1. Normal Pressure Hydrocephalus (NPH)
Date: 2005/09/27
Speaker: Int. 吳忠泰
Supervisor: V.S. 俞芹英

2. Outlines Definition Epidemiology and etiology
Physiology and pathophysiology
Diagnosis and differential diagnosis
Treatment and complication
Prognosis

3. Definition First described in 1965 by Hakim and Adams
Normal CSF pressure
Ventriculomegaly
Clinical triad:
Slowly progressive gait disorder
Impairment of mental function
Sphincteric incontinence
(1) Normal CSF pressure: 40~50 mmH2O in infant, 100~150 mmH2O in older child and adult

4. Epidemiology
1 per 25’000
Accounts for approximately 0.5-5% (up to 6%) of dementias
One of the few treatable causes of dementia
Most common in patient > 60 y/o
M > F

5. Etiology Idiopathic: Elderly, unknown cause, 50% of NPH
With a preceding cause: Young
Subarachnoid hemorrhage (SAH)
Trauma
Meningitis (TB, syphilitic, etc.)
Surgery, irradiation
Storage disease (mucopolysaccharidosis)
Initially, only idiopathic type can be called NPH in 40 yrs ago.
Recently, communicating and obstructive forms can be called NPH because they share the same S/S and Tx.

6. Physiology of CSF Flow

7. Pathophysiology of Hydrocephalus
Communicating hydrocephalus
Obstructive: Aqueductal stenosis, tumor, IVH, arachnoid cyst, congenital problem
Communicating: Thickened leptomeninges (infection, hemorrhage, carcinomatosis meningitis)
Acute onset: IICP sign (headache, vomiting, papilloedema, consciousness change)
Gradual onset: NPH
Obstructive hydrocephalus

8. Pathophysiology of NPH
Incontinence
Enlarged lateral
ventricles
Gait disturbance
Dementia

9. Pathophysiology of NPH
On the basis of both dynamic and ischemic factors
Ventricular enlargement
Vascular stretching → Ischemia
Decreased compliance of ventricular wall
High pulse pressure
Barotrauma or shearing stress

10. Dynamics of NPH Transmantle pressure gradient B wave (plateau)
Difference in pressure between ventricle and subarachnoid space
Gradient ↑ temporarily → Ventricle↑
B wave (plateau)
Transient elevations of mean and pulse pressure
Water-hammer effect → Ventricle↑
More than 50% of time

11. Dynamics of NPH Aqueductal CSF flow void Aqueductal CSF stroke volume
Increased CSF flow velocity
Favorable response to CSF diversion
Aqueductal CSF stroke volume
CSF pulsating back and forth through the aqueduct during systole and diastole
Favorable response to shunting
Hyperdynamic CSF flow

12. Dynamics of NPH Saline infusion test Venous compromise
CSF resorption in NPH is abnormal
Arachnoid granulation? Arachnoidal villi?
Venous compromise
Increased transvenular resistance in superior saggital sinus cause NPH
What cause venous compromise? Microangiopathy? Deep white matter ischemia?

13. Ischemia of NPH Acetazolamide challenge test
Cerebral blood flow (CBF)↑ in normal person
Failed to cause CBF↑ in NPH p’t
Indicate the arterioles are already maximally dilated because of ischemia
CSF diversion → CBF improve and response to acetazolamide

14. Ischemia of NPH Compensatory CSF flow Loss of parenchymal compliance
Periventricular white matter
Increased interstitial fluid
Loss of parenchymal compliance

15. Pathophysiology of NPH
Dynamic
Hyperdynamic CSF flow
Impaired CSF resorption
Ischemic
Reduced CBF
Periventricular white matter lesion

16. Diagnosis Clinical symptoms and signs Image Gait disturbance Dementia
Urinary incontinence
The moment when highly suspect NPH !!
Image
MRI (T2WI) with CSF flow study
CT with lumbar puncture

17. Image Findings - CT Ventriculomegaly Sulcal atrophy
Ventriculosulcal disproportion
Can DDx with other dementia syndromes

18. Image Findings - CT Rounded frontal and temporal horns
Periventricular lucency
Transependymal CSF flow
Corpus callosum thinning
CT alone cannot make a diagnosis of NPH
Periventricular lucency may be confused with leukoencephalopathy resulting from microvascular ischemia

19. Image Findings - MR The same as CT
Temporal horn out of proprotion to hippocampal atrophy
Corpus callosum bowed upward

20. Image Findings - MR Periventricular lesions in T2WI
Transependymal CSF flow
Deep white matter damage
(1) The same confusion as with CT

21. Image Findings - MR Aqueductal flow void sign Jet sign
A jet of turbulent CSF flow on the distal aqueduct
Predictive of shunt responsiveness

22. Image Studies - MR CSF flow study VV/ICV ratio MRS
Aqueductal stroke volume
Increased velocity (hyperdynamic flow)
VV/ICV ratio
VV/ICV ratio > 30% (in 13 of 14 pts)
(VV: ventricular volume; ICV: intracranial CSF space volume)
MRS
Intraventricular lactate peaks (ischemia)

23. Differential Diagnosis
Dementia syndromes
Alzheimer’s disease
Hydrocephalus ex vacuo
Intraventricular lactate
Parkinsonism
Parkinson’s disease
Periventricular leukomalacia

24. Treatment Surgical shunting Lumbar puncture VP shunt
Miller Fisher test: Gait assessment before and after 30mL CSF drainage
(high rate of false negative)
Continuous CSF drainage of 200 mL per day for 3-5 days

25. Complications of shunt
Infection: S. aureus, S. epidermidis
Subdural hematoma
Shunt obstruction
Low pressure state
Epilepsy
Pneumocephalus
Ascites

26. Prognosis Response rate for shunt Non-selective patient
50-70% with known preceding cause
30% with idiopathic group
Non-selective patient
1/3 improve, 1/3 arrest, 1/3 deteriorate

27. Prognosis Positive response to shunting:
Absence of central atrophy or ischemia
Gait apraxia as dominant symptoms
Prominent CSF flow void (stroke volume > 42 mL)
Known history of cause (nonidiopathic type)

28. References
Raymond D. Adams, Maurice Victor. Principles of Neurology, 5th edition: 545-6
Roger N. Rosenberg et al. The Clinical Neuroscience – Neurology/ Neurosurgery:
Kenneth W. Lindsay, Ian Bone. Neurology and Neurosurgery Illustrated, 4th edition: 128-9, 370-3
Anne G. Osborn et al. Pocket Radiologist – Brain Top 100 Diagnosis:
William G. Bradley. Normal Pressure Hydrocephalus: New Concepts on Etiology and Diagnosis. AJNR 2000; 21:
eMedicine:

29. Thanks for Your Attendance…