hydrocephalus comprehensive, etiology, clinical presentation, evan's index and findings on CT head, pathophsiology, Shunt surgeries

1. HYDROCEPHALUS
EVALUATION & MANAGEMENT

2. Anatomy and Physiology
Ventricular System & CSF
• 80% from the choroid plexus
• Interstitial spaces Production
• Ependymal lining
• Dura of nerve root sheaths

3. CHOROID PLEXUS

5. 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

7. 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. CSF Flow path

9. CSF PRESSURE
• The CSF volume and pressure are
maintained every minute by the
systemic circulation
• CSF pressure is in equilibrium
with capillary pressure (arteriolar
tone)
• Hypoventilation 
– ↑ in blood PCO2 
– ↓ pH & ↓ arteriolar resistance 
– ↑ cerebral blood flow 
– ↑ CSF pressure
• Hyperventilation has the
opposite effect

10. CSF PRESSURE
• Normal adult intracranial pressure
2-8 mmHg
• Up to 16 mmHg are considered
normal
• ICP higher than 40 mmHg or lower BP
may combine to cause ischemic
damage to the brain

11. Definition
• An increase in CSF volume in an enlarged
ventricular system resulting
- primarily from decreased absorbtion
- rarely b’coz of increased production
• Prevalance: 1-1.5%
• Incidence: 0.3-3.5%
- Upto 20% after SAH
- 1% after meningitis

12. Definition
• Results in ventricular enlargement
• Lat ventricles
- frontal and occipital horns
• Volumes decrease in cerebral sulci, fissures
and cisterns

13. Classification
• Functional
• Clinical
• Age wise
• Pathological
• ICP/ R-out
• Special Types

14. Functional
• Communicating:
- Block at the level of the arachnoid
granulations
• Non-communicating:
- Block proximal to the arachnoid granulations

15. Clinical
• High pressure hydrocephalus
- Acute
- Chronic
• Normal pressure hydrocephalus
• Arrested hydrocephalus
• Hydrocephalus ex vacuo

16. Age wise
• Paediatric
• Juvenile/Adult

17. Pathological
• Congenital
1. Chiari type 1 malformation
2. Chiari type 2 malformation and/or
Meningimyelocele
3. Primary aqueductal stenosis
4. Secondary aqueductal gliosis ( germinal matrix
hge)
5. Dandy Walker malformation
6. Rare X- linked disorder

18. Pathological
• Acquired
1. Infectious
- Post meningitic
- Granuloma
- Cysticercosis
- Abscess
2. Post haemorrhagic
- SAH
- IVH
- Trauma

19. Pathological
• Acquired
3. Secondary to mass effect
- Non neoplastic
- Neoplastic
- Choroid plexus papilloma
- Post operative
- Neurosarcoidosis
- Assoc with spinal tumours
- Constitutional ventriculomegaly

20. ICP
• High Pressure
- Monitored ICP > 15mmhg
- B waves
- R out increased
• Normal Pressure
- Monitored ICP < 15mmHg
- R out increased

21. 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

22. 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

23. 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

24. Special Types
OTITIC HYDROCEPHALUS
• Obsolete term
• Describes the increased ICP in patients with
otitis media

25. 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

26. 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

27. 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

28. 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

29. CLINICAL FEATURES

30. 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

31. 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

32. INFANCY
• Brain Stem Compression
– Swallowing difficulties, Stridor, Apnea, Aspiration,
Respiratory difficulties
• Lower Brainstem Dysfunction
– Difficulty in sucking and feeding
– High-pitched shrill cry

33. INFANCY
• Emesis, Somnolence, Seizures, and Cardio Pulmonary Distress
• Severely affected infants may not survive neonatal period

34. CHILDHOOD
• Headache on awakening, improvement following emesis or sitting
• Papilledema, strabismus, and Extrapyramidal signs, ataxia
• Irritability, Lethargy, Apathy, Confusion, and often incoherent

35. SYMPTOMS AND SIGNS
• Irritability
• Poor feeding
• Headache
• Nausea, vomiting
• Diplopia
• Visual impairment
• Dementia
• Incontinence
• Gait disturbances
• Accelerated head growth
• Bulging fontanelles
• Forced down gaze
• Developmental delay
• Exotropia
• Papilledema
• Posturing
• Bradycardia
• Apnea / Death

36. Evaluation
• Clinical
• CT
• MRI
• ICP
• R (out)
• Isotope cisternography

37. 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

40. CT CRITERIAE

41. CT CRITERIAE
<40% - Normal
FH/ID 40-50% - Borderline
> 50% - Hydrocephalus

42. Evan’s Index

43. 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

44. 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

45. R (Out)
• Assesses the degree of blockage to CSF
absorbtion back into the blood stream
• Simultaneous infusion of artificial CSF and
measurement of ICP
• Spinal subarachnoid space cannulated
• ICP monitor inserted
• Calculated resistance value high
Better response to surgery

46. 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

47. TREATMENT OF HYDROCEPHALUS

48. THERAPEUTIC MANAGEMENT
• Goals:
– Relieve hydrocephaly
– Treat complications
– Manage psychomotor problems
– Usually surgical

49. 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

50. Drug Therapy
 To counteract acidosis:
• tricitrate (Polycitra®) 4 ml/kg/day divided QID (each ml
is equivalent to 2 mEq of bicarbonate, and contains 1
mEq K+ and 1 mEq Na+)
• measure serial electrolytes, and adjust dosage to
maintain serum HC03 > 18 mEqIL .
• change to Polycitra-K® (2 mEq K+ per ml, no Na+)
ifserum potassium becomes low
• or to sodium bicarbonate if serum sodium becomes
low

51. Drug Therapy
• Watch for electrolyte imbalance and acetazolamide
side effects:
- Lethargy - tachypnea
- diarrhea - paresthesias
• 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

52. 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

53. Surgical Modalities
1. Choroid Plexectomy
2. 3rd Ventriculostomy
3. Shunts

54. 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
• Endoscopic choroid plexus coagulation - 1910

55. 3rd Ventriculostomy
• Resurgence of interest in third ventriculostomy (TV)
with the recent increased use ofventriculoscopic
surgery
• Indications:
- Obstructive HCP.
- Mgt of shunt infection
- Subdural hematomas after shunting
- Slit ventricle syndrome

56. 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

57. 3rd Ventriculostomy
• Complications
- Hypothalamic injury
- Transient 3rd and 6th nerve palsies
- Uncontrollable bleeding
- Cardiac arrest
- Traumatic basilar artery aneurysm

58. Shunts

59. 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

60. 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

61. e. Lumbo-peritoneal shunt:
»Only for communicating hydrocephalous
f. Cyst/Subdural-Peritoneal shunt:
»Draining arachnoid cyst/subdural
hygroma cavity

62. SHUNT MATERIALS
• Shunts are composed of Silastic material made from silicone.

63. 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

64. VA Shunt
• The VA shunt
– Must be accurately located
– Requires frequent revisions
– Distal end position to be maintained
– Infection may be more serious

65. VP SHUNT
• If both the VPS & VAS do not function to absorb CSF the shunt have to
placed in the pleural space

66. POST-OP CARE
• Observe for signs of Increased ICP
– Assessment pupil size
– Cushing’s Reflex
– Abdominal distention
• due to CSF peritonitis or post-op ileus due to catheter placement.

67. Complications
i. General:
a. Obstruction
b. Disconnection
c. Infection
d. Erosion through Skin
e. Seizures
f. Metastatic route
g. Silicone allergy

68. • 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

69. 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

70. 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