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1 Journ al of the Korean Radiological Society, 1994 ; 30(4) : MR Findings in Palatal Myoclonus 1 Sang Joon Kim, M.D.2, Dae Chul Suh, M.D., Man Soo Park, M.D., Jae - Hong Lee, M.D.3, Ki Bum Sung, M.D.4 Purpose: Palatal myoclonus(pm) is an involuntary cyclic movement ofthe soft palate and is known to be caused bythe hypertrophic degeneration ofthe inferior olivary nucleus of the medulla, secondary to the dentato-rubro-tegmental tract lesions. Our purpose is to describe the brain magnetic resonance(mr) imaging findings in palatal myoclonus. Materials and Methods: We retrospectively analyzed the locations and causes of primary lesions in the dentato-rubro-tegmental tract and correlated them with changes in MR signal intensity and size of the inferior olive on T2-weighted MR images in 1 0 patients with palatal myoclonus. Results: AII cases showed hyperintensity in one or both inferior olive and six cases showed accompaning enlargement. The locations of the primary lesions were dorsal aspect of pons(central tegmental tract) in eight patients and the dentate nucleus in one, and no lesion was found in the dentato-rubro-tegmental tract in one. Among eight patients who had lesions in the pons, the ipsilateral inferior 이 ivary nuclei showed changes in five and bilateral olive were involved in three. ln the case with a lesion in the dentate nucleus, the contralateral inferior 이 ivary nucleus was involved. The causes of primary lesions were hemorrhage in eight cases and traumatic brain stem injury in one. Conclusion: MR specifically showed enlargement and hyperintensity of the inferior olivary nucleus on T2-weighted images and matching lesions in the pons or the dentate nucleus in patients with palatal myoclonus. Index Words: Brain stem Brain stem, MR studies B rai n, atrophy Hypertrophic olivary degeneration may cause palatal myoclonus(pm), which is characterized by continuous involuntary movement of the soft palate. This specific change of the inferior olivary nucleus(ion) is known to be a transsynaptic degeneration secondary to damage to the structures along the dentato - rubro - ol ivary tract(1, 2)(Fig. 1). With the advent of MR imaging, changes in the ION could be demonstrated in vivo, which was not possible with CT before. We describe MR findings of palatal myoclonus in 10 'DepartmentofRadiology, Asan Medical Center, UniversityofUlsan 2Department ofradiology, Dankook University 3Department ofneurology, Asan Medical Center, University of Ulsan 4Department ofneurology, Chung-Ang Gil Hospital Received September 4, 1993, Accepted December 16, 1993 Address reprintrequests to: Department ofradiology, Dankook University, 29 An Seo-Dong, Cheon An, Choong Nam, Te l. (041 7) Fax. (0417) αωpatients showing lesions in the ION with accompanying lesions in the dentate nucleus(dn) or central tegmental tract(ctt). PATIENTSand METHODS From April 1991 through March 1993, PM was found in 10 patients (9 men and 1 woman, age ranged from years with mean 51 years). Presenting symptoms were headache, dizziness, dysarthria, and hemiparesis, etc. No one had subjective symptoms of PM and in most cases, PM was found on neurologic examinations just before or after MR studies. In addition to PM, eight patients had myoclonus of eyeball, eyelid orfingers. Among the ten patients, four had clear history of pontine hemorrhage occurred 3 to 24 months prior to presentation, which had been confirmed by CT pertormed

Journal of the Korean Radiological Society, 1994 : 30(4) : 633-637 at the time of ictus. Three had history of attacks which were relevant to brain stem lesions occurred 10 months to 5 years ago.

2 Journal of the Korean Radiological Society, 1994 : 30(4) : at the time of ictus. Three had history of attacks which were relevant to brain stem lesions occurred 10 months to 5 years ago. AII seven patients had hypertension. In other three patients who did not have hypertension, one had brain stem injury occurred 10 months ago, one had presumed occult cerebrovascuar malformation (OCVM) in pontine tegmentum on MR images, and one had no history of brain stem lesion. MR examinations were performed on either 1.5-T Signa (GE Medical Systems, Milwaukee, USA) or 1.0 -T SMT-100X (Shimadzu, Kyoto, Japan). Axial and sagittal or coronal images (or both) were obtained. Imaging protocols included T1 - weighted( /1-3, TRITE/excitation) images and T2 - weighted ( / ) images. Section thickness was 5-6 mm with an intersection gap mm. The field of view was 200 mm and the matrix size was 256 X 256 or 192 We evaluated on MR images the location and nature of the lesions in DN or CTT, and defined these lesions as primary r causative At the level of medulla oblongata the size and signal changes of the ION were evaluated. The size was assessed by comparing both sides in unilaterally involved cases. When bilaterally involved, comparison was made with other normal cases. We defined the medullary lesion as secondary, on the basis of the well - known fact that the lesion in ION follows the lesion in dentato - rubro -tegmental tract in PM(1). Most observations were based on axi al T2W I. RESUlTS DN Fig. 1. Schematic diagram of brain stem and cerebellum shows the relationship between the dentate nucleus(dn), red nucleus (RN) and inferior olivary nucleus(ion). Dentate nucleus projects to the contralateral red nucleus. The inferior ol ivary nucleus receives projections from the red nucleus through the central tegmental tract(ctt). The inferior olivary nucleus undergoes secondary hypertrophic degeneration following a I esion in the contralateral dentate nucleus or in the ipsilateral central tegmental tract. The pathway from the inferior olivary nucleus to the contralateral dentate nucleus through the inferior cerebellar peduncle is not believed to work in producing palatal myoclonus (question mark) AII 10 patients showed lesions in the ION on T2 - weighted images: the lesions were of high signal intensity(si) in all cases and enlargement of ION was accompanied in six cases. High SI of the 이 ive was round in shape with internal U- shaped or band - like less high signal in six cases, and the shape of less high signal was quite similar to that of gray lamina of the ION (Fig. 2). Interval between the attack ofthe primary lesion and MR studies in five out of these six cases was more than one year as opposed to less than one year in cases with round or ovoid shape high signal without internal low signal in the ION except in one case which had n lesion in the dentat 이 ivary pathway The primary lesions were located in the contralateral DN in one case(fig. 3) and in the ipsilateral CTT in eight cases. In one case, no priπlary lesion was demonstrated in the course of dentato - rubro -tegmental tract. In three cases who showed bilateral ION lesions, the primary lesions were located in both CTT in one case and in the decussation just below the red nucleus in two(fig. 4). The natures of the primary lesions were hypertensive hemorrhage in seven cases(fig. 2), traumatic brain stem injury in one(fig. 4), Fig. 2. A 57-year-old man who developed left hemiplegia 5 years ag a. Axial T2-weighted(2500/80/1 )(TR /TE /ex citation) image shows hypointense lesion in right pontine tegmental area due to hemosiderin deposit(outlined arrows) b. At the level of medulla, right 이 ive reveals mild hypertrophy with high signal and internal U-shape less high signal band mimicking the shape of gray lamina of the infer ior olivary nucleus(arrows) a b - 634

3 Sang Joon Kim, et 81 : MR Findings in Palatal Myoclonus Fig. 3. A 72-year-old man with left dentate nucleus hemorrhage occurred 10 months ago a. Axial T2-weighted(2000/80/2) image shows hypointense lesion with surrounding high signal in left dentate nucleus area (arrows) b. Right 이 ive shows enlargement with high signal intensity lesion(arrows) a b a b Fig. 4. A 57-year-old man who was in the vegetative state for 1 0 months due to a automobile accident a. Axial T2-weighted(2500/80/1) image sh ws high signal intensty in central pons in volving decussation area(outlined arrows) and in the right side pons and the left superior cerebellar peduncle(arrow), probably due to shearing injuries. Note high signal intensities in both temporal tip(white arrows), typical area of cortical cerebral contusion b. At the level of medulla both olive are enlarged with high signal intensity presumed OCVM,in one and no primary lesion was fo 니 nd in one case. Interval between attack of the primary lesions and MR studies was 3 months to 15 years, with median of 20 months DISCUSSION Palatal myoclonus can be caused by hypertrophic degeneration of the ION located in the ventral part of the medulla. Neurons of ION are believed to be generators of palatal myoclonus, and when they are denervated, spontaneous generation of rhythmic discharge occurs(3, 4). This was proved in animal experiments with a preparation of is이 ated slices of guinea pig brain stem(5). The histopathologic changes in the ION are neuronal cell body enlargement, fibrillary gliosis, vacuolation of the nerve cells, and demyel ination and astrocyte proliferation of white matte r( 2, 6, 7), which are very peculiar responses to afferent pathway damage. These changes are responsible for the MR changes of hypertrophy and high SI in the ION. One interesting finding is the pattern of high signal of the ION. In six out of 10 patients T2WI revealed U shaped less high signal band surrounded by high signal area in the affected olive, resembling the shape of gray lamina of ION. To our knowlege, this finding was not reported previously in English literature. Our finding may show signal differences between affected nucleus itself and surrounding white matter. The prominence of presumed white matter damage suggests that white matter injury might contribute to the enlargement of the olive more than gray lamina, which correlates well with pathologic reports describing white matter change as the main factor of increased size of the olive, although both gray and white matter is enlarged(2). And the fact that these findings were prominent in cases with longer interval between the attack of causative lesion and the ION lesion suggests that the high signal in the gray matter might regress with time elapse. The changes of the ION are caused by the preceding lesions located on the same side CTT or the opposite side DN. Guillain and Mollaret proposed triangular relationship among the RN and ION on one side and the contralateral DN as an explanation of these association(1). However, the pathway between the DN and ION through the inferior cerebellar peduncle(icp) in this proposal was not considered significant in PM by other authors(1) because no lesion in the ICP was bserved associated with PM. The pathway from DN to contralaterallon via superior cerebellar peduncle and descending in the CTT after crossing midline is belie- -635

Journal of the Korean Radiological Society, 1994; 30( 4) ; 633-637 ved to be associated with PM or hypertrophic degeneration of ION (Fig. 1).

4 Journal of the Korean Radiological Society, 1994; 30( 4) ; ved to be associated with PM or hypertrophic degeneration of ION (Fig. 1). The exact mechanism of the specific secondary changes in the ION is not clearly understood yet, but a transsynaptic degeneration is thoughtto be a possible mechanism(1, 8) The underlying causes of the primary lesions are various; infarction, hemorrhage, tumor, trauma, encephalitis, multiple sclerosis or others(4). However, in our study, eight out of nine cases who showed primary lesions in the CTT or DN were old hemorrhages, which were demonstrated as low signallesions on T2WI with or without central high signal. Among eight cases with old hemorrhage, seven patients had hypertension. One patient who was not hypertensive showed thick low signal intensity rim with internal inhomogeneous high signal in pontine tegmentum on T1 - and T2 weighted images due to repeated hemorrhage suggesting OCVM In our cases, the interval between attack of brain stem sym ptom and MR study was 3 m onths to 15 years, but the exact time of occurrence of PM was not known because of absence of subjective symptoms in PM However it seems that more than several months should have passed to develop lesions in the ION and to evoke PM following lesions in brain stem or DN. In Goto and Kaneco's autopsy investigation, hypertrophy of the neurons began to appear about 3 weeks after the hemorrhage(9), an d others reported that 4 to 12 months were needed to develop ION lesion following CTT or DN lesions(2) One patient in our ten cases had no visible lesion in dentato- olivary pathway, and the patient was a 25 years old woman as opposed to old aged men in re maining cases. In reviewing MR findings 21 cases reported in nine English articles, four patients had no lesion in the ION or dentato- rubro - tegmental tract, two had lesion in ION only, and two had lesions in dentato rubro - tegmental tract without lesion in ION(3, 7, 10-16). The reason why all the patients with PM did not show lesions in the ION and CTT or the DN is not yet clear, but may be partly due to insufficient sensitivity of M R. Another possible explanation is that some ofthem had essential PM which was described by Deuschl et a l. as showing no abnormal finding in ION, CTT or DN pathologically(4) In conclusion, MR imaging is useful to show the brain lesions in patiens with PM and the lesions are hypertrophy with high SI in ION on T2WI with accompanying lesions in the ipsilateral CTT or contralateral DN, which is very specific. In addition, MR nal surrounded by higher signal area resembling the shape of the gray lamina surrounded by white matter of olive, which, to our knowlege, was not reported in the literature REFERENCES 1. Lapresle J, Hamida MB. The dentato- 이 ivary pathway: somatotopic relationship between the dentate nucleu s and the contralateral inlerior olive. Arch Neuro/1970; 22: Gautier JC, Blackwood W. Enlargement olthe inlerior 이 Ivary nu cleus in association with lesions olthe central tegmental tract or dentate nucleus. Brain 1961 ; 84: Dubinsky RM, Hallett M, Di Chiro G, Fulham M, Schwankhaus J Increased glucose metabolism in the medulla 01 patients with palatal myoclonus. Neurology 1991 ; 41 : Deuschl G, Mischke G, Schenck E, Schulte-M nting J, L king CH Symptomatic and essential rhythmic palatal myoclonus. Brain 1990; 113 : Ll in s RR. Rebound excitation as the physiological basis for tremor: a biophysical study of the oscillatory properties of mamma/ian central nervous system in vitro. In: Findley LJ, Capiled R, eds Movement disorders: tremor. New York : Oxlord University Press, Goto N, Kakimi S, Kaneko M. Olivary enlargement: stage 01 in itial astrocytic changes. Clin Neuropatho/1988; 7: Pierot L, Cervera-Pierot P, Delattre J-Y, Duyckaerts C, Chiras J, Brunet P. Palatal myoclonus and inlerior olivary lesions : MRIpathologic correlation. JCompu AssiTomo 1992 ; 16: Koeppen AH, Barron KD, Dentiger MP. Olivary hypertrophy histochemical demonstration 01 hydrolytic enzymes. Neurology 1980 ; 30 : Goto N, Kaneko M. Olivary enlargement: chronological and morphometric analyses. Acta Neuropathol(Ber!) 1981 ; Sperling MR, Herrmann C. Syndrome 01 palatal myoclonus and progressive ataxia: two cases with magnetic resonance imaging. Neurology 1985 ; 35: Yokota T, Hirashima F, Fukukawa T, Tsukagoshi H, Yoshikawa H MRI lindings 01 inlerior oli ves in palatal myoclonus. J Neurol 1989 ; 236 : Hirono N, Kameyama M, Kobayashi Y. et al. MR demonstration 01 a unilateral olivary hypertrophy caused by pontine tegmental hematoma. Neuroradio/1990; 32 : Zarranz JJ, Fontan A, Forcadas 1. MR imaging 01 presumed 이 IVary hypertrophy in palatal myoclonus. AJNR 1990 ; 11 : Revel MP, Mann M, Brugieres P, Poirier J, Gaston A. MR appea r ance 01 hype rtrophic olivary degeneration after contralateral cerebellar hemorrhage. AJNR 1991 ; 12 : Birbamer G, Buchberger W, Felber S, Aichner F. Letter: MR appearance 01 hypertrop hic olivary degeneration: temporal re lationship. AJNR 1992 ; 13: Revel MP, Gaston AP, Gray F. Repl y. MR appearance 01 hypertrophi -636

5 Sang Joon Kim, et a/ : MR Findings in Palatal Myoclonus 대한방사선의학회지 1994: 30(4) : 구개간대성근경련의자기공명영상소견 1 김상준 2 서대철 박만수.01 재홍 3 성기범 4 1 울산대학교밤사선과학교실신경과학교실 2 단국대학교방사선과학교실 3 중앙길병원신경과 목 적 : 구개간대성근경련 ( 口蓋間代性節헬짧 ) 은연구개의주기성경련으로, 연수에위치한하몰리브핵의비후성토 행에 기인하며이런특이한퇴행성변화늠뇌교나소뇌의치상핵에선행되는병변의결과로생기는것으로알려져있다. 저자들은 이러한병리학적으로밝혀진소견이자기공명영상에서어떤앙상으로나타나는지알고자하였다. 대상및방법 10 여 의구개간대성큰경런을보였던환자의자기공명영상을후향적으로분석하였다. 치상핵이나뇌교의피 개중심로 ( central tegmental tract) 의병변의위치와원인을분석하고이와관련된하올리브핵병변의위치및앙상을분석 하였다. 결 과 T2 강조영상소견상하올리브핵은전예에서고신호강도를보였고그중 6 예늠하올리브핵이커져있었다. 하올리브 핵병변의앙상은 6 예에서고신호병변내약간저신호의 U 형태또는병렬하는띠모양을보였고 4 예에서는원형또는타원형 의고신호병변으로나타났다. 선행병변의위치늠 8 여 에서이환된하올리브핵과같은쪽의뇌교의피개중심로에있었고, 1 예 에서반대쪽소뇌의치상핵에있었으며 1 예에서는선행병변이관찰되지않았다. 선행병번의원인은 7예가고혈압에동반된 뇌내출혈, 1 예가뇌간의외상, 1 예는잠복성뇌혈관기형에동반된것으로보이는출혈이었다. 결 론 : 구개간대성근경련환자에서자기공명영상은피개중심로나치상핵의병변에동반된하올리브핵의병변이라는매 우특이적인소견을보였고자기공명영상에서이러한소견을보일경우후자는분리된또하나의병변이아니라퇴행성변화 임을이해하늠것이중요하다하겠다. R /

6 겨 뼈 94 년도경희의대진단방사선과학교실연수교육 경희대학교의과대학방사선과학교실에서는다음과같이 1 994년도연수강좌를실시합니다. 본연수강좌의목적은육안적형태또는병리학적변화를이해하고, 이것을근거로방사선학적소견을이해하는데있습니다. 금년에는복부와흉부방사선해부및병리학을공부합니다. 많이참석하시어강사와청중이함께공부하는좋은기회가되었으면감사하겠습니다. 방사선과병리학 1994 년 5 월 15 일 ( 일요일 ) 연수교육담당교수이 드드 그 호 Gastric tumor 경희의대 동호교수 Inflammatory bowel disease 연세의대 검 기황교수 Intest1na l tumor 경희의대 그 l 최영태교수 Hepatic tumor 서울의대 병Al ~ 까..1ιT... "t..!. Bile duct disease 경희의대 임오재훈교수 Pancreati c disease 울산의대 용송호교수 Kidney & retroperitoneal tumor 서울의대 검 협교수 Uterine tumor Ovarian disease Lung tumor 가톨릭의대울산의대경회의대 하 --'- = 윤현권교수 λl~ζ느 -, - I 엽교수 Pulmonary interstitial disease 삼성의료원 이켜 U 수교수 Neuroradiology and Neuroscience 1994 년 11 월 20 일 ( 일요일 ) 연수교육담당교수최 C그 T 석 연수내용추후공고 장 소경희의료원강당 접수방법및연수비추후공고 경희대학병원진단방사선과 연수교육책임교수윤 엽 연락처 l -5( 교환 253 이

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