3. Anatomy and Physiology CSF
• Absorbtion:
- Primarily by the Arachnoid villi
• Rate of production
- 0.3ml/min or approx 450ml/24 hrs
• Turnover: 3 times/day
4. CSF CIRCULATION
• Lateral ventricles – Foramen of Monro
• 3rd Ventricle – Cerebral Acqueduct
• 4th Ventricle – F. of Magendie & Luschka
• Perimedullary and Perispinal subarachnoid spaces –
upward to the basal cistern
• Superior and lateral surfaces of the cerebral hemispheres
8. Pathological
• Acquired
3. Secondary to mass effect
- Non neoplastic
- Neoplastic
- Choroid plexus papilloma
- Post operative
- Neurosarcoidosis
- Assoc with spinal tumours
- Constitutional ventriculomegaly
9. Special Types
HYYDROCEPHALUS EX VACUO
• enlargement of the ventricles due to loss of
cerebral tissue (cerebral atrophy)
• usually as a function of normal ageing
• Accelerated by Alzheimer's
disease, Creutzfeldt-Jakob,
Alcoholism
10. Special Types
EXTERNAL HYDROCEPHALUS
• enlarged subarachnoid spaces over the frontal poles in the
first year
of life
• ventricles are normal or minimally enlarged
• may be distinguished from subdural hematoma by the "cortical
vein sign"
• usually resolves spontaneously by 2 years of age
• Etiology :
• Unclear
• Defect in CSF resorption is postulated
• External hydrocephalus (EH) may be a variant of
communicating hydrocephalus
11. Special Types
ARRESTED HYDROCEPHALUS
• Compensated hydrocephalus
interchangeably
• There is no progression or
deleterious sequelae requiring CSF
shunting
• Criteriae in the absence of a CSF shunt:
- Near normal ventricular size
- Normal head growth curve
- Continued psychomotor development
13. Special Types
HYDRANENCEPHAL Y
• A post-neurulation defect
• Total or near-total absence ofthe cerebrum
• Intact cranial vault and meninges
• Intracranial cavity being filled with CSF
• There is usually progressive macrocrania
• Most commonly cited cause : B/L ICA infarcts
• Infection
- Congenital or neonatal herpes
- Toxoplasmosis
- Equine virus
14. Special Types
ENTRAPPED FOURTH VENTRICLE
• AKA isolated fourth ventricle,
• 3rd Ventricle X 4th ventricle X
Foramina of Luschka or
Magendie
- Post-infectious hydrocephalus( fungal)
- Repeated shunt infections
• Choroid plexus of the 4th ventricle :
produces CSF which enlarges the ventricle
15. Special
Types
NPH
• Classic triad:
- Dementia
- Gait disturbance
- Urinary incontinence
• Communicating hydrocephalus on CT or
MRI
• Normal pressure on random LP
• Symptoms remediable with CSF
shunting
16. NPH
• Etiology
- Post SAH
- Post-traumatic
- Post-meningitic
- Following posterior fossa surgery
- Tumors including carcinomatous
meningitis
- Also seen in -15% of patients with
Alzheimer's disease
- Deficiency of the arachnoid granulations
- Aqueductal stenosis
18. INFANCY
• Head grows at alarming rate with hydrocephalus.
– First sign: Bulging pulsatile fontanelles
– Tense, non-pulsatile anterior fontanelle
– Dilated scalp veins
– Thin skull bones with separated sutures
• Cracked pot sounds on percussion : Mc Ewans sign
19. INFANCY
• Depressed eyes or SUN SET sign
– Eyes downward with sclera visible
above
• Pupils sluggish with unequal response to
light
• Irritability, lethargy, feeds poorly,
• Changes in Level of Consciousness
• Arching of back (Opisthotonus)
• Lower extremity spasticity
21. INFANCY
• Emesis, Somnolence, Seizures, and Cardio Pulmonary
Distress
• Severely affected infants may not survive neonatal period
22. CHILDHOOD
• Headache on awakening, improvement following emesis or sitting
• Papilledema, strabismus, and Extrapyramidal signs, ataxia
• Irritability, Lethargy, Apathy, Confusion, and often incoherent
25. Clinical
• Occipito Frontal Circumference
- OFC of a normal infant = Distance from
Crown to Rump
• Indicators:
- Crossing curves
- Head growth > 1.25cm/wk
- OFC approaching 2 SD above normal
- Out of proportion with body length or
weight, even if normal for age
29. CT/ MRI Findings Acute
Hydrocephalus
• Preferential AP dilatation of the Temporal Horns
> 2mm
• Ballooning of the Frontal Horns and 3rd
Ventricles (Mickey Mouse sign)
• Periventricular interstitial edema
• Flattening of the Inter-hemispheric and
Sylvian fissures
• Upward bowing of corpus callosum on
sagittal MRI
• 4th Ventricle normal in size
30. CT/ MRI Findings Chronic
Hydrocephalus
• Temporal horns may be less prominent
• 3rd ventricle may herniate into Sella
Turcica
• Erosion of Sella
• Corpus callosum atrophy
• Irreversible white matter demyelination
31. Isotope Cisternography
• Radioisotope injected into Lumbar
Sub- arachnoid space
• Absorbtion of CSF monitored periodically
over 96 hrs
• Positive cisternogram does not
predict response to shunt surgery
34. Drug Therapy
• The choroid plexus shares many ion pumps and
enzyme
systems with renal tubular epithelium
– Acetazolamide:
Start @ 25mg/kg/day PO TID
Increase @ 25mg/kg/day to 100mg/kg/day
Simultaneously start Frusemide @1mg/kg/day
36. Drug Therapy
• Watch for electrolyte imbalance and
acetazolamide side effects:
- tachypnea
- paresthesias
- Lethargy
- diarrhea
• Perform weekly CT scan and insert ventricular
shunt if progressive ventriculomegaly occurs.
• Otherwise, maintain therapy for a 6 month trial,
then taper dosage over 2-4 weeks
37. Spinal Taps
• HCP after IVH may be transient
• Serial taps (ventricular or LP) may temporize
until resorption resumes
• LPs only for Communicating HCP
• No reabsorption when the protein content of
the CSF is < 100 mg/dl
Spontaneous resorption unlikely
SHUNTING
39. Choroid Plexectomy
• Described by Dandy in 1918 for
communicating hydrocephalus
• May reduce the rate but does not totally halt
CSF production
• Open surgery associated with a high mortality
rate
• Now a Days Can Be done Endoscopically
40. 3rd Ventriculostomy
• Resurgence of interest in third ventriculostomy
(TV) with the recent increased use of
ventriculoscopic surgery
• Indications:
- Obstructive HCP.
- Mgt of shunt infection
- Subdural hematomas after shunting
- Slit ventricle syndrome
41. 3rd Ventriculostomy
• Contraindications:
- Communicating Hydrocepalus
- Tumor
- Previous shunt
- Previous SAH
- Previous whole brain radiation
- Significant adhesions visible when
perforating through the floor of the 3rd
ventricle at the time of performance of TV
43. Endoscopic third ventriculostomy
Endoscopic third ventriculostomy (ETV) is
considered as a treatment of choice for obstructive
hydrocephalus. It is indicated in hydrocephalus
secondary to congenital aqueductal stenosis,
posterior third ventricle tumor, cerebellar infarct,
Dandy-Walker malformation
44. History
The first ETV was performed by William Mixter, an
urologist, in 1923. He used a urethroscope to
perform the third ventriculostomy in a child with
obstructive hydrocephalus. Tracy J. Putnam made
the necessary modifications in this urethroscope
for cauterization of the choroid plexus
45. Proper Pre-operative imaging for detailed
assessment of the posterior communicating
arteries distance from mid line, presence or
absence of Liliequist membrane or other
membranes, located in the prepontine cistern is
useful
Liliequist membrane is an arachnoid
membrane separating the chiasmatic
cistern, interpeduncular cistern and prepontine
cistern. It arises anteriorly from the diaphragma
sellae and extends posteriorly separating into two
sheet
50. Historical Aspect
Wernicke Introduced ventricular puncture and
continuous external CSF drainage in 1881; this
technique was furthered by Keen in 1891.
Quincke in 1891 first described LP as a diagnostic
and therapeutic modality for HCP.
In 1893 , Mikulicz attempted permanent
ventriculosubarachnoid-ventriculosubgaleal CSF
diversion using GOLD tubes and catgut strands.
51. In 1939, Torkilsden used a valveless catheter to
connect and permit bypass drainage from the
occipital horn to cisterna magna
( Ventriculocisternostomy)
52. Types of Shunt
Shunt Types By Category
a. VP Shunt
» Most commonly used shunt in modern era
» Lateral ventricle is the usual proximal location
» Intraperitoneal pressure
b. Ventriculo-atrial shunt (Vascular shunt)
» Through jugular veins to sup. Vena cava
» Treatment of choice in abdominal abnormalities
53. c. Torkildsen shunt:
»Shunting ventricle to cisternal space
»Rarely used
»Effective only in acquired obstructive
hydrocephalus
d. Miscellaneous:
»Pleural space
»Gall bladder
»Ureter/Urinary Bladder
54. e. Lumbo-peritoneal shunt:
» Onlyfor communicating hydrocephalous
f. Cyst/Subdural-Peritoneal shunt:
»Draining arachnoid cyst/subdural
hygroma cavity
56. VP SHUNT
• Shunt systems include three
components:
– Ventricular catheter
– One way valve
– Distal catheter
• The ventricular catheter
– Straight piece of tube
– Closed on the proximal end
– With multiple holes upto 2cm for the entry of
CSF
57. Most of the tubes are impregnated with barium or
tantalum to permit radiographic identification
58. Valve choice
Shunt valve are classified in 3 broad cat:
1.Fixed Differential Pressure Valve
2.Flow regulating Valve
3.Programmable Valve
59. 1.Fixed Differential Pressure Valve
It was 1st to be developed and used for CSF
Shunts.
These valves close to prevent flow of CSF when
the difference in pressure across the valve (i.e
Driving pressure ) drops below a fixed threshold
(I.e. Closing pressure of the valve)
Available in Low, Med, High Pressure settings.
60. Valve Mechanism
Operate by one of four general mechanism.
1)Ball-in-cone and spring 2) Diaphagram
3)Slit
4)Miter
61.
62. Problems Fixed Differential Pressure
Valve
One of the problem that quickly became apparent
with Fixed Differential Pressure Valve was that of
Over drainage , which occour by and large
secondary to “Siphoning”
Q. What is Siphoning?
A tube running from liquid in a vessel to a lower
level outside the vessel , such that liquid flow
through the tube to the lower level.
63. Problems related to overdrainage
1.Low Pressure symptoms ( e.g, headache,
nausea, emesis, diplopia)
2.Tearing of briging vein ( subdural hematoma)
3.Premature closure of cranial sutures
(Craniosynostosis)
4.Slit Venticle syndrome
65. Q. How do they Work?
These device lie in direct contact with the overlying
scalp , and their flow-pressure characteristics are
dependent on the pressure gradient between the
internal lumen of the shunt and the surrounding
atmosphere. This pressure diff is transmitted
through skin and ASD membrane . If and when the
Internal shunt prs fall below the atm prs (e.g
negative pressure created by postural change to
an upright position) , The ASD membrane is drawn
inward a, which increases the resistance and thus
decrease flow through the shunt system.
66.
67. Programmable differential pressure valve
Working mechanism same as ball in cone and
spring mechanism.
Externally adjustable pressure setting using
magnet.
Drawbacks:
1. Costly
2. MRI or other external magnetic field and disturb
the shunt.
68.
69.
70. Q. Which Valve system to choose ?
A study found out no significant difference in the
rate of ventricular reduction , final ventricular size
or overall shunt failure rate among the three valve
designs.
In the absence of a clear universally superior valve
design, the choice of valve should be adapted to
the individual clinical scenario and guided by the
surgeon’s sound clinical judgment.
71. Shunt Surgery
General principle:
-Aseptic technique
-Meticulous Handling of tissue
-All Non antibiotic impregnated catheters shoud be
soaked in bacitracin solution immedaitely on
opening , because these carry a static electrical
charge and may otherwise attract airborne dust
particle carrying microorganism.
72. General principle contd..
-No-Touch Technique is advocated ( avoid
touching catheter by gloved hand, used instrument
as far as possible)
-Prior to wound closure , a mixture of 1 ml(10/mL )
of Vancomycin and 2mL (2mg/Ml) of Gentamycin
both preservative free, is injected into the shunt
resorvior .
-The wound to be close using antibiotic
impregnated sutures.
73. Ventricular access
Frontal Approach : Kocher’s point
Occipito-parietal approach
A. Infants- Parietal Boss
B. Children And Adults- Fraziers & Keen
78. VA Shunt
• The VA shunt
– Must be accurately
located
– Requires frequent
revisions
– Distal end position to be
maintained
– Infection may be more
serious
79.
80. How to check for correct tip
placement? In Right Atria
Chest X ray Tip At D6 Vertebral level
Ultrasound
ECG: Biphasic T wave
81. VPL SHUNT
• If both the VPS & VAS do not function to absorb CSF the shunt
have to placed in the pleural space
83. POST-OP CARE
• Observe for signs of Increased ICP
– Assessment pupil size
Abdominal distention
• due to CSF peritonitis or post-op ileus due to catheter
placement.
85. • VP Shunt
- Inguinal hernia
- Hydrocele
- Peritonitis
- Intestinal Obstruction
- Volvulus
- Migration of tip to scrotum/ bowel/ stomach
- Malposition of tip
- Over-shunting
- Needs frequent length adjustment
86. VA shunt:
– Requires repeated lengthening:
– High risk of infection/septicaemia:
– Risk of retrograde flow of blood: in case of valve
malfunction (rare)
– Shunt embolus
– Vascular complications: perforation,
thrombophlebitis, pulmonary micro-emboli
87. LP Shunt:
– Laminectomy incurs 15% chance of scoliosis
– Progressive cerebellar tonsillar herniation (up to 70%)
– Slit ventricle syndrome
– Overshunting is harder to control
– Difficult proximal end revision (if required:
– Lumber radiculopathy
– CSF leak
– Difficult pressure regulation
– Bilateral 6th, 7th, nerve dysfunction due to overshunting
– High incidence of arachnoiditis & adhesions
