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Normal Pressure Hydrocephalus (NPH)

by Bruce Leff, M.D.

(**For a clinical referral and in depth information on NPH, visit the Hydrocephalus Center website**)

History
  • 8/01: trouble w balance x 1 year, fatigue, fall x 4 (retropulse x 3)
  • Walking slowly for few years – getting worse
  • Trouble going to standing from sitting position
  • No tremor, handwriting OK, no shuffling gait
  • Urinary incontinence without urgency – just leaks, not at night
  • Inattentive per husband
  • Cooks, but husband must redirect at times
  • Gave up driving 1 yr ago because she was nervous about her skills
  • Decline in function – no aerobics x 2-3 yrs
  • Depressive symptoms – had seen a psychiatrist for years.  Had been on prozac but it “made her feel too great” and she gave it up

Overall, there had been a significant deterioration in function which resulted in the patient and family strongly considering admission to a nursing home.

Past Medical History

1991Serial TIAs – anterior circulation symptoms - Carotid ultrasound (-), treated with aspirin 81mg qd
1993Another TIA - ASA 325mg.  Repeat carotid ultrasound (-)
1997Right hemisensory symptoms – Left thalamic infarct on MRI
2000

Neurology evaluation – problems with balance, coordination, reduced exercise tolerance

MRI – mild prominence 3rd and lateral vents, periventricular white matter changes, old left thalamic lacune. Low normal B12.  Normal: TSH, folate, ESR, CBC, HbA1C.


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Presentation and Examination

June/July
From there

  • SH: retired English teacher
  • British war bride, lived in Vermont
  • Recently move to 1 story house. 
  • Requires help with instrumental activities of daily living

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Physical Examiniation

  • Cranial nerves normal
  • Motor: normal x LUE extensor, LE flex 4/5
  • Normal tone, no cogwheeling, no shuffle, normal facies
  • 3+ patellar DTR, 1+ ankles DTR, toes downgoing
  • Retropulses with challenge
  • Normal cerebellar exam
  • Gait – normal base, no shuffle, slow and unsteady turns, normal arm swing, no magnetic gait

Data and Scans
Review of head MRI / CTs from ’97, ’00, ‘01, ‘02:

  • Enlarging ventricles over time
  • Substantial white matter changes
  • Thalamic infarct

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Differential Diagnosis

Imbalance, gait, incontinence troubles >> memory

  1. Sequelae of stroke?
  2. Normal Pressure Hydrocephalus?
  3. Depression?
  4. Dementia?
  5. Depression?
  6. Dementia?

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Discussion: Normal Pressure Hydrocephalus (NPH)


Clinical Features
   
Triad:  Gait disturbance, incontinence, dementia

  • Gait ataxia – usually first sign – ~ 90% - difficulty initiating gait or hesitant (magnetic), slow, shuffle, hesitant
  • Dementia – in up to 80% - often mild cognitive deficit – subcortical type, resembles frontal disorder: forgetful, inattentive, inertia, psychomotor and thought retardation, apathy, flat affect.
  • Urinary incontinence – 25 – 50% - early or late sign

The data on outcomes of shunt surgery in the early to mid 1990’s suggested that the decision calculus for treating possible NPH with a shunt was complex.  NPH was probably rare and some patients will improve, but the complications of the procedure are substantial.  For example, in Amsterdam, 166 procedures were reviewed in 4 centers – 2 liberal, 2 conservative. (Vanneste et al, Neurology 1992;42:54-9)  The findings showed:

  • Reasonable follow-up & criteria to judge success and failure
  • Substantial improvement:  21 % overall
  • Severe and moderate shunt complications: 28 % - led to death/severe residual morbidity in 7%
  • NPH rare, over diagnosed, risk benefit is difficult

Main Hypotheses and available tests:

  • Main hypotheses:
       - Deficit in absorption of CSF leads to increased CSF pressure.  This is measured by computing resistance to CSF outflow.
       – Ischemia – ventricular enlargement leads to vascular stretching, decreased compliance, and high pulse pressure leading to barotrauma or shear stress
  • Lumbar infusion test
       – Spinal needle – two ports – pressure transducer, infusion
       – Measure CSF steady pressure
       – Infuse LR. CSF pressure is recorded continuously for ~ 45 min to establish steady state pressure plateau (pressure level at which absorption balanced infusion)
       – R out = (P plateau – P opening) / infusion rate
  • CSF Tap Test
         
       – Remove CSF ~ 50cc / day over several days and monitor functional tests  - e.g. walking, reaction time, memory

Diagnostic tests are not well validated and confusion remains on how best to determine who to shunt.

(References for above: Eide et al.  Acta Neurol Scand 2003;108:381, Agnita JW et al Surg Neurol 2000;53:201, Ullrich et al Eur Neurol 2004;51:59, Shiino et al.  J Neurol Neurosurg Psychiatry 2004;75:114)

Comparison of Lumbar Infusion Test (LIT) and CSF Tap Test (Kahlon et al; J Neurol Neurosurg Psychiatry 2002;73:721-6)

  • N=68
  • All got LIT and CSF tap test, those with either test (+) got shunt,
  • Mean age 72, most not with prior neurological diagnosis
  • 91% gait, 76% cognitive, 60% incontinence

Outcomes and Diagnostic Tests

% of Cohort% with Objective
Improve
% with Subjective
Improve
No surgery
      LIT-/TT-

31

24

19

LIT +

59

80

96

TT+

25

94

94

LIT+/TT-

44

73

97

LIT-/TT+

10

86

86

LIT+/TT+

15

100

100

The literature on what test to choose to predict the outcome with shunt remains murky – e.g.

– “LIT or  TT is the most powerful predictive test”
– “LIT or TT - only minimum relevance to outcome”
– “Clinical findings are key to predicting outcome”
– “Better outcome when dementia / CVA present”
– “Presence of dementia / CVA didn’t matter”

More recent literature indicate shunts have improved.

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Patient Follow-up


The patient returned to Hopkins in May, 2002.  Her gait was widening and her balance and thinking were declining.  On physical exam, she had difficulty initiating gait, 12 sec for 30 feet walk, was unsteady and retropulses more; MMSE 25/30.

8/5/02CSF drainage at JHH.  Catheter placed
8/7/02More stable walk
8/8/02Up from chair on own
8/9/02Gait still wide base, no retropulsion, family notes improvement
8/16/02Shunt placed
10/02 “Signifcant improvement”  Gait better - walking unassisted, base narrow
12/02“Engaging.”  30/30, gait markedly better.  Has done “spectacularly well”
6/03 “Doing fantastic,” normal gait, memory improved, urinary symptoms improved, 30/30
12/04Improvements sustained

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Conclusions

  • It remains to be a very difficult decision calculus when deciding on shunt for possible NPH.
  • New work on pathophysiology / imaging techniques should help us in the future.
  • Questions regarding NPH will continue to come our way.

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