Notes

Toward optomechanical parametric fluctuations idea throughout ground-based gravitational influx devices.
In addition to R
, intracranial pressure (ICP) values at the baseline and plateau, CSF production rate and ICP amplitude to slope ratio showed significant Chi-Statistics values (more than 5). Using these variables, an overall accuracy of 0.70±0.09 was achieved for prediction of the shunt outcome.

Rout can be used for selecting patients for shunt surgery but not for excluding patients from treatment. Critical, multivariable approaches are required to comprehend CSF dynamics and pressure-volume compensation in NPH. Outcome definition and assessment could also be brought to question.
Rout can be used for selecting patients for shunt surgery but not for excluding patients from treatment. Critical, multivariable approaches are required to comprehend CSF dynamics and pressure-volume compensation in NPH. Outcome definition and assessment could also be brought to question.
Tools available for diagnosis of normal pressure hydrocephalus (NPH) and prediction of shunt-response are overnight ICP monitoring, infusion studies, and extended lumbar drainage (ELD). We investigated the shunt-response predictive value by infusion tests versus ELD.

We retrospectively recruited 83 patients who had undergone both infusion study and ELD assessments and compared infusion study hydrodynamics with improvement at clinic follow-up after ELD and after shunting.

62 patients had Rout >11mmHg/mL/min. 28 Showed physiotherapy-documented improvement following ELD, and were selected for shunting, of which 21 were shunted. Of these, 19 showed improvement. Eight patients with Rout >20mmHg/mL/min showed no response to ELD and were not shunted.There were 21 patients with Rout <11mmHg/mL/min five were shunted, showed improvement at follow-up, and had Rout >6mmHg/mL/min. ICP amplitude did not differ at baseline or plateau between responders and non-responders.

ELD response and CSF dynamics differed remarkably. All patients with Rout <6mmHg/mL/min showed no improvement with ELD, indicating that ELD and shunting might be contraindicated in these subjects. High Rout patients with no response to ELD could merit further consideration.
ELD response and CSF dynamics differed remarkably. All patients with Rout less then 6 mmHg/mL/min showed no improvement with ELD, indicating that ELD and shunting might be contraindicated in these subjects. High Rout patients with no response to ELD could merit further consideration.
We previously examined the relationship between global autoregulation pressure reactivity index (PRx), mean arterial blood pressure (ABP), Resistance to cerebral spinal fluid (CSF) outflow (Rout) and their possible effects on outcome after surgery on 83 shunted patients. In this study, we aimed to quantify the relationship between all parameters that influence Rout, their interaction with the cerebral vasculature, and their role in shunt prognostication.

From 423 patients having undergone infusion tests for possible NPH, we selected those with monitored ABP and calculated its mean and PRx. After shunting, 6months patients' outcome was marked using a simple scale (improvement, temporary improvement, and no improvement). We explored the relationship between age, different CSF dynamics variables, and vascular parameters using multivariable models.

Rout had a weaker predictive value than ABP (Fisher Discrimination Ratio of 0.02 versus 0.42). ABP>98 was an independent predictor of shunt outcome with odd ratio 6.4, 95% CI 1.8-23.4 and p-value=0.004. There was a strong and significant relationship between the interaction of age, PRx, ABP, and Rout (R=0.53 with p=7.28×10
). Using our linear model, we achieved an AUC 86.4% (95% CI 80.5-92.3%) in detecting shunt respondents. The overall sensitivity was 94%, specificity 75%, positive predictive value (PPV) of 54%, and negative predictive value of 97%.

In patients with low Rout and high cerebrovascular burden, as described by high ABP and disturbed global autoregulation, response to shunting is less likely. The low PPV of high resistance, preserved autoregulation and absence of hypertension could merit further exploration.
In patients with low Rout and high cerebrovascular burden, as described by high ABP and disturbed global autoregulation, response to shunting is less likely. The low PPV of high resistance, preserved autoregulation and absence of hypertension could merit further exploration.
Challenges in diagnosing post-traumatic hydrocephalus (PTH) have created a need for an accurate diagnostic tool. We aim to report CSF dynamics in PTH and atrophy, along with differences before and after cranioplasty.

We retrospectively analyzed traumatic brain injury patients with ventriculomegaly who had infusion studies. We divided patients depending on CSF dynamics into two groups 'likely PTH' (A) and 'likely atrophy' (B). A group of idiopathic normal pressure hydrocephalus shunt-responsive patients was used for comparison (C).

Group A consisted of 36 patients who were non-decompressed or had a cranioplasty in situ for over 1month. Group B included 16 patients with low Rout, AMP, and dAMP, 9 of whom were decompressed. Rout and dAMP were significantly higher in Group A than B, but significantly lower than Group C (45 iNPH patients). RAP change during infusion in group A indicated depleted compensatory reserve compared to ample reserve in group B. Repeat studies in five decompressed patients post-cranioplasty showed all parameters increased.

Infusion tests are not useful in decompressed patients, whilst cranioplasty allowed differentiation between possible PTH and atrophy. Rout and AMP were significantly lower in PTH compared to iNPH and did not always reflect the degree of hydrocephalus reported on imaging.
Infusion tests are not useful in decompressed patients, whilst cranioplasty allowed differentiation between possible PTH and atrophy. N-Formyl-Met-Leu-Phe Rout and AMP were significantly lower in PTH compared to iNPH and did not always reflect the degree of hydrocephalus reported on imaging.
Mechanisms underlying postural regulation of ICP remain unclear.

Literature review in Medline 1900-2019 with search terms "Intracranial pressure," "Posture," "Jugular vein," "Collapse," "Regulation," "Physiology," resulting in 40 selected papers.

Postural transition from supine to sitting position results in a biphasic decrease of ICP a fast decrease during phase 1 (low tilt) followed by a stabilization during phase 2 (higher tilt/erect). Two main factors have been proposed to explain this decrease (a) Fast CSF transfers from the non-distensible cranial compartment to the distensible spinal compartment during phase 1; the maximal spinal expansion corresponds to phase 2; (b) The gravitational effect within the venous system is transferred to the CSF system according to Davson's equation, modulated by jugular collapse that would be responsible for the stabilization of ICP decrease in phase 2.

The impact of CSF transfers, from the cranial to spinal compartment, on postural regulation of ICP, has been well documented.
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