Normal Pressure Hydrocephalus

1. Normal Pressure
Hydrocephalus
Jerry Ryan MD
University of Wisconsin - Madison

2. Objectives
1. Evaluate patients suspected of having NPH
and distinguish NPH from other causes of gait
disturbance, incontinence and dementia
2. Identify patients who need referral for
consideration of treatment of NPH.
3. Understand treatment of NPH and follow
patients who have received neurosurgical
interventions for NPH in the office.
4. Educate patients with NPH and their
families about the disorder.

3. How big is the problem?
Prevalence Normal Pressure Hydrocephalus
(NPH)
Estimates vary from 0- 5% as a cause for
dementia
Some of variation due to inconsistent
definition of NPH
Study of 166 patients shunted for presumed
NPH calculated incidence of shunt responsive
NPH to be one patient per 2.2 million persons
per year
J Vanneste, P Augustijn, C Dirven, WF Tan and ZD Goedhart
Neurology 1992;42:54–9

4. So why do I need to know
about NPH?
Potentially reversible cause of
significant morbidity
Recent direct to consumer advertising

5. What should Family
Physicians know about NPH?
Diagnostic features
Diagnostic studies
Limitations of prognostic studies
Patients likely to benefit from treatment
Complications of treatment
Patient follow up

6. Etiology
50% cases idiopathic
Leading theory is impairment of CSF
outflow
Intraventricular pressure studies reveal
waves of increased pressure- B-waves
Adult hydrocephalus syndrome
Adult symptomatic hydrocephalus

7. Etiology
50% cases NPH secondary to other
illnesses
Subarachnoid hemorrhage
Meningitis
Cranial trauma
Secondary NPH has higher response
rate to shunting than idiopathic NPH

8. Pathophysiology
Ventricle enlargement leads to
periventricular ischemia regardless of
etiology
Compression and stretching of
arterioles and venules
Arterial hypertension and cerebral
arteriosclerosis increased in NPH

9. CSF pathway
CSF produced by choroid plexus at rate
approximately 20 ml/hr
Flows from lateral ventricles through foramina
of Monro into third ventricle
Enters fourth ventricle through aqueduct of
Sylvius
Enters subarachnoid space
Resorbed by arachnoid villi at top of brain

10. CSF pathway

11. Diagnostic Triad
Gait Disturbance
Urinary Incontinence
Dementia

12. Diagnostic Triad
Gait disturbance
No classic gait disturbance
Gait may be wide based, shuffling
More severely affected patients have “magnetic
gait”- feet stuck to ground and difficult to initiate
walking
Difficulties with walking motions resolve with
minimal support of patient or lying patient down
May resemble Parkinson’s gait
Not associated with limb weakness
Hyperreflexia

13. Diagnostic Triad
Urinary Incontinence
True incontinence found only in severely
affected patients
Urinary urgency in most patients with NPH
Due to stretching of periventricular nerve
fibers and loss of detrusor inhibition
Bladder sphincter muscle unaffected

14. Diagnostic Triad
Dementia
Presence of dementia in NPH extremely
variable
Some shunt responsive patients have little or
no dementia
Dementia usually least responsive of symptoms
to intervention
Mental status changes may resemble
depression

15. Differential Diagnoses-
Alzheimer’s (AD)
Both AD and NPH cause memory impairment
AD- “cortical” abnormalities
Aphasia, Apraxia, Agnosia
Impaired recognition and encoding deficits
NPH- “subcortical” abnormalities
Memory impairment but intact recognition
Slow information processing
Difficulty with complex tasks

16. Cognitive Impairments AD
versus NPH
Auditory memory
Attention/concentration
Executive function
Behavior/personality
changes
Motor and psychomotor skills
Visuospatial skills
Language
Reading
Borderline
Impaired
Psychomotor slowing
Fine motor speed
Fine motor accuracy
Memory
Learning
Orientation
Attention/concentration
Executive function
Writing
Impaired
NPHAD

17. Differential Diagnoses-
Alzheimer’s (AD)
AD and NPH can usually be distinguished
with formal neuropsychological testing
Primary care office testing may not be
adequate to distinguish
Mental impairment early in course of AD but
usually late in course of NPH and often
minimal impairment
AD often associated with hippocampal
atrophy on imaging studies

18. Differential Diagnoses-
Parkinson’s Disease
Both NPH and Parkinson’s Disease
(PD) can have similar gait disturbances
Hypokinesia
Freezing
Imbalance
Extrapyramidal symptoms
Trial of levadopa can help distinguish
between PD and NPH

19. Differential Diagnoses- Other
Depression
Subcortical arteriosclerotic encephalopathy
Multi-infarct encephalopathy
Chronic alcoholism
B
12
, Folate deficiency
Electrolyte abnormalities
Cervical or lumbar stenosis
Peripheral neuropathy

20. Diagnostic studies
Ventricle enlargement on CT or MRI
Severity graded by ratio of maximal frontal horn
width divided by transverse inner diameter of skull
0.32 minimal for NPH but 0.40 more typical
Lack of hippocampus or cortical atrophy
Periventricular and cortical white matter
lesions may be found in patients with NPH
Large number white matter lesions may be
marker for poor response to shunting

21. Normal Ventricles

22. Enlarged
Ventricles

23. Enlarged
Ventricles

24. Enlarged Ventricles

25. Enlarged
Ventricles

26. So now that I know it’s NPH
what next?
Response to shunting varies
significantly between patients
Study 166 shunted NPH patients
Overall response 36%, only 21%
significant improvement
Only 15% of patients with idiopathic NPH
showed marked improvement
J Vanneste, P Augustijn, C Dirven, WF Tan and ZD Goedhart
Neurology 1992;42:54–9

27. Any Problems With Shunting?
Complications of shunting
Low immediate post-surgical risks
Severe to moderate shunt related morbidity
of 28%
Infection
Shunt malfunction
Intracranial bleed
Death or severe morbidity 7%
J Vanneste, P Augustijn, C Dirven, WF Tan and ZD Goedhart
Neurology 1992;42:54-9

28. Overdrainage

29. Are Benefits of Shunting Long
Lasting?
Most studies show fairly significant
decline in benefits over time
Initial improvement 60-75% of patients
Sustained improvement only 24-42%
Results confounded due to high
mortality from co-morbid conditions
57% patients dead within 5 years in study
by Raftopoulos et.al.

30. How can I tell who will
benefit?
Good response to shunting
Clinical presentation
Gait disturbance preceded mental impairment
Short duration of mild mental impairment
Known cause of NPH- e.g. infection, bleed

31. How can I tell who will
benefit?
Good response to shunting
Special studies
Lack of white matter lesions on MRI
Marked resolution of symptoms with CSF drainage
One time removal 30-50 cc CSF
Multi-day drainage of 100-150 cc CSF
B-waves greater than 50% of time with continuous
intracranial pressure (ICP) monitoring
Resistance to CSF outflow greater than 18 mmHg

32. How can I tell who will
benefit?
Poor response to shunting
Severe dementia
Dementia presenting symptom
MRI abnormalities
Cerebral atrophy
Multiple white matter lesions

33. How can I tell who will
benefit?
Indeterminate significance
Patient age
Duration of symptoms
Lack of response to removal CSF

34. How accurate are predictors of
response to shunting?
Normal pressure hydrocephalus: an update, Stein, SC, Neurosurgery
Quarterly (2001)11(1):26–35

35. How accurate are predictors of
response to shunting?
Normal pressure hydrocephalus: an update, Stein, SC, Neurosurgery Quarterly
(2001)11(1):26–35

36. NPH Guidelines
Worldwide group of experts assembled to
develop guidelines for diagnosis and
treatment of NPH
Meetings supported by shunt manufacturer
Limited number of RCT’s noted by group
Report published in Neurosurgery: Vol. 57
(3), Sept 2005 Supplement

37. Diagnosis- Probable Idiopathic
NPH
History
Insidious onset
Age over 40
Symptom duration 3-6 months
No antecedent event known to cause secondary
NPH
Progressive over time
No other medical, psychiatric or neurological
condition that could cause symptoms

38. Diagnosis- Probable Idiopathic
NPH
Brain imaging
Ventricular enlargement not attributable to
cerebral atrophy or congenital disorder
No macroscopic obstruction present
At least one of the following
Enlargement of lateral horns not attributable to
hippocampus atrophy
Callosal angle greater or equal to 40 degrees
Evidence of altered brain water content on imaging not
attributable ischemia or demylination
An aqueductal or fourth ventricular flow void on MRI

39. Callosal angle
Angle of roof of lateral ventricles in A-P projection

40. MRI flow void
Loss of MRI signal due to flow of CSF
Normal aqueduct Abnormal aqueduct

41. MRI flow void
Normal fourth ventricle Abnormal fourth ventricle

42. Diagnosis- Probable Idiopathic
NPH
Clinical
Gait/Balance- at least two of following present
Decreased step height
Decreased step length
Decreased cadence/speed
Decreased trunk sway
Widened stance
Toes turned outward while walking
En bloc turning- turns take three or more steps
Impaired balance- two or more corrective steps for eight
steps on tandem gait testing

43. Diagnosis- Probable Idiopathic
NPH
Cognition- two of following present
Psychomotor slowing
Decreased fine motor speed
Decreased fine motor accuracy
Difficulty dividing or maintaining attention
Impaired recall especially for recent events
Impairment of executive functions- multi-step
procedures, working memory, formulation of
abstractions, insight
Behavioral or personality changes

44. Diagnosis- Probable Idiopathic
NPH
Urinary Symptoms- one of following
Episodic urinary incontinence not attributable to
other causes
Persistent urinary incontinence
Fecal and urinary incontinence
OR
One of following
Urinary urgency
Urinary frequency- 6 or more voids in 12 hour
period
Nocturia- more than two voids in night

45. Diagnosis- Probable Idiopathic
NPH
Physiological
Opening pressure 5-18 mmHg

46. Possible INPH
History- Symptoms are
Subacute or indeterminate onset
Onset any time after childhood
<3 months or indeterminate duration
May follow trauma, hemorrhage or meningitis
Symptoms not entirely explained by co-existing
neurological conditions
Non-progressive or not clearly progressive

47. Possible INPH
Brain imaging- Ventricular enlargement
associated with following
Cerebral atrophy of sufficient severity to
explain ventricular enlargement
Structural lesion that may increase
ventricular size

48. Possible INPH
Clinical
Incontinence and/or cognitive impairment
in absence of gait or balance dysfunction
Gait disturbance or dementia alone
Physiological
Opening pressure unavailable or outside of
range for probable NPH

49. Unlikely INPH
No ventriculomegaly
Signs of increased intracranial pressure
such as papilledema
No component of clinical triad
Symptoms explained by other causes
(eg, spinal stenosis)

50. UCLA workup for NPH and
selecting shunt candidates
Ventricular enlargement by CT or MRI (Evans
Index >0.3)
Complete history and neurological exam,
neuropsychiatric testing and gait analysis
Patients with significant dementia component
referred for more extensive evaluation to rule
out Alzheimer’s Disease of other forms of
dementia

51. UCLA workup for NPH and
selecting shunt candidates
Patients felt at risk for NPH undergo
intracranial pressure monitoring
Inserted with local anesthesia
Fine wire placed just under calvarium
Elevated pressure- shunt
B-waves- further evaluation

52. UCLA workup for NPH and
selecting shunt candidates
Cerebrospinal Fluid Outflow Resistance
Lumbar puncture performed
Artificial spinal fluid infused
Rise in ICP recorded by previously inserted
ICP monitor
Resistance to absorbtion of infused fluid
calculated
High resistance- shunt
Normal resistance- further testing

53. UCLA workup for NPH and
selecting shunt candidates
Trial CSF drainage
3 day trial
Small volumes removed- 30-50 cc
Improved symptoms- shunt
No improvement- no further studies,
shunt no longer considered

54. UCLA workup for NPH and
selecting shunt candidates
Studies not performed
Cisternogram
High volume CSF drainage
PET scan
SPECT scan
Tests felt not warranted due to expense or
increased patient risk
MRI flow void not routinely done as felt to be
non-specific
Further testing felt to add minimal additional
prognostic information

55. Yet another workup
Treating Normal Pressure Hydrocephalus, Luciano, M,
AAFP CME Bulletin, 2004, Vol. 3 (4)

56. Yet another workup
Treating Normal Pressure Hydrocephalus, Luciano, M,
AAFP CME Bulletin, 2004, Vol. 3 (4)

57. What kind of shunt is used?
Externally programmable valve allows
transcutaneous adjustment CSF outflow
resistance

58. What kind of shunt is used?

59. Shunt placement

60. Shunt Valve Adjustments

61. Now that my patient has had a
shunt what happens next?
Monitoring of mental function
Patients should have neuropsychiatric
testing prior to shunt
Periodic testing post shunt to document
improvement

62. Now that my patient has had a
shunt what happens next?
Monitor for complications of shunt
Infection
Shunt malfunction
Excessive CSF drainage
Subdural hematoma

63. Summary
Best patients for shunt have gait
disturbance with mild mental
impairment
Improvement with CSF drainage predict
good response to shunt but lack of
improvement of limited prognostic value
Patients with significant dementia and
limited gait disturbance unlikely to
benefit from shunt.

64. Cochrane Database
Conclusion: There is no evidence to
indicate whether placement of a shunt is
effective in the management of NPH.
Conclusion based upon lack of randomized
controlled trials

65. Suggested references
Diagnosis and management of normal pressure
hydrocephalus, Vanneste, JA, JNeurol (2000) 247:5–14
Neurosurgery: Vol. 57(3) Supplement, September 2005
Normal pressure hydrocephalus: an update, Stein, SC,
Neurosurgery Quarterly (2001)11(1):26–35
University of California- Los Angeles-
http://www.neurosurgery.ucla.edu/Diagnoses/Adult/AdultDis_1.html
University of Virginia-
http://www.healthsystem.virginia.edu/internet/neurogram/neurogram3_3_nph.cfm