2. Introduction
Complex series of diseases
Interaction of multiple organs (brain, csf,
blood)
Inside a semi-enclosed space
Fundamental change is perturbation of
– ICP
– Intracranial volume
Usually accompanied by changes in
ventricular size
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
3. Cntd.
Degree of change in ventricular volume
limited by
1. Volume of material inside the cranial vault
2. Intrinsic brain properties
Elasticity, Fluid flow, Porosity, Compliance
Atrophy etc.
A mathematical model can be applied
to predict changes
Neurosurgery Focus 22 (4):E3, 2007
Michelle J. Clarke MD, Frederic B Meyer MD:
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
4. Adequate understanding of hydrocephalic
diseases involve the interaction 4 major
research arms
1. Basic science
Physical parameters or organ properties (eg. Intracranial volumes...)
Understanding disease on a cellular level (eg. Oedema, tumours...)
2. Computer based mathematical
modelling
Macroscopic biomechanical framework
3. Animal studies
Platform to test theoretical interventions
4. Clinical correlation
Accuracy of the model systems
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
5. HISTORY
Ancient Greeks : ventricular puncture
Hippocrates : first attempt at CSF drainage
1898 : shunt into peritoneal cavity
(silver wire thru’ L5 into peritoneum hoping for a fistula!)
1907 : diversion into SSS
(mortality at 4 months, 100%)
1908 (Cushing) : first VP shunt
1910 (Lespinasse) : first attempt at endoscopic
cauterization of choroid plexus
1918 (Dandy) : surgical extirpation of CP
1939 (Torkildsen) : shunt from lat.vent. to cisterna
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
magna (50% mortality)
6. HISTORY
Many body cavities served as the distal terminus
for CSF diversion. (mastoid, salivary glands, thoracic
duct, spinal epidural space, bone marrow, omental bursa,
stomach, gallbladder ,ileum, ureter , fallopian tube !)
1952 (Nulsen and Spitz) : first valve system to
prevent reflux of blood
1955 : first successful ventricular-
atrial shunt
1955 (Holter) : multiple slit valve made of
silicone
1960 (Ransohoff et al) : 65% success with
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
ventricular-pleural shunts
7. HISTORY
1963 (Scarff) : 55% of 230, had arrested
hydrocephalus after VP shunting
1970 (Ames) : suggested peritoneum was best,
but risk of infection
(rate of VP shunting rose rapidly)
1979 (George et al) : VA and VP shunts showed similar
infection rates
The seventies : V-Peritoneal shunting
established as first line therapy for
hydrocephalus
Future : Endoscopy, antisiphon devices, kink
resistant tubes, silastic and new alloys,
Dr. Nishantha Gunasekera flow regulation, programmable shunts..
MBBS, MS, MRCS
8. HYDROCEPHALUS
Anatomy & Physiology
of CSF Circulation
Definition
Pathogenesis
Classification
Clinical Syndromes
Investigations
Management
The Future
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
9. HYDROCEPHALUS
Anatomy and Physiology of CSF
Circulation
Production
80% by choroid plexus
(95% lateral ventricles)
Interstitial spaces
Ependymal lining
Dura of nerve root sleeves
Rate 0.3ml/min, 450/24h
(largely independent of ICP!)
Turnover 3x /24h
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
10. HYDROCEPHALUS
Anatomy and Physiology of CSF
Circulation
Absorption
Primarily by arachnoid villi
bulk flow thru’ villi or absorbed from
hemisphere surface?)
Choroid plexus
Rate of absorption
pressure dependent
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
11. HYDROCEPHALUS
Anatomy and Physiology of CSF
Circulation
Property Paediatric Adult
newborn 1-10yrs
Total 5 varies with 150 (50%
volume(ml) age cranial 50%
spine)
Formation 25 changes 450-750
rate(ml/d) with age
Pressure 9-12 mean 10 7-15
(cm fluid) normal <15 (>18
Dr. Nishantha Gunasekera
abnormal)
MBBS, MS, MRCS
12. HYDROCEPHALUS
Definitions
An increase in CSF volume, in an enlarged
ventricular system, usually resulting from
impaired absorption, rarely from excessive
secretion.
This definition excludes hydrocephalus ex
vacuo. (atrophy, Alzheimer’s, CJD)
Prevalence: 1-1.5%
Incidence cong. HCP 0.2-3.5/1000 births
– Upto 20% after SAH
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
– 1% after meningitis
13. HYDROCEPHALUS
Pathogenesis
Fundamentally caused by disturbed csf
circulation or absorption
Pressure gradient between cortical
subarachnoid space and ventricular system
Sudden obstruction of csf pathways causes
immediate rise in R(out) and ICP,
followed usually by HCP
This results almost always in symptoms
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
and signs
14. HYDROCEPHALUS
Pathogenesis
Cytological changes are found in cortical
areas and in the white matter
Especially in the periventricular white
matter
Ependymal lining is flattened
Subependymal layer becomes degenerated
and its function decreases
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
15. HYDROCEPHALUS
Pathogenesis
Ventricular enlargement is NOT uniform
Begins in the lat. ventricles
Mostly in the frontal and occipital horns
The areas of least resistance
Volumes diminish in the cerebral sulci,
fissures and cisterns
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
16. HYDROCEPHALUS
Pathogenesis
Periventricular
lucency
Sharp demarcation between the
oedematous and normal white matter
CT or MRI correlates well with the ICP
and R(out)
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
17. HYDROCEPHALUS
Classification
Classified in many ways .. no consensus as yet!
However, practical systems have survived
Functional classification
Clinical
Age wise
Pathological /Aetiological
ICP and/or R(out)
There fore a Multi-axial Classification is suggested
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
18. HYDROCEPHALUS
Classification- Functional
Obstructive Communicating
(Non communicating) (Non obstructive)
Block proximal to the Block at the level of
arachnoid granulations arachnoid granulations
eg. aqueduct stenosis eg. Post meningitic
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
20. HYDROCEPHALUS
Classification- Clinical
1. High pressure hydrocephalus
– Acute
– Chronic
2. Normal pressure hydrocephalus
3. Arrested hydrocephalus
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
21. HYDROCEPHALUS
Classification- Age
1. Paediatric
2. Juvenile/adult
Symptoms and signs differ considerably
Therefore a very useful classification
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
22. HYDROCEPHALUS
Classification- Aetio-pathological
Congenital
a. Chiari type 2 malformation and or
meningomyelocoele (paeds, vermis, medulla )
b. Chiar type 1 malformation (young adults, tonsils)
c. Primary aqueductal stenosis
d. Secondary aqueductal gliosis (IU inf. /geminal
matrix h’rhage
e. Dandy-Walker malformation (2.4% of HCP)
f. Rare X linked inherited disorder
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
23. HYDROCEPHALUS
Classification- Aetio-pathological
Acquired
a. Infectious (most cmn. cause of com.HCP)
- Post meningitic (esp. purulent, basal, incl. TB)
- Abscess
- Cysticercosis, granuloma
b. Post haemorrhagic(2nd most cmn cause of com.HCP)
- Post SAH
- Post IVH (transient but 20-50% permanent HCP )
- Trauma
c. Secondary to masses
- Non neoplastic (eg. Vascular malformations, arachnoid cysts)
- Neoplastic (block CSF pathways)
Medulloblastoma, colloid cyst, pituitary tumour, suprasellar t.
- Choroid plexus papilloma (inc. production + block)
- Post op (20 % paed. pts. Require shunts after P. fossa tumour
Dr. Nishantha Gunasekera
removal)
MBBS, MS, MRCS
24. HYDROCEPHALUS
Classification- Aetio-pathological
Cntd.
d. Post op (20% paeds. develop permanent HCP
requiring shunt foll. P- fossa tumours)
e. Neurosarcoidosis
f. Constitutional ventriculomegaly (asymtomatic- no
Rx)
g. Associated with spinal tumours
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
25. HYDROCEPHALUS
Classification- ICP / R(out)
High pressure
monitored ICP >= 15mmHg
R(out) increased
B waves
symptoms depend on the speed of development of HCP
CBF and metabolism reduced periventricularly
Normal pressure
Monitored ICP <15mmHg
R(out) increased
Global CBF and metabolism usually normal
Management implications
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
26. HYDROCEPHALUS
Clinical syndromes
Age Infants and young Juvenile and
Onset children adults
Acute Irritability, low GCS,V, HA, V, Papillodema,
tense font. low GCS, upward gaze
palsy
Chronic MR, fail to thrive, cracked GAIT ATAXIA
pot, inc.skull circ., lid INCONTINENCE
retraction, Parinauds synd. DEMENTIA
(setting sun), thin scalp & (classic triad of NPH)
skull, dil. veins +Visual loss
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
27. HYDROCEPHALUS
Investigations
CT
MRI
ICP
R(OUT) Measured using specialized equipment and infusion sets
Isotope cisternography
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
28. HYDROCEPHALUS
4th ventricle NOT
dilated
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
29. HYDROCEPHALUS
Complicated dilatation
of ventricles
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
34. CT parameters for Diagnosis of HCP
FH = inter frontal horn diameter
ID = internal diameter
a.
b. TH = Temporal horn diameter >2mm
MID
Evans ratio = FH: Maximum interparietal
c.
diameter >30%=HCP
Mickey mouse sign!
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
35. Resistance to outflow of CSF
This is a more involved test
Requires a specialized hospital setting.
In essence, this test assesses the degree of blockage to CSF
absorption back into the bloodstream.
It requires the simultaneous infusion of artificial spinal fluid and
measurement of CSF pressure.
Spinal subarachnoid space is cannulated
ICP monitor is inserted
ICP is monitored while fluid is infused into the subarachnoid space
If the calculated resistance value is abnormally high, then there is a
very good chance that the patient will improve with shunt surgery.
Unit of measurement is mmHg/ml/min
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
36. Isotopic cisternography:
Radioactive isotope injected into the lumbar subarachnoid space
(lower back) through a spinal tap.
This allows the absorption of CSF to be evaluated over a period of
time (up to 96 hours) by periodic scanning.
This will determine whether the isotope is being absorbed over
the surface of the brain or remains trapped inside the ventricles.
Isotopic cisternography involves spinal puncture and is
considerably more involved than either the CT or MRI.
This test has become less popular because a "positive"
cisternogram result does not reliably predict whether a patient will
respond to shunt surgery.
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
37. HYDROCEPHALUS
Management flow chart
Clinical signs of HCP
Signs of high pressure
Signs of NPH
HCP
HCP (-) Obstructive
Further tests CT CT shunt
HCP (+) nonobstructive
ICP monitoring and MRI Ventriculostomy
perfusion test
raised
ICP? shunt
normal
No Shunt B Waves? shunt
<5% >50%
5-50%
No Shunt R out? shunt
>12mmHg/ml/min
Dr. Nishantha Gunasekera <12
MBBS, MS, MRCS
38. The basic shunt valve system
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
52. Evaluation of shunt function
History and examination
Radiographic evaluation (X rays, CT, MRI)
Shunt-o-gram
– Radioneuleid shun-to-gram (1mCi of Tc pertechnetate in 1cc fluid)
– X ray shunt-o-gram(omnipaque 180)
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
53. Programmable shunt systems
Programming with ext. magnet
Fig. 4. Dig ita l p a lp a -tio n a nd lo c a liz a tio n o f v a lve with e x te rna l p ro g ra m m e r o ve rla y . (I tra tio n c o urte s y o f Co d m a n, a Jo hns o n & Jo hns o n
llus
Dr. Nishantha Gunasekera Co , Ra y nha m , M s s . )
a
MBBS, MS, MRCS
57. Radiology of the pressure valve
Fig. 8A. Ra d io g ra p h o f a 3 5 -y e a r-o ld m a n re fe rre d fo r a ro u-tine p re s s ure
s e tting c he c k. The PACa ld we ll p ro je c tio n is d if- fic ult to inte rp re t d ue to va lv e
Dr. Nishantha Gunasekera s up e rim p o s itio n o n the p e tro us rid g e (a rro w).
MBBS, MS, MRCS
62. Before and after - progammable shunt
with regular adjustments
Fig. 6B. CT im a g e o f the s a m e p a tie nt a s in 6 Aa fte r p la c e m e nt o f a
Fig. 6A. Sp in-e c ho , T1 -we ig hte d tra ns a x ia l M im a g e d e m o n-s tra ting
R
Co d m a n Ha kim va lve , d e m o ns tra ting s hunt (white line a r o b je c t) a nd
v e ntric ulo m e g a ly o f the la te ra l v e ntric le s in a 6 4-y e a r-o ld wo m a n with
d e c re a s e d ve ntric ula r s iz e .
no rm a l-p re s s ure hy d ro c e p ha lus .
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
63. Synopsis
1. Complex and common group of conditions
2. Clinical syndromes vary
3. Choosing the correct intervention needs proper clinical
evaluation and target investigations
4. Selectively intervene depending on the individual case
5. Many options are available, shunts have stood the test of time
6. Some may not require shunts but observation
7. Minimally invasive techniques are available
8. Meticulous surgical technique to avoid complications
9. Sophisticated shunt systems can circumvent some shunt related
problems
10. Majority of patients can be gainfully integrated into society
Dr. Nishantha Gunasekera
MBBS, MS, MRCS
