Normal Pressure Hydrocephalus
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Transcript of Normal Pressure Hydrocephalus
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