Normal Pressure Hydrocephalus

Jerry Ryan MD

University of Wisconsin - Madison

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.

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 GoedhartNeurology 1992;42:54–9

So why do I need to know about NPH? Potentially reversible cause of

significant morbidity Recent direct to consumer advertising

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

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

Etiology 50% cases NPH secondary to other

illnesses Subarachnoid hemorrhage Meningitis Cranial trauma

Secondary NPH has higher response rate to shunting than idiopathic NPH

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

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

CSF pathway

Diagnostic Triad

Gait Disturbance Urinary Incontinence Dementia

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

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

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

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

Cognitive Impairments AD versus NPH

AD NPH

Impaired

Memory

Learning

Orientation

Attention/concentration

Executive function

Writing

Psychomotor slowing

Fine motor speed

Fine motor accuracy

Borderline Impaired

Motor and psychomotor skills

Visuospatial skills

Language

Reading

Auditory memory

Attention/concentration

Executive function

Behavior/personality changes

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

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

Differential Diagnoses- Other Depression Subcortical arteriosclerotic encephalopathy Multi-infarct encephalopathy Chronic alcoholism B12, Folate deficiency Electrolyte abnormalities Cervical or lumbar stenosis Peripheral neuropathy

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

Normal Ventricles

EnlargedVentricles

EnlargedVentricles

Enlarged Ventricles

EnlargedVentricles

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 GoedhartNeurology 1992;42:54–9

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 GoedhartNeurology 1992;42:54-9

Overdrainage

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.

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

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

How can I tell who will benefit? Poor response to shunting

Severe dementia Dementia presenting symptom MRI abnormalities

Cerebral atrophy Multiple white matter lesions

How can I tell who will benefit? Indeterminate significance

Patient age Duration of symptoms Lack of response to removal CSF

How accurate are predictors of response to shunting?

Normal pressure hydrocephalus: an update, Stein, SC, Neurosurgery Quarterly (2001)11(1):26–35

How accurate are predictors of response to shunting?

Normal pressure hydrocephalus: an update, Stein, SC, Neurosurgery Quarterly (2001)11(1):26–35

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

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

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

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

MRI flow void Loss of MRI signal due to flow of CSF

Normal aqueduct Abnormal aqueduct

MRI flow void

Normal fourth ventricle Abnormal fourth ventricle

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

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

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

Diagnosis- Probable Idiopathic NPH Physiological

Opening pressure 5-18 mmHg

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

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

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

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)

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

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

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

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

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

Yet another workup

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

Yet another workup

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

What kind of shunt is used? Externally programmable valve allows

transcutaneous adjustment CSF outflow resistance

What kind of shunt is used?

Shunt placement

Shunt Valve Adjustments

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

Now that my patient has had a shunt what happens next? Monitor for complications of shunt

Infection Shunt malfunction Excessive CSF drainage Subdural hematoma

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.

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

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