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Normal PressureHydrocephalus

Jerry Ryan MD

University of Wisconsin - Madison

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Obj ectives1. Evaluate patients suspected of having NPHand distinguish NPH from other causes of gait

distur bance, incontinence and dementia2. Identify patients who need referral for consideration of treatment of NPH.3. Understand treatment of NPH and follow

patients who have received neurosurgicalinterventions for NPH in the office.4. Educate patients with NPH and their families a bout the disorder.

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How big is the pro blem?Prevalence Normal Pressure Hydrocephalus(NPH)

Estimates vary from 0- 5% as a cause for dementiaSome of variation due to inconsistentdefinition of NPH

Study of 166 patients shunted for presumedNPH calculated incidence of shunt responsiveNPH to be one patient per 2.2 million personsper year

J Vanneste, P Augustijn, C Dirven, WF Tan and ZD Goedhart

Neurology 1992;42:54±9

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S o why do I need to know

a bout NPH?Potentially reversi ble cause of significant mor bidityRecent direct to consumer advertising

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What should Family

Physicians know a bout NPH?Diagnostic features

Diagnostic studiesLimitations of prognostic studiesPatients likely to benefit from treatment

Complications of treatmentPatient follow up

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Etiology50% cases idiopathic

Leading theory is impairment of C S FoutflowIntraventricular pressure studies revealwaves of increased pressure- B-waves

Adult hydrocephalus syndrome Adult symptomatic hydrocephalus

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Etiology50% cases NPH secondary to other illnesses

S ubarachnoid hemorrhageMeningitisCranial trauma

S econdary NPH has higher responserate to shunting than idiopathic NPH

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PathophysiologyVentricle enlargement leads toperiventricular ischemia regardless of etiologyCompression and stretching of arterioles and venules

Arterial hypertension and cere bralarteriosclerosis increased in NPH

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CS F pathwayCS F produced by choroid plexus at rateapproximately 20 ml/hr Flows from lateral ventricles through foraminaof Monro into third ventricleEnters fourth ventricle through aqueduct of S

ylviusEnters su barachnoid spaceResor bed by arachnoid villi at top of brain

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CS F pathway

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Diagnostic TriadGait Distur bance

Urinary IncontinenceDementia

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Diagnostic TriadGait distur bance

No classic gait distur bance

Gait may be wide based, shufflingMore severely affected patients have ³magneticgait´- feet stuck to ground and difficult to initiatewalkingDifficulties with walking motions resolve withminimal support of patient or lying patient downMay resem ble Parkinson¶s gaitNot associated with lim b weaknessHyperreflexia

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Diagnostic TriadUrinary Incontinence

True incontinence found only in severelyaffected patientsUrinary urgency in most patients with NPHDue to stretching of periventricular nerve

fibers and loss of detrusor inhi bitionBladder sphincter muscle unaffected

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Diagnostic TriadDementia

Presence of dementia in NPH extremelyvaria ble

S ome shunt responsive patients have little or no dementiaDementia usually least responsive of symptomsto intervention

Mental status changes may resem bledepression

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Differential Diagnoses-

Alzheimer¶s (AD)

Both AD and NPH cause memory impairment

AD- ³cortical´ a bnormalities Aphasia, Apraxia, AgnosiaImpaired recognition and encoding deficits

NPH- ³su bcortical´ a bnormalitiesMemory impairment but intact recognitionS low information processingDifficulty with complex tasks

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Cognitive Impairments AD

versus NPH AD NPH

Impaired

MemoryLearningOrientation

Attention/concentrationExecutive function

Writing

Psychomotor slowingFine motor speedFine motor accuracy

BorderlineImpaired

Motor and psychomotor skillsVisuospatial skillsLanguage

Reading

Auditory memory Attention/concentrationExecutive functionBehavior/personalitychanges

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Alzheimer¶s (AD) AD and NPH can usually be distinguishedwith formal neuropsychological testing

Primary care office testing may not beadequate to distinguishMental impairment early in course of AD butusually late in course of NPH and often

minimal impairment AD often associated with hippocampalatrophy on imaging studies

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Parkinson¶s DiseaseBoth NPH and Parkinson¶s Disease(PD) can have similar gait distur bances

HypokinesiaFreezingImbalance

Extrapyramidal symptomsTrial of levadopa can help distinguishbetween PD and NPH

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Differential Diagnoses- Other DepressionS ubcortical arteriosclerotic encephalopathyMulti-infarct encephalopathyChronic alcoholismB12 , Folate deficiency

Electrolyte a bnormalitiesCervical or lum bar stenosisPeripheral neuropathy

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Diagnostic studiesVentricle enlargement on CT or MRI

S everity graded by ratio of maximal frontal horn

width divided by transverse inner diameter of skull0.32 minimal for NPH but 0.40 more typical

Lack of hippocampus or cortical atrophyPeriventricular and cortical white matter

lesions may be found in patients with NPHLarge num ber white matter lesions may bemarker for poor response to shunting

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Normal Ventricles

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E nlargedVentricles

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E nlargedVentricles

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E nlarged Ventricles

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E nlargedVentricles

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S o now that I know it¶s NPH

what next?Response to shunting variessignificantly between patients

S tudy 166 shunted NPH patientsOverall response 36%, only 21%significant improvement

Only 15% of patients with idiopathic NPHshowed marked improvement

J Vanneste, P Augustijn, C Dirven, WF Tan and ZD Goedhart Neurology 1992;42:54±9

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Any Pro blems With S hunting?Complications of shunting

Low immediate post-surgical risksS evere to moderate shunt related mor bidityof 28%

InfectionS

hunt malfunctionIntracranial bleed

Death or severe mor bidity 7%

J Vanneste, P Augustijn, C Dirven, WF Tan and ZD Goedhart

Neurology 1992;42:54-9

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Overdrainage

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How can I tell who will

benefit?Good response to shunting

Clinical presentationGait distur bance preceded mental impairmentS hort duration of mild mental impairmentKnown cause of NPH- e.g. infection, bleed

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benefit?Good response to shunting

S pecial studies

Lack of white matter lesions on MRIMarked resolution of symptoms with C S F drainage

One time removal 30-50 cc C S FMulti-day drainage of 100-150 cc C S F

B-waves greater than 50% of time with continuous

intracranial pressure (ICP) monitoringResistance to C S F outflow greater than 18 mmHg

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benefit?Poor response to shunting

S evere dementiaDementia presenting symptomMRI a bnormalities

Cere bral atrophy

Multiple white matter lesions

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benefit?Indeterminate significance

Patient ageDuration of symptomsLack of response to removal C S F

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How accurate are predictors of

response to shunting?

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

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How accurate are predictors of

response to shunting?

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

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NPH GuidelinesWorldwide group of experts assem bled to

develop guidelines for diagnosis andtreatment of NPHMeetings supported by shunt manufacturer Limited num ber of RCT¶s noted by group

Report pu blished in Neurosurgery: Vol. 57(3), S ept 2005 S upplement

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Diagnosis- Pro ba ble Idiopathic

NPHHistory

Insidious onset

Age over 40S ymptom duration 3-6 monthsNo antecedent event known to cause secondaryNPH

Progressive over timeNo other medical, psychiatric or neurologicalcondition that could cause symptoms

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NPHBrain imaging

Ventricular enlargement not attri buta ble to

cere bral atrophy or congenital disorder No macroscopic o bstruction present At least one of the following

Enlargement of lateral horns not attri buta ble tohippocampus atrophy

Callosal angle greater or equal to 40 degreesEvidence of altered brain water content on imaging notattri buta ble ischemia or demylination

An aqueductal or fourth ventricular flow void on MRI

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Callosal angleA ngle of roof of lateral ventricles in A -P projection

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MRI flow voidLoss of MRI signal due to flow of C S F

Normal aqueduct Abnormal aqueduct

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MRI flow void

Normal fourth ventricle Abnormal fourth ventricle

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NPHClinical

Gait/Balance- at least two of following present

Decreased step heightDecreased step lengthDecreased cadence/speedDecreased trunk swayWidened stanceToes turned outward while walkingEn bloc turning- turns take three or more stepsImpaired balance- two or more corrective steps for eightsteps on tandem gait testing

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NPHCognition- two of following present

Psychomotor slowing

Decreased fine motor speedDecreased fine motor accuracyDifficulty dividing or maintaining attentionImpaired recall especially for recent eventsImpairment of executive functions- multi-stepprocedures, working memory, formulation of a bstractions, insightBehavioral or personality changes

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NPHPhysiological

Opening pressure 5-18 mmHg

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Possi ble INPHHistory- S ymptoms are

S ubacute or indeterminate onset

Onset any time after childhood<3 months or indeterminate durationMay follow trauma, hemorrhage or meningitisS ymptoms not entirely explained by co-existing

neurological conditionsNon-progressive or not clearly progressive

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Possi ble INPHBrain imaging- Ventricular enlargementassociated with following

Cere bral atrophy of sufficient severity toexplain ventricular enlargementS tructural lesion that may increase

ventricular size

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Possi ble INPHClinical

Incontinence and/or cognitive impairmentin a bsence of gait or balance dysfunctionGait distur bance or dementia alone

PhysiologicalOpening pressure unavaila ble or outside of range for pro ba ble NPH

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Unlikely INPHNo ventriculomegalyS igns of increased intracranial pressuresuch as papilledemaNo component of clinical triadS ymptoms explained by other causes(eg, spinal stenosis)

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UCLA workup for NPH and

selecting shunt candidatesVentricular enlargement by CT or MRI (EvansIndex >0.3)

Complete history and neurological exam,neuropsychiatric testing and gait analysisPatients with significant dementia componentreferred for more extensive evaluation to ruleout Alzheimer¶s Disease of other forms of dementia

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selecting shunt candidatesPatients felt at risk for NPH undergointracranial pressure monitoring

Inserted with local anesthesiaFine wire placed just under calvarium

Elevated pressure- shunt

B-waves- further evaluation

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selecting shunt candidatesCere brospinal Fluid Outflow Resistance

Lum bar puncture performed

Artificial spinal fluid infusedRise in ICP recorded by previously insertedICP monitor Resistance to a bsor btion of infused fluidcalculated

High resistance- shuntNormal resistance- further testing

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selecting shunt candidatesTrial C S F drainage

3 day trialS mall volumes removed- 30-50 cc

Improved symptoms- shuntNo improvement- no further studies,shunt no longer considered

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selecting shunt candidatesS tudies not performed

Cisternogram

High volume CS

F drainagePET scanS PECT scan

Tests felt not warranted due to expense or

increased patient riskMRI flow void not routinely done as felt to benon-specificFurther testing felt to add minimal additional

prognostic information

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Y et another workup

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

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Y et another workup

Treating Normal Pressure Hydrocephalus, Luciano, M,

AAFP CME Bulletin, 2004, Vol. 3 (4)

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What kind of shunt is used?Externally programma ble valve allowstranscutaneous ad justment C S F outflow

resistance

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What kind of shunt is used?

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S hunt placement

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S hunt Valve Ad justments

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Now that my patient has had a

shunt what happens next?Monitoring of mental function

Patients should have neuropsychiatrictesting prior to shuntPeriodic testing post shunt to documentimprovement

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Now that my patient has had a

shunt what happens next?Monitor for complications of shunt

InfectionS hunt malfunctionExcessive C S F drainageS ubdural hematoma

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S ummaryBest patients for shunt have gaitdistur bance with mild mental impairment

Improvement with C S F drainage predictgood response to shunt but lack of improvement of limited prognostic valuePatients with significant dementia andlimited gait distur bance unlikely tobenefit from shunt.

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Cochrane Data baseConclusion: There is no evidence toindicate whether placement of a shunt iseffective in the management of NPH.Conclusion based upon lack of randomizedcontrolled trials

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S uggested references

Diagnosis and management of normal pressure

hydrocephalus, Vanneste, JA, JNeurol (2000) 247:5±14Neurosurgery: Vol. 57(3) S upplement, S eptem ber 2005Normal pressure hydrocephalus: an update, S tein, S C,Neurosurgery Quarterly (2001) 11 (1):26±35University of California- Los Angeles-http://www.neurosurgery.ucla.edu/Diagnoses/Adult/AdultDis_1.htmlUniversity of Virginia-http://www.healthsystem.virginia.edu/internet/neurogram/neurogram3_3_nph.cfm

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