Through the looking glass: early non-invasive imaging in TBI predicts the need for interventions

mTBI Biological Biomarkers as Predictors of Postconcussion Syndrome-Review

Postconcussion syndrome (PCS) is one of the leading complications that may appear in patients after mild head trauma. Every day, thousands of people, regardless of age, gender, and race, are diagnosed in emergency departments due to head injuries. Traumatic Brain Injury (TBI) is a significant public health problem, impacting an estimated 1.5 million people in the United States and up to 69 million people worldwide each year, with 80% of these cases being mild. An analysis of the available research and a systematic review were conducted to search for a solution to predicting the occurrence of postconcussion syndrome. Particular biomarkers that can be examined upon admission to the emergency department after head injury were found as possible predictive factors of PCS development. Setting one unequivocal definition of PCS is still a challenge that causes inconsistent results. Neuron Specific Enolase (NSE), Glial Fibrillary Acidic Protein (GFAP), Ubiquitin C-terminal Hydrolase-L1 (UCH-L1), Serum Protein 100 B (s100B), and tau protein are found to be the best predictors of PCS development. The presence of all mentioned biomarkers is confirmed in severe TBI. All mentioned biomarkers are used as predictors of PCS. A combined examination of NSE, GFAP, UCH-1, S100B, and tau protein should be performed to detect mTBI and predict the development of PCS.

Efficacy of Noninvasive Technologies in Triaging Traumatic Brain Injury and Correlating With Intracranial Pressure: A Prospective Study

BACKGROUND

There is interest in methods of measuring noninvasive intracranial pressure (ICP), including pupillometry, ultrasonographic transcranial Doppler (TCD), and optic nerve sheath diameter (ONSD), for diagnosing traumatic brain injury (TBI) in limited resource environments. Whether these technologies have diagnostic agreement is unknown. We hypothesized that ONSD, pupillometry, and TCD could both distinguish severe TBI and correlate with ICP.

METHODS

A prospective study of 135 patients was conducted at a level 1 trauma center. Four test groups were established: nontrauma patients with ICP monitoring, trauma patients without TBI, trauma patients with mild TBI, and trauma patients with severe TBI with ICP monitoring. All patients underwent daily measurements of ONSD, pupillometry, and TCD with both CX50 Sonosite and the Spencer ST3 Yi Pencil probe.

RESULTS

ONSD differed significantly in patients with severe TBI compared with patients with mild and no TBI, but did not correlate with ICP. Pupillometric constriction velocity, dilation velocity, and percent change in pupil diameter were significantly different in patients with severe TBI, but also did not correlate with ICP. TCD did not differ among TBI severities, but middle cerebral artery peak systolic velocity, middle cerebral artery flow velocity, and carotid flow velocity correlated with ICP.

CONCLUSIONS

This is a novel study of four noninvasive tests to screen for severity of TBI and measure ICP. Our analysis indicates that no single device can do both. However, ONSD and pupillometry may be used as a supplementary screening tool for severe TBI, whereas TCD could be used to estimate and follow ICP in patients with severe TBI.

Neuroimaging and advanced research techniques may lead to improved outcomes in military members suffering from traumatic brain injury

Recent military conflicts in Iraq and Afghanistan have resulted in the significant increase in blast-related traumatic brain injury (TBI), leading to increased Department of Defense interest in its potential long-term effects ranging from the mildest head injuries termed subconcussive trauma to the most debilitating termed chronic traumatic encephalopathy (CTE). Most patients with mild TBI will recover quickly while others report persistent symptoms called postconcussive syndrome. Repeated concussive and subconcussive head injuries result in neurodegenerative conditions that may hinder the injured for years. Fundamental questions about the nature of these injuries and recovery remain unanswered. Clinically, patients with CTE present with either affective changes or cognitive impairment. Genetically, there have been no clear risk factors identified. The discovery that microglia of the cerebral cortex discharged small extracellular vesicles in the injured and adjacent regions to a TBI may soon shed light on the immediate impact injury mechanisms. The combination of neuroimaging and advanced research techniques may, one day, fill critical knowledge gaps and lead to significant TBI research and treatment advancements.

Noninvasive Cerebral Perfusion and Oxygenation Monitoring Augment Prolonged Field Care in a Non-Human Primate Model of Decompensated Hemorrhage and Resuscitation

BACKGROUND

Decompensated hemorrhagic shock (DHS) is the leading cause of preventable death in combat casualties. "Golden hour" resuscitation effects on cerebral blood flow and perfusion following DHS in prolonged field care (PFC) are not well investigated. Using an established non-human primate model of DHS, we hypothesized noninvasive regional tissue oxygenation (rSO2) and Transcranial Doppler (TCD) would correlate to the invasive measurement of partial pressure of oxygen (PtO2) and mean arterial pressure (MAP) in guiding hypotensive resuscitation in a PFC setting.

METHODS

Ten rhesus macaques underwent DHS followed by a 2 h PFC phase (T0-T120), and subsequent 4 h hospital resuscitation phase (T120-T360). Invasive monitoring (PtO2, MAP) was compared against noninvasive monitoring systems (rSO2, TCD). Results were analyzed using t tests and one-way repeated measures ANOVA. Linear correlation was determined via Pearson r. Significance = P < 0.05.

RESULTS

MAP, PtO2, rSO2, and mean flow velocity (MFV) significantly decreased from baseline at T0. MAP and PtO2 were restored to baseline by T15, while rSO2 was delayed through T30. At T120, MFV returned to baseline, while the Pulsatility Index significantly elevated by T120 (1.50 ± 0.31). PtO2 versus rSO2 (R2 = 0.2099) and MAP versus MFV (R2 = 0.2891) shared very weak effect sizes, MAP versus rSO2 (R2 = 0.4636) displayed a low effect size, and PtO2 versus MFV displayed a moderate effect size (R2 = 0.5540).

CONCLUSIONS

Though noninvasive monitoring methods assessed here did not correlate strongly enough against invasive methods to warrant a surrogate in the field, they do effectively augment and direct resuscitation, while potentially serving as a substitute in the absence of invasive capabilities.

Prediction of Early Intracranial Hypertension After Severe Traumatic Brain Injury: A Prospective Study

OBJECTIVE

This study aimed to assess the reliability of clinical features, noninvasive transcranial Doppler-related pulsatility index (PI) calculation, and optic nerve sheath diameter (ONSD) measured by ultrasound (US) and initial computed tomography (CT) scan (Marshall CT scan classification) in predicting the occurrence of early (<24 hours) high intracranial pressure (EHICP) (>20 mm Hg) after severe traumatic brain injury (TBI).

METHODS

We conducted an observational prospective study in a level 1 trauma center. Patients were measured simultaneously for PI and US ONSD in the triage zone. Patients were categorized into 2 groups: those who had EHICP after TBI (EHICP+) and those who did not (EHICP-).

RESULTS

Fifty-four patients were included; 32 were categorized as EHICP+ and 22 as EHICP-. PI >1.4 did not correlate with EHICP+ patients (69% vs. 46%, P = 0.09). US ONSD measurement was higher in the EHICP+ group (6.25; range, 6-6.95 vs. 5.7; range, 5.2-6.4; P = 0.005). The area under the receiver operating characteristic curve for US ONSD as a predictor of developing EHICP was 0.73 (95% confidence interval [CI], 0.59-0.86). CT ONSD measurement was higher in the EHICP+ group (6.71; range, 6.35-7.87 vs. 6.25; range, 5.8-6.93; P = 0.04). The area under the receiver operating characteristic curve for CT ONSD measurement as a predictor for EHICP+ was 0.67 (95% CI, 0.53-0.81). The diffuse injury III and IV categories in the Marshall CT scan classification were associated with the occurrence of EHICP (P = 0.004).

CONCLUSIONS

None of the clinical features or noninvasive tools assessed in this study enabled clinicians to strictly ascertain EHICP. Further studies are needed to establish their potential role before intracranial pressure probe insertion.

Cerebral Blood Flow in Polytrauma: Transcranial Doppler Analysis in a Nonhuman Primate Shock Model

BACKGROUND

In combat-related trauma, resuscitation goals are to attenuate tissue hypoxia and maintain circulation. During hemorrhagic shock, compensatory and autoregulatory mechanisms are activated to preserve cerebral blood flow. Transcranial Doppler (TCD) ultrasonography may be an ideal noninvasive modality to monitor cerebral hemodynamics. Using a nonhuman primate (NHP) model, we attempted to characterize cerebral hemodynamics during polytraumatic hemorrhagic shock using TCD ultrasonography.

MATERIALS AND METHODS

The ophthalmic artery was insonated at multiple time points during varying stages of shock. Hemorrhage was controlled and pressure targeted to 20 mmHg to initiate and maintain the shock period. Mean flow velocity (MFV), peak systolic velocity (PSV), end diastolic velocity (EDV), pulsatility index (PI), and resistance index (RI) were recorded. Results represent mean ± standard deviation; statistical significance is P < 0.05; n = 12.

RESULTS

Compared to baseline, MFV, PSV, EDV, and RI show significant changes after 60 min of hemorrhagic shock, (9.81 ± 3.60 cm/s; P < 0.01), (21.15 ± 8.59 cm/s; P < 0.01), (5.15 ± 0.21 cm/s; P < 0.01), (0.70 ± 0.11; P < 0.05), respectively. PI did not change during hemorrhagic shock. At end of prehospital care (T30), cerebral flow recovers for MFV, PSV, and RI while EDV remained decreased at T30 (6.15 ± 1.13 cm/s; P < 0.01) and 1 h of simulated transport (T90) (5.87 ± 0.62 cm/s; P < 0.01). Changes in PI at T30 and T90 were not significant. MFV diminished (16.45 ± 3.85 cm/s; P < 0.05) at T90.

CONCLUSIONS

This study establishes baseline and hemorrhagic shock values for NHP cerebral blood flow velocities and cerebrovascular indices. TCD ultrasonography may represent an important area of research for targeted resuscitation investigations using a hemorrhagic shock model in NHPs.