Content area

|

Treatment and clinical outcome in patients with idiopathic normal pressure hydrocephalus – a systematic review

Authors
Linnea Torsnes1, 2, Vibeke Blåfjelldal1, 2 & Frantz Rom Poulsen1, 2 1) Department of Neurosurgery, Odense University Hospital2) Clinical Institute, Faculty of Medicine, University of Southern Denmark

Abstract

Introduction: Treatment of idiopathic normal pressure hydrocephalus (iNPH) is challenging. It is well known that patients with iNPH experience short-term symptom relief after shunt implantation, but the long-term effect of shunting has yielded diverging results. The objective of the present study was to review the literature and to investigate the diagnostics, treatment and outcome of patients with iNPH after shunt treatment.

METHODS: A PubMed search was performed and 430 articles were identified. The search was further limited to humans, language (English and Norwegian) and publication dates after 1990. A total of 343 articles were retrieved, and 43 of these articles were found to be applicable to the research question and were therefore screened. A total of ten articles were discarded after reviewing their abstracts as the articles were not relevant to the question of interest. Another ten articles were identified from the reference lists of the initial articles which yielded a total of 43 relevant articles. The main reason for exclusion of articles was a lack of match between the articles’ search criteria and the research question herein.

RESULTS: Approximately 40% of the studies were prospective. The overall success rate from surgical treatment varied from 30% to 90%. Direct comparison was hampered by the lack of a common protocol regarding symptoms and outcome. Factors suggestive of a good outcome were early diagnosis, gait disturbance as the predominant preoperative complaint, and a positive response to cerebrospinal fluid dynamic tests.

CONCLUSION: Shunting remains the preferred treatment, but endoscopic third ventriculostomy is reported as a possible alternative in some studies.

The term normal pressure hydrocephalus (NPH) was initially introduced by Adams and Hakims in 1965. NPH is typically characterised by the clinical triad of abnormal gait, urinary incontinence and dementia, accompanied by normal cerebrospinal fluid (CSF) pressure on lumbar puncture and the absence of papillary oedema [1]. NPH can be divided into two main categories: idiopathic normal pressure hydrocephalus (iNPH) and secondary NPH. Secondary NPH can be caused by traumatic head injury, subarachnoid haemorrhage, infections and tumours. The syndrome of iNPH most commonly manifests in the sixth or seventh decade of life [2], and is one of the few potentially reversible causes of dementia, gait disturbance and urinary incontinence. It is therefore important to establish the correct diagnosis [3-5]. In elderly, the symptoms may resemble other causes of dementia including Parkinson’s disease, which can cause problems when diagnosing these patients. Currently, there is no standardised means of diagnosing iNPH or of identifying the candidates in whom surgery would be beneficial. It is therefore difficult to give an exact incidence estimate for iNPH. Studies suggest an incidence range of iNPH from 0.7 to 5.5 per 100,000 persons [6, 7].

Prognostic tests like the CSF tap test, the lumbar infusion test and intracranial pressure (ICP) monitoring have made it easier to identify the patients who will most likely benefit from surgery. The cause of iNPH has not yet been fully established, but several mechanisms regarding its pathophysiology have been suggested. Ventricular dilatation on computed tomography (CT)/magnetic resonance imaging (MRI) is a characteristic, but not a specific sign of iNPH and is thought to be due to defective CSF absorption and stagnation of the CSF flow [8, 9]. Among the recently suggested mechanisms, various authors have highlighted a new theory concerning the morphological changes in iNPH patients’ brains. The theory proposes that malfunction of arachnoid granulations causes a decreased subarachnoid space and thereby alters CSF absorption [7, 9-11)]. Another theory is that diverse cephalic degenerative changes may impair CSF absorption [3, 12].

The gold standard in treatment is shunting [13-17], but more recent studies have suggested a positive effect of endoscopic third ventriculostomy (ETV) [8, 9, 16-19].

The purpose of this review was to provide an overview of the current literature investigating the treatment and outcome in iNPH patients.

METHODS

Search strategy

We performed a literature search in accordance with the preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement [18].

The clinical question posed was: does diagnostics and treatment of patients with idiopathic normal pressure hydrocephalus affect the outcome and prognosis in a positive matter?

A PubMed search on publications from 1990 to 2012 was performed (Figure 1) in September 2013. Search words were normal pressure hydrocephalus, iNPH, treatment, therapy, and outcome.

Selection criteria and study eligibility

Titles were examined by both authors (LT and VB). Titles that were not relevant were excluded after both authors had examined the abstracts. Any studies of interest to the systematic review were included. The selected full papers were individually studied by both authors. Articles concerning iNPH and articles discussing diagnostics, treatment and outcome were included.

Risk of bias in individual studies

The studies were selected carefully with a focus on biases concerning the authors’ possible economic and personal interests.

RESULTS

The PubMed search returned a total of 430 articles. After excluding articles that did not fulfil our criteria, we were left with 43 articles to screen. Ten articles were excluded. Ten articles were included from reference lists. The eliminated articles did not match our clinical question properly.

The inclusion criteria were patients diagnosed with NPH, articles discussing treatment and outcome, and articles of a newer date.

Some only discussed NPH in general, and not the iNPH subgroup. Finally, some articles were excluded due to selection bias, including financial interests. The final result was therefore 43 articles. These studies were both retrospective and prospective. Approximately 40% were prospective (Figure 1).

Clinical symptoms before shunting

The classic triad of iNPH includes gait disturbance, cognitive impairment and urinary incontinence. These symptoms vary in severity and appearance. Gait impairment is the most common clinical feature in iNPH, with a frequency ranging from 80% to 100%. Gait disturbance is often the patient’s initial complaint. The second most frequent symptom is cognitive impairment, which ranges from 42% to 100%. Urinary incontinence ranges from 34% to 82%. The full clinical triad is present in 38-82% of cases [4, 5, 7, 8, 10, 13, 20-25]. The gait is described variably, but is most often characterised by a slow and magnetic gait as if the patients’ feet were stuck to the ground. Initiating movement is problematic and the walk is unsteady [22, 23].

Gait disturbance is the clinical symptom most likely to respond to surgery [10, 13, 19, 26, 27].

Instability and balance problems during walking were reported to be an element of poor outcome from shunting in one study [7], whereas another study found that balance dysfunction before shunting was associated with a better outcome after surgery [5].

The cognitive deficits observed in these patients comprise loss of subcortical and frontal functions, including memory decline, impaired attention and general mental sluggishness. The cognitive deficits make Alzheimer’s disease and other causes of dementia important and common differential diagnoses. It is difficult to distinguish iNPH from other types of dementia, but it is crucial as only symptoms related to iNPH will improve from surgery. The cognitive impairment in iNPH does, however, not usually include aphasia, apraxia or agnosia [27]. Through neuropsychological testing, deficits in attention, executive function, visuoperceptual and visuospatial functions have been found to be more severe in patients with iNPH than in patients with Alzheimer’s disease [28].

Urinary incontinence is the least prominent symptom, and usually a late sign of the disease [29]. This is partly due to the pathophysiology of iNPH, but it is also evident that a prominent gait disturbance may contribute to problems getting to the toilet in time. Severe cognitive deficits and the presence of urinary incontinence are associated with a poor prognosis [7, 15, 25, 29, 30]. It has been discussed whether the duration of the symptoms is important in predicting the outcome after surgery. Klassen & Ahlskog found no clear coherence between symptom duration and shunt response [7]. This observation runs counter to other studies stating that a longer duration of symptoms prior to shunting yields a lower success rate [2, 29, 30]

Diagnostic and prognostic tests

There is no standardised way to diagnose iNPH, and various assessments have been applied. It is difficult to compare severity of symptoms and improvement after surgery as there is no consensus on the diagnostic protocol. Some common elements in today’s diagnostics include: one/two or more of the classic triad symptoms, normal intracranial pressure, and enlarged ventricles on CT/MRI, cereprospinal fluid (CSF) stasis/increased Rout or improvement of symptoms after CSF removal (tap test) [3-5, 10, 11,17, 21, 22, 26, 29, 31-34]. Some also included a lack of secondary causes in the diagnostic criteria [10, 17, 34].

Clinical tests

For evaluation of the clinical symptoms, various test batteries were applied in different series. The NPH Scale was applied for clinical assessment before shunting, and some authors used corresponding NPH grading systems for assessment of symptoms. These include evaluation of the severity of gait, cognitive and urinary problems. The minimum score is three and the maximum score is 15 [3, 4, 31, 35-37]. Other studies use similar grading systems for assessment [31, 37, 38]. Bech et al used scales from 1-5 (one is normal, five is worst condition) for gait disturbance and urinary incontinence [10, 21]. One study scored NPH and graded symptoms from 1-10, assessing gait, living condition and urinary symptoms [38]. The Mini Mental State Examination (MMSE) is widely used for evaluation of cognitive impairment [3, 10, 13, 16, 17, 19, 20, 21, 26, 30, 37]. Another tool used for assessment of cognitive deficits is the Global Deterioration Scale (GDS) [3, 4, 21].

More extensive scales are also used, but may be difficult to apply in everyday use [14, 15, 31, 35, 37, 38].

Computed tomographyEvans ratio is used to evaluate ventricular enlargement. An Evans index > 0.30 on CT confirms significant enlargement and is frequently used as a diagnostic criterion [3, 10, 16, 20, 23, 29, 31-33].

Intracranial pressure monitoringAn ICP-sensitive transducer is used to monitor prolonged ICP and amplitude changes. B-waves represent oscillations of ICP and are often recorded [3, 4, 10, 19, 21, 30, 32]. Eide & Sorteberg reported that when using ICP monitoring as a diagnostic tool for identification of iNPH patients, improvement after surgery can be expected in 90% of subjects [31].

Bib ref: 
Dan Med J 2014;61(10):A4911
Magazine: 

LITERATURE

1. Adams RD, Fisher SM, Hakim S et al. Symptomatic occult hydrocephalus

with “normal” cerebrospinal-fluid pressure. A treatable syndrome. N Engl J

Med 1965;273:117-26.

2. Kiefer M, Meier U, Eymann R. Does idiopathic normal pressure

hydrocephalus always mean a poor prognosis? Acta Neurochir Suppl

2010;106:101-6.

3. Bech RA, Juhler M, Waldemar G et al. Frontal brain and leptomeningeal

biopsy specimens correlated with cerebrospinal fluid outflow resistance

and B-wave activity in patients suspected of normal-pressure

hydrocephalus. Neurosurgery 1997;40:497-502.

4. Poca MA, Solana E, Martinez-Ricarte FR et al. Idiopathic normal pressure

hydrocephalus: results of a prospective cohort of 236 shunted patients.

Acta Neurochir Suppl 2012;114:247-53.

5. Razay G, Vreugdenhil A, Liddell J. A prospective study of ventriculoperitoneal

shunting for idiopathic normal pressure hydrocephalus. J Clin

Neurosci 2009;16:1180-3.

6. Brean A, Fredø HL, Sollid S et al. Five-year incidence of surgery for

idiopathic normal pressure hydrocephalus in Norway. Acta Neurol Scand

2009;120:314-6.

7. Klassen BT, Ahlskog JE. Normal pressure hydrocephalus: how often does

the diagnosis hold water? Neurology 2011;77:1119-25.

8. Gangemi M, Maiuri F, Colella G et al. Is endoscopic third ventriculostomy

an internal shunt alone? Minim Invasive Neurosurg 2007;50:47-50.

9. Rangel-Castilla L, Barber S, Zhang YJ. The role of endoscopic third

ventriculostomy in the treatment of communicating hydrocephalus. World

Neurosurg 2012;77:555-60.

10. Bech RA, Waldemar G, Gjerris F et al. Shunting effects in patients with

idiopathic normal pressure hydrocephalus; correlation with cerebral and

leptomeningeal biopsy findings. Acta Neurochir (Wien) 1999;141:633-9.

11. Ishikawa M, Oowaki H, Matsumoto A et al. Clinical significance of

cerebrospinal fluid tap test and magnetic resonance imaging/computed

tomography findings of tight high convexity in patients with possible

idiopathic normal pressure hydrocephalus. Neurol Med Chir (Tokyo)

2010;50:119-23; discussion 123.

12. Tedeschi E, Hasselbalch SG, Waldemar G et al. Heterogeneous cerebral

glucose metabolism in normal pressure hydrocephalus. J Neurol

Neurosurg Psychiatry 1995;59:608-15.

13. Bech-Azeddine R, Waldemar G, Knudsen GM et al. Idiopathic normalpressure

hydrocephalus: evaluation and findings in a multidisciplinary

memory clinic. Eur J Neurol 2001;8:601-11.

14. Hailong F, Guangfu H, Haibin T et al. Endoscopic third ventriculostomy in

the management of communicating hydrocephalus: a preliminary study.

J Neurosurg 2008;109:923-30.

15. Meier U, Lemcke J, Neumann U. Predictors of outcome in patients with

normal-pressure hydrocephalus. Acta Neurochir Suppl 2006;96:352-7.

16. Paidakakos N, Borgarello S, Naddeo M. Indications for endoscopic third ventriculostomy in normal pressure hydrocephalus. Acta Neurochir Suppl

2012;113:123-7.

17. Scollato A, Gallina P, Gautam B et al. Changes in aqueductal CSF stroke

volume in shunted patients with idiopathic normal-pressure

hydrocephalus. AJNR Am J Neuroradiol 2009;30:1580-6.

18. Liberati, A, Altman DG, Tetzlaff J et al. The PRISMA statement for reporting

systematic reviews and meta-analyses of studies that evaluate health care

interventions: explanations and elaboration. Ann Intern Med 2009;151:65-

94.

19. Pujari S, Kharkar S, Metellus P et al. Normal pressure hydrocephalus: longterm

outcome after shunt surgery. J Neurol Neurosurg Psychiatry

2008;79:1282-6.

20. Aygok G, Marmarou A, Young HF. Three-year outcome of shunted

idiopathic NPH patients. Acta Neurochir Suppl 2005;95:241-5.

21. Bech-Azeddine R, Høgh P, Juhler M et al. Idiopathic normal-pressure

hydrocephalus: clinical comorbidity correlated with cerebral biopsy

findings and outcome of cerebrospinal fluid shunting. J Neurol Neurosurg

Psychiatry 2007;78:157-61.

22. Katzen H, Ravdin LD, Assuras S. Postshunt cognitive and functional

improvement in idiopathic normal pressure hydrocephalus. Neurosurgery

2011;68:416-9.

23. Kilic K, Czorny A, Auque J et al. Predicting the outcome of shunt surgery in

normal pressure hydrocephalus. J Clin Neurosci 2007;14:729-36.

24. Mirzayan MJ, Luetjens G, Borremans JJ. Extended long-term (> 5 years)

outcome of cerebrospinal fluid shunting in idiopathic normal pressure

hydrocephalus. Neurosurgery 2010;67:295-301.

25. Savolainen S, Hurskainen H, Paljärvi L et al. Five-year outcome of normal

pressure hydrocephalus with or without a shunt: predictive value of the

clinical signs, neuropsychological evaluation and infusion test. Acta

Neurochir (Wien) 2002;144:515-23; discussion 523.

26. Marmarou A, Young HF, Aygok GA et al. Diagnosis and management of

idiopathic normal pressure hydrocephalus: a prospective study in 151

patients. J Neurosurg 2005;102:987-97.

27. Woodworth GF, McGirt MJ, Williams MA et al. Cerebrospinal fluid drainage

and dynamics in the diagnosis of normal pressure hydrocephalus.

Neurosurgery 2009;64:919-25; discussion 925-6.

28. Saito M, Nishio Y, Kanno S et al. Cognitive profile of idiopathic normal

pressure hydrocephalus Dement Geriatr Cogn Disord Extra 2011;1:202-11.

29. Kiefer M, Eymann R, Steudel WI. Outcome predictors for normal-pressure

hydrocephalus. Acta Neurochir Suppl 2006;96:364-7.

30. McGirt MJ, Woodworth G, Coon AL et al. Diagnosis, treatment, and

analysis of long-term outcomes in idiopathic normal pressure

hydrocephalus. Neurosurgery 2005;57:699-705; discussion 699-705.

31. Eide PK, Sorteberg W. Diagnostic intracranial pressure monitoring and

surgical management in idiopathic normal pressure hydrocephalus: a

6-year review of 214 patients. Neurosurgery 2010;66:80-91.

32. Kahlon B, Sjunnesson J, Rehncrona S. Long-term outcome in patients with

suspected normal pressure hydrocephalus. Neurosurgery 2007;60:327-32;

discussion 332.

33. Meier U, Lemcke J, Al-Zain F. Course of disease in patients with idiopathic

normal pressure hydrocephalus (iNPH): a follow-up study 3, 4 and 5 years

following shunt implantation. Acta Neurochir Suppl 2008;102:125-7.

34. Stranjalis G, Kalamatianos T, Koutsarnakis C et al. Twelve-year hospital

outcomes in patients with idiopathic hydrocephalus. Acta Neurochir Suppl

2012;113:115-7.

35. Lemcke J, Meier U. Idiopathic normal pressure hydrocephalus (iNPH) and

co-morbidity: an outcome analysis of 134 patients. Acta Neurochir Suppl

2012;114:255-9.

36. Meier U, Zeilinger FS, Schonherr B. Endoscopic ventriculostomy versus

shunt operation in normal pressure hydrocephalus: diagnostics and

indication. Acta Neurochir Suppl 2000;76:563-6.

37. Solana E, Sahuquillo J, Junque C et al. Cognitive disturbances and

neuropsychological changes after surgical treatment in a cohort of 185

patients with idiopathic normal pressure hydrocephalus. Arch Clin

Neuropsychol 2012;27:304-17.

38. Czosnyka Z, Owler B, Keong N et al. Impact of duration of symptoms on

CSFdynamics in idiopathic normal pressure hydrocephalus. Acta Neurol

Scand 2011;123:414-8.

39. Wikkelsø C, Hellström P, Klinge PM et al. The European iNPH multicentre

study on the predictive values of resistance to CSF outflow and the CSF

Tap Test in patients with idiopathic normal pressure hydrocephalus.

J Neurol Neurosurg Psychiatry 2013;84:562-8.

40. Meier U, Lemcke J. Clinical outcome of patients with idiopathic normal

pressure hydrocephalus three years after shunt implantation. Acta 11

Neurochir Suppl, 2006;96:377-80.

41. Meier U, Lemcke J. Comorbidity as a predictor of outcome in patients with

idiopathic normal pressure hydrocephalus. Acta Neurochir Suppl,

2010;106:127- 30.

42. Longatti, PL, Fiorindi A, Martinuzzi A. Failure of endoscopic third

ventriculostomy in the treatment of idiopathic normal pressure

hydrocephalus. Minim Invasive Neurosurg 2004;47:342-5.

43. Meier U, Mutze S. Does the ventricle size change after shunt operation of

normal-pressure hydrocephalus? Acta Neurochir Suppl 2005;95:257-9.

Art icles retrieved fro m reference lists

Adams RD, Fisher SM, Hakim S et al. Symptomatic occult hydrocephalus with

“normal” cerebrospinal-fluid pressure. A treatable syndrome. N Engl J Med

1965;273:117-26.

Bech RA, Waldemar G, Gjerris F et al. Shunting effects in patients with

idiopathic normal pressure hydrocephalus; correlation with cerebral and

leptomeningeal biopsy findings. Acta Neurochir (Wien) 1999; 141:633-9.

Meier U, Zeilinger FS, Schonherr B. Endoscopic ventriculostomy versus shunt

operation in normal pressure hydrocephalus: diagnostics and indication. Acta

Neurochir Suppl 2000;76:563-6.

Bech-Azeddine R, Waldemar G, Knudsen GM et al. Idiopathic normal-pressure

hydrocephalus: evaluation and findings in a multidisciplinary memory clinic.

Eur J Neurol 2001;8:601-11.

Kahlon B, Sjunnesson J, Rehncrona S. Long-term outcome in patients with

suspected normal pressure hydrocephalus. Neurosurgery 2007;60:327-

32;discussion 332.

Woodworth GF, McGirt MJ, Williams MA et al. Cerebrospinal fluid drainage

and dynamics in the diagnosis of normal pressure hydrocephalus.

Neurosurgery 2009;64:919- 25; discussion 925-6.

Katzen H, Ravdin LD, Assuras S. Postshunt cognitive and functional

improvement in idiopathic normal pressure hydrocephalus. Neurosurgery

2011;68:416-9.

Wikkelsø C, Hellström P, Klinge PM et al. The European iNPH multicentre study

on the predictive values of resistance to CSF outflow and the CSF Tap Test in

patients with idiopathic normal pressure hydrocephalus. J Neurol Neurosurg

Psychiatry 2013;84:562-8.

Saito M, Nishio Y, Kanno S et al. Cognitive profile of idiopathic normal pressure

hydrocephalus. Dement Geriatr Cogn Disord Extra 2011;1:202-11.

Liberati, A, Altman DG , Tetzlaff J et al. The PRISMA statement for reporting

systematic reviews and meta-analyses of studies that evaluate health care

interventions: explanations and elaboration. Ann Intern Med 2009;151:65-94.

💬 0 Comments

Right side