scholarly journals Cerebral Autoregulation, CSF outflow resistance and outcome following CSF diversion in Normal Pressure Hydrocephalus

2017 ◽  
Author(s):  
Afroditi Despina Lalou ◽  
Marek Czosnyka ◽  
Joseph Donnelly ◽  
John D. Pickard ◽  
Eva Nabbanja ◽  
...  
Keyword(s):  
Cerebrospinal Fluid ◽  
Normal Pressure Hydrocephalus ◽  
Cerebral Autoregulation ◽  
Normal Pressure ◽  
Reactivity Index ◽  
Outflow Resistance ◽  
Cardiovascular Comorbidity ◽  
Csf Circulation ◽  
Csf Diversion ◽  
The Relationship

AbstractIntroductionNormal pressure hydrocephalus (NPH) is not simply the result of a disturbance in cerebrospinal fluid (CSF) circulation, but often includes cardiovascular comorbidity and abnormalities within the cerebral mantle. In this study, we have examined the relationship between the global autoregulation pressure reactivity index (PRx), the profile of disturbed CSF circulation and pressure-volume compensation, and their possible effects on outcome after surgery.Materials and methodsWe studied a cohort of 131 patients, investigated for possible NPH. Parameters describing CSF compensation and circulation were calculated during the cerebrospinal fluid (CSF) infusion test and PRx was calculated from CSF pressure and arterial pressure recordings. A simple scale was used to mark the patients’ outcome 6 months after surgery (improvement, temporary improvement, and no improvement).ResultsPRx was negatively correlated with Rout (R=−0.18; p=0.044); patients with normal CSF circulation tended to have worse autoregulation. The correlation for patients who were surgically-managed (N=83) was: R=−0.28; p=0.03, and stronger in patients who improved after surgery (N=64; R=−0.36; p=0.03). In patients who did not improve, the correlation was not significantly different from zero (N= 19; R=0.17; p=0.15). There was a trend towards higher values for PRx in non-responders than in responders (PRx =0.16+/− 0.04 vs 0.09 +/−0.02 respectively; p=0.061), associated with higher MAP values (107.2+/−8.2 in non-responders vs 89.5+/−3.5 in responders; p=0.195). The product of MAP* (1+PRx), proposed as a measure of combined arterial hypertension and deranged autoregulation, showed a significant association with outcome (greater value in non-responders; p=0.013).ConclusionAutoregulation proves to associate with cerebrospinal fluid circulation, and appears strongest in shunt responders. Outcome following CSF diversion is possibly most favorable when CSF outflow resistance is increased and global cerebral autoregulation is intact, in combination with arterial normotension.

scholarly journals Cerebral autoregulation, cerebrospinal fluid outflow resistance, and outcome following cerebrospinal fluid diversion in normal pressure hydrocephalus

2018 ◽  
Vol 130 (1) ◽  
pp. 154-162 ◽  
Author(s):  
Afroditi Despina Lalou ◽  
Marek Czosnyka ◽  
Joseph Donnelly ◽  
John D. Pickard ◽  
Eva Nabbanja ◽  
...  
Keyword(s):  
Cerebrospinal Fluid ◽  
Normal Pressure Hydrocephalus ◽  
Cerebral Autoregulation ◽  
Normal Pressure ◽  
Reactivity Index ◽  
Outflow Resistance ◽  
Cardiovascular Comorbidity ◽  
Csf Circulation ◽  
Cerebrospinal Fluid Diversion ◽  
Arterial Blood

OBJECTIVENormal pressure hydrocephalus is not simply the result of a disturbance in CSF circulation, but often includes cardiovascular comorbidity and abnormalities within the cerebral mantle. In this study, the authors have examined the relationship between the global autoregulation pressure reactivity index (PRx), the profile of disturbed CSF circulation and pressure-volume compensation, and their possible effects on outcome after surgery.METHODSThe authors studied a cohort of 131 patients in whom a clinical suspicion of normal pressure hydrocephalus was investigated. Parameters describing CSF compensation and circulation were calculated during the CSF infusion test, and PRx was calculated from CSF pressure and mean arterial blood pressure (MAP) recordings. A simple scale was used to mark the patients’ outcome 6 months after surgery (improvement, temporary improvement, and no improvement).RESULTSThe PRx was negatively correlated with resistance to CSF outflow (R = −0.18; p = 0.044); patients with normal CSF circulation tended to have worse autoregulation. The correlation for patients who were surgically treated (n = 83) was R = −0.28; p = 0.01, and it was stronger in patients who experienced sustained improvement after surgery (n = 48, R = −0.43; p = 0.002). In patients who did not improve, the correlation was not significantly different from zero (n = 19, R = −0.07; p = 0.97). There was a trend toward higher values for PRx in nonresponders than in responders (0.16 ± 0.04 vs 0.09 ± 0.02, respectively; p = 0.061), associated with higher MAP values (107.2 ± 8.2 in nonresponders vs 89.5 ± 3.5 in responders; p = 0.195). The product of MAP × (1 + PRx), which was proposed as a measure of combined arterial hypertension and deranged autoregulation, showed a significant association with outcome (greater value in nonresponders; p = 0.013).CONCLUSIONSAutoregulation proves to associate with CSF circulation and appears strongest in shunt responders. Outcome following CSF diversion is possibly most favorable when CSF outflow resistance is increased and global cerebral autoregulation is intact, in combination with arterial normotension.

Dependency of cerebrospinal fluid outflow resistance on intracranial pressure

2008 ◽  
Vol 109 (5) ◽  
pp. 918-922 ◽  
Author(s):  
Nina Andersson ◽  
Jan Malm ◽  
Anders Eklund
Keyword(s):  
Cerebrospinal Fluid ◽  
Intracranial Pressure ◽  
Scientific Evidence ◽  
Normal Pressure ◽  
Outflow Resistance ◽  
General Belief ◽  
Baseline Pressure ◽  
Pressure Increment ◽  
Pressure Independent ◽  
The Relationship

Object The outflow resistance (Rout) of the cerebrospinal fluid (CSF) system has generally been accepted by most investigators as independent of intracranial pressure (ICP), but there are also those claiming that it is not. The general belief is that this question has been investigated numerous times in the past, but few studies have actually been specifically aimed at looking at this relationship, and no study has been able to provide scientific evidence to elucidate fully this fundamental and important issue. The objective of this study was to investigate the relationship between ICP and CSF outflow in 30 patients investigated for idiopathic normal-pressure hydrocephalus. Methods Lumbar infusion tests with constant pressure levels were performed, and ICP and corresponding flow were measured on 6 pressure levels for each patient. All data were standardized for comparison. Results In the range of moderate increases from baseline pressure (~ 5–12 mm Hg, mean baseline pressure 11.7 mm Hg), the assumption of a pressure-independent Rout was confirmed (p = 0.5). However, when the pressure increment from baseline pressure was larger (~ 15–22 mm Hg), the relationship had a nonlinear tendency (p < 0.05). Conclusions The results of this study support the classic textbook theory of a pressure-independent Rout in the normal ICP range, where the CSF system is commonly operating. However, the theory might have to be questioned in regions where ICP exceeds baseline pressure by too much.

scholarly journals Validation of Davson’s equation in patients suffering from idiopathic Normal Pressure Hydrocephalus

2018 ◽  
Author(s):  
Afroditi-Despina Lalou ◽  
Virginia Levrini ◽  
Matthew Garnett ◽  
Eva Nabbanja ◽  
Dong-Joo Kim ◽  
...  
Keyword(s):  
Cerebrospinal Fluid ◽  
Normal Pressure Hydrocephalus ◽  
Fundamental Equation ◽  
Indirect Evidence ◽  
Correlation Coefficients ◽  
Normal Pressure ◽  
Hospital Data ◽  
Sagittal Sinus ◽  
Key Factor ◽  
The Relationship

AbstractIntroductionThe 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.MethodWe 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.ResultsWe 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).ConclusionsThe 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.

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