Posterior fossa malformations

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Berenice Hall
5 years ago
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1 ANDREA ROSSI, MD Head, Department of Pediatric Neuroradiology G. Gaslini Children s Research Hospital Genoa Italy andrearossi@ospedale-gaslini.ge.it Posterior fossa malformations Cerebellar ataxia Hypotonia Asthenia and fatigue Superior cognitive function deficits Cerebellar Syndrome Patients with posterior fossa malformations typically present with psychomotor/developmental delay Desmond JE et al., J Neurosci months, nystagmus, apnea 5-mm study 3D 1 mm 3-mm Molar tooth malformation normal Anterior vs posterior vermis: 1:2 Midbrain/medulla vs Pons 1:2 Primary fissure Primary fissure T Ex vacuo enlargement megacisterna magna! Inferior vermis hypoplasia Brainstem dysplasia (early AP patterning) 1

2 DWI b 700 T1 FGF8 Otx2 Isthmic organizer Cr10q4 Cr14q22 26 W 40 W Barkovich, Front Neuroanatomy W normal 21 W 28 W Be careful with early diagnoses of vermian hypoplasia/dwm! BPC 2

3 CEREBELLAR AGENESIS DIABETES MELLITUS, PERMANENT NEONATAL, WITH CEREBELLAR AGENESIS PTF1A: 10p12.3 RHOMBENCEPHALOSYNAPSIS Absence of the vermis with midline fusion of the cerebellar hemispheres, dentate nuclei, and cerebellar peduncles normal 22 W Case courtesy Daniela Prayer, Vienna, Austria PCH PONTOCEREBELLAR HYPOPLASIA PCH type 1 (with spinal anterior horn degeneration) (Barth, type 1) PCH type 2 (with extrapyramidal features) (Barth, type 2) PCH type 3 (with optic atrophy, 7q11-21) PCH type 4 (fatal infantile OPCH) PCH type 5 (with hypocellular vermis and fetal seizures) PCH type 6 (multiple respiratory chain defects and mutations in the mt RARS2 gene) MRI: the dragonfly sign Consequence of extreme prematurity with a birth weight <1500 g Proposed mechanisms: - Selective vulnerability at weeks - Presence of hemosiderin At birth (28 W) 3

4 DANDY-WALKER MALFORMATION 1) Complete or partial agenesis of the vermis with counter-clockwise rotation 2) Cystic dilatation of the fourth ventricle 3) Enlarged posterior fossa with upward displacement of lateral sinuses, tentorium, and torcular Affected individuals often have motor deficits such as delayed motor development, hypotonia, and ataxia; about half have mental retardation and some have hydrocephalus Who knows what a Dandy-Walker malformation really is? Case courtesy Anna Pichiecchio, Pavia, Italy 22 W 2 months 2 years 21 W 30 W 5 days 1 year 4

5 Anterior Membranous Area choroidal fold Counter-clockwise rotation of a hypoplastic vermis with torcular elevation is the key feature indicating a developmental arrest of the anterior membranous area Flat fastigium Large ( > 45 ) tegmento-vermian angle Who knows what a Dandy-Walker malformation really is? My own opinion in 2014: There is no Dandy-Walker malformation, but rather a Dandy-Walker sign resulting from two hits: (i) inferior vermian hypoplasia plus (ii) a mechanical expansion of the fourth ventricle that causes rotation (perhaps due to overlying meningeal dysplasia, or even acquired defects) D Dx: Retrocerebellar cysts with intact cerebellum Posterior Membranous Area choroidal fold BP Blake s pouch Megacisterna Magna (No hydrocephalus, incidental finding) Blake s Pouch Cyst persistent > 25 W!! (macrocrania, raised ICP) Normal 25 W UNILATERAL CEREBELLAR HYPOPLASIA 3 years 7 days Affected patients are typically asymptomatic or minimally symptomatic and, typically, no associated abnormalities are found elsewhere in the brain Early disruption 29 W 5

6 CEREBELLAR CORTICAL DYSGENESIS HME MEB Z Rumboldt MOLAR TOOTH MALFORMATION MOLAR TOOTH MALFORMATION 20 W Joubert syndrome Abnormal breathing (hyperpnea/apnea) Ataxia Abnormal eye movements Developmental delay Joubert syndrome Abnormal breathing (hyperpnea/apnea) Ataxia Abnormal eye movements Developmental delay normal Joubert-related cerebello-oculo-renal syndromes In JS, the fibers of the pyramidal tract and the superior cerebellar peduncles do not cross, irrespective of the underlying mutation Poretti et al, AJNR 2007? JS Ophthalmologic and nephrologic evaluation Abdominal US 6

7 PTCD: PONTINE TEGMENTAL CAP DYSPLASIA inverted pons HGPPS HORIZONTAL GAZE PALSY WITH PROGRESSIVE SCOLIOSIS SPLIT PONS SIGN Rossi A, AJNR 2003 DORSAL TRANSVERSE AXONAL BAND Jissendi-Tchofo 2009, Barth 2007 PTCD NORMAL HGPPS HORIZONTAL GAZE PALSY WITH PROGRESSIVE SCOLIOSIS SPLIT PONS SIGN Rossi A, AJNR 2003 KAL1 L1 PROK2 ROBO3 PROKR2 CHN1 KIF21A NORMAL HGPPS Wahl M, 2010 Engle et al

Han-Sung Kwon M.D. Department of Obstetrics and Gynecology Konkuk University School of Medicine Seoul, Korea

Han-Sung Kwon M.D. Department of Obstetrics and Gynecology Konkuk University School of Medicine Seoul, Korea Embryologic features of the developing hindbrain Embryologic features of the developing hindbrain