Journal of neurotrauma
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Journal of neurotrauma · Jul 2018
Estimating Pressure Reactivity Using Noninvasive Doppler-Based Systolic Flow Index.
The study objective was to derive models that estimate the pressure reactivity index (PRx) using the noninvasive transcranial Doppler (TCD) based systolic flow index (Sx_a) and mean flow index (Mx_a), both based on mean arterial pressure, in traumatic brain injury (TBI). Using a retrospective database of 347 patients with TBI with intracranial pressure and TCD time series recordings, we derived PRx, Sx_a, and Mx_a. We first derived the autocorrelative structure of PRx based on: (A) autoregressive integrative moving average (ARIMA) modeling in representative patients, and (B) within sequential linear mixed effects (LME) models with various embedded ARIMA error structures for PRx for the entire population. ⋯ Through using linear mixed effects modeling and accounting for the ARIMA structure of PRx, one can estimate PRx using noninvasive TCD-based indices. We have described our first attempts at such modeling and PRx estimation, establishing the strong link between two aspects of cerebral autoregulation: measures of cerebral blood flow and those of pulsatile cerebral blood volume. Further work is required to validate.
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Journal of neurotrauma · Jul 2018
Worsening Dual-Task Gait Costs after Concussion and their Association with Subsequent Sport-Related Injury.
Prior studies suggest that concussion may lead to an increased risk of a subsequent time-loss sport-related injury, but the mechanisms responsible are unknown. We measured the symptom and dual-task gait outcomes for athletes initially post-concussion and after clinical recovery. Participants then self-reported any additional injuries incurred in the year after their concussion. ⋯ Symptoms improved for all participants (main effect of time, p < 0.001; Post-Concussion Symptom Scale [PCSS] = 25.0 ± 16.9 vs. 2.8 ± 7.5; p < 0.001), but did not differ between groups (p = 0.77). Significant dual-task gait cost worsening throughout concussion recovery was associated with time-loss injuries during sports in the year after a concussion. These findings indicate that worsening ability to execute a concurrent gait and cognitive task may relate to the risk of incurring an injury during sports after clinical concussion recovery.
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Journal of neurotrauma · Jul 2018
Transient Receptor Potential Melastatin 4 Induces Astrocyte Swelling But Not Death after Diffuse Traumatic Brain Injury.
Traumatic brain injury (TBI) is a prevalent disease with significant costs. Although progress has been made in understanding the complex pathobiology of focal lesions associated with TBI, questions remain regarding the diffuse responses to injury. Expression of the transient receptor potential melastatin 4 (Trpm4) channel is linked to cytotoxic edema during hemorrhagic contusion expansion. ⋯ Correlative H&E assessments demonstrated little evidence of hippocampal damage, suggesting that Trpm4 expression by astrocytes does not precipitate cell death following diffuse TBI. Additionally, ultrastructural assessments showed Trpm4+ astrocytes exhibited twice the soma size compared with Trpm4- astrocytes, indicating that astrocyte swelling is associated with Trpm4 expression. This study provides a foundation for future investigations into the role of Trpm4 in astrocyte swelling and edema following diffuse TBI.
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Journal of neurotrauma · Jul 2018
Intracranial and Extracranial Injury Burden as Drivers of Impaired Cerebrovascular Reactivity in Traumatic Brain Injury.
Impaired cerebrovascular reactivity has been associated with outcome following traumatic brain injury (TBI), but it is unknown how it is affected by trauma severity. Thus, we aimed to explore the relationship between intracranial (IC) and extracranial (EC) injury burden and cerebrovascular reactivity in TBI patients. We retrospectively included critically ill TBI patients. ⋯ In summary, diffuse IC injury markers (thickness of SAH and the presence of a subdural hematoma) and APACHE II were most associated with dysfunction in cerebrovascular reactivity after TBI. Standard CT scoring systems and evidence of macroscopic parenchymal damage are poor predictors, implicating potentially both microscopic injury patterns and host response as drivers of dysfunctional cerebrovascular reactivity. Age remains a major variable associated with cerebrovascular reactivity.
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Journal of neurotrauma · Jul 2018
Observational StudyFeasibility of Telemetric Intracranial Pressure Monitoring in the Neuro Intensive Care Unit.
Intracranial pressure (ICP) monitoring is crucial in the management of acute neurosurgical conditions such as traumatic brain injury (TBI). However, pathological ICP may persist beyond the admission to the neuro intensive care unit (NICU). We investigated the feasibility of telemetric ICP monitoring in the NICU, as this technology provides the possibility of long-term ICP assessment beyond NICU discharge. ⋯ Therefore, telemetric ICP monitoring in an acute neurosurgical setting is feasible. Signal quality and stability are sufficient for clinical decision making based on mean ICP. The low sampling frequency (5 Hz) does not permit analysis of intracranial pulse wave morphology, but resolution is sufficient for calculation of derived indices such as the pressure reactivity index (PRx).