1、NeurologyClinical PracticeDiagnosis andmanagement of idiopathicnormal-pressurehydrocephalusMichael A. Williams, MD, FAANNorman R. Relkin, MD, PhDSummaryThe diagnosis and management of idiopathic normal-pressure hydrocephalus (iNPH), a disorder of gaitimpairment, incontinence, and dementia that affec
2、tselderly patients, incorporates an organized approachusing familiar principles for neurologists. The startingpoint is a comprehensive history and neurologic exam-ination, review of neuroimaging, and evaluation of thedifferential diagnosis. Coexisting disorders should betreated before specific iNPH
3、testing is performed.Specific iNPH testing includes assessing patientresponse to temporary CSF removal and testing CSFhydrodynamics. In properly selected patients, all iNPHsymptoms, including dementia, can improve aftershunt surgery. The longitudinal care of iNPH patientswithshuntsincludesevaluation
4、ofthedifferentialdiag-nosis of worsening iNPH symptoms and treatment ofcoexisting disorders. Evaluation of shunt obstructionisoftenindicated, and ifitisfound, surgicalcorrectionis likely to result in symptomatic improvement.Idiopathic normal-pressure hydrocephalus (iNPH)is a disorder of the elderly
5、with symptoms ofimpaired gait and mobility, urinary urgencyand incontinence, and mild cognitive impairment or dementia in the presence of ventri-culomegaly. The clinical presentation alone is usually not sufficient to diagnose iNPH and rec-ommend shunt surgery, as each of the primary iNPH symptoms c
6、an have multiple potentialetiologies, and enlarged ventricles can be seen with either hydrocephalus or brain atrophy.The Sandra and Malcolm Berman Brain and Clinical Neurology and Neuroscience, Department of Neurology and Neuroscience(NRR), Weill Cornell Medical College, New York, NY.Funding informa
7、tion and disclosures are provided at the end of the article. Full disclosure form informationprovided by the authors is available with the full text of this article at Neurology.org/cp.Correspondence to: michwilllifebridgehealth.orgNeurology: Clinical Practice|October 2013 www.neurology.org/cp 375“N
8、FSJDBO“DBEFNZPG/FVSPMPHZ6OBVUIPSJFESFQSPEVDUJPOPGUIJTBSUJDMFJTQSPIJCJUFEOrganized approach to diagnosis and treatmentThe goaloftheevaluation ofpossibleiNPHistopredictwhethershuntsurgeryislikelyto benefitthe patient sufficiently to justify the risks of surgery and postoperative morbidities. Following
9、 isan organized approach to evaluation.1. Clinical evaluation2. Treatment of other disorders before undertaking specific testing for iNPH3. Testing that is specific for prognosticating treatment response in iNPH4. Shunt surgery5. Longitudinal follow-upClinical evaluationKey neurologic features A com
10、parison of key clinical findings for iNPH from the Interna-tional and Japanese guidelines is presented in table 1.14By definition, iNPH is idiopathic;however, the neurologic history should include known risk factors for communicating hy-drocephalus, including meningitis, encephalitis, traumatic brai
11、n injury (including concus-sion), subarachnoid hemorrhage, and brain radiation. Enlarged head circumference is also arisk factor that may indicate a congenital component to the disorder.5Patients with secondarycommunicating hydrocephalus should be evaluated for the need for shunt surgery in themanne
12、r outlined below, except in clinically obvious cases, such as the development of hy-drocephalus during hospitalization for subarachnoid hemorrhage.Symptom onset The onset of iNPH symptoms is insidious and should have been evident forat least 6 months. Some patients and families are not aware of symp
13、toms until a precipitatingevent occurs (e.g., a fall or a change in symptoms after a surgical procedure). Careful question-ing can clarify the nature of symptom onset.Gait In iNPH, a higher-level gait disorder is seen with disturbed postural and locomotorreflexes in the absence of primary sensorimot
14、or deficits.6Findings include difficulty withtransitional movements (sitting to standing or standing to sitting); gait initiation failure;poor foot clearance with shuffling, tripping, falling, or festination; multistep turns withinstability; and retropulsion or anteropulsion of stance.7Theuseofastan
15、dardizedgaitevaluation (e.g., the Tinetti score, Boon Scale, or the timed up-and-go test) can be helpful.Spasticity, hyperreflexia, and other upper motor neuron findings are not typical. Symp-toms of iNPH are symmetric; therefore, lateralizing findings should increase suspicion ofother disorders.Bla
16、dder dysfunction The bladder dysfunction of iNPH is usually urinary urgency with dif-ficulty inhibiting bladder emptying.8In the early stages, patients may experience urgencywithout incontinence or with loss of a few drops of urine before reaching the toilet. Night-time urinary frequency is common.
17、Patients are usually aware of their need to urinate and areconcerned about their accidents. Incontinence without awareness of urinary urge or that onesclothes are wet is not characteristic of iNPH.Dementia The dementia of iNPH includes apathy or amotivation, daytime sleepiness, psy-chomotor slowing,
18、 and other features of frontal-subcortical dysfunction.911Functional lossesThe terms hydrocephalus and ventriculomegalyare not synonymous. Although all patients withiNPH should have enlarged ventricles, not allelderly patients with enlarged ventricles haveiNPH.376 2013 American Academy of NeurologyM
19、ichael A. Williams and Norman R. Relkin“NFSJDBO“DBEFNZPG/FVSPMPHZ6OBVUIPSJFESFQSPEVDUJPOPGUIJTBSUJDMFJTQSPIJCJUFETable 1 Key clinical features of idiopathic normal-pressure hydrocephalus: Comparison between the International and theJapanese guidelinesFeature International guidelines Japanese guideli
20、nesEssentialsymptomsFindings of gait/balance disturbance must be present,plus at least one other area of impairment in cognition,urinary symptoms, or bothMore than one of the clinical triad: gait disturbance,cognitive impairment, and urinary incontinenceGait disturbance is the most prevalent feature
21、, followedby cognitive impairment and urinary incontinenceSymptomonsetInsidious Symptoms progress slowlySymptomdurationMinimum duration of 36 monthsAge at onset After age 40 years After age 60 yearsEtiology No evidence of an antecedent event such as headtrauma, intracerebral hemorrhage, meningitis,
22、or otherknown causes of secondary hydrocephalusPreceding diseases possibly causing ventricular dilationare not obvious, including subarachnoid hemorrhage,meningitis, head injury, congenital hydrocephalus, andaqueductal stenosisComorbiddisordersNo other neurologic, psychiatric, or general medicalcond
23、itions that are sufficient to explain the presentingsymptomsClinical symptoms cannot be completely explained byother neurologic or non-neurologic diseasesOther neurologic diseases, including Parkinson disease,Alzheimer disease, and cerebrovascular diseases, maycoexist but should be mildGaitimpairmen
24、tAt least 2 of the following should be present and not beentirely attributable to other conditions:Small stride, shuffle, instability during walking, andincrease of instability on turningDecreased step heightDecreased step lengthDecreased cadence (speed of walking)Increased trunk sway during walking
25、Widened standing baseToes turned outward on walkingRetropulsion (spontaneous or provoked)En bloc turning (3 or more steps for 180)Impaired walking balance, as evidenced by 2 or morecorrections out of 8 steps on tandem gait testingUrinaryurgency/incontinence One of the following should be present:Ove
26、ractive bladder, mainly manifesting as increasednocturnal urinary frequency, urgency, and urinaryincontinenceEpisodic or persistent urinary incontinence notattributable to primary urologic disordersUrinary and fecal incontinenceOr any 2 of the following should be present:Urinary urgency (frequent pe
27、rception of a pressingneed to void)Urinary frequency (more than 6 voiding episodes in anaverage 12-hour period)Nocturia (the need to urinate more than twice a night)CognitiveimpairmentDocumented impairment (adjusted for age andeducational attainment) or decrease in performance on acognitive screenin
28、g instrument, or bothCognitive impairment is detected on cognitive testsContinuedNeurology: Clinical Practice|October 2013 www.neurology.org/cp 377Diagnosis and management of idiopathic normal-pressure hydrocephalus“NFSJDBO“DBEFNZPG/FVSPMPHZ6OBVUIPSJFESFQSPEVDUJPOPGUIJTBSUJDMFJTQSPIJCJUFEwith dement
29、ia in iNPH overlap with those of other dementias, including difficulty managingfinances, taking medications properly, driving, and keeping track of appointments. Impairedexpressive or receptive language, impaired naming, agnosia, poor immediate recall that doesnot benefit from cueing, hallucinations
30、, and failure to recognize close family or friends shouldraise concern for other causes of dementia. Delirium implies the presence of a concomitantdisorder or medication side effect.Neuroimaging The terms hydrocephalus and ventriculomegaly are not synonymous. Al-though all patients with iNPH should
31、have enlarged ventricles, not all elderly patients with en-larged ventricles have iNPH. In neurodegenerative disorders, cerebral atrophy results inventriculomegaly (so-called hydrocephalus ex vacuo). Neuroimaging can be used to raise orlower suspicion of iNPH; however, it can rarely exclude it entir
32、ely. A comparison of key neuro-imaging findings from the International and Japanese guidelines is presented in table 2.14The distinction between normal and enlarged ventricular size for age is difficult to ascertain;however, for screening purposes, the Evans ratio (the ratio of the widest diameter o
33、f the frontalhorns to the widest diameter of the brain on the same axial slice) suffices (figure). The Inter-national and Japanese guidelines use a threshold of $0.3, but research on normal elderlysubjects suggests a threshold of $0.33.14,12MRI is considered superior to CT in terms of providing more
34、 information on diagnosticrelevance and avoiding exposure to ionizing radiation. High-speed and high-resolution MRItechniques can better identify aqueductal stenosis, and MRI phase-contrast techniques showthe hyperdynamic aqueductal CSF flow that has been associated with shunt-responsive iNPH.Featur
35、es that distinguish hydrocephalus from atrophyThe Japanese guidelines for iNPH4identify several features that distinguish iNPH fromatrophy, including disproportionately enlarged subarachnoid spaces (particularly in the Syl-vian fissure and basal cisterns) and the “tight high convexity,” which is eff
36、acement of thesubarachnoid space over the convexity.13,14These findings may suggest a block of CSF flowbetween the basal cisterns and the arachnoid granulations, a condition that has been termeddisproportionately enlarged subarachnoid space hydrocephalus (DESH). By implication, theabsence of DESH on
37、 brain imaging is suggestive of brain atrophy, but it does not exclude thepossibility of iNPH.4,14Enlargement of the ventricles from iNPH will change the shape of the corpus callosum, withbowing and effacement seen on sagittal views (figure),15and impingement against the falxcerebri, resulting in an
38、 acute callosal angle (#90) seen on coronal views.Cisternography Radionuclide cisternography has a high false-positive rate, and the Interna-tional and Japanese guidelines recommend against it.14Table 1 ContinuedFeature International guidelines Japanese guidelinesOr evidence of at least 2 of the fol
39、lowing on examinationthat is not fully attributable to other conditions:Psychomotor slowing (increased response latency)Decreased fine motor speedDecreased fine motor accuracyDifficulty dividing or maintaining attentionImpaired recall, especially for recent eventsExecutive dysfunctionBehavioral or p
40、ersonality changesData for table assembled from references 1 and 4.378 2013 American Academy of NeurologyMichael A. Williams and Norman R. Relkin“NFSJDBO“DBEFNZPG/FVSPMPHZ6OBVUIPSJFESFQSPEVDUJPOPGUIJTBSUJDMFJTQSPIJCJUFEDifferential diagnosis Each of the primary symptoms of iNPH has multiple potentia
41、l eti-ologies (table 3). Most patients with iNPH have other conditions contributing to theirsymptoms, and it is uncommon to see “pure” iNPH. Further, patients without iNPH mayappear to have the iNPH syndrome because of multiple comorbidities. The first step is toidentify or exclude other disorders t
42、hat should be treated before evaluating iNPH.Although iNPH is described as a symptom “triad,” patients need not have all 3 symptoms.However, most published series and guidelines indicate that nearly all patients have gaitimpairment. A patient who has only dementia or incontinence should first be eva
43、luatedfor other disorders. Patients with gait impairment and urinary symptoms but no cognitiveimpairment may need evaluation for spinal cord disorders. Although any of the primaryiNPH symptoms may be the initial symptom, gait impairment is usually either the first orworst symptom.The tests ordered t
44、o evaluate the differential diagnosis include the so-called “dementia blood-work” (complete blood count, biochemical profile, B12, folate, thyroid-stimulating hormone,and when indicated, rapid plasma reagin, Lyme, vitamin D); neuropsychological testing;MRI of the cervical, thoracic, or lumbar spine;
45、 EMG/nerve conduction velocity; and urologyconsultation.Treatment of other disordersSeveral rationales support excluding or treating other disorders before pursuing iNPH testing.First, no evidence suggests that the time required to identify and treat other disorders diminishesthe likelihood of respo
46、nse to shunt surgery. Patients who have had iNPH symptoms for severalyears can still respond to shunt surgery. Patients can be reassured that it is more beneficial to un-dertake a thorough evaluation than it is to rush. Second, should the patients symptoms resolvewith treatment of other disorders, t
47、hen testing for iNPH may no longer be necessary. Finally,Table 2 Key imaging and CSF pressure features of idiopathic normal-pressure hydrocephalus: Comparison between theInternational and the Japanese guidelinesFeature International guidelines Japanese guidelinesVentricularsizeVentricular enlargemen
48、t not entirely attributable to cerebralatrophy or congenital enlargement (Evans index .0.3 orcomparable measure)Ventricular dilation (Evans index .0.3)OtherneuroimagingfeaturesNo macroscopic obstruction to CSF flow Sylvian fissures and basal cistern are usuallyenlargedAt least one of the following supportive features: Periventricular changes are not essentialnEnlargement of the temporal horns of the later
