반면뇌경색에의한경우는대체로갑작스럽게발생하고고혈압, 당뇨, 폐 Address for correspondence: Ji Soo Kim, MD, PhD Department of Neurology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, 300 Gumi-dong, Bundang-gu, Seongnam 463-707, Korea Tel: +82-31-787-7463, Fax: +82-31-719-6828 E-mail: jisookim@snu.ac.kr 이논문은분당서울대학교병원집중육성연구비에의해이루어진것임. 색성혈관질환혹은심장이상등의뇌졸중위험인자들이있고심한어지럼이수일이상지속될수있고, 6,7 뇌줄기 (brainstem) 병변에서는복시, 구음장애, 삼킴곤란, 운동혹은감각이상, 뇌신경마비등이동반되기도한다. 7,8 하지만이런신경학적증상없이현훈과자발안진그리고자세불안정만나타나는경우도있기때문에전정신경염과같은말초성현훈으로오인하는경우도있다. 실제다른증상없이현훈만으로응급실을방문한환자의 25% 에서아래소뇌에경색이있었고, 소뇌경색의 21.9% 가다른증상없이급성현훈으로발현하였다. 7 소뇌뇌졸중은부종으로인해수두증을유발하거나뇌줄기를압박하여심혈관계이상을초래할수있으며, 허혈성뇌졸중의재발로치명적인결과를야기할수있기때문에다른증상없이급성현훈을호소하는환자에서도원인질환으로중추성현훈을감별하는것이중요하다. 9-13 말초성현훈으로오인되기쉬운중추성현훈이잘발생되는위치로는 8번뇌신경이뇌줄기로들어가는부위 (entry zone), 14 전정신경핵 (vestibular nucleus) 혹은전정소뇌 (vestibulocerebellum) 가있고, 15 내이동맥 (internal auditory ) 폐색의경우는말초성질환이나뇌졸중에대 128 Copyright c 2008 The Korean Neurocritical Care Society
Central Vertigo Mimicking Peripheral Vertigo S Kim, et al. 한예방치료가필요하다는점에서임상적중요성이있다. 16,17 내측후하소뇌동맥영역경색 (Infarction in the Territory of the Medial Branch of the Posterior Inferior Cerebellar Artery) 후하소뇌동맥 (posterior inferior cerebellar : PICA) 은추골동맥 (verebral ) 에서분지되어숨뇌 (medullar) 를가로질러내려가첫번째고리를형성하고다시위로향하면서두번째고리를형성한뒤소뇌벌레아래를따라내려가면서세번째고리를형성하는데처음두고리사이에서내측 PICA 와외측 PICA 가분지된다. 내측 PICA 는소뇌결절 (nodulus), 소뇌목젖 (uvular), 모뿔 (pyramis), 결절 (tuber) 과때로는비스듬틀 (declive) 을포함하는소뇌벌레의아래부위와소뇌편도 (tonsil) 를포함한내측소뇌에혈류를공급한다. 경우에따라서는내측 PICA 에서숨뇌등쪽부위 (dorsal part) 의혈류전체를공급하기도한다. 내측 PICA 영역경색은무증상이거나다음의 3가지형태로나타날수있다. 첫째겨냥이상 (dysmetria) 이나실조등이없이어지럼만으로나타나가성미로증후군 (pseudolabyrinthin syndrome) 으로혼동되는경우, 둘째현훈과함께몸통과안구의측방돌진 (lateropulsion), 겨냥이상또는자세불안정이동반되는경우, 셋째동반된숨뇌의병변으로 Wallenberg증후군이완전또는불완전한형태로발생하는경우이다. 18,19 내측 PICA 영역경색의 1/3에서는 Wallenberg 증후군이뚜렷할수있지만, 96% 에서지속적인현훈과균형장애만을보이거나처음에현훈으로발현하였다가 2일이내에다른신경학적증상이동반되기때문에내측 PICA 영역경색은내이질환과의감별이필요하다. 15,19,20 내측 PICA 영역경색에서전정계증상은소뇌결절과목젖의병변에의해나타나는데, 이곳으로부터전정신경핵으로가는억제성신호가소실되어발생된다. 13,20-22 뇌졸중위험인자를가진고령의환자가다른신경학적이상없이현훈과자세불안정으로응급실을내원하였을때, 17% 가 PICA 영역의경색이었고, 25% 가내측 PICA 영역의경색이었던연구결과를고려해볼때이들환자에서소뇌경색과말초성현훈의감별은중요하다. 15 특히심한자세불안정을보일때, 측방주시에의해안진의방향이바뀌는주시유발안진 (gaze evoked nystagmus) 이있을때, 매끈따라보기 (smooth pursuit) 와눈운동눈떨림 (optokinetic nystagmus) 의비대칭성이있을때, 그리고두부충동검사 (head impulse test) 가정상일때는중추성현훈의가능성을고려해야한다. 15,21-23 소뇌경색을시사하는다른소견으로는주기교대눈떨림 (periodic alternating nystagmus), 24 그리고체위성하방안진 (positional downbeat nystagmus) 등 25 이있으므로자세한신경학적검사와안구운동검사가중요하다. 전하소뇌동맥영역경색 (Infarction in the Territory of the Anterior Inferior Cerebellar Artery) 전하소뇌동맥 (anterior inferior cerebellar : AICA) 은기저동맥 (basilar ) 의아래 1/3부위에서기시하여 5번뇌신경아래를지나소뇌다리뇌각 (cerebellopotine angle) 에도달하여 8번뇌신경을가로지른후내이동맥으로분지된다. 이후 AICA는다리뇌를감싸고돌면서뒤쪽으로주행하여다리뇌의후외측, 중간소뇌다리 (middle cerebellar peduncle), 가쪽숨뇌의윗부분과소뇌의타래 (flocclus) 에혈류를공급한다. 26 AICA 영역경색에서내이, 다리뇌의후외측, 중간소뇌다리와타래가침범되면현훈과안진, 청력소실, Horner 증후군, 안면감각소실, 안면마비, 동측성실조등의증상이흔히동반된다. 18,27 AICA 영역경색의증상은 PICA 경색에서의증상과유사한면이있어때로는임상적으로이들둘을감별하기힘들때가있다. AICA 경색에서는청력소실이동반되고, 소뇌타래의침범여부가 AICA 영역의경색을가름하는중요한증거가된다. AICA 경색에서내이동맥이선택적으로막히거나다리뇌의뒤판 (tegmentum) 에서전정신경핵이침범될때, 외측다리뇌부위에서 8번뇌신경섬유가손상되거나, 타래나그연결구조물에경색이생기면미로성현훈이발생될수있다. 6,26 내이동맥은 45~87% 에서 AICA로부터기시하여내이관 (internal auditory canal) 을지나공통와우동맥 (common cochlear ) 과앞전정동맥 (anterior vestibular ) 으로나뉘고, 공통와우동맥은주와우동맥 (main cochlear ) 과속귀동맥 (vestibulocochlear ) 이되며, 속귀동맥은다시뒤전정동맥 (posterior cochlear ) 과달팽이가지 (cochlear ramus) 를형성한다. 주와우동맥은와우의꼭지로부터 3/4영역의혈류를공급하고, 하단부의 1/4영역은달팽이가지로부터혈류공급을받는다. 앞전정동맥은타원낭 (utricle) 과원형낭 (saccule) 의상위부, 앞쪽과가쪽반고리관 (semicirular canal) 의혈류를공급하고, 뒤반고리관과원형낭의하단부는뒤전정동맥으로부터혈류를공급받는다 (Fig. 1). 내이동맥과이로부터나오는가지동맥들은종말가지 (end ) 로곁순환 (collateral circulation) 이적어짧은기간동안의허혈상태에서도쉽게손상받을수있다. 28 Lazorthes(1961) 는 AICA 를 129
J Neurocrit Care 2008;1:128-133 Anterior inferior cerebellar Basilar Anterior semicircular canal Intemal auditory Anterior vestibular Common cochlear Saccule Utricle Main cochlear Posterior vestibular Posterior semicircular canal Horizontal semicircular canal FIGURE 1. Arterial circulation of inner ear. cerebellolabyrinthine 로명명하기도하였는데, 내이동맥이선택적으로폐색되면어지럼만단독으로발생될수있다. 16,17 그러나내이동맥은전정기관뿐만아니라달팽이관도같이혈액을공급하기때문에내이동맥폐색에서청력증상없이어지럼만단독으로발생하는것을설명하는데는어려움이있다. 앞전정동맥에의해혈류를공급받는내이부위가허혈에더취약하다는주장과, 29 색전증이앞전정동맥부위를더흔하게침범한다는주장들이있고, 30 어떠한원인에의해서든지내이동맥의분지인앞전정동맥에의해공급되는부위만이선택적으로손상이된다면청력증상없이현훈만이단독증상으로발생할수있을것이다. 청력소실과현훈이있었던환자의부검에서앞쪽과가쪽반고리관, 타원낭이반 (macule) 의모세포 (hair cell) 와감각신경손상이뒤쪽반고리관과원형낭에비해심했던점등 16 을볼때선택적내이경색에서앞전정동맥에의해혈류를공급받는부위가더심하게손상받는다고할수있겠다. 또한 AICA 경색의 31% 에서뇌줄기와소뇌병변이발생하기 1~10 일전에청력감소또는청력소실이전조증상으로나타났는데, 이러한내이경색이추골기저동맥폐색에의한뇌경색이발생되기전의경고증상으로보일수있어주의를요한다. 31 가쪽숨뇌경색 (Lateral Medullary Infarction) 가쪽숨뇌경색 (lateral medullary infarction) 환자의 25% 가어지럼을포함한현훈, 보행실조를첫증상으로경험하였고, 전체환자의 92% 가어지럼을호소하였으며, 현훈은 57%, 안진은 56% 에서있었다. 32 그러나가쪽숨뇌경색에서다른신경학적증상없이어지럼과현훈으로만나타나는경 우는흔하지않다. 가쪽숨뇌경색에서전정증상은내측과아래전정신경핵의손상이나아래소뇌다리 (inferior cerebellar peduncle) 의침범으로발생할수있는데, 33-35 순수하게어지럼과보행실조만을보였던 3명의환자에서병변은꼬리쪽숨뇌 (caudal medulla) 의뒤가쪽 (dorsolateral) 에있었고, 이부위에는전정신경핵과아래소뇌다리가위치하고있다. 35 가쪽숨뇌경색에서는다양한신경안증상을보일수있는데이러한소견들이말초성현훈과의감별에도움이될수있다. 안증상은자발안진, 주시유발안진, 두진후안진 (head shaking nystagmus), OTR, 안구의측방돌진 (ocular lateropulsion), 따라보기장애등다양하다 (Table 1). 자발안진은수평안진, 36,37 회선안진 (torsional nystagmus), 38 수평과회선이혼합된안진 (mixed nystagmus) 39 과수직안진등다양하고, 수평안진은대부분에서빠른성분이병변반대쪽 38,39 을향하지만드물게병변쪽으로향하기도한다. 34,36 회선안진의방향은다양하고, 수직안진은주로위쪽을향한다. 39 주시유발안진은많은환자에서보이며 (97%), 수평방향의주시유발안진이흔하다. 34 가쪽숨뇌경색에서두진후안진은 87.5% 에서나타났고, 자발안진이병변반대쪽으로향했던환자에서는물론병변쪽으로향했던경우에서도두진후안진의수평방향은병변쪽을향했다. 40 이외에도두진후안진이매우강하게나타나거나, 수평방향으로머리회전후에수직방향의안진 (perverted head shaking nystagmus) 이보일수있다. 7 안구의측방돌진현상은안구운동범위에는제한이없으면서양안이병변쪽으로몰리는현상으로, 환자에게눈을감았다가뜨게하면양쪽눈이병변쪽으로쏠려있거나, 쏠려있다가다시중앙으로돌아오는것을볼수있다. 39,41,42 이러한긴장성편위 (tonic deviation) 는수직안구운동에도영향을미쳐, 환자에게위나아래를 130
Central Vertigo Mimicking Peripheral Vertigo S Kim, et al. TABLE 1. Ocular motor abnormalities in 36 patients with Wallenberge s syndrome 34 Ocular motor abnormality N (%) Note Gaze-evoked nystagmus 35 (97) 14 horizontal bilateral (4c=i, 5c>i, 5c<i), 11 ipsiversive, 3 contraversive, 7 upward Lateropulsion of the closed eyes a 21 (91) Evaluation of 23 EOGs: 18 ipsilateral (11 severe>15 degrees, 6 moderate 5-15 degrees, 1 slight<5 degrees), 3 contralateral, 2 no lateropulsion Spontaneous nystagmus 27 (75) 14 contraversive, 6 ipsiversive, 5 horizontal alternating, 2 up-ward, 4 no spontaneous nystagmus (6 no registration) Saccadic pursuit 26 (72) 17 horizontal bilateral, 5 ipsiversive, 3 contraversive, 7 up & downward, 4 upward, 4 no deficit (6 no registration) Skew deviation 16 (44) Hypotropia of the ipsilateral eye Ocular tilt reaction b 12 (33) Triad of head tilt, skew deviation, and ocular torsion: all feature ipsilateral Dysmetria of saccades 09 (25) 4 contralateral hypometria, 2 ipsilateral hypometria, 1 ipsi & contralateral, 2 slowness Central positional nystagmus 03 (8.3) Rotatory nystagmus in head-hanging position Horizontal gaze paresis 01 Ipsiversive a Lateropulsion: horizontal deviation of eyes, b Ocular tilt reaction: triad of lateral head tilt, skew deviation, and ocular torsion in the direction of head tilt, c > i: contralateral more than ipsilateral (c: contralateral, i: ipsilateral). EOG: electrooculogram TABLE 2. Clinical feature of peripheral benign paroxysmal positioning vertigo/nystagmus (BPPV) and central paroxysmal positioning vertigo/nystagmus (central PPV) 45 Features BPPV Central PPV Latency following precipitating 1-15 sec (shorter in h-bppv) 0-5 sec positioning manoever Duration of attack 5-60 sec (longer in h-bppv) 5-<60 sec Direction of nystagmus During stimulation in the plane of the affected canal: torsional/vertical for Pure vertical; pure torsional, not attributable to the stimulated canal plane p-bppv and a-bppv; horizontal for h-bppv Fatigability Typical, rare in h-bppv Possible Course of nystagmus and vertigo in attack Crescendo-decrescendo typical, not common in h-bppv Crescendo-decrescendo possible Vertigo Typical Typical Nausea and vomiting Rare on single precipitating maneuvers (associated with intense nystagmus), not uncommon after several manoevers Frequent on single precipitating manoevers (not necessarily associated with strong nystagmus intensities) Natural course of the condition Spontaneous recovery within several weeks in 70-80% Spontaneous recovery within weeks possible Associated neurologic signs and symptoms None None possible, often cerebellar and other oculomotor signs Brain imaging Normal Normal; lesions of the dorsal vermis and/or dorsolateral to the fourth ventricle a: anterior, h: horizontal, p: posterior canal 쳐다보게하면환자의눈이곧바로위아래를향하지못하고병변쪽으로비스듬히움직인후다시중앙으로향하는양상을보인다. 안구의측방돌진현상은홱보기에서도나타나는데, 병변쪽으로향할때는겨냥과다 (hypermetria), 병변반대쪽에서는겨냥부족 (hypometria) 을보이며, 병변반대쪽으로의따라보기장애도관찰된다. 39 안구측방돌진의정확한기전은모르나, 반대편아래올리브핵에서소뇌로가는오름섬유가외측숨뇌에서침범되면소뇌의 Purkinje 세포가과활성화되어동측의꼭지핵 (fastigial nucleus) 을억제함으로써꼭지핵에의해활성화되는반대편방중교뇌그물체 (paramedian pontine reticular formation: PPRF) 가억제되어긴장성불균형이초래되기때문으로설명한다. 43 매끈따라보기는반대쪽보다병변쪽으로향할때이득 (gain) 이더높게나오고, 눈운동눈떨림에서느린성분의속도도따라보기에서와같이비대칭을보인다. 39 중추성발작성두위현훈 (Central Paroxysmal Positional Vertigo: CPPV) 두위 (positional) 또는두위변환성 (positioning) 안진은 3가지형태로나타날수있는데, 첫번째가중추성두위안진 (central positional nystagmus) 으로이는머리를떨어뜨린상태에서자세를유지하는동안지속적으로안진이나타나고, 현훈이동반되지않으며대부분중추성원인에의하여나타난다. 두번째는양성돌발성두위현훈 (benign paroxysmal positioning vertigo: BPPV) 으로말초반고리관 131
J Neurocrit Care 2008;1:128-133 TABLE 3. Features in the history that help distinguish between peripheral and central causes of vertigo 46 Peripheral Central Imbalance Mild-moderate Severe Nausea and vomiting Severe Variable, may be minimal Auditory symptoms Common Rare Neurologic symptoms Rare Common Compensation Rapid Slow 의이석에의하여발생되며, 현훈이특징적인증상이다. 세번째로중추성두위변환성현훈 / 안진 (central paroxysmal positioning vertigo and nystagmus: central PPV) 은짧은시간지속되는안진이현훈과함께나타나고, 소뇌충부및제 4 뇌실을포함한중추성병변에의해발생되며, 44 이는가성-BPPV 로불리기도해임상적으로 BPPV 와감별이필요하다. 45 중추성 PPV 에서안진의잠복기, 방향, 현훈의지속시간, 그리고반복적인체위변환검사에따른피로현상등은 BPPV 에서와동일한양상으로보일수있어이들두질환을임상적으로감별하는것은어렵다. 잠복기의존재, 피로도, 수평방향의안진, 점점강해졌다약해지는양상 (crescendo-decrescendo pattern) 의안진등은더이상 BPPV 만의특징은아니다. 45 그러나상향안진, 하향안진혹은순수한회선안진이보이는경우에는중추성 PPV 의가능성이높다. 45 중추성 PPV 에서는소뇌이상이나홱보기양상의매끈따라보기이상 (saccadic pursuit), 주시유발안진등의안구운동이상이나타날수있어감별진단에도움이될수있다 (Table 2). 45 결 론 중추성현훈과말초성현훈을감별하기위해자세한병력청취가도움이된다 (Table 3). 그리고환자의나이와고혈압, 동맥경화증, 혈관질환, 또는뇌졸중의과거력이있을경우에는중추성현훈의가능성을고려해야한다. 46 전정신경염환자와가성전정신경염 ( 중추성현훈 ) 환자에서두부충동검사, 안구편위 (skew deviation), 주시유발안진, 매끈따라보기이상을비교하였을때두부충동검사는전정신경염환자에서의미있게높았고, 나머지는가성전정신경염에서높게나와감별진단에있어서유용하다. 특히안구편위는민감도가 40% 로높지는않았지만전정신경염에서는관찰되지않아중추성현훈의진단에있어도움이될수있다. 47 다른신경학적증상없이지속적인현훈이다음과같은상황에서보이는경우는중추성현훈의가능성을시사하는데, 1) 고령에서지속적인현훈을보일때, 2) 뇌졸중의위험인 자가있는환자에서지속적인현훈을호소하지만두부충동검사에서이상이없을때, 3) 지속적인현훈과함께주시유발안진이나심한체위불안정을동반할때, 4) 두진후안진이강하거나방향이바뀔때, 5) 안구편위를보일때, 6) 수직방향으로의매끈따라보기의장애를보일때, 7) 현훈과안진이 48시간이경과해도호전되지않을때는뇌영상을고려해야한다. REFERENCES 1. Kroenke K, Price RK. Symptoms in the community. Prevalence, classification, and psychiatric comorbidity. Arch Intern Med 1993;153: 2474-80. 2. Yardley L, Owen N, Nazareth I, Luxon L. Prevalence and presentation of dizziness in a general practice community sample of working age people. Br J Gen Pract 1998;48:1131-5. 3. Neuhauser HK, von Brevern M, Radtke A, Lezius F, Feldmann M, Ziese T, et al. Epidemiology of vestibular vertigo: a neurotologic survey of the general population. Neurology 2005;65:898-904. 4. Cappello M, di Blasi U, di Piazza L, Ducato G, Ferrara A, Franco S, et al. Dizziness and vertigo in a department of emergency medicine. Eur J Emerg Med 1995;2:201-11. 5. Silvoniemi P. Vestibular neuronitis. An otoneurological evaluation. Acta Otolaryngol Suppl 1988;453:1-72. 6. Oas JG, Baloh RW. Vertigo and the anterior inferior cerebellar syndrome. Neurology 1992;42:2274-9. 7. Norrving B, Magnusson M, Holtas S. Isolated acute vertigo in the elderly; vestibular or vascular disease? Acta Neurol Scand 1995;91:43-8. 8. Grad A, Baloh RW. Vertigo of vascular origin. Clinical and electronystagmographic features in 84 cases. Arch Neurol 1989;46:281-4. 9. Sypert GW, Alvord EC Jr. Cerebellar infarction. A clinicopathological study. Arch Neurol 1975;32:357-63. 10. Hornig CR, Rust DS, Busse O, Jauss M, Laun A. Space-occupying cerebellar infarction. Clinical course and prognosis. Stroke 1994;25: 372-4. 11. Heros RC. Cerebellar hemorrhage and infarction. Stroke 1982;13:106-9. 12. Koh MG, Phan TG, Atkinson JL, Wijdicks EF. Neuroimaging in deteriorating patients with cerebellar infarcts and mass effect. Stroke 2000; 31:2062-7. 13. Duncan GW, Parker SW, Fisher CM. Acute cerebellar infarction in the PICA territory. Arch Neurol 1975;32:364-8. 14. Thomke F, Hopf HC. Pontine lesions mimicking acute peripheral vestibulopathy. J Neurol Neurosurg Psychiatry 1999;66:340-9. 15. Lee H, Sohn SI, Cho YW, Lee SR, Ahn BH, Park BR, et al. Cerebellar infarction presenting isolated vertigo: frequency and vascular topographical patterns. Neurology 2006;67:1178-83. 16. Kim JS, Lopez I, DiPatre PL, Liu F, Ishiyama A, Baloh RW. Internal auditory infarction: clinicopathologic correlation. Neurology 1999;52:40-4. 17. Choi KD, Chun JU, Han MG, Park SH, Kim JS. Embolic internal auditory infarction from vertebral dissection. J Neurol Sci 2006;246:169-72. 18. Amarenco P, Roullet E, Hommel M, Chaine P, Marteau R. Infarction in the territory of the medial branch of the posterior inferior cerebellar. J Neurol Neurosurg Psychiatry 1990;53:731-5. 19. Amarenco P. The spectrum of cerebellar infarctions. Neurology 1991; 41:973-9. 20. Kumral E, Kisabay A, Atac C, Calli C, Yunten N. Spectrum of the posterior inferior cerebellar territory infarcts. Clinical-diffusionweighted imaging correlates. Cerebrovasc Dis 2005;20:370-80. 21. Lee H, Yi HA, Cho YW, Sohn CH, Whitman GT, Ying S, et al. No- 132
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