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CONGENITAL BRAIN ANOMALIES for radiology.pptx
- 1. CONGENITAL BRAIN ANOMALIES Dr.Mahfuza AkterMahi DMRD(Course) Radiology and Imaging SOMC.
- 3. • Posterior fossaHerniations /Malformations • Disorders of Commissural development • Disorders of Cortical development • Disorders of Diverticulation/Cleavage
- 4. Posterior fossa herniation/malformations •CHIARI MALFORMATION • DANDY WALKER MALFORMATION • MEGA CISTERNA MAGNA • RHOMBOENCEPHALOSYNAPSIS • JOUBERT’S SYNDROME
- 5. CHIARI MALFORMATION- I •Herniation of cerebellar tonsils into cervical canal • Incidental (50 % asymptomatic)
- 6. • Elongated, peg-shapedcerebellar tonsils • Tonsillar descent below basion-opisthion line • Diminished/absent CSF flow at posterior FM • Crowded foramen magnum IMAGING FEATURES
- 8. Associated conditions Hydrocephalusin up to 30% of cases- In ~35% -associated skeletal anomalies : platybasia/basilar invagination/reduced clival length atlanto-occipital assimilation syndromic associations Klippel-Feil syndrome, Achondroplasia, Marfans
- 9. • Complex hindbrainmalformation with myelomeningocele • Pathology and imaging manifestation: It is a complex anomaly having abnormalities of the following: 1. Skull and dura. 2. Brain. 3. Ventricles. 4. Spine and spinal cord CHIARI II
- 10. . Small posteriorfossa . Inferiorly displaced medulla, vermis . “Straw shaped” fourth ventricle . Prominent massa intermedia . Lacunar skull . Abnormal dura (gaping FM, fenestrated falx) . “Towering” and “creeping” cerebellum . Myelomeningocele in nearly 100% IMAGING
- 12. Chiari malformation type III oSmall posterior fossa o Caudally displaced brainstem o Low occipital or upper cervical bony defect o Cephalocele with herniation of meninges, dysplastic brain, ventricles
- 13. Hindbrain Malformations Dandy-Walker Spectrum •Dandy-Walkermalformation (“classic”) •Dandy-Walker variant - • isolated inferior vermian hypoplasia •Persistent Blake pouch cyst (BPC) •Mega cisterna magna (MCM)
- 14. Large posteriorfossa (PF) Cyst extending posteriorly from fourth ventricle Variable vermian, cerebellar hypoplasia High-inserting venous confluence CLASSIC DANDY WALKER ON MRI
- 16. Dandy -Walker variant/Vermianhypoplasia PF normal size “Keyhole” opening of fourth ventricle
- 17. BLAKE POUCH CYSTMEGA CISTERNA MAGNA
- 18. DWM DWV Persistent Blake’spouch Mega cisterna magna Retro-cerebellar cyst Vermis Hypo-plastic Rotated upwards Hypo-plastic No or mild hypoplasia No or mild hypoplasia 4th ventricle Markedly dilated Dilated Dilated Normal Posterior fossa Expanded Normal size Normal size Normal size hydrocephalus 75 % of cases 25% of cases Present No
- 19. Commissural maldevelopment Major Commissures Corpus callosum (13th wk) Anterior (8th wk) Posterior (11th wk)
- 20. Corpus Callosum agenesis Corpuscallosumagenesis Complete corpuscallosum agensis Partial corpuscallosum agenesis Splenium & rostrum absent Genu & body present Common congenital brain disorder:
- 21. COMPLETE AGENESIS Complete absence ofcorpus callosum (CC) = agenesis o Hippocampal commissure (HC) absent o Anterior commissure (AC) often present
- 22. Coronal o “Viking helmet”or “moose head” appearance o “High-riding” third ventricle o Probst bundles IMAGING
- 23. Axial • Parallel lateralventricles • Nonconverging, widely separated
- 24. Note the widenedand dilated lateral ventricles, that create an appearance reminiscent of a formula one car seen from above
- 25. Moose head appearance Note the absence of the corpus callosum, with the ventricles taking on the appearance of a moose head, with the third ventricle representing the moose's actual head, and the lateral ventricles the horns.
- 27. The vikinghelmet appearance refers to the lateral ventricles in coronal projection in patients with dysgenesis of the corpus callosum. . An alternative name is moose head appearance. Viking helmet sign Typical appearance of the lateral ventricles, remaniscient of a viking helmet.
- 28. Malformations of CorticalDevelopment • Abnormal Glial proliferation/apoptosis • Microcephaly • Megalencephaly • Cortical dysgenesis • Abnormal Neuronal migration • Heterotropia • Lissencephaly spectrum Abnormal Postmigration development • Polymicrogyria • Schizencephaly • Focal cortical dysplasia
- 29. Malformations Secondary toGlial/Neuronal Proliferation or Apoptosis Microcephaly Primary- genetic Secondary –Infection. Ischemia, Maternal DM, Trauma Imaging Small cranial vault Closely opposed sutures Cortex may be normal or show simplified gyration
- 30. Enlargement of apart or whole of one cerebral hemisphere, Ipsilateral ventricle is frequently dilated. Heterotopic gray matter is common. Sulcation is frequently abnormal. The underlying white matter may be hyperplastic or hypoplastic. Hemimegaloencephaly
- 31. Abnormal Neuronal migration Heterotopias: -Characterized by the presence of normal neurons at abnormal sites Nodular type(common) Diffuse(uncommon) Subependymal/ Periventricular Lissencephaly Subcortical Band type
- 32. -Nodular type: Focal subependymalnodules - indent the ventricular wall Diffuse subependymal nodules - border the walls of the lateral ventricle. Do not enhance on administration of intravenous contrast.
- 34. Subcortical heterotropia • focal subcorticalmass of heterotopic gray matter • Thin overlying cortex
- 35. Band Heterotopia Double cortexsyndrome Affects Females Imaging Band of GM deep to cortex
- 36. Lissencephaly pachygyria spectrum Refersto “smooth brain” with absent or poor sulcation. Due to neuronal under migration type I (classic) lissencephaly type II (cobblestone complex) lissencephaly
- 37. Classic Lissencephaly • CT APPEARANCE •smooth, nearly agyric surface • shallow sylvian fissures (Axial)
- 38. Classic Lissencephaly • MRI APPEARANCE •Thin cortical ribbon • Hyperintense cell-sparse zone • Thickened cortex • Agyria
- 39. Type 2 Lissencephaly • Cobblestoneappearance • Associated with muscular dystrophy syndromes
- 40. Schizencephaly (Split Brain) •Characterized by presence of gray matter lined CSF filled cleft that extends from the ventricular (ependymal) surface of the brain through the white matter to the pia. • Can be unilateral or bilateral, symmetric or asymmetric. • Two types: Closed lip (type 1) or open lip (type II)
- 41.
- 42. • Holoprosencephaly andvariants • Septo-optic dysplasia ANOMALIES OF VENTRAL PROSENCEPHALON DEVELOPMENT
- 43. HOLOPROSENCEPHALY Incomplete separation ofthe two hemispheres ‘Holo’ –Single alobar holoprosencephaly semilobar holoprosencephaly lobar Holoprosencephaly Can effect diencephalic structures
- 44. Alobar Holoprosencephaly • singlemidline monoventricle • absent midline structures • absent septum pellucidum • agenesis or hypoplasia of the corpus callosum • absent interhemispheric fissure and falx cerebri
- 45. Semilobar holoprosencephaly • absenceof septum pellucidum • monoventricle with partially developed occipital and temporal horns • rudimentary falx cerebri: absent anteriorly • incompletely formed interhemispheric fissure
- 46. Lobar Holoprosencephaly • fusionof the frontal horns of the lateral ventricles • wide communication of this fused segment with the third ventricle • absence of septum pellucidum
- 47. Findings Alobar SemilobarLobar Craniofacial anomalies Severe Variable Absent or mild Ventricles Monoventricle Rudimentary occipital horn Squared-off frontal horns Septum pellucidum Absent Absent Absent Falx cerebri Absent Patrial Well formed Interhemispheric fissure Absent Partial Present Thalami, basal ganglia Fused Partially separated Separated
- 48.
Editor's Notes
- #5 4 types--Sag t1 scan showing elongated extend below foramen magnum into upper cervical spinal canal
- #6 5mm//McRae line // hyperintensity in the upper cervical cord ſt that may represent "presyrinx“ state.// obliterated retrotonsillar csf spaces//
- #8 DIFFERENTIAL DIAGNOSIS--Normal anatomic variant // Intracranial hypotension(CSF leak)//Acquired tonsillar herniation(hydrocephalus, tauma) Clivus/ant arch of atlas/dens
- #13 Blake’s pouch cyst
- #14 Lambdoid torcula inversion(torcular lying above the level of the lambdoid due to abnormally high tentorium) Sagittal T2WI MR DWS shows a hypoplastic, rotated vermis , lack of fastigial crease, and incomplete vermian lobulation of the posterior lobules beyond the primary fissure . The cyst wall is faintly seen .
- #15 Sagittal MRV demonstrates torcular lambdoid inversion. The transverse sinuses st angle upward toward the torcular as the cyst has prevented normal fetal torcular descent. Note the persistent fetal occipital sinus ſt. (Right)Green arrow = vermian hypoplasia. Thick red line = superior border of the fourth ventricle. Yellow line = upward sloping tentorium cerebelli. Thin red line - outline of brainstem
- #16 Veins and falx do not traverse CSF collection.//Arachnoid cyst erosion of the overlying bone//
- #19 Posterior also known as hippocampal// habenular // supraoptic/// white matter tracts that cross midline connecting 2 cerebral hemispheres// rostrum genu body isthmus splenium
- #20 Splenium and rostrum is usually last to develops
- #21 ?CT/MRI..Absent corpus callosum with spoke of wheel gyri radiating from third ventricle and normal ant. Commisure.
- #22 Coronal T2WI showing upturned lateral ventricles ,Probst bundles , heterotopic GM(curved) .// third ventricle expands into the interhemispheric fissure
- #23 (Fill arrow) Probst bundles/// common association is colpocephaly- Disproportionately dilated occipital horns of lateral ventricle.
- #28 Mental retardation, developmental delay and seizures
- #29 Gyration may be simplified , mcrogyric, pachygyric//ventricles may be enlarged//primary microcephaly shows craniofacial disproportion with a 1.5:1 ratio, sloping forehead . Note the thin dysplastic corpus callosum , simplified gyral pattern (fewer gyri with shallow appearing sulci)
- #30 Hamartomatous overgrowth of on cerebellar hemisphere//displaced falx//enlarged I/l ventricle
- #31 - Result of arrested neuronal migration from periventricular germinal zone to the cortex along the radial glial fibers
- #32 Diffuse are X linked//They are best appreciated on medium tau inversion recovery sequences.
- #33 Extensive subependymal nodules line the walls of the lateral ventricles. These nodules follows gray matter signal intensity on all sequences and appearance is typical of periventricular nodular heterotopia. Background of semi-confluent periventricular and external capsule white matter hyperintensities consistent with microangiopathy.Partial empty sella.
- #34 Deformed underlying ventricle// d/d -Gangliocytoma
- #35 MRI of an 8 year old demonstrates a continuous ribbon of grey matter seen just deep to the cortex, separated from it with a thin layer of white matter. The overlying brain demonstrates some shallowness of sulci. Incidental cavum septum pellucidum et vergae is noted. o Thin, gyriform cortex o Normal-appearing WM under cortex o Smooth inner band of GM o Normal-appearing periventricular WM
- #36 No gyri -Agyria Poorly formed (BROAD) gyri –Pachygyria (sparse flat)
- #37 Ncct scan showing “hourglass” configuration// figure of 8 appearance
- #38 A hyperintense cell-sparse zone ſt separates the thin cortical ribbon from the thicker band of disorganized neurons, which is in turn separated from the ventricles by white matter.
- #39 Due to overmigration//frontal-predominant cobblestone lissencephaly
- #40 Closed opposed //wider separation //Open is more significantly impared
- #43 Single ventricle / monoventricle// Normal separation is complete by 5 weeks/// craniofacial abnormalities
- #44 lateral and third ventricles are absent//absent olfactory tract// small rim of cortex , fused thalami, horseshoe monoventricle
- #45 incomplete forebrain division//Axial non-contrast CT of the brain (with thick slice sagittal reformat) demonstrates fused frontal lobes with absent anterior part of the falx cerebri. There is also absence of the septum pellucidum with fusion of the lateral ventricles with rudimentary occipital and temporal horns, with a prominent dorsal cyst. 2 study questions available
- #46 Two selected images from an MRI of the brain demonstrate fusion of the frontal horns of the lateral ventricles with abnormal genu and rostrum of the corpus callosum and partial fusion of the cingulate gyrus anteriorly. The anterior cerebral artery is azygous and displaced anteriorly.