Validation of Davson’s equation in patients suffering from idiopathic normal pressure hydrocephalus
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The so-called Davson’s equation relates baseline intracranial pressure (ICP) to resistance to cerebrospinal fluid outflow (Rout), formation of cerebrospinal fluid (If) and sagittal sinus pressure (PSS) There is a controversy over whether this fundamental equation is applicable in patients with normal pressure hydrocephalus (NPH). We investigated the relationship between Rout and ICP and also other compensatory, clinical and demographic parameters in NPH patients.
We carried out a retrospective study of 229 patients with primary NPH who had undergone constant-rate infusion studies in our hospital. Data was recorded and processed using ICM+ software. Relationships between variables were sought by calculating Pearson product correlation coefficients and p values.
We found a significant, albeit weak, relationship between ICP and Rout (R = 0.17, p = 0.0049), Rout and peak-to-peak amplitude of ICP (AMP) (R = 0.27, p = 3.577e-05) and Rout and age (R = 0.16, p = 0.01306).
The relationship found between ICP and Rout provides indirect evidence to support disturbed Cerebrospinal fluid circulation as a key factor in disturbed CSF dynamics in NPH. Weak correlation may indicate that other factors—variable PSS and formation of CSF outflow—contribute heavily to linear model expressed by Davson’s equation.
KeywordsNormal pressure hydrocephalus Resistance to CSF outflow Intracranial pressure Davson’s equation
Compliance with ethical standards
Conflict of interest
For this type of study, formal consent is not required.
Informed consent was obtained from all individual participants included in the study.
- 2.Andersson N (2007) Cerebrospinal fluid infusion methods: development and validation on patients with idiopathic normal pressure hydrocephalus. (Doctoral dissertation, Umeå universitet). http://umu.diva-portal.org/smash/record.jsf?pid=diva2%3A140775&dswid=-5901
- 7.Boon AJ, Tans JT, Delwel EJ, Egeler-Peerdeman SM, Hanlo PW, Wurzer HA, Avezaat CJ, de Jong DA, Gooskens RH, Hermans J (1997) Dutch normal-pressure hydrocephalus study: prediction of outcome after shunting by resistance to outflow of cerebrospinal fluid. J Neurosurg 87(5):687–693CrossRefPubMedGoogle Scholar
- 10.Brgesen SE, Gjerris FLEMMING (1982) The predictive value of conductance to outflow of CSF in Normal pressure hydrocephalus. Brain J Neurol 105(Pt1):65-86Google Scholar
- 11.Czosnyka M, Czosnyka Z, Agarwal-harding KJ, Pickard JD (2012) Hydrocephalus. doi: https://doi.org/10.1007/978-3-7091-0923-6
- 18.Kalyvas A V, Hughes M, Koutsarnakis C, Moris D, Liakos F, Sakas DE, Stranjalis G, Fouyas I (2017) Efficacy, complications and cost of surgical interventions for idiopathic intracranial hypertension: a systematic review of the literature. Acta Neurochir 33–49Google Scholar
- 20.Lalou AD, Czosnyka M, Donnelly J, Pickard JD, Garnett MR, Nabbanja E, Keong NC, Czosnyka Z (2017) Cerebral autoregulation, its relationship with Rout and outcome after CSF diversion in normal pressure hydrocephalus. J Neurosurg. https://doi.org/10.1101/223867
- 22.Momjian S, Owler BK, Czosnyka Z, Czosnyka M, Pena A, Pickard JD (2004) Pattern of white matter regional cerebral blood flow and autoregulation in normal pressure hydrocephalus. Brain 127(pt5):965–972Google Scholar
- 23.Nabbanja E, Czosnyka M, Keong NC, Garnett MR, Pickard JD, Lalou AD CZI (2018) Is there a link between ICP-derived infusion test parameters and outcome after shunting in NPH? In: Heldt T (ed) Intracranial pressure & neuromonitoring XVI. Acta Neurochir Suppl. https://doi.org/10.1007/978-3-319-65798-1
- 24.National Institute For Health And Clinical Excellence (2007) Lumbar infusion test for the investigation of normal pressure hydrocephalus. In: Interventional procedure guidance [IPG263] (March). p 1–23. Available at: https://www.nice.org.uk/guidance/ipg263