Youmans Neurological Surgery

1. Clinical evaluation of
adult hydrocephalus
Youmans 6th editon

2. Out line
• Classification and etiology
• Pathophysiology , Sign and Symptom
• Normal pressure hydrocephalus
• Neuroradiologic features of hydrocephalus
• Physiologic testing of cerebrospinal fluid dynamics
• Management
• Shunt

3. Classification and etiology
• Greek : Hydro(water) + Kefale(skull)
• The state of excessive intracranial accumulation
of CSF that results from excessive production,
circulation, or absorption of CSF

4. Classification and etiology
• Communicating Hydrocephalus
• Panventricular dilation and occurs as a result of
obstruction to the flow of CSF in the subarachnoid space,
distal to the foramina of Luschka and Magendie
• Noncommunicating or Obstructive Hydrocephalus
• Pattern of ventricular dilation that reflects the site of
obstruction

6. Classification and etiology
• Long-Standing Overt Ventriculomegaly in Adults
• This form of hydrocephalus develops during
childhood, with symptoms being manifested during
adulthood
• Normal-Pressure Hydrocephalus
• Gait disturbance, dementia, incontinence with normal CSF
pressure and dilate ventricles

7. Classification and etiology
• Isolated Fourth Ventricle Syndrome
• fourth ventricle no longer communicates with the third
ventricle
• prolonged infection or multiple shunt operations
• Arrested Hydrocephalus
• Hydrocephalus reach a state in which ventricular size
remains unchanged in the absence of a shunt or in the
presence of a nonfunctioning one

8. Pathophysiology

9. Pathophysiology
• CSF obstruction  transpendymal passage of
CSF(periventricular edema ) + edematous white
matter  white matter damage  cerebral atrophy
• Ventricular enlargement progress
• distortion of tissue, white matter, blood vessel  damage
ischemia
• Loss elasticity tissue  pressure gradient between ventricle
and periventricular tissue  failure drainage of toxic
metabolite

10. Initial feature of hydrocephalus

11. Normal Pressure hydrocephalus

12. Clinical finding
• Gait disturbance
• Common initial symptoms : unsteadiness, recurrent
falls, shuffling, and reduced walking speed
• Advanced symptoms : difficulty initiating gait and
imbalance on turning
• DDx : Parkisonism – tremor, lead pipe rigidity, poker face
• NPH : mobilize with a relatively preserve arm swing
• UMN sign : cervical myopathy, lumbar canal stenosis

13. Clinical finding
• Urinary incontinence
• Cognitive impairment
• memory loss, reduced attention, difficulty planning,
slowness in thought, and apathy
• Ddx : Alzheimer’s disease – neurolopsychological testing,
aphasia, apraxia, agnosia
• Binswanger’ disease : frontal cognitive disteriotation , gait
disturbance

14. Neuroradiologic features
• Evans’ index : maximal
width of the anterior
ventricular horn /
maximal width of the
calvaria at the level of
Foramen of Monroe
• >0.3 ventricular
enlargement

15. Neuroradiology features
• Bicaudate ratio :
minimal intercaudate
distance / by the
brain width along the
same line
• > 0.25 ventriculomegaly

16. Neuroradiology features
• One of the following support
• enlargement of the temporal horns of the lateral ventricles
not entirely attributable to hippocampus atrophy
• callosal angle of 40 degrees or greater
• evidence of altered brain water content, including
periventricular signal changes not attributable to
microvascular ischemic changes or demyelination
• aqueductal or fourth ventricular flow void on MRI

17. Supplementary Prognostic testing
• Lumbar puncture “tap test”
• Specifity 100 % , Sensitivity 26 %
• External lumbar drainage
• specificity 80% , sensitivity 50-80%
• Measures of CSF outflow resistance
• specificity 87% ,sensitivity 46%

18. Neuroradiologic features of hydrocephalus

22. Physiologic testing of
cerebrospinal fluid dynamics

23. Cerebrospinal Fluid Drainage
and Dynamics
• Communicating hydrocephalus
• Intrathecal injection of radioisotropes
• Ventricular > 48 hr  ventricular stasis or reflux

24. Mathematical Modeling of the
Cerebrospinal Fluid Circulation—
a Platform for
Interpretation of Pressure-Volume

25. Monitoring of Intracranial pressure
• Overnight monitoring : Lundberg “B waves.”
• B waves are slow waves of ICP lasting 20 seconds to
2 minutes
• Intraparenchymal probe
• Normal : < 15 mmHg
• Vasogenic wave : greater
• than 25 mmHg, for a period
• around 10 min

26. Monitoring of Intracranial pressure
• The average overnight RAP index should be less
than 0.6 in patients with good compensatory
reserve.
• The overnight magnitude of slow waves is
considered increased when their average value is
greater than 1.5 mm Hg.

27. Clinical tests of
cerebrospinal fluid dynamics
• The computerized infusion test
• Resistance to CSF outflow
= Plateau P – Resting P
infusion rate

28. NPH and Brain atrophy
NPH Brain atrophy
1.Baseline ICP
2.Resistance to
CSF outflow
3.AMP
4.RAP
5.Elastance
coefiicient
normal (<18 mmHg)
Increase (>13 mmHg/ml
/minute)
Correlated with Mean ICP
Good (< 0.6 )
Increase (E > 0.2 1/ml)
Low (<12 mmHg)
Low (<12 mmHg/ml
/minute)
Low (<2mmHg)
Good (<0.5)
Low (E < 0.2 1/ml)

29. NPH and Brain atrophy

30. NPH and Brain atrophy

31. Noncommunicating and
acute hydrocephalus
Noncommunicating acute hydrocephalus
1.Baseline ICP increase increase
2.Resistance to CSF
outflow
increase increase
3.AMP increase increase
4.RAP > 0.6 normal
5.Elastance
coefiicient
high low

32. Testing of Cerebrospinal Fluid
Dynamics in Shunted Patients

33. Testing of Cerebrospinal Fluid
Dynamics in Shunted Patients

34. Management

35. Management
• Surgical Management
• Shunt insertion
• Endoscopic third
ventriculostomy
• Medical Management
• Acetazolamide
• Repeated lumbar
puncture

36. Shunt insertion
• VP shunt : most common
• Lumboperitoneal shunt
• Lumbopleural shunt
• Ventriculoatrial shunt

37. Endoscopic third ventriculostomy
• Obstructive hydrocephalus
• Passage an endoscopre through lateral ventricle to
third ventricle  create stoma at floor of 3rd
ventricle
• Advantage : prevent shunt infection, lifelong risk for
revision

38. Shunt

39. Mechanism of Shunt
• Fixed differential pressure valves
• Adjustable differential pressure valves
• Flow-regulating valves
• Accerory device

40. Valve classification
• 1. Silicon membrane
• 2. Ball-on-spring
• 3. Miter valve
• 4. Proximal or distal slit valves.
• 5. Moving diaphragm

41. Shunt
• Magnetric programming : prevent magnetric field
near
• Overdrainage : dependence on diameter and length
of the distal drain
• Membrane device : impede CSF flow by skin tense
• A flow –regulating : may permanent increase
hydrodynamic resistance

42. Complication
• Surgery
• Infection
• Bleeding
• CSF leakage
• Seizure
• Neurological deficit
• Intracerebral hemorrhage

43. Complication

44. Complication
• Excessive drainage  SDH 2-17%  neurological
deficit,coma,death
• Conservative c serial scanning
• Symptomatic : evacuation, ligation of shunt tubing
• Shunt malformation
• blockage, malpositon from peristalsis, disconnect in
movement disorder or seizure
• Revision surgery

45. Complication
• Shunt infection
• Meningtis, peritonitis,subacute bacterial endocarditis follow
• Shunt hardware adverse effect
• Intestinal obstruction or volvulus
• Wound breakdown
• CSF leakage
• Hernias

46. Thanks you