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

Normal Pressure Hydrocephalus

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

Text of Normal Pressure Hydrocephalus

  • 1. A Sharing Sessionon 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 byvenous 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 ndsymptom 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. NOTExpected 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 rdand 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 ndpreferred 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 areS. 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?.ClevelandClinic 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