hydrocephalus and csf disorders powerpoint presentation

1. HYDROCEPHALUS

2. Hydrocephalus
a) VentricularAnatomy
b) CSFDynamics
c) Etiology
d) Classification

3. a) Ventricular Anatomy :
-Theventricularsystemconsistsoftwolateral
ventriclesandmidlinethird&fourthventricles
-TheforamenofMonro connectsthelateralventricles with
thethirdventricle
-Thecerebralaqueduct(ofSylvius)connectsthethird
ventriclewiththefourthventricle
-Thefourthventriclecontinuesinferiorlyasthecentral canal
ofthespinalcord,thefourthventriclealso drainsintothe
subarachnoidspace&basalcisterns viathreeforamina:
PairedforaminaofLuschka(LuschkaisLateral) Single
foramenofMagendie (Magendie isMedial)

4. Pathway of CSF
Flow
Lateral ventricles
Foramen of Monro  Third ventricle
Aqueduct of Sylvius
Fourth ventricle
Foramina of Magendie and Luschka
Subarachnoid space of brain &spinal
cord
Reabsorption into venous sinus

5. Subarachnoid
cisterns

7. 1-Midbrain ,2-Pons ,3-Medulla ,4-Cisterna magna ,5-4thventricle ,6-
Cerebellum ,7-Tentorium cerebelli ,8-Cerebral aqueduct (of Sylvius)

8. Normal Sagittal T2 shows CSF flow-related signal void at the aqueduct of
Sylvius (long black arrow) ,foramen of Magendie (thick black arrow) and
foramen magnum (white arrows)

9. b) CSFDynamics :
-CSFisproducedbythechoroidplexus,whichislocated in
specificlocationsthroughouttheventricular system:
1 Body&temporalhorns ofeachlateralventricle
2 Roofofthirdventricle
3 Roofoffourthventricle
-Nochoroidplexusinthecerebralaqueductoroccipitalor
frontalhornsofthelateralventricles

10. -Theventricularvolumeisapproximately25mL,the volume
ofthesubarachnoidspaceisapproximately 125 mL,fora
totalCSFvolumeofapproximately150 mL
-CSFproductionis500 mL/day,whichcompletely
replenishesthetotalCSFvolume3-4timesperday
-CSFisabsorbedprimarilybythearachnoid granulations
(leptomeningeal evaginationsextending intothedural
venoussinuses)&toalesserextentby thelymphatic
system&cerebralveins

11. T1 of the normal brain showing typical flow of CSF) ,CSF is black ,from the paired lateral
ventricles (LV) ,CSF passes through the paired interventricular foramina of Monro (yellow
arrow) into the single midline third ventricle (TV) ,CSF then flows down the single midline
aqueduct of Sylvius (a channel shaped like a toothpick and slender in all diameters ;green
arrow) into the single midline fourth ventricle (FV) ,CSF leaves the ventricular system
through the two lateral foramina of Luschka and the midline foramen of Magendie ,here ,
CSF is shown exiting through the foramen of Magendie (blue arrow) and entering the
cisterna magna (CM) ,within the subarachnoid space (SAS) ,CSF flows over the convexities of
the brain and the folia of the cerebellum and around the brainstem (curved arrows) ,from
the CM ,CSF also courses inferiorly to surround the spinal cord (orange arrow)

12. c)Etiology :
-Largeventriclesnotalwaysduetoincreased CSF
volume:
1 Cerebralatrophicprocessescanleadto
relativeenlargementofventricles
2 Ventriclesmaybecongenitallylarge(probably
secondarytoreducedwhitemattervolume)

13. -Increased CSF volume may be due to :
1 Overproduction(choroidplexustumors,i.e.
papilloma&carcinoma)
2 Obstructionofflow(non-communicating/
obstructive)
3 ReducedCSFresorption(communicatingnon-
obstructive)

14. -Hydrocephalus more likely if :
1 Commensurate(identical)enlargementof
temporalhorns
2 Ventriclesdisproportionately enlarged
comparedtosulci
3 Effacementofthirdventricularrecess
4 EvidenceofCSFtransudation(periventricular)

15. d)Classification :
(i) Non-CommunicatingHydrocephalus
(ii) Communicating Hydrocephalus

16. T
y
p
e
s
&

17. (i)Non-Communicating
Hydrocephalus :
a) Etiology
b) RadiographicFeatures

18. a)Etiology :
1 ForamenofMonro Obstruction
2 AqueductObstruction
3 Fourth VentricleObstruction

19. 1 Foramen of Monro Obstruction :
a) 3rdVentricleTumors:
1 ColloidCyst
2 Oligodendroglioma
3 CentralNeurocytoma
4 Giantcellastrocytomaintuberoussclerosis
5-Ependymoma
6-Meningioma (rare)
b)SuprasellarTumors

20. 2-Aqueduct Obstruction :
a) Congenitalaqueductstenosis
b) Ventriculitis
c) Intraventricularhemorrhage
d) Tumors:
-Mesencephalic(Mid Brain)
-Pineal,posterior3rdventricularregion
-Tectalglioma

21. 3-Fourth Ventricle Obstruction :
a) Congenital:Dandy-Walker(DW)
malformation
b) Intraventricular hemorrhage
c) Infection(cysticercosis)
d) Subependymoma
e) Exophyticbrainstemglioma
f) Posteriorfossatumors:ependymoma,
medulloblastoma,hemangioblastoma ,
metastasis,astrocytoma

22. b)Radiographic Features :
1 Disproportionatedilatationofventriclesupto the
pointofobstruction
2 Underlyingabnormalitycausingthe
obstruction
3 Ballooningoftemporalhorns(MickeyMouse
ears)isasensitivesign
4 Effacementofsulciduetomasseffect

23. Mickey mouse ears

24. Increased frontal horn radius (Mickey
mouse ventricle)
Dilatation of the temporal horns (>2mm)
Acute ventricular angles

25. The Evans' index
Ratio of maximum width of the frontal
horns of the lateral ventricles (A) and
maximal internal diameter of skull (B) at
the same level
Employed in axial CT / MRI images Varies
with the age and sex
Marker of ventricular volume A/B > 0.3 -
Hydrocephalus

26. (ii)Communicating
Hydrocephalus :
a) Etiology
b) RadiographicFeatures
c) NormalPressureHydrocephalus
d) Spontaneous IntracranialHypotension

27. a) Etiology :
-NoobstructiontoCSFflowbutpoorresorption
througharachnoidgranulationssecondaryto:
1-Posthemorrhagic(especiallySAH)
2-BacterialMeningitis
3-Malignant Meningitis
4-Surgery
5-VenousThrombosis

28. b)Radiographic Features : (1-3as
non- communicating)
1 Ballooningoftemporalhorns
2 Effacementofsulci(masseffect)
3 Periventricularinterstitialedema(T2Wbright
halo)
4 Symmetrical dilatation of all ventricles
5 The4thventricleisusuallynotveryenlarged

29. c)Normal Pressure
Hydrocephalus :
1 Definition
2 RadiographicFeatures

30. 1-Definition :
-Formofcommunicatinghydrocephalusin
whichthereisnoevidenceofincreased
intracranialpressure
-Clinicaltriad:gaitincoordination,dementia&
urinaryincontinence
-ClinicalresponsetoCSFtapisthegoldstandard for
establishingthediagnosis

31. Types
Idiopathic NPH : When no obvious cause is
identified
Secondary NPH :Impaired absorption of CSF is
the suspected mechanism in most cases of
secondary NPH.

32. The MC causes are :
Intra-ventricular or subarachnoid hemorrhage
Prior acute or ongoing chronic meningitis
Paget disease at the skull base,
mucopolysaccharidosis of the meninges, and
achondroplasia are other rarely reported causes of
secondary NPH

33. 2-Radiographic Features :
-No specificimagingfindings
-Dilatedventricles(frontalandtemporalhorns of the
lateralventriclesmostaffected)
-PeriventricularT2brighthalo
-Prominentcerebralaqueductflowvoid(classically referredto
hypointensityintheSylvianaqueductasa resultofto-and-
froCSFflow,onT1:CSFsignalis replacedbysignalthatis
lowerthanthatofthe contentsofthelateralventricles,on
T2:thereislow signalinsteadoftheexpectedhighfluid
signal)

34. T2 shows enlarged ventricles with normal volume of brain parenchyma ,the
frontal horns (solid arrow) and the posterior horns (open arrow) of the
lateral ventricles are dilated ,the third ventricle (arrowhead) is very wide ,
the hypointensity in the third ventricle signifies turbulent flow of
cerebrospinal fluid

35. Cingulate sulcus sign :
Denotes the posterior part of the cingulate
sulcus being narrower than the anterior
part.

36. Hydrocephalus
ex vacuo
Compensatory enlargement of the CSF spaces
Seen in :
asymptomatic elderly people : aging brain with related volume
loss
pathological conditions that promote brain shrinkage:
• generalised brain degeneration(eg:.Alzheimer’s disease
and leukodystrophies)
• Encephalomalacia due to focal damage(eg: stroke &
traumatic injuries)

37. Benign
external
hydrocephalus
Enlargement of the subarachnoid space
frontal or
frontoparietal regions
Ventriculomegaly : absent or mild.
Clinically, infants have macrocephaly but otherwise well-appearing and
have normal development.
Presentation : progressive increase in the head circumference with normal
anterior fontanel.
Family history of macrocephaly : Frequent
Self-limited
Do not require any intervention

38. Arrested
hydrocephalus
Asymptomatic/ occult/ compensated/ long standing overt
ventriculomegaly of adulthood/ late onset idiopathic aqueductal
stenosis
Moderate to severe tri-ventricular enlargement
No evidence of periventricular fluid
accumulation on imaging
Stable for years
Incidental diagnosis

39. d)Spontaneous Intracranial
Hypotension : (SIH)
1 Incidence
2 RadiographicFeatures

40. 1-Incidence :
-The syndrome of intracranial hypotension results
when CSF volume is lowered by leakage or by
withdrawal of CSF in greater amounts than can be
replenished by normal production
-Manifests as postural headache exacerbated by
upright position

41. 2-Radiographic Features :
-Downwarddisplacementofcerebellartonsilsand
midbrain(sagging),(D.D.fromChiariI)
-Flatteningofpons againstthedorsalclivus
-Subdural collection
-Diffusebrainswelling
-Distention of major dural venous sinuses , the dural
sinuses enlarge as they compensate for the loss of
intracranialCSFvolume:
Venousdistensionsign>>thesignispositivewhen thereisa
convexinferiormarginofthemidportionof thedominant
transversesinusonasagittalimage,thisisdistinctfromthe
normalappearanceofthis segmentwhichusuallyhasa
concaveorstraight lowermargin
-Diffuseduralenhancementseenin100% ofcases

42. T1 showing superiorly a hyperaemic and engorged pituitary gland (superior
arrow) ,the inferior arrow shows the abnormal inferior displacement of the
cerebellar tonsils through the foramen magnum

43. T1 shows the sagging brain appearance with distortion of the anterior margin
of the pons and medulla (black arrows) and decreased vertical dimension
of the suprasellar cistern and sagging tuber cinereum (dashed arrow) ,as
well as the prominent pituitary gland (white arrow)

44. Sagittal T2 & T1+C show :sagging of the midbrain as well as cerebellar
tonsils ,enlarged dural sinuses and hypophysis

45. T1+C shows diffuse pachymeningeal (dural) enhancement (open
arrows)

46. Axial T1+C showing increased dural enhancement and slightly increased
subarachnoid space seen on coronal T2

47. T1+C shows marked enhancement of thickened pachymeninges
(small arrows) and downward displacement of the cerebellar
tonsils (large arrow)

48. (a) Normal inferior margin of the midportion of the dominant
transverse sinus (concave or straight lower margin) ,(b)
Venous distension sign

49. T1 through the approximated middle third of the dominant
transverse sinus shows convex inferior margin of the
transverse sinus (curved arrow) that is the Venous Distension
Sign indicative of IH