Acta Neurochirurgica

, Volume 160, Issue 5, pp 1097–1103 | Cite as

Validation of Davson’s equation in patients suffering from idiopathic normal pressure hydrocephalus

  • Afroditi-Despina Lalou
  • Virginia Levrini
  • Matthew Garnett
  • Eva Nabbanja
  • Dong-Joo Kim
  • Laurent Gergele
  • Anna Bjornson
  • Zofia Czosnyka
  • Marek Czosnyka
Original Article - Neurosurgery Training



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.


Normal pressure hydrocephalus Resistance to CSF outflow Intracranial pressure Davson’s equation 



MC and DJK are supported by a grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health and Welfare, Republic of Korea (grant number: HI17C1790).

Compliance with ethical standards

Conflict of interest


Ethical approval

For this type of study, formal consent is not required.

Informed consent

Informed consent was obtained from all individual participants included in the study.


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Copyright information

© Springer-Verlag GmbH Austria, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Division of Neurosurgery, Cambridge University HospitalUniversity of Cambridge Department of Clinical NeuroscienceCambridgeUK
  2. 2.School of Clinical MedicineUniversity of CambridgeCambridgeUK
  3. 3.University of KoreaSeoulSouth Korea
  4. 4.Ramsay Générale de Santé, Hôpital privé de la LoireSaint EtienneFrance

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