A Sharing Session on

Normal Pressure Hydrocephalus(NPH)

Suhaila Mohamed Usuludin17 April 2008

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

Cerebrospinal Fluid (CSF)

Cerebrospinal Fluid (CSF)

• 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)

• 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)

NPH

• Gradual decrease CSF absorption at arachnoid granulations– back pressure effect– Increase pressure in ventricles

• Compensatory mechanisms to maintain pressure– Distension of ventricles

NPH

• Slowly progressive• Onset > 40 years• Most common in elderly

Symptoms of NPH

• Adams triad– Impaired gait– Urinary incontinence– Impaired cognitive function

Impaired gait• Usually first and prominent symptom

– reduced step height– stride length– velocity– Shuffling gait– wide-based – trunk sway– ‘magnetic gait’– gait apraxia

• Timed walking test• GAITRite gait analysis

Assessment: Impaired gait

Urinary Incontinence

• Usually 2nd symptom to follow– Urgency and frequency

• Fecal incontinence– Rare except in advanced cases

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

• MMSE• AMT• Neuropsychological tests:

– Trail Making Test– Digit/Letter Cancellation– Kendrick Object Learning Test (KOLT): visual

memory

Assessment of Impaired Cognitive Functions

NOT Expected Symptoms

• Seizures• Signs and symptoms of increased ICP

– Headache– Nausea– Vomiting– Altered level of consciousness– Papilledema

Differential Diagnoses

• Old age• Parkinsonism• Dementia – AD, vascular• Depression• Cerebellar/spinal cord involvement

How is it Diagnosed?

• MRI– Ventricles (lateral, 3rd and 4th) and Sylvian fissure

dilated with normal hippocampus

MRI showing ventriculomegaly

• CT scan– Rounding of horns– Thinning of corpus

callosum

How is it Diagnosed?

Surgical Management

• Ventriculoperitoneal Shunt (VP shunt)– Performed under general

anaesthesia– Catheter placed within a

ventricle, and another end at the peritoneal cavity

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.

Venticuloatrial Shunt (VA Shunt)

• CSF is shunted from the cerebral ventricles into the right atrium of the heart.

• 2nd preferred choice if VP shunt is not possible– Eg. Infection of peritoneal cavity -> affects

reabsorption rate of CSF

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

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.

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.

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

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.

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.

Thank You