Normal Pressure Hydrocephalus

A Presentation based on the Symposium I had attended 2 weeks back on NPH.

1. A Sharing Session
on
Normal Pressure Hydrocephalus
(NPH)
Suhaila Mohamed Usuludin
17 April 2008

2. Cerebrospinal Fluid (CSF)
•A clear, colourless fluid that contains small
quantities of glucose and protein
•Fills the ventricles of the brain and the central
canal of the spinal cord
•Production by choroid plexus in lateral
ventricle at 20ml/hr

3. Cerebrospinal Fluid (CSF)

4. Cerebrospinal Fluid (CSF)

5. •Functions
–drainage route for waste products of brain
metabolism
–bouyancy
–electrolytes and nutrient exchange
•Pressure decrease from site of production ->
site of absorption
–determined by venous pressure
Cerebrospinal Fluid (CSF)

6. •Pressure is raised if
–Brain volume increases
–Venous pressure increases
–Outflow obstruction
•At ventricles (non-communicating hydrocephalus)
•At absorptive site (communicating hydrocephalus)
Cerebrospinal Fluid (CSF)

7. NPH
•Gradual decrease CSF
absorption at arachnoid
granulations
–back pressure effect
–Increase pressure in ventricles
•Compensatory mechanisms
to maintain pressure
–Distension of ventricles

8. NPH
•Slowly progressive
•Onset > 40 years
•Most common in elderly

9. Symptoms of NPH
•Adams triad
–Impaired gait
–Urinary incontinence
–Impaired cognitive function

10. Impaired gait
•Usually first and prominent symptom
–reduced step height
–stride length
–velocity
–Shuffling gait
–wide-based
–trunk sway
–‘magnetic gait’
–gait apraxia

11. •Timed walking test
•GAITRite gait analysis
Assessment: Impaired gait

12. Urinary Incontinence
•Usually 2
nd
symptom to follow
–Urgency and frequency
•Fecal incontinence
–Rare except in advanced cases

13. Impaired Cognitive Functions
•Reversible cause of dementia
•Subcortical dementia
–Inattention
–Delayed recent recall
–Delayed psychomotor functioning
–Behavioural changes
–Emotional instability
•Executive functioning may be affected as
disease progresses

14. •MMSE
•AMT
•Neuropsychological tests:
–Trail Making Test
–Digit/Letter Cancellation
–Kendrick Object Learning Test (KOLT): visual
memory
Assessment of Impaired Cognitive
Functions

15. NOT Expected Symptoms
•Seizures
•Signs and symptoms of increased ICP
–Headache
–Nausea
–Vomiting
–Altered level of consciousness
–Papilledema

16. Differential Diagnoses
•Old age
•Parkinsonism
•Dementia – AD, vascular
•Depression
•Cerebellar/spinal cord involvement

17. How is it Diagnosed?
•MRI
–Ventricles (lateral, 3
rd
and 4
th
) and Sylvian fissure
dilated with normal hippocampus
MRI showing
ventriculomegaly

18. •CT scan
–Rounding of horns
–Thinning of corpus
callosum
How is it Diagnosed?

19. Surgical Management
•Ventriculoperitoneal Shunt
(VP shunt)
–Performed under general
anaesthesia
–Catheter placed within a
ventricle, and another end at the
peritoneal cavity

20. VP Shunt
•Valve (fixed or
programmable)
ensures one-way flow
and regulates CSF flow
•Permanent or
temporary
•May need
replacement or
revision if not working
properly
With five pressure level settings, the programmable,
adjustable Strata® valve (top) can be "fine-tuned" by the
physician after shunt surgery for NPH. Adjusting the
valve and verifying the setting is done quickly in the
physician's office using a simple set of magnetic tools
(bottom), eliminating the need for additional surgery.

21. Venticuloatrial Shunt (VA Shunt)
•CSF is shunted from the cerebral ventricles into
the right atrium of the heart.
•2
nd
preferred choice if VP shunt is not possible
–Eg. Infection of peritoneal cavity -> affects
reabsorption rate of CSF

22. To Shunt or Not To Shunt?
•High Volume Lumbar Tap test or External Lumbar
Drainage (ELD)
– 40-50ml CSF-> beneficial from shunt
•Decrease atrophy/ischemia
•Prominent CSF flow void
–aqueductal stroke volume >42 Ym (Bradley, 1998)
•No known history of intracranial infection
•Pre-morbid functional status

23. Operation Risks
•Ileus
–Slow gastric and bowel movement post operation
and may feel nausea
•Infection
–Most common organisms are S. epidermidis and S.
aureus
•Obstruction
–Most often due to the head tip is obstructed with
cells, choroid plexus, or debris.

24. Operation Risks
•Misplacement
–Occurs when the ventricular or peritoneal end of
the shunt tubing is in a position which does not
facilitate free flow of CSF
•Wound breakdown/shunt tube exposure
–Occurs when the wound does not heal well or the
overlying skin is thin with minimal subcutaneous
tissue layer resulting in wound breakdown.

25. Prognosis
•Gait shows highest improvement rates
•Better gait does not correlate to better ADLs
functioning
•All components of triad considered to achieve
higher ADL scores
•Temporary improvements from 1 to 3 years
–May be substantial for improving QoL
•> 1 year, co-morbidities may affect effects of
shunting

26. Rehabilitation Implications
•Difficulties in walking
–If given walking aid, may not know how to use it
•Gait apraxia
•Caregiver training on facilitation
–Changing the environment
•Urinary Incontinence
–Time scheduling
•Cognitive Issues
–Caregiver training on psychomotor dysfunctions,
behavioural issues etc.

27. References
•Presentations from various professionals from the symposium
•Bradley, W.G. (1998). MR Prediction of Shunt Response in NPH: CSF Morphology
versus Physiology. American Journal of Neuroradiology, 19, 1285-1286.
•Department of Neurosurgery (2007). A Patient / Family Informed Consent Guide to
Ventricular Peritoneal (VP) Shunt Insertion /Revision. Singapore: National
Neuroscience Institute.
•Factora, R. (2006). When do common symptoms indicate normal pressure
hydrocephalus?. Cleveland Clinic Journal of Medicine, 73 (5), 447-457.
•Gallia, G.L., Rigamonti, D., & Williams, M.A. (2006). The diagnosis and treatment of
idiopathic normal pressure hydrocephalus. Nature Clinical Practice Neurology, 2 (7),
375-381.

28. Thank You