pathologies de la substance blanche chez l’enfant
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DESCRIPTIONPathologies de la substance blanche chez l’enfant. Dr. Kalthoum TLILI-GRAIESS Master Neuroradiologie FMS Avril 2008. Children WM Disorders. Genetic disorders affecting WM in pediatric age Acquired pathologies : inflammatory, auto-immune, tumoral or vascular diseases. - PowerPoint PPT Presentation
Pathologies de la substance blanche chez lenfant Dr. Kalthoum TLILI-GRAIESSMaster NeuroradiologieFMS Avril 2008
Children WM DisordersGenetic disorders affecting WM in pediatric ageAcquired pathologies : inflammatory, auto-immune, tumoral or vascular diseases.Although uncommon, aware of their occurence and able to recognize MR appearances.MR imaging is highly sensitive in the detection of WM lesionsLimited specificity with regards to the pathologic conditions underlying WM signal abnormalitiesCorrect diagnosis need multidisciplinar approach : clinical history DataFindings laboratory Data
Herpetic meningo-encephalitisCerebral Abscess
Childhood WM Disorders : MR approachVariable pathologic changes may underlie WM signal abnormalitiesHypomyelinationdysmyelinationDemyelinationGliosisInterstitial edemaMyelin vacuolationCystic WM degenerationDiffuse infitration by tumors cells (Gliomatosis)All types : lead to a non specifically increase signal intensity T2 WI, discrease signal intensity T1 WI
Childhood WM Disorders : MRI Morphological sequences Functional or parametric sequences and techniques:Evaluation WM biochemistry: MRSEvaluation WM tissue microstructure: diffusion and Magnetization transfer sequences May provide new insights.
Primary disorders : ADEM, MSSecondary disorders : Toxic, Viral.
Hyo and dysmyelinating lesions: more common primary disorders Classified according to causative enzyme defect
Lysosomal storage diseases: metachromatic leucodystrophy, Krabbe diseasePeroxisomal disorders: Zellweger syndrome , ADL X..
Mitochondrial syndromes : leigh syndrome, Kearns Sayre syndrome, MELASChildren WM Disorders
Genetic WM DisordersWell defined leucoencephalopathies Hypomyelinating disordersDysmyelinating disordersLeucodystrophiesDisorders related to cystic degeneration of myelinDisorders secondary to axonal damageUndefined leucoencephalopathies Up to 50 % of leucoencephalopathies in childhood Requiring multidisciplinar approach in order to define novel homogenious subgroups of patients and therefore new genetic disorders Megalencephaly-leucoencephalopathy with sub cortical cysts (1995), CACH Sydrome or Vanishing WM disease (1997) Van der Knaap Leucoencephalopathy with high brain lactate.
Characteristic MR pattern : Metachromatic leucodystrohy, ALDX, Canavan disorder
Role of MR techniques in the discrimination of differents WM disorders: Parametic imaging.Genetic WM Disorders
Classic: Sparing of the subcortical U fibersand periventricular WM. Tigroid patternFrequent involvement: CC,IC, corticospinaltracts Metachromatic leukodystrophyKrabbe diseaseEarly-onset form: pyramidal tract, periventricular WM, cerebellar WM,and deep gray matter ,The most often affected
Adrenoleucodystrophy, X linked ALD(1) Cheon JE et al, Radiographics 2002;22:461Symmetric abnormal signal internal capsule, deep cerebelar WM and descending pyramidal tractSymmetric WM demyelination in peri-trigonal regions Extendion across the corpus callosum spleniumSpread outward and cephalad
Megalencephaly and abnormal WM
Canavan disease L -2-hydroxyglutaric AciduriaMegalencephaly-leucoencephalopathy with sub cortical cysts Alexander disease
Diagnosis relay on neuroimaging and biochemical findings
Canavan diseasePredominant subcortical WM and dentate nuclei lesionsVariable basal ganglia involvementTypical brainstem involvement
L -2-hydroxyglutaric AciduriaSimilarities with Canavan except brainstem involvementSRM
Megalencephaly-leucoencephalopathy with sub cortical cysts. Van der Knaap 1995
Mehdi 11years-old and 3SDNaim 13 years-old and 4 SDSyrine 7 years-old and 2.5 SDMegalencephaly-leucoencephalopathy with sub cortical cystsMutation MLC1 gene although variable phenotype
Cerebral WM involvement in Mitochondrial disordersMajor findings : Alteration of basal ganglia and Brainstem
Demonstrated that severe WM involvement is possible (1,2) and even the only abnormal neurologic features (3) : 3 unrelated families / 5
Suggestive findings of mitochondria disease :Multiples small cyst-like lesions in the abnormal WMInvolvement of cerebral and cereberal WMCombination of Leucoencephalopathy and bilateral basal ganglia lesionsMRS : may demonstrate lactate or succinate peak
(1) Valannel et al AJNR 1998 ; 19 : 369 (2) Nakai A et al Lancet 1994; 343 : 1397 (3) de Lonlay Debeney P et al J Pediatric 2000 ; 136 : 209
13 months-old. Complexe II deficiencyLeigh disease
8 month-old child, Axial hypotonia
16 months-old girl with one week respiratory distressAt the age of 9 months progressive loss of normal developmental and motor acquisitions with sudden alopecia and global hypotoniaMild optic atrophy Brain stem acoustic-evoked potentials were deteriorated.lactic acidosis with high concentration of lactate and pyruvate in CSF and bloodBiotin responsive encephalopathy
5 month MRI follow-up Pharmacologic doses of biotinProgression of myelination with resolution of WM and GM abnormalities except for the genu of the corpus callosum which remains in high signal T2, low signal T1 and high ADC level, stigmate of cystic degeneration.normal pattern of the spectrum from right caudate et putamen and no lactate is detected
Childhood WM Disorders and MR parametric approachProspective Study (1) of 41 patients with WM disorders of known cause : 12 hypomyelinating,14 Demyelinating (10 Metachromatic and 4 Krabb), 5 disorders with myelin vacuolation10 disorders with cystic degenerationUsing MR parameters : MTR, ADC, FA and MRSDiscrimination between different types of pathologic conditions thar underlie signal intensity abnormatities in the WMLinear discimination analysis showed The combination of tCr, Cho, MTR and ADC mesurements results in only 2 misclassification 95 % of patients were correctly classified. (1) Van der Voorn JP et al , Radiology 2006; 241 : 510.
Healthy 5-year-old boy2-year-old boy with hypomyelination3-year-old girl with cystic degeneration6-year-old boy with demyelination11-year-old girl with myelin vacuolation
Oumaima, 8 years-old. Fever, Sudden onset Upper Limbs paresthesiaTreated as viral encephalitisCT Day 7MRI Day 8
3 Weeks later: Fever, headache and seizures. Cerebellar ataxia, facial and brachial motor deficit 4 months
Acute disseminated Encephalomyelitis ADEM
CNS demyelinating disease more frequently diagnosed (1) : 0,4 / 100000/year with incidence quadruple (98 2000 v/s 91-98) >>> MRI and Flair in acute encephalopathy
Usually following benign infection or vaccination in healthy young person
Acute neurologic symptoms with imaging evidence of demyelination: MRI required, CT usually normal.
Dilemna >> distinguish ADEM from MS: 4/42 (9.5%) initially diagnosed with ADEM were MS cases after episodes of demyelination (1).
(1) Leake JA et al Pediatr Infect Dis J 2004, 23 : 756.
ADEM Clinical impairement faster than neuroradiological deterioration Usually complete regression of clinical and neuroradiological symptoms Remaining deficit 10 20 %J41 Week Later3 Weeks Later
Heterogenous disease with variable course and developmentMonophasic formRDEM : Relapses with sterotype symptoms and without new MRI lesionsMDEM : reccurent pattern in long lengths of time (years) with new symptoms and corresponding new MRI lesions AHEM : rare, hyperacute onset , monophasic course with fever and severe neurologic dysfunction. Fulminant and often mortel outcome.
Spectrum of pathologies still imprecisely knownMost important pronostic factor for differential diagnosis with MS : FOLLOW-UP
ADEM Differential diagnosis
Lymes diseaseSubacute Sclerosing Panencephalitis Progressive multifocal leucoencephalopathy Blood coagualtion diseasesVasculitisLeucodystrophiesMitochondrial diseasesHaematologie disordersOptic neuromyelitis subform of ADEMSchilder and Balo diseases (variant of MS)MS ++
5 Y 11 Y Blindness and paraplegia
4 reviews concerning MS in childhood and summarizing published literature between 2005 2007.2 Focusing on MRI features All reviews state that children are more likely to have monosymptomatic illnessHave typically fewer lesions than adults with lower propensity for lesions to enhance with gadolinium.
(1) Banwell B et al Neurology 2007; 68: 546 (2) Chabas D et al NeuroRX 2006; 3: 264 (3) Pena JA et al Invest Clin 2006; 47: 413 (4) Waldman A et al Ment Retard Dev Disabil Res Rev 2006; 12: 147
IRM J8Extensive WM hypodensities : relapse immediatly after TTT arrest3 years-old, right hemiparesis with rapidly progressive onset Corticotherapy: complete regression of the symptoms and considerable decrease in cerebral lesion IRM at 6 yearsSequellea: R hemiparesis