Normal pressure hydrocephalus: Diagnostic and predictive evaluation

Damasceno, Benito Pereira

doi:10.1590/S1980-57642009DN30100003

Abstract

In typical cases, normal pressure hydrocephalus (NPH) manifests itself with the triad of gait disturbance, which begins first, followed by mental deterioration and urinary incontinence associated with ventriculomegaly (on CT or MRI) and normal cerebrospinal fluid (CSF) pressure. These cases present minor diagnostic difficulties and are the most likely to improve after shunting. Problems arise when NPH shows atypical or incomplete clinical manifestations (25-50% of cases) or is mimicked by other diseases. In this scenario, other complementary tests have to be used, preferentially those that can best predict surgical outcome. Radionuclide cisternography, intracranial pressure monitoring (ICP) and lumbar infusion tests can show CSF dynamics malfunction, but none are able to confirm whether the patient will benefit from surgery. The CSF tap test (CSF-TT) is the only procedure that can temporarily simulate the effect of definitive shunt. Since the one tap CSF-TT has low sensitivity, it cannot be used to exclude patients from surgery. In such cases, we have to resort to a repeated CSF-TT (RTT) or continuous lumbar external drainage (LED). The most reliable prediction would be achieved if RTT or LED proved positive, in addition to the occurrence of B-waves during more than 50% of ICP recording time. This review was based on a PubMed literature search from 1966 to date. It focuses on clinical presentation, neuroimaging, complementary prognostic tests, and differential diagnosis of NPH, particularly on the problem of selecting appropriate candidates for shunt.

Key words:
normal pressure hydrocephalus; neuropsychological tests; cerebrospinal fluid tap test; shunt surgery

Resumo

Em casos típicos, a hidrocefalia de pressão normal (HPN) manifesta-se com a tríade: distúrbio da marcha, que começa primeiro, seguido de deterioração mental e incontinência urinária associados a ventriculomegalia (na TC ou RM) e pressão liquórica normal. Esses casos conferem pouca dificuldade diagnóstica e são os que mais provavelmente melhoram após a derivação liquórica. O problema é quando a HPN manifesta-se de forma incompleta ou atípica (25-50% dos casos) ou é mimetizada por outras doenças. Então, outros testes complementares têm que ser usados, preferencialmente aqueles que melhor predizem o resultado cirúrgico. A cisternocintilografia, o monitoramento da pressão intracraniana e o teste de infusão lombar podem realmente mostrar disfunção da dinâmica liquórica, mas nenhum deles pode confirmar se o paciente vai beneficiar-se da cirurgia. O teste de punção liquórica é o único que pode temporariamente simular o efeito definitivo da derivação. Uma vez que o teste de (uma única) punção liquórica tem baixa sensibilidade, ele não pode ser usado para excluir pacientes da cirurgia. Em tais casos, temos que apelar para o teste da punção liquórica repetida (PLR) ou da drenagem liquórica lombar externa contínua (DLE). Um diagnóstico preditivo mais seguro seria conseguido se a PLR ou a DLE é positiva, juntamente com a ocorrência de ondas B em mais que 50% do tempo de monitoramento da pressão intracraniana. Este artigo de revisão baseou-se em uma busca na literatura, via PubMed, desde 1966. Ele focaliza a apresentação clínica, diagnóstico diferencial, testes prognósticos complementares e a questão da seleção de candidatos apropriados para a derivação.

Palavras-chave:
hidrocefalia de pressão normal; testes neuropsicológicos; teste da punção liquórica; cirurgia de derivação ventriculoperitoneal

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References

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Krauss JK, Halve B. Normal pressure hydrocephalus: survey on contemporary diagnostic algorithms and therapeutic decision-making in clinical practice. Acta Neurochir (Wien) 2004;146:379-388.
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Brean A, Eide PK. Prevalence of probable idiopathic normal pressure hydrocephalus (iNPH) in a Norwegian population. Acta Neurol Scand 2008;118:48-53.
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Vanneste J. Diagnosis and management of normal-pressure hydrocephalus. J Neurol 2000;247:5-14.
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Hebb AO, Cusimano MD. Idiopathic normal pressure hydrocephalus: a systematic review of diagnosis and outcome. Neurosurgery 2001;49:1166-1184.
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Akai K, Uchigasaki S, Tanaka U, Komatsu A. Normal pressure hydrocephalus. Neuropathological study. Acta Pathol Jpn 1987;37:97-110.
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Kudo T, Mima T, Hashimoto R, et al. Tau protein is a potential biological marker for normal pressure hydrocephalus. Psychiatry Clin Neurosci 2000;54:199-202.
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Kondziella D, Sonnewald U, Tullberg M, Wikkelsö C. Brain metabolism in adult chronic hydrocephalus. J Neurochem 2008;106:1515-1524.
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Del Bigio MR, Crook CR, Buist R. Magnetic resonance imaging and behavioral analysis of immature rats with kaolin-induced hydrocephalus: pre- and postshunting observations. Exp Neurol 1997;148:256-264.
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Klinge P, Samii A, Niescken S, Brinker T, Silverberg GD. Brain amyloid accumulates in aged rats with kaolin-induced hydrocephalus. Neuroreport 2006;17:657-660.
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Larsson A, Stephensen H, Wikkelsö C. Normaltryckshydrocefalus: demenstillstånd som förbätttras med shuntkirurgi. Läkartidningen 1995;92:545-550.
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Fisher CM. Hydrocephalus as a cause of disturbances of gait in the elderly. Neurology 1982;32:1358-63.
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Graff-Radford NR, Godersky JC. Normal-pressure hydrocephalus. Onset of gait abnormality before dementia predicts good surgical outcome. Arch Neurol 1986;43:940-942.
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Larsson A, Wikkelso C, Bilting M, Stephensen H. Clinical parameters in 74 consecutive patients shunt operated for normal pressure hydrocephalus. Acta Neurol Scand 1991;84:475-482.
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Mori E. Gait disturbance in idiopathic normal pressure hydrocephalus. Brain Nerve 2008;60:219-224.
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Estañol BV. Gait apraxia in communicating hydrocephalus. J Neurol Neurosurg Psychiatry 1981;44:305-318.
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Knutsson E, Lying-Tunnel U. Gait apraxia in normal-pressure hydrocephalus: patterns of movement and muscle activation. Neurology 1985;35:155-160.
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Larsson A, Bergh AC, Bilting M, et al. Regional cerebral blood flow in normal pressure hydrocephalus: diagnostic and prognostic aspects. Eur J Nucl Med 1994;21:118-123.
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Owler BK, Momjian S, Czosnyka Z, et al. Normal pressure hydrocephalus and cerebral blood flow: a PET study of baseline values. J Cereb Blood Flow Metab 2004;24:17-23.
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Damasceno BD, Carelli EF, Honorato DC, Facure JJ. The predictive value of cerebrospinal fluid tap-test in normal pressure hydrocephalus. Arq Neuropsiquiatr 1997;55:179-185.
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Lindqvist G, Andersson H, Bilting M, Blomstrand C, Malmgren H, Wikkelsö C. Normal pressure hydrocephalus: psychiatric findings before and after shunt operation classified in a new diagnostic system for organic psychiatry. Acta Psychiatr Scand 1993;88(Suppl 373):18-32.
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Tullberg M, Hellström P, Piechnik SK, Starmark J-E, Wikkelsö C. Impaired wakefulness is associated with reduced anterior cingulated CBF in patients with normal pressure hydrocephalus. Acta Neurol Scand 2004;110:322-330.
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Ahlberg J, Norlén L, Blomstrand C, Wikkelso C. Outcome of shunt operation on urinary incontinence in normal pressure hydrocephalus predicted by lumbar puncture. J Neurol Neurosurg Psychiatry 1988;51:105-108.
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Sakakibara R, Kanda T, Sekido T, et al. Mechanism of bladder dysfunction in idiopathic normal pressure hydrocephalus. Neurourol Urodyn 2008;27:507-510.
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Gallia GL, Rigamonti D, Williams MA. The diagnosis and treatment of idiopathic normal pressure hydrocephalus. Nat Clin Pract Neurol 2005;2:375-381.
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Vanneste J, Augustijn P, Tan WF, et al. Shunting normal pressure hydrocephalus: the predictive value of combined clinical and CT data. J Neurol Neurosurg Psychiatry 1993;56:251-256.
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Vanneste J. Three decades of normal pressure hydrocephalus: are we wiser now? Editorial. J Neurol Neurosurg Psychiatry 1994;57:1021-1025.
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Curran T, Lang AE. Parkinsonian syndromes associated with hydrocephalus: case reports, a review of the literature, and pathophysiological hypotheses. Mov Disord 1994;9:508-520.
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Stolze H, Kuhtz-Buschbeck JP, Drücke H, Jöhnk K, Illert M, Deuschl G. Comparative analysis of the gait disorder of normal pressure hydrocephalus and Parkinson's disease. J Neurol Neurosurg Psychiatry 2001;70:289-297.
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Damasceno, BP. O valor preditivo da punção liquórica (tap-test) na hidrocefalia de pressão normal (Postdoctorate thesis). Campinas-SP: Universidade Estadual de Campinas, 2000.
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Hellström P, Edsbagge M, Archer T, Tisell M, Tullberg M, Wikkelsö C. The neuropsychology of patients with clinically diagnosed idiopathic normal pressure hydrocephalus. Neurosurgery 2007;61:1219-1226.
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Kazui H. Cognitive impairment in patients with idiopathic normal pressure hydrocephalus. Brain Nerve 2008;60:225-231.
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Tullberg M, Jensen C, Ekholm S, Wikkelsö C. Normal pressure hydrocephalus: vascular white matter changes on MRI must not exclude patients from shunt surgery. Am J Neuroradiol 2001;22:1665-1673.
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Kitagaki H, Mori E, Ishii K, Yamaji S, Hirono N, Imamura T. CSF spaces in idiopathic normal pressure hydrocephalus: morphology and volumetry. Am J Neuroradiol 1998;19:1277-1284.
³⁵
Holodny AI, George AE, De Leon MJ, Golomb J, Kalnin AJ, Cooper PR. Focal dilation and paradoxical collapse of cortical fissures and sulci in patients with normal-pressure hydrocephalus. J Neurosurg 1998;89:742-747.
³⁶
Bergstrand G, Oxenstierna G, Flyckt L, Larsson SA, Sedvall G. Radionuclide cisternography and computed tomography in 30 healthy volunteers. Neuroradiology 1986;28:154-160.
³⁷
Vanneste J, Augustijn P, Davies GAG, Dirven C, Tan WF. Normal-pressure hydrocephalus. Is cisternography still useful in selecting patients for a shunt? Arch Neurol 1992;49:366-370.
³⁸
Jack CR, Mokri B, Laws ER, Houser OW, Baker HL, Petersen RC. MR findings in normal-pressure hydrocephalus: significance and comparison with other forms of dementia. J Comput Assist Tomogr 1987;6:923-931.
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Bradley WG, Whittemore AR, Watanabe AS, et al. Association of deep matter infarction with chronic communicating hydrocephalus: implications regarding the possible origin of normal-pressure hydrocephalus. AJNR 1991;12:31-39.
⁴⁰
Krauss JK, Regel JP, Vach W, Jüngling FD, Droste DW, Wakhloo AK. Flow void of cerebrospinal fluid in idiopathic normal pressure hydrocephalus of the elderly: can it predict outcome after shunting? Neurosurgery 1997;40:67-73.
⁴¹
Sharma AK, Gaikwad S, Gupta V, Garg A, Mishra NK. Measurement of peak CSF flow velocity at cerebral aqueduct, before and after lumbar CSF drainage, by use of phase-contrast MRI: utility in the management of idiopathic normal pressure hydrocephalus. Clin Neurol Neurosurg 2008;110:363-368.
⁴²
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Marmarou A, Bergsneider M, Klinge P, Relkin N, Black PM. The value of supplemental prognostic tests for the preoperative assessment of idiopathic normal-pressure hydrocephalus. Neurosurgery 2005;57(Suppl 3):S17-28.
⁴⁴
Krauss JK, Halve B. Normal pressure hydrocephalus: survey of contemporary diagnostic algorithms and therapeutic decision-making in clinical practice. Acta Neurochir (Wien) 2004;146:379-388.
⁴⁵
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⁴⁶
Sorteberg A, Eide PK, Fremming AD. A prospective study on the clinical effect of surgical treatment of normal pressure hydrocephalus: the value of hydrodynamic evaluation. Br J Neurosurg 2004;18:149-157.
⁴⁷
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⁴⁸
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⁴⁹
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⁵¹
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⁵³
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⁵⁴
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⁵⁵
Chen IH, Huang CI, Liu HC, Chen KK. Effectiveness of shunting in patients with normal pressure hydrocephalus predicted by temporary, controlled-resistance, continuous lumbar drainage: a pilot study. J Neurol Neurosurg Psychiatry 1994;57:1430-1432.
⁵⁶
Kilic K, Czorny A, Auque J, Berkman Z. Predicting the outcome of shunt in normal pressure hydrocephalus. J Clin.Neurosci 2007;14:729-736.
⁵⁷
Damasceno BP. The predictive value of the tap-test in normal pressure hydrocephalus (Abstract of Thesis). Arq Neuropsiquiatr 2000;58:1155-1156.
⁵⁸
Damasceno BP, Carelli EF, Honorato DC, Borges G. Normal pressure hydrocephalus: the predictive value of cerebrospinal fluid tap-test. J Neurol Sci 2005;238(Suppl 10):S281.
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Publication Dates

Publication in this collection
Jan-Mar 2009

History

Received
31 Dec 2008
Accepted
12 Feb 2009

This is an open-access article distributed under the terms of the Creative Commons Attribution License

[1] ¹
Krauss JK, Halve B. Normal pressure hydrocephalus: survey on contemporary diagnostic algorithms and therapeutic decision-making in clinical practice. Acta Neurochir (Wien) 2004;146:379-388.

[2] ²
Brean A, Eide PK. Prevalence of probable idiopathic normal pressure hydrocephalus (iNPH) in a Norwegian population. Acta Neurol Scand 2008;118:48-53.

[3] ³
Vanneste J. Diagnosis and management of normal-pressure hydrocephalus. J Neurol 2000;247:5-14.

[4] ⁴
Hebb AO, Cusimano MD. Idiopathic normal pressure hydrocephalus: a systematic review of diagnosis and outcome. Neurosurgery 2001;49:1166-1184.

[5] ⁵
Akai K, Uchigasaki S, Tanaka U, Komatsu A. Normal pressure hydrocephalus. Neuropathological study. Acta Pathol Jpn 1987;37:97-110.

[6] ⁶
Kudo T, Mima T, Hashimoto R, et al. Tau protein is a potential biological marker for normal pressure hydrocephalus. Psychiatry Clin Neurosci 2000;54:199-202.

[7] ⁷
Kondziella D, Sonnewald U, Tullberg M, Wikkelsö C. Brain metabolism in adult chronic hydrocephalus. J Neurochem 2008;106:1515-1524.

[8] ⁸
Del Bigio MR, Crook CR, Buist R. Magnetic resonance imaging and behavioral analysis of immature rats with kaolin-induced hydrocephalus: pre- and postshunting observations. Exp Neurol 1997;148:256-264.

[9] ⁹
Klinge P, Samii A, Niescken S, Brinker T, Silverberg GD. Brain amyloid accumulates in aged rats with kaolin-induced hydrocephalus. Neuroreport 2006;17:657-660.

[10] ¹⁰
Larsson A, Stephensen H, Wikkelsö C. Normaltryckshydrocefalus: demenstillstånd som förbätttras med shuntkirurgi. Läkartidningen 1995;92:545-550.

[11] ¹¹
Fisher CM. Hydrocephalus as a cause of disturbances of gait in the elderly. Neurology 1982;32:1358-63.

[12] ¹²
Graff-Radford NR, Godersky JC. Normal-pressure hydrocephalus. Onset of gait abnormality before dementia predicts good surgical outcome. Arch Neurol 1986;43:940-942.

[13] ¹³
Larsson A, Wikkelso C, Bilting M, Stephensen H. Clinical parameters in 74 consecutive patients shunt operated for normal pressure hydrocephalus. Acta Neurol Scand 1991;84:475-482.

[14] ¹⁴
Mori E. Gait disturbance in idiopathic normal pressure hydrocephalus. Brain Nerve 2008;60:219-224.

[15] ¹⁵
Estañol BV. Gait apraxia in communicating hydrocephalus. J Neurol Neurosurg Psychiatry 1981;44:305-318.

[16] ¹⁶
Knutsson E, Lying-Tunnel U. Gait apraxia in normal-pressure hydrocephalus: patterns of movement and muscle activation. Neurology 1985;35:155-160.

[17] ¹⁷
Larsson A, Bergh AC, Bilting M, et al. Regional cerebral blood flow in normal pressure hydrocephalus: diagnostic and prognostic aspects. Eur J Nucl Med 1994;21:118-123.

[18] ¹⁸
Owler BK, Momjian S, Czosnyka Z, et al. Normal pressure hydrocephalus and cerebral blood flow: a PET study of baseline values. J Cereb Blood Flow Metab 2004;24:17-23.

[19] ¹⁹
Damasceno BD, Carelli EF, Honorato DC, Facure JJ. The predictive value of cerebrospinal fluid tap-test in normal pressure hydrocephalus. Arq Neuropsiquiatr 1997;55:179-185.

[20] ²⁰
Lindqvist G, Andersson H, Bilting M, Blomstrand C, Malmgren H, Wikkelsö C. Normal pressure hydrocephalus: psychiatric findings before and after shunt operation classified in a new diagnostic system for organic psychiatry. Acta Psychiatr Scand 1993;88(Suppl 373):18-32.

[21] ²¹
Tullberg M, Hellström P, Piechnik SK, Starmark J-E, Wikkelsö C. Impaired wakefulness is associated with reduced anterior cingulated CBF in patients with normal pressure hydrocephalus. Acta Neurol Scand 2004;110:322-330.

[22] ²²
Ahlberg J, Norlén L, Blomstrand C, Wikkelso C. Outcome of shunt operation on urinary incontinence in normal pressure hydrocephalus predicted by lumbar puncture. J Neurol Neurosurg Psychiatry 1988;51:105-108.

[23] ²³
Sakakibara R, Kanda T, Sekido T, et al. Mechanism of bladder dysfunction in idiopathic normal pressure hydrocephalus. Neurourol Urodyn 2008;27:507-510.

[24] ²⁴
Gallia GL, Rigamonti D, Williams MA. The diagnosis and treatment of idiopathic normal pressure hydrocephalus. Nat Clin Pract Neurol 2005;2:375-381.

[25] ²⁵
Vanneste J, Augustijn P, Tan WF, et al. Shunting normal pressure hydrocephalus: the predictive value of combined clinical and CT data. J Neurol Neurosurg Psychiatry 1993;56:251-256.

[26] ²⁶
Ishikawa M. Guideline Committee for Idiopathic Normal Pressure Hydrocephalus, Japanese Society of Normal Pressure Hydrocephalus. Clinical guidelines for idiopathic normal pressure hydrocephalus. Neurol Med Chir (Tokyo) 2004;44: 222-223.

[27] ²⁷
Vanneste J. Three decades of normal pressure hydrocephalus: are we wiser now? Editorial. J Neurol Neurosurg Psychiatry 1994;57:1021-1025.

[28] ²⁸
Curran T, Lang AE. Parkinsonian syndromes associated with hydrocephalus: case reports, a review of the literature, and pathophysiological hypotheses. Mov Disord 1994;9:508-520.

[29] ²⁹
Stolze H, Kuhtz-Buschbeck JP, Drücke H, Jöhnk K, Illert M, Deuschl G. Comparative analysis of the gait disorder of normal pressure hydrocephalus and Parkinson's disease. J Neurol Neurosurg Psychiatry 2001;70:289-297.

[30] ³⁰
Damasceno, BP. O valor preditivo da punção liquórica (tap-test) na hidrocefalia de pressão normal (Postdoctorate thesis). Campinas-SP: Universidade Estadual de Campinas, 2000.

[31] ³¹
Hellström P, Edsbagge M, Archer T, Tisell M, Tullberg M, Wikkelsö C. The neuropsychology of patients with clinically diagnosed idiopathic normal pressure hydrocephalus. Neurosurgery 2007;61:1219-1226.

[32] ³²
Kazui H. Cognitive impairment in patients with idiopathic normal pressure hydrocephalus. Brain Nerve 2008;60:225-231.

[33] ³³
Tullberg M, Jensen C, Ekholm S, Wikkelsö C. Normal pressure hydrocephalus: vascular white matter changes on MRI must not exclude patients from shunt surgery. Am J Neuroradiol 2001;22:1665-1673.

[34] ³⁴
Kitagaki H, Mori E, Ishii K, Yamaji S, Hirono N, Imamura T. CSF spaces in idiopathic normal pressure hydrocephalus: morphology and volumetry. Am J Neuroradiol 1998;19:1277-1284.

[35] ³⁵
Holodny AI, George AE, De Leon MJ, Golomb J, Kalnin AJ, Cooper PR. Focal dilation and paradoxical collapse of cortical fissures and sulci in patients with normal-pressure hydrocephalus. J Neurosurg 1998;89:742-747.

[36] ³⁶
Bergstrand G, Oxenstierna G, Flyckt L, Larsson SA, Sedvall G. Radionuclide cisternography and computed tomography in 30 healthy volunteers. Neuroradiology 1986;28:154-160.

[37] ³⁷
Vanneste J, Augustijn P, Davies GAG, Dirven C, Tan WF. Normal-pressure hydrocephalus. Is cisternography still useful in selecting patients for a shunt? Arch Neurol 1992;49:366-370.

[38] ³⁸
Jack CR, Mokri B, Laws ER, Houser OW, Baker HL, Petersen RC. MR findings in normal-pressure hydrocephalus: significance and comparison with other forms of dementia. J Comput Assist Tomogr 1987;6:923-931.

[39] ³⁹
Bradley WG, Whittemore AR, Watanabe AS, et al. Association of deep matter infarction with chronic communicating hydrocephalus: implications regarding the possible origin of normal-pressure hydrocephalus. AJNR 1991;12:31-39.

[40] ⁴⁰
Krauss JK, Regel JP, Vach W, Jüngling FD, Droste DW, Wakhloo AK. Flow void of cerebrospinal fluid in idiopathic normal pressure hydrocephalus of the elderly: can it predict outcome after shunting? Neurosurgery 1997;40:67-73.

[41] ⁴¹
Sharma AK, Gaikwad S, Gupta V, Garg A, Mishra NK. Measurement of peak CSF flow velocity at cerebral aqueduct, before and after lumbar CSF drainage, by use of phase-contrast MRI: utility in the management of idiopathic normal pressure hydrocephalus. Clin Neurol Neurosurg 2008;110:363-368.

[42] ⁴²
Boon AJ, Tans JT, Delwel EJ, et al. The Dutch normal-pressure hydrocephalus study. How to select patients for shunting? An analysis of four diagnostic criteria. Surg Neurol 2000;53:201-207.

[43] ⁴³
Marmarou A, Bergsneider M, Klinge P, Relkin N, Black PM. The value of supplemental prognostic tests for the preoperative assessment of idiopathic normal-pressure hydrocephalus. Neurosurgery 2005;57(Suppl 3):S17-28.

[44] ⁴⁴
Krauss JK, Halve B. Normal pressure hydrocephalus: survey of contemporary diagnostic algorithms and therapeutic decision-making in clinical practice. Acta Neurochir (Wien) 2004;146:379-388.

[45] ⁴⁵
Poca MA, Mataro M, Matarin MM, et al. Is the placement of shunts in patients with idiopathic normal-pressure hydrocephalus worth the risk? Results of a study based on continuous monitoring of intracranial pressure. J Neurosurg 2004; 100:855-866.

[46] ⁴⁶
Sorteberg A, Eide PK, Fremming AD. A prospective study on the clinical effect of surgical treatment of normal pressure hydrocephalus: the value of hydrodynamic evaluation. Br J Neurosurg 2004;18:149-157.

[47] ⁴⁷
Sovolainen S, Hurskainen H, Paljarvi 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;144:515-523.

[48] ⁴⁸
Meier U, Lemcke J, Neumann U. Predictors of outcome in patients with normal-pressure hydrocephalus. Acta Neurochir Suppl 2006;96:352-357.

[49] ⁴⁹
Adams RD, Fisher CM, Hakim S, et al. Symptomatic occult hydrocephalus with "normal" cerebrospinal fluid pressure: a treatable syndrome. N Engl J Med 1965;273:117-126.

[50] ⁵⁰
Fisher CM. Communicating hydrocephalus. Lancet 1978; 1:37.

[51] ⁵¹
Wikkelso C, Andersson H, Blomstrand C, Lindqvist G - The clinical effect of lumbar puncture in normal pressure hydrocephalus. J Neurol Neurosurg Psychiatry 1982;45:64-69.

[52] ⁵²
Wikkelso C, Andersson H, Blomstrand C, Lindqvist G & Svendsen P - Normal pressure hydrocephalus: predictive value of the cerebrospinal fluid tap-test. Acta Neurol Scand 1986;73:566-573.

[53] ⁵³
Milhorat TH. Comment. Neurosurgery 1997;40:73-74.

[54] ⁵⁴
Mori K. Management of idiopathic normal-pressure hydrocephalus: a multiinstitutional study conducted in Japan. J Neurosurg 2001;95:970-973.

[55] ⁵⁵
Chen IH, Huang CI, Liu HC, Chen KK. Effectiveness of shunting in patients with normal pressure hydrocephalus predicted by temporary, controlled-resistance, continuous lumbar drainage: a pilot study. J Neurol Neurosurg Psychiatry 1994;57:1430-1432.

[56] ⁵⁶
Kilic K, Czorny A, Auque J, Berkman Z. Predicting the outcome of shunt in normal pressure hydrocephalus. J Clin.Neurosci 2007;14:729-736.

[57] ⁵⁷
Damasceno BP. The predictive value of the tap-test in normal pressure hydrocephalus (Abstract of Thesis). Arq Neuropsiquiatr 2000;58:1155-1156.

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