Acute two-compartment low pressure hydrocephalus-a case report

Authors: Preuß M, Evangelou P, Hirsch W, Reiss-Zimmermann M, Fischer L, Merkenschlager A, Kieß W, Siekmeyer M, Meixensberger J, Nestler U.

A case of an 8-year-old-boy with shunt-dependent occlusive hydrocephalus after resection of a cerebellar medulloblastoma is presented, who experienced repeated episodes of severe neurologic deterioration with signs and symptoms of raised intracranial pressure after spinal tapping. However, intracranial pressure was recorded within low ranges, only up to the opening pressure of the implanted adjustable shunt valve. Multiple shunt revisions were performed, until the condition was recognized as acute normal pressure hydrocephalus. Either enforced recumbency and downadjustment of the valve system to 0 cm H2O alone or external ventricular drainage seems to be successful to resolve the critical condition, depending on severity of the symptoms. The case illustrates that acute pathologic enlargement of the ventricular system is not always associated with increased intracranial pressure, even when typical signs and symptoms are present. The very rare entity of acute normal pressure hydrocephalus by two separated compartments is postulated based on the pulsatile vector force theory of brain water circulation.

Magnetic Resonance-Based Estimation of Intracranial Pressure Correlates With Ventriculoperitoneal Shunt Valve Opening Pressure Setting in Children With Hydrocephalus

Authors: Muehlmann M, Koerte IK, Laubender RP, Steffinger D, Lehner M, Peraud A, Heinen F, Kiefer M, Reiser M, Ertl-Wagner B.

OBJECTIVES: The aim of this study was to investigate the relationship between the pressure setting of the ventriculoperitoneal (VP) shunt valve and a magnetic resonance (MR)-based estimate of intracranial pressure (ICP) in children with shunt-treated hydrocephalus without clinical signs of shunt malfunction.
MATERIALS AND METHODS: Institutional review board approval was obtained before the study, and all subjects and/or their legal guardians provided written informed consent. In this prospective study, 15 consecutive patients (median age, 8.25 years; range, 2.2-18.4 years; 6 girls and 9 boys) with shunt-treated hydrocephalus without signs of shunt malfunction were examined with retrospectively gated phase contrast sequences to quantify arterial inflow, venous outflow, and cerebrospinal fluid (CSF) flow to and from the cranial vault. The ratio of the maximal intracranial volume change and the pulse pressure gradient change was used to derive MR-ICP. Spearman ρ was used to test for the association of setting of the shunt valve opening pressure and MR-ICP.
RESULTS: Shunt valve opening pressure settings and MR-ICP were positively correlated (Spearman ρ = 0.64, P < 0.01). Median MR-ICP was 8.67 mm Hg (interquartile range , 1.59 mm Hg) and median setting of the VP-shunt valve was 6.62 mm Hg (IQR, 1.47 mm Hg). The median MR-ICP was 1.9 mm Hg (IQR, 0.73 mm Hg) higher than the setting of the shunt valve.
CONCLUSION: There is a positive correlation between MR-ICP and VP shunt valve opening pressure setting. The systematically higher assessment of MR-ICP is most likely a result of outflow resistance within the shunt tubing system and well within the known fluctuation rates of VP shunt systems.

Spectral analysis of intracranial pressure signals recorded during infusion studies in patients with hydrocephalus

Authors: García M, Poza J, Santamarta D, Abásolo D, Barrio P, Hornero R.

Hydrocephalus includes a number of disorders characterised by clinical symptoms, enlarged ventricles (observable using neuroimaging techniques) and altered cerebrospinal fluid (CSF) dynamics. Infusion tests are one of the available procedures to study CSF circulation in patients with clinical and radiological features of hydrocephalus. In them, intracranial pressure (ICP) is deliberately raised and CSF circulation disorders evaluated through measurements of the resulting ICP. In this study, we analysed seventy-seven ICP signals recorded during infusion tests using four spectral-based parameters: median frequency (MF) and relative power (RP) in three frequency bands. These measures provide a novel perspective for the analysis of ICP signals in the frequency domain. Each signal was divided into four artefact-free epochs (corresponding to the basal, early infusion, plateau and recovery phases of the infusion study). The four spectral parameters were calculated for each epoch. We analysed differences between epochs of the infusion test and correlations between these epochs and patient data. Statistically significant differences (p<1.7×10-3, Bonferroni-corrected Wilcoxon signed-rank tests) were found between epochs of the infusion test using MF and RP. Furthermore, some spectral parameters (MF in the basal phase, RP for the first frequency band and in the early infusion phase, RP for the second frequency band and in all phases of the infusion study and RP in the third frequency band and in the basal phase) revealed significant correlations (p<0.01) between epochs of the infusion test and signal amplitude in the basal and plateau phases. Our results suggest that spectral analysis of ICP signals could be useful for understanding CSF dynamics in hydrocephalus.

Dynamics of hydrocephalus: a physical approach

Authors: Bouzerar R, Tekaya I, Bouzerar R, Balédent O.

As brain ventricles lose their ability to regulate the cerebrospinal fluid (CSF) pressure, serious brain conditions collectively named hydrocephalus can appear. By modelling ventricular dynamics with the laws of physics, dynamical instabilities are evidenced, caused by either CSF transport dysregulations or abnormal properties of the elasticity of the ependyma. We show that these instabilities would lead, in most cases, to dilation of the ventricles, establishing a close connection to hydrocephalus, or in some other cases to a ventricular contraction as observed in the slit ventricle syndrome. Signs seem to indicate the possibility of phase transitions occurring as a result of these instabilities, which might have important clinical consequences, such as the inability to recover a healthy state. Even so, our dynamical approach could allow the development of a unified view of these complex intracranial conditions along with a classification that might be clinically relevant.

Diagnosis of normal pressure hydrocephalus in elderly patients: a review

Authors: Verny M, Berrut G.

The definition of normal pressure hydrocephalus (NPH), in adults, associates clinical signs (Adams and Hakim triad) involving gait disorders, urinary incontinence and dementia, associated with aspects on brain imaging that are consistent with this hypothesis and also normal or slightly increased intracranial pressure. The aim of this study was to clarify the techniques and methods facilitating the diagnosis of NPH. The literature review has been conducted from the Medline database without date limitation including the keywords "normal pressure hydrocephalus" and "diagnosis." They should appear in the article title. From the 43 initially sorted, only 13 have been selected using exclusion criteria. The proposed methods are very sparse and focused on the improvement after surgical shunt. This focus is independent from the diagnosis criteria proposed in 2005. This introduces an ambiguity in the interpretation of the results. In practice, the diagnosis of NPH is more difficult in the elderly population where differential diagnoses are frequent, particularly vascular lesions (notably microangiopathy) and Alzheimer's disease. The more invasive techniques as continuous spinal drainage (usually during 3 days) or some features of CSF dynamics (R(out), compliance) seem to be the best predictors of after shunt improvement. However, these techniques are difficult to use in routine in the elderly. The combination of Evans index and corpus callosum angle on MRI is very useful to improve the differential diagnosis with cerebral atrophy. Spinal tap test (lumbar puncture with the removal of 40 mL of CSF) can be repeated two or three times for consecutive days to improve the predictive value before shunting. Gait and balance often improve after shunt, more than cognition and bladder disorders. In the elderly population, the prognosis after 3 years is non conclusive despite initial improvement. Poor prognosis seems to be due to associated pathologies in particular neurodegenerative diseases. This should be considered in decision-making of CSF shunt.

Hydrocephalus and intracranial hypotension

Authors: Reith W, Yilmaz U. (Article in German)

Ventricular enlargement due to a imbalance of the production of cerebrospinal fluid and its absorption can be a symptom of a variety of diseases. The causes are increased production or decreased absorption of cerebrospinal fluid and obstructions to cerebrospinal fluid flow. Treatment requires thorough neuroradiological imaging with high-resolution thin-section magnetic resonance imaging (MRI) and cerebrospinal fluid flow measurements. Thus, for instance even small membranes causing aqueductal obstruction can be detected and their influence on cerebrospinal fluid flow can be analyzed. The results of neurosurgical therapy, such as ventriculostomy can also be evaluated. This article provides an overview about imaging features as well as clinical and therapeutic aspects of hydrocephalus.


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