Cerebral multimodality monitoring in adult neurocritical care patients with acute brain injury: A narrative review

Abstract

Cerebral multimodality monitoring (MMM) is, even with a general lack of Class I evidence, increasingly recognized as a tool to support clinical decision-making in the neuroscience intensive care unit (NICU). However, literature and guidelines have focused on unimodal signals in a specific form of acute brain injury. Integrating unimodal signals in multiple signal monitoring is the next step for clinical studies and patient care. As such, we aimed to investigate the recent application of MMM in studies of adult patients with traumatic brain injury (TBI), subarachnoid hemorrhage (SAH), intracerebral hemorrhage (ICH), acute ischemic stroke (AIS), and hypoxic ischemic brain injury following cardiac arrest (HIBI). We identified continuous or daily updated monitoring modalities and summarized the monitoring setting, study setting, and clinical characteristics. In addition, we discussed clinical outcome in intervention studies. We identified 112 MMM studies, including 11 modalities, over the last 7 years (2015-2022). Fifty-eight studies (52%) applied only two modalities. Most frequently combined were ICP monitoring (92 studies (82%)) together with PbtO₂ (63 studies (56%). Most studies included patients with TBI (59 studies) or SAH (53 studies). The enrollment period of 34 studies (30%) took more than 5 years, whereas the median sample size was only 36 patients (q1- q3, 20-74). We classified studies as either observational (68 studies) or interventional (44 studies). The interventions were subclassified as systemic (24 studies), cerebral (10 studies), and interventions guided by MMM (11 studies). We identified 20 different systemic or cerebral interventions. Nine (9/11, 82%) of the MMM-guided studies included clinical outcome as an endpoint. In 78% (7/9) of these MMM-guided intervention studies, a significant improvement in outcome was demonstrated in favor of interventions guided by MMM. Clinical outcome may be improved with interventions guided by MMM. This strengthens the belief in this application, but further interdisciplinary collaborations are needed to overcome the heterogeneity, as illustrated in the present review. Future research should focus on increasing sample sizes, improved data collection, refining definitions of secondary injuries, and standardized interventions. Only then can we proceed with complex outcome studies with MMM-guided treatment.

Keywords: AIS; HIBI; ICH; SAH; TBI; cerebral multimodality monitoring; intensive care; outcome.

FIGURE 1

Graphical representation of cerebral multimodality monitoring modalities. The eleven applied monitoring modalities with numbers and (raw) signals. Each modality presents the standard visualization on the bedside monitoring screen. For the readability of the figure, only two neuronal activity monitoring electrodes are displayed. In common practice, the numbers for sEEG are application of 21 electrodes, for ECoG and dEEG 4-8 electrodes. Cerebral T, cerebral temperature; CMD, cerebral microdialysis; dEEG, depth electroencephalography; ECoG, electrocorticography; ICP, intracranial pressure; NIRS, near-infrared spectroscopy; PbtO₂, partial pressure of brain tissue oxygenation; rCBF, regional cerebral blood flow; sEEG, surface electroencephalography; SvjO₂, jugular bulb venous oximetry; TCD, transcranial Doppler. Professional illustration by Anna Sieben (Sieben Medical Art).

FIGURE 2

Combinations of cerebral unimodal monitoring modalities in the literature over the last 7 years (112 studies). Circos-plot visualizing connections between unimodal continuous cerebral monitoring modalities. ICP monitoring is the modality most combined, followed by PbtO₂. As an illustration to understand the distribution of each part: ICP monitoring appears in study 1 in combination with modalities II and III, and in study 2, ICP appears with modalities IV and V. ICP monitoring is then displayed on 2/6 of the circle (ICP + ICP + II + III + IV + V, 6 of which 2x ICP). The colors represent intracranial volume (red), cerebral oxygenation (green), regional cerebral blood flow (purple), cerebral metabolism (dark blue), neuronal electrical activity (orange), and cerebral temperature (yellow). Cerebral T, cerebral temperature; CMD, cerebral microdialysis; dEEG, depth electroencephalography; ECoG, electrocorticography; ICP, intracranial pressure; NIRS, near-infrared spectroscopy; PbtO₂, partial pressure of brain tissue oxygenation; rCBF, regional cerebral blood flow; sEEG, surface electroencephalography; SvjO₂, jugular bulb venous oximetry; TCD, transcranial Doppler.

FIGURE 3

Unique cerebral multimodality monitoring combinations. The 47 unique combinations of MMM are shown. The first upper row shows the total number of studies per combination. The second to the sixth row shows the number of studies per acute brain injury: TBI, SAH, ICH, AIS, and HIBI. Each box describes the number of studies. The boxes in black do not include a monitoring combination for a particular disease. The references of the studies are added to Supplementary Tables S5A–D. The reference numbers per unique combination are: A (11,14,24,33,43,46,47,48,49,53, 69,71,87,90,91,94,97, 104,105,106,107,110); B (51,55); C (4); D (76,31); E (9,38,45,61,62,63,66,67,77,82,101); F (32,37,73); G (8,60); H (17,70,95,98); I (21); J (78); K (6,74); L (23,57,58); M(10,20); N (68,79); O (30,40,42,100); p (83,86,93,96); Q (35,44); R (1,3,13,19,34,52,56,59,89,102); S (2); T (27); U (29); V (112); W (64); X (99); Y (5); Z (15); AA (111); AB (16); AC (103); AD (80,92,108,109); AE (81); AF (41); AG (50); AH (12,39); AI (75,88); AJ (18); AK (84); AL (22); AM(72); AN (36); AO (7); AP (26); AQ (85); AR (54); AS (28); AT (65); AU (25). Note: the sum of studies for the individual diseases not count towards the total number of studies because a study can include patients with different diseases. AIS, acute ischemic stroke; Cerebral T, cerebral temperature; CMD, cerebral microdialysis; dEEG, depth electroencephalography; ECoG, electrocorticography; HIBI, hypoxic-ischemic brain injury following cardiac arrest; ICH, intracerebral hemorrhage; ICP, intracranial pressure; NIRS, near-infrared spectroscopy; PbtO₂, partial pressure of brain tissue oxygenation; rCBF, regional cerebral blood flow; SAH, subarachnoid hemorrhage; sEEG, surface electroencephalography; SvjO₂, jugular bulb venous oximetry; TBI, traumatic brain injury; TCD, transcranial Doppler.

FIGURE 4

Purposes of interventions across the MMM studies. MMM was examined in three different ways across the studies. Firstly, MMM was the outcome, and the intervention’s effectiveness was studied. Secondly, MMM was considered along with the intervention for its effect on clinical outcome. Thirdly, thresholds of MMM were used to dictate intervention, and the need for intervention was studied. Created with BioRender.com. MMM, multimodality monitoring.