1/16/2012 Neuroimaging in Childhood • Neuroimaging issues are distinct from Pediatric Neuroimaging in adults Neurometabolic-degenerative disorder • Sedation/anesthesia and Epilepsy • Motion artifacts Bhagwan Moorjani, MD, FAAP, FAAN • Requires knowledge of normal CNS developmental (i.e. myelin maturation) • Contrast media • Parental anxiety Diagnostic Approach Neuroimaging in Epilepsy • Age of onset • Peak incidence in childhood • Static vs Progressive • Occurs as a co-morbid condition in many – Look for treatable causes pediatric disorders (birth injury, – Do not overlook abuse, Manchausen if all is negative dysmorphism, chromosomal anomalies, • Phenotype presence (syndromic, HC, NCS, developmental delays/regression) systemic involvement) • Predominant symptom (epilepsy, DD, • Many neurologic disorders in children weakness/motor, psychomotor regression, have the same chief complaint cognitive/dementia) 1 1/16/2012 Congenital Malformation • Characterized by their anatomic features • Broad categories: based on embryogenesis – Stage 1: Dorsal Induction: Formation and closure of the neural tube. (Weeks 3-4) – Stage 2: Ventral Induction: Formation of the brain segments and face. (Weeks 5-10) – Stage 3: Migration and Histogenesis: (Months 2-5) – Stage 4: Myelination: (5-15 months; matures by 3 years) Dandy Walker Malformation Dandy walker • Criteria: – high position of tentorium – dysgenesis/agenesis of vermis – cystic dilatation of fourth ventricle • commonly associated features: – hypoplasia of cerebellum – scalloping of inner table of occipital bone • associated abnormalities: – hydrocephalus 75% – dysgenesis of corpus callosum 25% – heterotropia 10% 2 1/16/2012 Etiology of Epilepsy: Developmental and Genetic Classification of Gray Matter Heterotropia Cortical Dysplasia 1. Secondary to abnormal neuronal and • displaced masses of nerve cells • Subependymal glial proliferation/apoptosis (gray matter) heterotropia (most • most common: small nest common) 2. Secondary to abnormal neuronal adjacent to lateral ventricles • Band heterotropia (double migration • Range from nodular to band cortex) 3. Secondary to abnormal cortical heterotropia to schizencephaly, • Lissencephaly lissencephaly and • Cobblestone cortex (lis 2) organization or late migration polymicrogyria 4. Not otherwise classified • clinical: seizures • Subcortical heterotropia •IEM • MRI: isointense with gray • Other unclassified dysplasia matter in all sequence Subependymal heterotropia Subcortical heterotropia 3 1/16/2012 Double cortex Double cortex Double cortex Double cortex 4 1/16/2012 Polymicrogyria polymicrogyria • multiple abnormal tiny indentation along brain surface (5-7mm) • abnormal cortical histology • can be unilateral • MRI: decreased number of broad, thick, smooth gyri Polymicrogyria Pachygyria • thick and more completely developed gyri • commonly diffused with relative sparing of temporal lobes • associated with: agenesis of CC and heterotopias • clinical: microcephaly, seizures, MR, developmental delay • MRI: circumferential band of high signal on T2 within the cortex 5 1/16/2012 Lissencephaly Lissencephaly Imaging • Severe form of neuronal migration Disorder • Hourglass or figure of 8 • Can be seen in: – Shallow sylvian fissure – Isolation • LIS 1: parietal-occipital – Miller Dieker Syndrome • X-LIS: Subfrontal/temporal – TORCH infection (CMV) • 3 layers ay be seen in neonates on T2W • Clinical S/S: – Outer layer – thin, smooth – Mental Retardation – Intervening cell sparse layer – Intractable Epilepsy – Microcephaly – Deeper thick layer – mimicking band heterotropia • Posterior > Anterior involvement in LIS 1 lissencephaly Lissencephaly Variants 6 1/16/2012 Miller dieker Lissencephaly syndromes Agyria Lis 1 • Complete lissencephaly • Smooth brain Identified by figure eight due to shallow sylvian fissures. 7 1/16/2012 Schizencephaly Schizencephaly Imaging • Gray matter- lined • Transmantle gray matter lining clefts cleft that extends from – Dimple in wall of ventricle if closed or narrow the ventricular ependyma to the pia. • Frontal and Parietal lobes near central • Unilateral or bilateral sulcus • Two types: • Distinction of GM lining cleft can be – Closed lip (type I) difficult prior to myelination – Open lip (type II) • DVA overlie cleft seen on MRV Schizencephaly Schizencephaly Differential Diagnosis • Porencephaly – Lined by gliotic white matter – No dysplastic gray matter • Semilobar Holoprocencephaly – Can mimic bilateral open lip schizencephaly 8 1/16/2012 Schizencephaly Schizencephaly Hemimegalencephaly Hemimegalencephaly • Primary hamartomatous malformation • No differences between Isolated or Syndromic type. • Onset usually in neonatal period • Plain Skull Films: look for macrocrania & • Catastrophic asymmetry. • One type of onset is Tonic Seizure (Ohtahara • May see intracranial calcifications & bony Syndrome) dysplasia • US: prenatal may suggest HME, may see • Can be asymmetric and often precede or macrocephaly, ventricular asymmetry with overlap with West Syndrome (IS) enlargement of lateral ventricle – Postnatal: may see unilateral ventricular dilation with • IS= 50% hemispheric enlargement 9 1/16/2012 Hemimegalencephaly Imaging Hemimegalencephaly •CT & MRI: – Gross asymmetry – 1 hemisphere enlarged • Posterior falx and occipital pole displaced to contralateral side – Dysplastic Cortex – Asymmetry of Ventricular System - • 4 points of abnormal ventricle. – 1. Straightened frontal horns (pointed) – 2. mild-extreme dilation of lateral ventricle – 3. reverse of contralateral horn (mass effect appearance) –4. colpocephaly (disproportionate developmental dilation of occipital horn of lateral ventricle) in all grades of HME Hemimegalencephaly 10 1/16/2012 FCD with Balloon Cells FCD, Balloon Cell • Abnormal gyral pattern when large • Blurring of gray-white junction • Abnormal tissue: cortex to border of lateral ventricle • Typically associated with TS • Solitary – no other TS features • T2 hyperintense “comet tail” from cortex to ventricle – Best seen on flair FCD with balloon cell FCD with balloon cell 11 1/16/2012 DNET DNET • Intractable epilepsy • Focal deficits • More common 2nd and 3rd decade • Considered part of abnormal neuronal/glial proliferation - neoplastic • MRI Findings: – T1 hypointense – T2 hyperintense – Modest to no enhancement – Scalloping – Lack of mass effect, edema DNET DNET 12 1/16/2012 Neurometabolic-Degenerative Disorders Neurometabolic-Degenerative Disorders • Type of myelination involvement • Knowledge of normal myelination pattern – Delayed myelination is essential – Demyelination – Dysmyelination • General rules: – Caudal to cranial • Nervous system involvement – Brainstem involvement – Posterior to anterior – Cerebellar involvement • MRI provides the best imaging modality – Spinal Cord involvement – T1 matures at 12-14 months • Tissue Involvement – T2 matures at 24-26 months – Gray matter involvement – White matter involvement 1 month Factors to Consider • Age of Onset • Degree of derangement 9 months • Abnormal metabolite – Deficiency or excess • Stage of the disease process 36 months • Phenotype From Alberico 13 1/16/2012 Symptoms of Progressive CNS Disease Symptoms of Progressive CNS Disease Early Onset (Newborn or young infant) Later Onset ( older infant or child) • Intermittent lethargy, decreased responsiveness • Change in temperament, behavior or activity associated with emesis level • Irritability, excessive or absent startle response • Disturbance in gait (progressive ataxia), • Decreasing interest in surroundings, excessive clumsiness sleepiness, decreased smiling • Unusual movements, dystonia, chorea • Poor or absent eye fixation, nystagmus • Progressive muscle weakness, change in tone • Poor head control, weak suck • Feeding difficulties, FTT • Progressive loss of speech, vision or hearing • Excessive tongue trusting, asymmetric • Headaches movements • Change in bowel/bladder function • Floppy or spastic •Seizures •Seizures White Matter versus Gray Matter White Matter versus Gray Matter Early Disease Advanced Disease White Matter Gray Matter White Matter Gray Matter • Gait disturbance • Progressive cognitive • Progressive cognitive •Ataxia •Ataxia impairment impairment • Hyperreflexia • Brisk reflexes •Seizures • Blindness • Spasticity • Spasticity • Blindness • Deafness • Babinski sign • Babinski sign •Seizures 14 1/16/2012 Leukodystrophies Leukodystrophies Differential Diagnosis • Abnormal signal in white matter • Radiation and Chemotherapy injury • Symetric usually • Periventricular, deep or subcortical in location • Viral encephalitis • Failure to achieve myelination milestones •ADEM • MRS abnormalities reflect neuronal loss and •MS increased cellular turnover • In neonates: HIE • Some have contrast enhancement – Periventricular pattern – ALD: zone of active inflammation – Alexander: ventricular lining, periventricular rim, frontal WM, optic chiasm, fornix, BG, thalamus, dentate nucleus Head Circumference Alexander Disease Macrocephalic Microcephalic/Normal • Clinical S/S: macrocephaly, seizures • Canavan •ALD • Mutation: GFAP, Chromosome 17q21 • Alexander •MLD • Imaging • Tay Sachs (GM2 • Cockayne Disease – Extensive WM changes with frontal predominance gangliosidosis) • Pelizaeus Merzbacher – Abnormal signal in BG and thalami • Vanishing White Matter disease – Enhancement: ventricular lining, periventricular rim, • Van der Knaap Disease • Zellweger Disease frontal WM, optic chiasm, fornix, BG, thalamus, dentate nucleus • L-2-hydroxyglutaric • Krabbe aciduria • Give contrast to all unknown