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J. Douglas Mann, Albert B. Butler, Richard N. Johnson and Norman H. Bass

relatively high flows, even large decreases in CSF production can have little compensatory effect. Beyond those rates of infusion, equilibrium pressures were not consistently obtained, and EEG patterns began to reflect disturbed cerebral function. Similar manometric studies in the dog show only slightly higher maximal rates of fluid absorption from arachnoid villi, equivalent to 21 times the normal rate of CSF production. 11, 12 Another measure commonly used to express fluid efflux from the CSF compartment is the inverse of the outflow resistance or outflow conductance

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Michael J. Albeck, Svend E. Børgesen, Flemming Gjerris, Jes F. Schmidt and Per Soelberg Sørensen

✓ Conductance of cerebrospinal fluid (CSF) outflow (Cout) is an important parameter to be considered in patients with CSF circulation abnormalities. In patients with normal-pressure hydrocephalus it is the single most important parameter in determining if the patient needs CSF shunting. The lower normal limit for Cout has been estimated from the effect of shunting in patients with normal-pressure hydrocephalus, from patients retrospectively reevaluated after recovering from illness, and from patients with known abnormalities in the brain or the CSF system. The true value of Cout in normal individuals, however, has hitherto not been reported.

In the present study, Cout has been measured by a lumbar infusion test in eight young volunteers with no suspicion of disease. The mean intracranial pressure (ICP) was 11 mm Hg and a linear relationship was found between CSF absorption and ICP. The mean Cout was 0.11 ml/min/mm Hg and the lower 95% confidence level was 0.10 ml/min/mm Hg. These values are in accordance with those obtained from previous studies.

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Sakai Hiromu Yamada Hitoshi Iwata April 1991 74 4 585 589 10.3171/jns.1991.74.4.0585 The standardized assessment of argyrophilic nucleolar organizer regions in meningeal tumors Lawrence S. Chin David R. Hinton April 1991 74 4 590 596 10.3171/jns.1991.74.4.0590 Intracranial pressure and cerebrospinal fluid outflow conductance in healthy subjects Michael J. Albeck Svend E. Børgesen Flemming Gjerris Jes F. Schmidt Per Soelberg Sørensen April 1991 74 4 597 600 10.3171/jns.1991.74.4.0597 Subarachnoid

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Agnita J. W. Boon, Joseph T. J. Tans, Ernst J. Delwel, Saskia M. Egeler-Peerdeman, Patrick W. Hanlo, Hans A. L. Wurzer, Cees J. J. Avezaat, Dirk A. de Jong, Rob H. J. M. Gooskens and Jo Hermans

group. The Rcsf obtained by means of lumbar constant flow infusion is a reliable tool for the selection of patients to undergo shunt placement if the Rcsf limit is raised to 18 mm Hg/ml/minute. For lower Rcsf values, patients should undergo shunt placement when pathognomonic clinical and CT features of NPH are present. References 1. Albeck MJ , Børgesen SE , Gjerris F , et al : Intracranial pressure and cerebrospinal fluid outflow conductance in healthy subjects. J Neurosurg 74 : 597 – 600 , 1991 Albeck MJ

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Michael J. Albeck, Claus Skak, Per R. Nielsen, Karsten S. Olsen, Svend E. Børgesen and Flemming Gjerris

shunt is placed. References 1. Albeck MJ , Børgesen SE , Gjerris F , et al : Intracranial pressure and cerebrospinal fluid outflow conductance in healthy subjects. J Neurosurg 74 : 597 – 600 , 1991 Albeck MJ, Børgesen SE, Gjerris F, et al: Intracranial pressure and cerebrospinal fluid outflow conductance in healthy subjects. J Neurosurg 74: 597–600, 1991 2. Bech RA , Juhler M , Waldemar G , et al : Frontal brain and leptomeningeal biopsy specimens correlated with cerebrospinal

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Marek Czosnyka, Zofia H. Czosnyka, Peter C. Whitfield, Tim Donovan and John D. Pickard

The authors thank Dr. Tom Saul for his critical review of this manuscript and all our colleagues from the Academic Neurosurgical Unit, Addenbrookes Hospital in Cambridge, United Kingdom, who for years have helped us in the acquisition of clinical material. References 1. Albeck MJ , Børgesen SE , Gjerris F , et al : Intracranial pressure and cerebrospinal fluid outflow conductance in healthy subjects. J Neurosurg 74 : 597 – 600 , 1991 Albeck MJ, Børgesen SE, Gjerris F, et al: Intracranial pressure and

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Bo Lundkvist, Anders Eklund, Bo Kristensen, Markku Fagerlund, Lars-Owe D. Koskinen and Jan Malm

. Preoperatively, clinical characteristics were recorded and routine laboratory tests, a magnetic resonance study, and an informed consent form for all aspects of the trial were obtained. A CSF hydrodynamic investigation, which is described later, was used to measure the ICP and the CSF outflow conductance (that is, the inverse of resistance). Each patient's gait was recorded on videotape and the gait velocity was measured. An MMSE was also performed. After the baseline investigation was completed, all patients underwent implantation of a differential-pressure valve with an

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Maria A. Poca, Maria Mataró, Maria Del Mar Matarín, Fuat Arikan, Carmen Junqué and Juan Sahuquillo

, each patient was included in one of the following categories: 87 1) active hydrocephalus, mean ICP greater than 12 mm Hg with the presence of A- and/or B-waves; 2) compensated hydrocephalus, mean ICP less than or equal to 12 mm Hg with the presence of A- and/or B-waves; and 3) brain atrophy (ex vacuo hydrocephalus), mean ICP less than or equal to 12 mm Hg with no pathological waves in the total recording time. Additionally, in 31 of 43 patients CSF dynamics (that is, outflow resistance and outflow conductance) were determined using the Katzman and Hussey constant

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Michael A. Williams, James P. McAllister, Marion L. Walker, Dory A. Kranz, Marvin Bergsneider, Marc R. Del Bigio, Laurel Fleming, David M. Frim, Katrina Gwinn, John R. W. Kestle, Mark G. Luciano, Joseph R. Madsen, Mary Lou Oster-Granite and Giovanna Spinella

's Hospital of Michigan, Detroit, Michigan; Giovanna Spinella, NIH, Bethesda, Maryland; Curt Stewart, BrainChild Foundation, Carefree, Arizona; Greg Tocco, Hydrocephalus Foundation, Inc., Saugus, Massachusetts; Mark Wagshul, State University of New York, Stony Brook, New York; Bob Zalutsky, NINDS, Bethesda, Maryland References 1 Albeck MJ , Børgesen SE , Gjerris F , Schmidt JF , Sorensen PS : Intracranial pressure and cerebrospinal fluid outflow conductance in healthy subjects . J Neurosurg 74 : 597 – 600 , 1991 2 Anonymous : Recommendations for

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Nina Andersson, Jan Malm and Anders Eklund

, Eklund A : Assessment of cerebrospinal fluid outflow conductance using constant-pressure infusion - a method with real time estimation of reliability . Physiol Meas 26 : 1137 – 1148 , 2005 2 Børgesen SE , Gjerris F : The predictive value of conductance to outflow of CSF in normal pressure hydrocephalus . Brain 105 : 65 – 86 , 1982 3 Børgesen SE , Gjerris F , Sorensen SC : The resistance to cerebrospinal fluid absorption in humans. A method of evaluation by lumbo-ventricular perfusion, with particular reference to normal pressure