ion Unilateral Cerebellar Aplasia By E. ~oltshnuse?, Maja Steinlinz, E. art in' und Th.~ e o n n d Department of Pediatrics, Universities of 'Zuerich and 2~ausanne,Switzerland We describe three children with unrlateral cerebellar aplasia (UCA). Deliveries at term and neonatal periods were uneventful. Pregnancy was normal in one and complicated by mild bleeding (in second and fourth month respectively) in two instances. Presenting signs were delayed motor development with marked contralateral torticollis (n = I), hemiplegia (n = 1) and unusual head nodding (n = 1).Neuroradiological investigations revealed complete aplasia (n = 1) and subtotal aplasia (n = 2) of one cerebellar hemisphere with only a residual wing-like structure below the tentorium. There was contralateral underdevelopmenl of the brainstem. The infant with hemiplwc cerebral palsy had an additional supratentorial periventricular parenchymal defect, contralateral to the cerebellar hypoplasia. In view of literature reports, describing similar neuroradiological or neuropathological £indings in asymptomatic individuals, it is doubtful whether UCA is responsible for our patient's problems. In our cases UCA has presumably resulted from a prenatal destructive lesion, possibly an infarct, but the timing and exact nature are d o w n . I Case reports Relevant anamnestic, clinical and neuroradiological data are summarized in Tables 1 and 2. Representative illustrations are gven in Figures 1-3. Mental development in Cases 2 and 3 was assessed by GrifFth Lest. In all three children, (fie neonatal period was uneventful, feeding was easy. There was no subsequent history of any severe illness, trauma, operation or anesthesia. Additional informations are given regarding neurological findings. Case 1 This boy's development was normal in the first few months. Noddug head movements started around 6 months of age, they were fluctuating in severity and disappeared when the chid was concentrating for tasks. These movements consisted of slow head rotation and of rhythmic anteroposterior excursions. Head tilt, head thrust and nystagmus were not observed. This head "tremor" was still present at the last examination. Cagmtive development was within normal limits, later he was able to attend regular school classes. Language development was initially considered to be rmldly delayed, but was later not remarkable, his reading was fluent. Alternating finger tapping movements were slightly slower Key words compared to controls, but his writing was perfed, there was no tremor or dysrnetria. Gross motor development was slower Cerebellum - Term neonate - MRI - CT in his mfaancy, he was considered clumsy. There was no frank Infarct truncal ataxia. When entering kindergarten, he was well able to stand on one leg and to ride a bicycle. He leamed to pay flute without particular difficulties. When examined at 8 years, ocular movements were normal, no cerebellar signs (tremor, ataxia, dysarthria) could be detected, intermitted head nodding Introduction was noted. Compared to his peers he was considered to be midline cerebellar malformations and symmet- clumsy rical neocerebellar hypoplasias are not uncommon (2, 3). W~th Case 2 increasing access to neurojmaging, minor d a t e r a l cerebellar hemisphere asymmetries are occasionally seen, but complete or This boy was first seen at 5 months because of subtotal absence of one cerebellar hemisphere is exceptional. motor delay. He was found to be hypotonic, he did not grasp for For the latter condition the terms agenesis or aplasia are found objects, head control was poor. There were no lateralizing in the literature. Although these cases appear to result horn neurological signs. Left torticollis was noted. Subsequently, in destruction of cerebelIar tissue, we use in this context the term the second year, symmetrical spasticity was found. Ocular aplasia, but Uus does not imply a particular pathogenetic movements were normal. Tremor was not a feature. Around mechanism. Unilateral cerebellar aplasia (UCA) is used to three years he managed to walk with assistance, increased tone descnbe total or subtotal absence of a cerebellar hemisphere. being the prominent feature. No truncal ataxia and dysarthria We wish to report three children with UCA. was found. Cognitive and language development was clearly delayed. At 31/2 years he was adrmtted following sudden onset of vomitmg and loss of consciousness. CT revealed extensive intraventricular and subarachnoid hemorrhage in the basal Received June 13, 1995; revised, accepted September 25, 1995 cisterns. Post-contrast examination was suggestive of an aneurysm at the skull base (Willis' circle). Angiog9phy was not Neuropediatrics 27 (1996) 50-53 Q Hippohtes Verlag Stutlgart performed. He died a few horn later. Autopsy was refused. 1 - - Downloaded by: University of British Columbia. Copyrighted material. Abstract Nevropediotrics 27 (1996) Table 1 Unllateral cerebellar aplasla: Anamnestlc and cllnlcal data. Sex Cerebellar Pregnancy Gest slde age affected Blrth Presentlng Presentlng welght age slgns Case 1 1983 M left bleeding 6th week term 2300 12 months Case 2 M rlght normal term 3220 5 months Year of blrth Case 3 Table 2 Unllateral cerebellar aplasla - Neuroradlologlcal flndlngs. 1991 1993 F left bleedlng term 4th month 3400 6 months motor retardatlon head tremor motor retardatlon left tortlcollls lefl hemlplegla Follow-up clumsy head tremor normal school motor and mental retardation IDQ 601 death at 3112 Y Ilntracranial hemonhagel mental retardation lDQ t 601 tetraspastlc left\ rlght - Age at examlnatlon Mode Cerebellar aplasla Bralnstem Supratentorial compartment Case 1 18 months CT subtotal pons asymmeMc mesencephalon normal Case 2 7 months MR total Case 3 8 months CT subtotal no asymmetry underdeveloped pons asymmetey symmetric Case 3 The ~ ~ ldevelopment ' s was considered normal in the first 3-4 months. She was then referred to an ophthalmologist for convergent squint. Her pediatrician noted asymmetry of her movements. This prompted CT examination at 8 months (Fig. 3). When seen as an outpatient at 10 months, marked left-sided hemiplegia was found. There was also in- flg. la Fig. la and b aspect. 51 - normal rlght perlventrlcular creased muscle tone in her right leg. She learned to crawl at 15 months, to stand up with support at 18 months, to walk unaided a t 24 m o n h . When last seen at 27 months, her developmental age companded to 1518 months. she talked in short sentences.~ ~truncalataxia ~ and tremor ~ were~ not present. ng. l b CTof Case 1. alSubtotal aplasla of left cerebellar hemisphere. blAsyrnmetry of bralnstem wlth underdevelopment of contralateral Downloaded by: University of British Columbia. Copyrighted material. Unilateral Cerebellar Aplasia E. Boltshauser et a1 27 (1996) Fig. 2b Fig. 2a flg. 2a and b MRI of Case 2. Total apiasla of rlght cerebellar hemisphere. Brainstem appears small but symmetric. Discussion In additional pathological reports of usually single cases of UCA, the cerebellar abnormality was "incidentally" detected (5, 10, 15, 18). For most cases no anamnestic details of pregnancy and delivery are given, it may thus be tempting to speculate that no relevant events in the perinatal and postnatal personal history have been noted. These pathological reports usually do not address specificallythe pathogenesis, and the terms aplasia and agenesis have been used. From the semantic point of view, these terms are problematic, as at least some cases are likely to result horn a secondary, destructive lesion of cerebellar tissue. Strong was probably the first to give a detailed postmortem description of an unsteady and retarded 3-year-old girl found to have "unilateral cerebellar agenesia" (17). Death was due to measles and bronchopneumonia. Unfortunately, no data are known regarding pregnancy, delivery and neurological examination. Strong drew attention to associated secondary changes, namely hypoplasias of ipsilateral middle and superior cerebellar peduncIes and superior colliculus, highly asymrnetncal pons with absent contralateral olivary body, contralateral reduction of red nucleus and substantia nigra. The pontine asymmetry and absent contralateral olive can well be recogModern neuroimaging methods have allowed nized in vivo by neuroimaging in our Cases 1 and 3 (Fig.1 and to recognize UCA in vivo, a few cases have been mentioned or illustrated in reports, mostly without supplying detailed ana3). Downloaded by: University of British Columbia. Copyrighted material. 52 Neuropediatrics - Unilateral Cerebellar Aplasia The pathogenesis of UCA is poorly understood and may not be uniform. In perinatal asphyxia at term, the cerebellum is almost always spared. In our ongoing study of perinatal asphyxla in term neonates, we have occasionally seen minor lesions but never resultmg in a substantial cerebellar defect (8).It is therefore suggested to consider a prenatal event. Cerebellar hemorrhages are well-known to occur in prematures and have been repeatedly reported in very low birth-weight preterrn babies of 26-28 weeks gestational age, however, these lesians are usually affecting only part of a cerebellar hemisphere (7, 14). In our own cases, we cannot draw firm conclusions, but we consider a localised hypoxic-ischemic lesion, an mfard, more likely than a hemorrhagic event. flg.3a to c CT of Case 3, alsubtotal aplasla of left cerebellar hemisphere. blHigher sections reveal marked contralateral asymmetry of bralnstern c) Perlventrlcular parenchymal defect responsible for contralateral congenital hemlplegla. mnestic and cluucal data (1,4, 6, 12, 13).In our cases delivery was considered completely uneventful in all patients, while pregnancy was complicated by minor hemorrhage in two instances. The neonatal period and the early personal history were completely uneventful. Our Case 2 died unexpectedly due to intracranial hemorrhage at 3l/2 years, presumably from aneurysmal bleeding. Postmortem study is not available. Since similar observations have not been found in the literature, the relationship of this hemorrhage to UCA may be coincidental. In our Case 3 there was an additional supratentorial periventricular lesion resulting in congenital hemiple~iccerebral palsy. In our previous MRI study of congenital hemiplegia, none of the 33 children had a cerebellar abnormality (16).In our view the observation of a combined supra- and lnfratentorial lesion is exceptional, and we cannot determine whether both defects occurred at the same time. Recovery from acqpred partial unilateral cerebellar lesions is usually substantial to complete (11). The Altmann, N. R., T. P. Naidich, B. H.Braman: Posterior fossa malformations. AJNR 13 (1992)691-724 Barth, P. G.: Pontocerebellar hypoplasias: an overview of a group of inherited newodegenerative disorders with fetal onset. Brain Dev. 15 (1993)411-422 De Souza, N.,R. Chaudhuri, I. Bingham, T. Cox: MRJ in cerebellar hypoplasia. Neuroradiology 36 (1994)148-151 Diebltr, C . , 0.Dulac: Pediatric Neurology and Neuroradiology Berlin, Heidelberg, New York, Springer-Verlag (1987) Erskine, C. A.:Asymptomatic unilateral agenesis of the cerebellum. Monatsscbr. Psychiatr. 119 (1950)321-339 Haddad, 1..1. Messer: Magnetic resonance imaging and hypoxic-ischemic brain injuries. In: Haddad, I., E. Saliba (Eds.): Perinatal Asphyxia. Berlin, Springer-Verlag (1993)1 1 5-1 18 Hadi, H.A,, 1. Finley, 1. Q. Mallette, D. Strickland: Prenatal diagnosis of cerebeUar hemorrhage: medicolegal implications. Am. 3: Obstet. Gynecol. 170 (1994)1392-1395 Kuenzle, Ch., 0.Baemiger, E. Martin, L. Thun-Hohenstein, M . Steinlin, M . Good, S. Fanconi, E. Boltshauser, R. H. Largo: Prognostic d u e of early MR imaging in term infants with severe perinatal asphyxia. Neuropedlatrics 25 (1994)191-200 Leiner, H. C.,A. L. Leiner, R. S . Dora: Cognitive and language functions of the human cerebellum. TINS 16 (1993)444-447 'O Mackimuicz, S.: fher einen Fall von halbseitiger Aplasie des Kleinhhs. Schweiz. Arch. Neurocbir. Neurol. Psychiatr 36 (1935)81-111 " Manto, M . , E. Godaux, 1.Jacquy: Detection of silent cerebellar lesions by increasing the inertid load of the moving hand. Ann. Neuml. 37 (1995) 344-350 l2 Mendelsohn, D. B., Y: Herhanu, R. B. J. Glass, E Spiro: Unilateral cerebellar hypoplasia. J. Comput. Assist. Tomogr. 7 (1983)107771078 l 3 Meyer, B.-U., S. R&icht, I. Machetanz: Reduction of carticospinal excitability by magnetic stimulation over the cerebellum in patient. with large defects of one cerebellar hemisphere. EJectroencephalogr. Clin. Neurophysiol. 93 (1994)372-379 14 Rorke, L. B., R. A. Z i m m m a n : Prematurity, posbnaturity, and destructive lesions in ukm. AJNR 13 (1992)517-536 l5 Simon, M., D. Kafitsas: Unilateral cerebellar hypoplasia. Clin. Newopalhol. 11 (1992)71-73 Steinlin, M., M . Good, E. Martin, 0.Baenziger, R. H. Largo, E. Baltshavser: Congenital hemiplegia: morphology of cerebral lesions and pathogenetic aspects horn MRJ. Neuropediatrics 24 (1993)224-229 l7 Sfrong, 0. S.: A case of unilateral cerebellar agenesia. J. Comp. Neurol. 25 (1915)361-391 l 8 Tennstedf, A.: Kleinhimaplasie beim Envachsenen. Zentralbl. AUg. Pathol. 107 (1965)301-304 clinical neurological and cognitive consequences of a large unilateral cerebellar defect are difficult (or impossible?) to predict. Judging kom the alder pathological literature describ'' ing UCA as an incidental kcling, one can assume that at least in some patients compensatory mechanisms prevent cerebellar motor deficits. However, since there is increasing evidence that the cerebellum seems to play an important role in learning, such lesions may be prognostically relevant (9). The limited experience with only few affected children not having uniform cerebellar lesions does not allow definite conclusions. In addition it seems that selection bias of cases recognized in vivo may play Prof. E. Boltshauser an important role. Our children's probIems are not explained Children's University Hospital by the finding of UCA. "Conventional" cerebellar signs were not Steinwiesstrabe 75 recognized. CH-8032Ziirich / Switzerland Downloaded by: University of British Columbia. Copyrighted material. References