Abstract
The relationship between intracranial pulse amplitude (AMP) and mean intracranial pressure (ICP) has been previously described. Generally, AMP increases proportionally to rises in ICP. However, at low ICP a lower breakpoint (LB) of amplitude-pressure relationship can be observed, below which pulse amplitude stays constant when ICP varies. Theoretically, below this breakpoint, the pressure-volume relationship is linear (good compensatory reserve, brain compliance stays constant); above the breakpoint, it is exponential (brain compliance decreases with rising ICP).
Infusion tests performed in 169 patients diagnosed for idiopathic normal pressure hydrocephalus (iNPH) during the period 2004–2013 were available for analysis. A lower breakpoint was observed in 62 patients diagnosed for iNPH. Improvement after shunt surgery in patients in whom LB was recorded was 77% versus 90% in patients where LB was absent (p < 0.02). There was no correlation between improvement and slope of amplitude-pressure line above LB.
The detection of a lower breakpoint is associated with less frequent improvement after shunting in NPH. It may be interpreted that cerebrospinal fluid dynamics of patients working on the flat part of the pressure-volume curve and having a ‘luxurious’ compensatory reserve, are more frequently caused by brain atrophy, which is obviously not responding to shunting.
This is a preview of subscription content, log in via an institution to check access.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Similar content being viewed by others
References
Marmarou A, Shulman K, Rosende RM (1978) A nonlinear analysis of the cerebrospinal fluid system and intracranial pressure dynamics. J Neurosurg 48(3):332–344
Qvarlander S, Lundkvist B, Koskinen LO, Malm J, Eklund A (2013) Pulsatility in CSF dynamics: pathophysiology of idiopathic normal pressure hydrocephalus. J Neurol Neurosurg Psychiatry 84(7):735–741
Szewczykowski J, Sliwka S, Kunicki A, Dytko P, Korsak-Sliwka J (1977) A fast method of estimating the elastance of the intracranial system. J Neurosurg 47(1):19–26
Czosnyka M, Price DJ, Williamson M (1994) Monitoring of cerebrospinal dynamics using continuous analysis of intracranial pressure and cerebral perfusion pressure in head injury. Acta Neurochir 126(2–4):113–119
Anile C, De Bonis P, Albanese A, Di Chirico A, Mangiola A, Petrella G, Santini P (2010) Selection of patients with idiopathic normal-pressure hydrocephalus for shunt placement: a single-institution experience. J Neurosurg 113(1):64–73
Löfgren J, von Essen C, Zwetnow NN (1973) The pressure-volume curve of the cerebrospinal fluid space in dogs. Acta Neurol Scand 49(5):557–574
Shapiro K, Fried A, Marmarou A (1985) Biomechanical and hydrodynamic characterization of the hydrocephalic infant. J Neurosurg 63(1):69–75
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2021 Springer Nature Switzerland AG
About this chapter
Cite this chapter
Czosnyka, Z.H. et al. (2021). Lower Breakpoint of Intracranial Amplitude-Pressure Relationship in Normal Pressure Hydrocephalus. In: Depreitere, B., Meyfroidt, G., Güiza, F. (eds) Intracranial Pressure and Neuromonitoring XVII. Acta Neurochirurgica Supplement, vol 131. Springer, Cham. https://doi.org/10.1007/978-3-030-59436-7_57
Download citation
DOI: https://doi.org/10.1007/978-3-030-59436-7_57
Published:
Publisher Name: Springer, Cham
Print ISBN: 978-3-030-59435-0
Online ISBN: 978-3-030-59436-7
eBook Packages: MedicineMedicine (R0)