Use of non-invasive sensor to assess intracranial compliance in the management of migraine patients: case report

The objective of this study is to report the use of a non-invasive sensor to assess intracranial compliance (ICC) in patients complaining of migraine. This case report presents a 34-year-old, female patient that was treated for idiopathic intracranial hypertension (IIH) by placing a non-adjustable lumboperitoneal shunt. After one year, she presented with headache and signs of overdrainage. Non-invasive monitoring of ICC was done, suggesting a reduction in the ICC, but no change in the opening pressure of the valve. A diagnosis of migraine was made, with improvement after brain monitoring, leading treatment without any new surgical intervention. With this case, we conclude that the use of non-invasive sensor helped the medical team to understand the information obtained by the ICP curve in the office, and in the management of patients with headache complaints, supporting clinical decision making, improving the quality of care, correlated with underlying diseases and procedural and patient safety.

Analysis of relative changes in pulse shapes of intracranial pressure and cerebral blood flow velocity during infusion test

Objective: Analysis of relative changes in the shapes of pulse waveform of intracranial pressure (ICP) and transcranial Doppler cerebral blood flow velocity (CBFV) may provide information on intracranial compliance. We tested this hypothesis, introducing an index named the Ratio of Pulse Slopes (RPS) that is based on inclinations of the ascending parts of ICP and CBFV pulse waveforms. It has hypothetically a simple interpretation: 1 – good compliance, the less than 1, reduced compliance. Here, we investigated the usefulness of RPS for intracranial compliance assessment. Approach: ICP and CBFV signals recorded simultaneously in 30 normal pressure hydrocephalus patients during infusion test were retrospectively analysed. CBFV was measured in the middle cerebral artery. Changes in RPS during the test were compared to changes in the height ratio of the first and second peak of ICP pulse (P1/P2) and the shape of ICP pulse classified from normal (1) to pathological (4). Values are medians (lower, upper quartiles). Main results: There was a significant correlation between baseline RPS and brain elasticity (R = -0.55, p=0.0018). During infusion test, both RPS and P1/P2 decreased with rising ICP (RPS: 0.80 (0.56, 0.92) vs. 0.63 (0.44, 0.80), p = 0.00015; P1/P2: 0.58 (0.50, 0.91) vs. 0.52 (0.36, 071), p=0.00009) while the ICP pulses became more pathological in shape (class: 3 (2, 3) vs. 3 (3, 4), p=0.04). The magnitude of decrease in RPS during infusion was inversely correlated with baseline P1/P2 (R= -0.40, p<0.03). Significance: During infusion, the slopes of ascending parts of ICP and CBFV pulses become increasingly divergent with a shift in opposite directions. RPS seems a promising methodological tool to monitor brain compliance with no additional volumetric manipulation required.

Effect of position on intracranial pressure and compliance: a cross-sectional study including 101 patients

OBJECTIVE A better understanding of the effect of position on intracranial pressure (ICP) and compliance is important for the development of treatment strategies that can restore normal cerebrospinal fluid (CSF) dynamics. There is limited knowledge on the effect of position on intracranial compliance. In this cross-sectional study the authors tested the association of pulse amplitude (PA) with position and the day/night cycle. Additionally, they describe the postural ICP and PA changes of patients with “normal” ICP dynamics. METHODS This single-center retrospective study included patients with suspected and/or confirmed CSF dynamics abnormalities who had been examined with elective 24-hour ICP monitoring between October 2017 and September 2019. Patients had been enrolled in a short exercise battery including four positions: supine, lumbar puncture position in the left lateral decubitus position, sitting, and standing. Each position was maintained for 2 minutes, and mean ICP and PA were calculated for each position. The 24-hour day and night median ICP and PA data were also collected. Linear regression models were used to test the correlation of PA with position and day/night cycle. All linear regressions were corrected for confounders. The postural ICP monitoring results of patients without obvious ICP dynamics abnormality were summarized. RESULTS One hundred one patients (24 males and 77 females) with a mean age of 39 ± 13years (mean ± standard deviation) were included in the study. The adjusted linear regression models demonstrated a significant association of ICP with position and day/night cycle, with upright (sitting and standing) and day ICP values lower than supine and night ICP values. The adjusted linear regression model was also significant for the association of PA with position and day/night cycle, with upright and day PA values higher than supine and night PA results. These associations were confirmed for patients with and without shunts. Patients without clear ICP dynamics abnormality had tighter control of their postural ICP changes than the other patients; however, the difference among groups was not statistically significant. CONCLUSIONS This is the largest study investigating the effect of postural changes on intracranial compliance. The results of this study suggest that PA, as well as ICP, is significantly associated with posture, increasing in upright positions compared to that while supine. Further studies will be needed to investigate the mechanism behind this association.

Intracranial Compliance Assessed by Intracranial Pressure Pulse Waveform

Background: Morphological alterations in intracranial pressure (ICP) pulse waveform (ICPW) secondary to intracranial hypertension (ICP >20 mmHg) and a reduction in intracranial compliance (ICC) are well known indicators of neurological severity. The exclusive exploration of modifications in ICPW after either the loss of skull integrity or surgical procedures for intracranial hypertension resolution is not a common approach studied. The present study aimed to assess the morphological alterations in ICPW among neurocritical care patients with skull defects and decompressive craniectomy (DC) by comparing the variations in ICPW features according to elevations in mean ICP values. Methods: Patients requiring ICP monitoring because of acute brain injury were included. A continuous record of 10 min-length for the beat-by-beat analysis of ICPW was performed, with ICP elevation produced by means of ultrasound-guided manual internal jugular vein compression at the end of the record. ICPW features (peak amplitude ratio (P2/P1), time interval to pulse peak (TTP) and pulse amplitude) were counterweighed between baseline and compression periods. Results were distributed for three groups: intact skull (exclusive burr hole for ICP monitoring), craniotomy/large fractures (group 2) or DC (group 3). Results: 57 patients were analyzed. A total of 21 (36%) presented no skull defects, 21 (36%) belonged to group 2, whereas 15 (26%) had DC. ICP was not significantly different between groups: ±15.11 for intact, 15.33 for group 2 and ±20.81 mmHg for group 3, with ICP-induced elevation also similar between groups (p = 0.56). Significant elevation was observed for the P2/P1 ratio for groups 1 and 2, whereas a reduction was observed in group 3 (elevation of ±0.09 for groups 1 and 2, but a reduction of 0.03 for group 3, p = 0.01), and no significant results were obtained for TTP and pulse amplitudes. Conclusion: In the present study, intracranial pressure pulse waveform analysis indicated that intracranial compliance was significantly more impaired among decompressive craniectomy patients, although ICPW indicated DC to be protective for further influences of ICP elevations over the brain. The analysis of ICPW seems to be an alternative to real-time ICC assessment.

Cerebral Hemodynamics and Intracranial Compliance Impairment in Critically Ill COVID-19 Patients: A Pilot Study

Introduction: One of the possible mechanisms by which the new coronavirus (SARS-Cov2) could induce brain damage is the impairment of cerebrovascular hemodynamics (CVH) and intracranial compliance (ICC) due to the elevation of intracranial pressure (ICP). The main objective of this study was to assess the presence of CVH and ICC alterations in patients with COVID-19 and evaluate their association with short-term clinical outcomes. Methods: Fifty consecutive critically ill COVID-19 patients were studied with transcranial Doppler (TCD) and non-invasive monitoring of ICC. Subjects were included upon ICU admission; CVH was evaluated using mean flow velocities in the middle cerebral arteries (mCBFV), pulsatility index (PI), and estimated cerebral perfusion pressure (eCPP), while ICC was assessed by using the P2/P1 ratio of the non-invasive ICP curve. A CVH/ICC score was computed using all these variables. The primary composite outcome was unsuccessful in weaning from respiratory support or death on day 7 (defined as UO). Results: At the first assessment (n = 50), only the P2/P1 ratio (median 1.20 [IQRs 1.00–1.28] vs. 1.00 [0.88–1.16]; p = 0.03) and eICP (14 [11–25] vs. 11 [7–15] mmHg; p = 0.01) were significantly higher among patients with an unfavorable outcome (UO) than others. Patients with UO had a significantly higher CVH/ICC score (9 [8–12] vs. 6 [5–7]; p < 0.001) than those with a favorable outcome; the area under the receiver operating curve (AUROC) for CVH/ICC score to predict UO was 0.86 (95% CIs 0.75–0.97); a score > 8.5 had 63 (46–77)% sensitivity and 87 (62–97)% specificity to predict UO. For those patients undergoing a second assessment (n = 29), after a median of 11 (5–31) days, all measured variables were similar between the two time-points. No differences in the measured variables between ICU non-survivors (n = 30) and survivors were observed. Conclusions: ICC impairment and CVH disturbances are often present in COVID-19 severe illness and could accurately predict an early poor outcome.

INTRACRANIAL COMPLIANCE ASSESSED BY INTRACRANIAL PRESSURE PULSE WAVEFORM

Background: Morphological alterations in intracranial pressure pulse waveform (ICPPW) secondary to intracranial hypertension (ICP &gt;20 mmHg) and reduction in intracranial compliance (ICC) are well known indicators of neurological severity. To date, no studies have documented the ICPPW modifications after intracranial hypertension resolution with decompressive craniectomy (DC). The present study aimed to assess the morphological alterations in ICPPW among neurocritical care patients with and without DC, by comparing the variations of ICPPW features according to elevations in mean ICP values. Methods: Patients requiring ICP monitoring because of severe traumatic or spontaneous conditions were included. Mean ICP values were compared with ICPPW features (P2/P1 ratio, TTP and pulse amplitude). Elevation in ICP was produced by means of ultrasound-guided manual internal jugular veins compression. Results were distributed for three groups: intact skull (exclusive burr hole for ICP monitoring), craniotomy/large fractures (group 2) or DC (group 3). Results: 57 patients were analyzed. 21 (36%) presented no skull defects, whereas 15 (26%) had DC. ICP was not significantly different between groups: &plusmn;13.59 for intact and &plusmn;17.66 mmHg for DC, with ICP induced elevation also similar between groups (p= 0.56). Significant elevation was observed for P2/P1 ratio for groups 1 and 2, whereas reduction was observed in group 3 (elevation of &plusmn;0.09 for groups 1 and 2, whereas reduction of 0.03 for group 3, p=0.01). Conclusion: In the present study, intracranial pressure pulse waveform analysis indicated that intracranial compliance was significantly more impaired among decompressive craniectomy patients, although ICPPW indicated DC to be protective for further influences of ICP elevations over the brain. Analysis of ICPPW seems to be an alternative to real time ICC assessment.

Phase-Contrast MRI Indices can Reflect Intracranial Compliance Deterioration Induced by Intra-Abdominal/ Thoracic Hypertension

BackgroundIdentifying elevated intracranial pressure (ICP) and decreased intracranial compliance (ICC) is imperative for optimizing patient management in neurocritical care settings. Intra-abdominal hypertension (IAH) and intrathoracic hypertension (ITH) is common in trauma patients, which affects homeostasis of ICP/ICC. Knowledge of this effects is little and monitoring this effect is difficult. In the current study, we examined whether the indices generated from 2D cine phase contrast MRI (2D cine PC-MRI) could reflect ICC/ICP alterations induced by elevated IAH/ITH during VM.MethodsA total of 50 healthy young volunteers participated in this study (male: female = 24:26), and took a 2D cine PC-MRI during normal breath and VM respectively. Cross-section area (CSA) of dominant IJV and ipsilateral ICA, the maximum blood flow (Fmax), minimum blood flow (Fmin), mean blood flow (MBF), pulsatility index (PI), arteriovenous delay (AVD) and time to peak of arterial pulse (TTP) were gauged from images or calculated from the blood flow curves generated from 2D cine PC-MRI. ResultsDuring VM state, in comparison to NB, CSAIJV increased significantly (p<0.0001), indicating an elevation of cerebral venous outflow resistance; Fmax_ICA, Fmax_IJV, Fmean_ICA and Fmean_IJV decreased significantly (p<0.0001, p<0.0001, p<0.001, p<0.0001, respectively); PI_ICA and PI_IJV decreased significantly (p<0.0001, p<0.0001); both absolute and normalized AVD decreased significantly (p<0.0001, p<0.0001), while absolute and normalized TTP increased significantly (p=0.0329, p=0.0376).Conclusions Indices generated from 2D cine PC-MRI, especially AVD and TTP, can reveal the ICC/ICP dynamics induced by elevated IAP/ITP. These indices have potential clinical application in ICC/ICP monitoring in patients who was speculated with an IAH or ITH.