The Linear Relationship Between Transcranial Doppler Pulsatility Indices and Intracranial Pressure Is Influenced by Traumatic Brain Injury and Vasospasm

Abstract

The pulsatility index (PI) and the intracranial -pressure (ICP) may or may not be correlated; the evidence to date differs widely. A study of multiple measures of PI and the corresponding ICP in patients with severe traumatic brain injury (TBI) showed that some of the relationships were moderately strong when calculated as conventional Pearson correlation coefficients. However, that method makes no adjustment of any kind for statistical outliers in the data. With the TBI patients demonstrating a large fraction of skewed measurements, a set of robust correlations were calculated that demonstrated that the apparent relationships between PI and ICP were entirely attributable to the statistical outliers. We conclude that the fundamental relationship of PI to ICP is weakly positive at best.

Blast Overpressure Waves Induce Transient Anxiety and Regional Changes in Cerebral Glucose Metabolism and Delayed Hyperarousal in Rats

“…Shear stress, mechanical stretching of the brain tissue/neurons, acceleration/deceleration of the brain within the intracranial space (1, 9, 56) increased intracranial pressure, cerebral vasospasm (65), and thoracic contributions from the periphery to the CNS (35, 44, 66–68) can all contribute to primary blast TBI. Additionally, mild TBI in general is commonly linked to disturbances in cerebral metabolism, hemodynamics, and ion homeostasis that ultimately lead to the release of oxygen radicals, axolemmal damage, uncoupling of cerebral blood flow (CBF), and metabolic demand (corresponding to increased glucose utilization) that subsequently results in neuronal degeneration and tissue damage via apoptosis (9, 28, 69–71).…”

Transcranial Doppler Identifies a Malfunctioning Extraventricular Drain

“…There are many studies on the contrary that do not show this strong relationship . TCD with increased PI demonstrates physiologic changes of increased ICP but they cannot make an exact ICP measurement . The algorithm above is the commonly accepted mechanism for interpretation of PI values for ICP .…”

“…7,8 TCD with increased PI demonstrates physiologic changes of increased ICP but they cannot make an exact ICP measurement. 9 The algorithm above is the commonly accepted mechanism for interpretation of PI values for ICP. 2 Spectral waveform analysis adds information about resistive waveforms associated with increased ICP.…”

Impaired cerebral compensatory reserve is associated with admission imaging characteristics of diffuse insult in traumatic brain injury

“…These studies outlined the strong linear relations between pulse amplitude of ICP and ICP itself. Furthermore, other techniques for compliance analysis have been attempted in the past including, but not limited to ICP slope analysis [12], ICP pulse amplitude in isolation [6, 8, 12], assessing ICP waveform morphology [11, 13, 14, 24], TCD-based pulsatility indices and CBV estimates [2, 5, 10], and magnetic resonance imaging (MRI)-based elastography [3, 16]. All of these previous measures suffer from complexity in signal analytic techniques and intermittent or semi-intermittent data capture (i.e., TCD and MRI elastography).…”