21/01/2021
Learning Objectives
Congenital Malformations of the • 10 key concepts CSF Spaces • CSF biomechanics modified by genetic and environmental factors • Approach to supratentorial and infratentorial cystic malformations • Tie up some loose ends Dr K Mankad • Reflections Consultant Paediatric Neuroradiologist Great Ormond Street Hospital for Children, London No Disclosures
Concept 1: Bulk flow and Laminar flow Normal ciliary movement No outer dynein arms
• Bulk flow- driven by arteriovenous pressure gradients and arterial pulsations. • Laminar flow- Ciliary beating (Near wall CSF dynamics).
A lack of outer dynein arms results in virtually no ciliary movement
Chilvers et al, J Allergy Clin Immunol 2003;112:518-24
Primary Ciliary Dyskinesia
In 24 hours each brain ependymal cilia will beat 3,200,000 times
Hirst et al: Infect Immun 2004;72:6694-8 & J Infect Dis 2008;1;197(5):744-51
1 21/01/2021
Concept 2: Fetal onset/ Congenital hydrocephalus
• Genetic factors • Environmental- Vitamin deficiency, infection, haemorrhage
L1CAM
Syndromic congenital hydrocephalus
• Neural tube defects Gene locus Suggested pathways • Ciliopathies L1CAM Neuronal adhesion AP1S2 Vesicle trafficking • RASopathies MPDZ Planar cell polarity • CCDC88C WNT signalling pathway Dystroglycanopathies EML1 Planar cell polarity • mTORopathies WDR81 Neuronal differentiation • Skeletal dysplasias Bona fide human congenital hydrocephalus genes
Cerebrospinal Fluid Disorders, Springer 2019
Environmental causes- Meningitis
2 21/01/2021
Concept 3: Midline cysts (supratentorial)
Holospheric dorsal cyst Hemispheric dorsal cyst
Cyst Type Comm. with Vent. Descriptor 1a Yes No other cerebral malformations Concept 4: Interhemispheric cysts 1b Yes Hydrocephalus 2nd to malformations 1c Yes Small head size with cerebral hypoplasia 2a No Only associated with callosal dysgenesis 2b No Multiloculated cysts with PMG and PVNH 2c No Associated with subcortical heterotopia 2d No Arachnoid cysts
Concept 5: Arachnoid cysts Aicardi Syndrome • Congenital or acquired- arachnoid ‘splitting’ • Up to 60% in the middle cranial fossa/ Sylvian fissure. • Inner layer of arachnoid cells and outer collagenous membrane.
Callosal dysgenesis + Infantile spasms + chorioretinal lacunae
Choroid plexus papilloma; Gastric polyps; Cardiac defects 30 weeks prenatal Day 1 17 weeks
3 21/01/2021
A different twist… Concept 6: Midline cysts (infratentorial)
CMN Syndrome
Dandy Walker Inf ver hypoplasia Blakes Pouch cyst Mega cisterna M Arachnoid cyst Vermis Hypoplastic Hypoplastic Normal Normal Normal 4th ventricle Enlarged Enlarged Enlarged Normal Normal Post fossa Enlarged Normal +/- Normal Normal Hydroceph. Yea Nay Yes Nay Nay T-V angle >40 18-45 <30 <18 <18
Role of fetal biometry Taenia-Tela Choroidea
DWM BPC IVH
Courtesy: Matthew Whitehead, USA
4 21/01/2021
The ‘tail sign’
• Thick and elongated nodulus. • Sign of increased thickness of the 4th ventricular roof. • Always indicative of a vermian pathology.
Concept 7: How benign is BESS?
4 days of life 10 weeks of life
‘External hydrocephalus’ due to delayed maturation of the arachnoid villi-inability to absorb CSF. They mature by 18 months.
Concept 8: Cyst of the Velum Interpositum Concept 9: Perivascular spaces
• Involved in clearance of interstitial fluid and waste from the brain • Periarteriolar > perivenular • Crucial role in the pathogenesis of small vessel disease- adults
Are perivascular spaces components of the glymphatic system?
5 21/01/2021
Concept 10: Choroid fissure cysts
Hurler’s Syndrome Hypomelanosis of Ito RHOA- mosaic Companion case
• Occur in the plane of the choroidal fissure. In summary • Neuroglial/ Neuroepithelial/ Arachnoid origin. • Often asymptomatic. • • If there are temporal seizures, look around it. CSF flow dynamics- bulk and laminar. • Genetic and environmental factors – CH. • Syndromic associations are plenty. • Cysts- supratentorial and infratentorial. • Look hard for associated malformations.
The tail end
Not all cysts are CSF containing…….TBC Thank you for listening in. Cheers! 10 months apart @drmankad
6