RADIOLOGY OF DISEASES AFFECTING VENTRICLES OF BRAIN WITH IMAGES

1. RADIOLOGY OF VENTRICLES
DR ANJANEYULU SRIRAMA
RESIDENT ,NEUROLOGY
KING GEORGE HOSPITAL,VIZAG.

2. Anatomic overview.
• The brain CSF spaces- ventricular system and
subarachnoid spaces (SAS).
• The ventricular system -4 interconnected CSF-filled,
ependymal-lined cavities that lie deep within the brain.
• The paired lateral ventricles communicate with the 3rd
ventricle via the Y-shaped foramen of Monro.
• The 3rd ventricle communicates with the 4th ventricle
via the cerebral aqueduct (of Sylvius).
• In turn, the 4th ventricle communicates with the SAS
via its outlet foramina (the midline foramen of
Magendie and the 2 lateral foramina of Luschka).

5. Lateral ventricles.
• Body, atrium, and 3 projections ("horns").
• The roof of the frontal horn is formed by the
corpus callosum genu.
• Laterally and inferiorly by the head of the caudate
nucleus.
• The septum pellucidum, a thin sheet of tissue
that extends from the corpus callosum genu
anteriorly to the foramen of Monro posteriorly,
forms the medial borders of both frontal horns.

6. • The body of the lateral ventricle passes
posteriorly under the corpus callosum.
• Its floor is formed by the dorsal thalamus and
its medial wall is bordered by the fornix.
• Laterally, it curves around the body and tail of
the caudate nucleus.

7. • The atrium contains the choroid plexus glomus and is
formed by the confluence of the body with the
temporal and occipital horns.
• The temporal horn extends anteroinferiorly from the
atrium and is bordered on its floor and medial wall by
the hippocampus.
• Its roof is formed by the tail of the caudate nucleus.
• The occipital horn is surrounded entirely by white
matter fiber tracts, principally the geniculocalcarine
tract and the forceps major of the corpus callosum.

8. Lateral ventricle mass
• Choroid plexus cysts (xanthogranulomas) are a common, generally age-related,
degenerative finding with no clinical significance.
• They are usually bilateral and calcified.
• They may be hyperintense on FLAIR and occasionally show reduced diffusivity on
DWI.
• A strongly enhancing choroid plexus mass in a child is most likely a choroid plexus
papilloma.
• With the exception of the 4th ventricle, a choroid plexus mass in an adult is usually
meningioma or metastasis, not a choroid plexus papilloma.
• An innocent-appearing frontal horn mass in a middle-aged or older adult is most
often a subependymoma.
• A "bubbly" mass in the body of the lateral ventricle is usually a central
neurocytoma.
• Neurocysticercosis cysts can occur in all ages and in virtually every CSF space.

9. Foramen of Monro mass.
• The most common "abnormality" here is a pseudolesion
caused by CSF artifact.
• Colloid cyst is the only relatively common pathology here.
• It is rare in children and typically a lesion of adults.
• Flow artifact can mimic a colloid cyst, but mass effect is
absent.
• In a child with an enhancing mass in the interventricular
foramen, tuberous sclerosis with subependymal nodule
&/or giant cell astrocytoma should be a consideration.
• Masses such as ependymoma, papilloma, and metastasis
are rare.

10. 3rd ventricle.
• Single, slit-like, midline, vertically oriented cavity that
lies between the thalami.
• Roof- formed by the tela choroidea, a double layer of
invaginated pia.
• The lamina terminalis and anterior commissure lie
along the anterior border of the 3rd ventricle.
• Floor-formed by several critical anatomic structures.
• From front to back these include the optic chiasm,
hypothalamus with the tuber cinereum and
infundibular stalk, mamillary bodies, and roof of the
midbrain tegmentum.

11. • The 3rd ventricle has 2 inferiorly located CSF-
filled projections, the slightly rounded optic
recess and the more pointed infundibular recess.
• Two small recesses, the suprapineal and pineal
recesses, form the posterior border of the 3rd
ventricle.
• A variably sized interthalamic adhesion (also
called the massa intermedia) lies between the
lateral walls of the 3rd ventricle.
• The massa intermedia is not a true commissure.

12. 3rd ventricle mass.
• Most common "lesion" in this location is either CSF flow artifact or
a normal structure (the massa intermedia).
• Colloid cyst is the only common lesion that occurs in the 3rd
ventricle; 99% are wedged into the foramen of Monro.
• Extreme vertebrobasilar dolichoectasia can indent the 3rd
ventricle, sometimes projecting upward as high as the
interventricular foramen.
• Primary neoplasms in children are uncommon here but include
choroid plexus papilloma, germinoma, craniopharyngioma, and a
sessile-type tuber cinereum hamartoma.
• Primary neoplasms of the 3rd ventricle in adults are also
uncommon, though an intraventricular macroadenoma and
chordoid glioma are examples.
• Neurocysticercosis occurs here but is uncommon.

13. 4th ventricle
• Diamond-shaped cavity that lies between the
pons anteriorly and the cerebellar vermis
posteriorly.
• Its roof is covered by the anterior (superior)
medullary velum above and the inferior
medullary velum below.

14. • The 4th ventricle has 5 distinctly shaped recesses.
• The posterior superior recesses are paired, thin, flat CSF-
filled pouches that cap the cerebellar tonsils.
• The lateral recesses curve anterolaterally from the 4th
ventricle, extending under the brachium pontis (major
cerebellar peduncle) into the lower cerebellopontine angle
cisterns.
• The lateral recesses transmit choroid plexus through the
foramina of Luschka into the adjacent subarachnoid spaces.
• The fastigium is a triangular, blind-ending, dorsal midline
outpouching that points towards the cerebellar vermis.

15. Cerebral aqueduct
• Other than aqueductal stenosis, intrinsic
lesions of the cerebral aqueduct are rare.
• Most are related to masses in adjacent
structures (e.g., tectal plate glioma).

16. 4th ventricle mass
• Pediatric masses are the most common .
• Medulloblastoma, ependymoma, and astrocytoma predominate.
• Atypical teratoid-rhabdoid tumor (AT/RT) is a less common neoplasm that may
occur here.
It usually occurs in children under the age of 3 years and can mimic
medulloblastoma.
• Metastases to the choroid or ependyma are probably the most common 4th
ventricle neoplasm of adults.
• Primary neoplasms are rare.
• Choroid plexus papilloma does occur .
• Subependymoma is a lesion of middle-aged adults that is found in the inferior 4th
ventricle, lying behind the pontomedullary junction.
• A newly described rare neoplasm, rosette-forming glioneuronal tumor, is a midline
mass of the 4th ventricle.
It has no particular distinguishing imaging features and, although it may appear
aggressive, it is a benign (WHO grade I) lesion.
• Hemangioblastomas are intraaxial masses but may project into the 4th ventricle.
• Epidermoid cysts and neurocysticercosis cysts can be found in all ages.

17. HYDROCEPHALUS
AQUEDUCTAL STENOSIS

18. • Terminology
• Focal reduction of cerebral aqueduct diameter
• Imaging
• Ventriculomegaly of lateral and 3rd ventricles
with normal-sized 4th ventricle
• ± periventricular interstitial edema
(uncompensated hydrocephalus)

19. Differential Diagnoses
• Obstructing extraventricular pathology
– Neoplasm
– Vein of Galen malformation
– Quadrigeminal cistern arachnoid cyst
• Obstructing intraventricular (aqueductal)
pathology
• Postinflammatory gliosis (aqueductal gliosis)

20. • Pathology
• Congenital AS is common cause of fetal hydrocephalus
• Aqueductal web and fork are pathological subsets
• Clinical Issues
• Onset often insidious, may occur at any time from birth to adulthood
• DIAGNOSTIC CHECKLIST
• Consider
• Postinflammatory gliosis (aqueductal gliosis), particularly if history of prematurity or meningitis
• Carefully scrutinize posterior 3rd ventricle, tectum, and tegmentum for neoplastic mass
• Image Interpretation Pearls
• Tectal astrocytomas large enough to obstruct aqueduct may be missed on routine CT scanning
– MR more sensitive than CT for detecting obstructing mass lesion
– Consider neurofibromatosis type 1 when tectal astrocytoma is identified

37. NORMAL PRESSURE HYDROCEPHALUS

38. • Terminology
• Ventriculomegaly with normal CSF pressure, altered CSF dynamics
• Imaging
• Ventricles/sylvian fissures symmetrically dilated
– Out of proportion to sulcal enlargement
– Hippocampus is normal (distinguishes from atrophy)
• ± aqueductal flow void
• Periventricular high signal transependymal CSF flow
• 50-60% periventricular & deep white matter lesions
• MRS: Lactate peaks in lateral ventricles in NPH
• Aqueduct stroke volume > 42 μL reported to correlate with good
response to shunt

39. • Differential Diagnoses
• Normal aging brain
• Alzheimer disease
• Multi-infarct dementia (MID)
• Subcortical arteriosclerotic encephalopathy

40. • Pathology
• Leading theory: Poor venous compliance in superior
sagittal sinus impairs CSF pulsations and CSF
absorption through arachnoid granulations
• Pathogenesis of NPH poorly understood
• Clinical Issues
• Heterogeneous syndrome (classic clinical triad =
dementia, gait apraxia, urinary incontinence)
• Image Interpretation Pearls
• Intraventricular lactate level may be useful in
differentiating NPH from other types of dementia

59. THANK U

60. EXTRAVENTRICULAR OBSTRUCTIVE
HYDROCEPHALUS

61. • Terminology
• Extraventricular obstructive hydrocephalus (EVOH)
– "Communicating" hydrocephalus
• Enlarged ventricles due to mismatch between CSF formation,
absorption
• Imaging
• Obstruction distal to 4th ventricle outlet foramina
• Size varies with duration of obstruction
• All ventricles enlarged with no intraventricular obstructive cause
• Lateral 3rd, 4th ventricles dilated
• ± abnormal density/intensity of cisternal CSF ± leptomeningeal
enhancement

62. • Top Differential Diagnoses
• Intraventricular obstructive hydrocephalus
• Ventricular enlargement 2° to parenchymal loss
• Normal pressure hydrocephalus
• Pathology
• Subarachnoid hemorrhage
– Most common cause of EVOH
• Other etiologies include suppurative meningitis, neoplastic or inflammatory
exudates
• SAH, exudates may fibrose/occlude subarachnoid space
• Clinical Issues
• Headache, papilledema
• Nausea, vomiting, diplopia (cranial nerve palsy)
• Diagnostic Checklist
• EVOH: Generalized ventricular enlargement with abnormal density/intensity in
basal cisterns ± leptomeningeal enhancement

68. INTRAVENTRICULAR OBSTRUCTIVE
HYDROCEPHALUS

69. • Terminology
• Intraventricular obstructive hydrocephalus (IVOH) =
obstruction proximal to foramina of Luschka, Magendie
– Acute (aIVOH)
– Chronic "compensated" (cIVOH)
• Imaging
• aIVOH = "ballooned" ventricles plus indistinct ("blurred")
margins
– "Fingers" of CSF extend into periventricular WM
– Most striking around ventricular horns (periventricular "halos")
– After decompression, corpus callosum may show hyperintensity
• cIVOH = "ballooned" ventricles without periventricular
"halo"

70. • Top Differential Diagnoses
• Ventricular enlargement 2° to parenchymal loss
• Normal pressure hydrocephalus
• Extraventricular obstructive hydrocephalus
• Choroid plexus papilloma
• Longstanding overt ventriculomegaly in adults
• Pathology
• Intraventricular obstruction to CSF flow
– CSF production continues, ventricular pressure ↑
• CSF production continues, ventricular pressure ↑
• Ventricles expand, compress adjacent parenchyma
• Periventricular interstitial fluid increases
– Leads to myelin vacuolization, destruction
• Leads to myelin vacuolization, destruction
• Pathology varies depending on obstruction etiology
• Diagnostic Checklist
• Ventricle size generally correlates poorly with intracranial pressure
• Image Interpretation Pearls
• Size of ventricles generally correlates poorly with intracranial pressure
• Pulsatile CSF may create confusing signal intensity, even mimic intraventricular mass
• Ventricular asymmetry can be normal variant

89. CSF SHUNTS AND COMPLICATIONS

90. • Imaging
• Shunt failure → dilated ventricles + edema around
ventricles, along catheter and reservoir
• Use CT or MR to evaluate ventricle size, plain
radiograph shunt series to identify mechanical shunt
failure
• Top Differential Diagnoses
• Shunt failure with normal ventricle size or lack of
interstitial edema
• Noncompliant ("slit") ventricle syndrome
• Acquired Chiari 1 malformation/tonsillar ectopia

91. • Pathology
• Obstructive hydrocephalus: Secondary to physical blockage by tumor, adhesions, cyst
• Communicating hydrocephalus: Secondary to ↓ CSF absorption across arachnoid granulations
• Clinical Issues
• Older children/adults: Headache, vomiting, lethargy, seizure, neurocognitive symptoms
• Infants: Bulging fontanelle, ↑ head circumference, irritability, lethargy
• DIAGNOSTIC CHECKLIST
•
• Consider
• Shunt + headache does not always mean shunt failure
– Consider sinusitis, trauma, sinovenous thrombosis, viral infection!
• Confirm programmable shunt valve setting after MR
• Plain film shunt series has extremely low yield in absence of clinical evidence for mechanical shunt
failure
• Image Interpretation Pearls
• Compare with prior studies to detect subtle ventricular size changes
• Poor ventricular compliance may prevent change in ventricular size despite florid clinical shunt
failure
• Fluid tracking along shunt may be only sign of failure, possible even if ventricles normal or
unchanged size

112. THANX