Cerebral Net Water Uptake in Posttraumatic Cerebral Ischemia.

We assessed net water uptake changes (NWU) in regions of posttraumatic ischemia in relation to cerebral microcirculation mean transit time (MTT) at moderate-to-severe traumatic brain injury (TBI). MATERIALS AND METHODS: 128 moderate-to-severe traumatic brain injury patients (44 women, 84 men, age: 37 ± 12 years) were stratified into 3 groups: Marshall 2-3: 48 patients, Marshall 4: 44 patients, Marshall 5: 36 patients. The groups were matched by sex and age. Patients received multiphase perfusion computed tomography (PCT) 1-5 days after admission. Net water uptake was calculated from non-contrast computed tomography. Data are shown as a median [interquartile range]. P < 0.05 was considered statistically significant. RESULTS: Cerebral blood flow in posttraumatic ischemia foci in Marshall 4 group was significantly higher than that in the Marshall 5 group (p = 0.027). Net water uptake in posttraumatic ischemia zones was significantly higher than in zones without posttraumatic ischemia (8.1% versus 4.2%, p < 0.001). Mean transit time in posttraumatic ischemia zones was inversely and significantly correlated with higher net water uptake (R2 = 0,089, p < 0.01). CONCLUSIONS: Delay of blood flow through the cerebral microvascular bed was significantly correlated with the increased net water uptake in posttraumatic ischemia foci. Marshall's classification did not predict the progression of posttraumatic ischemia.

Non-enzymatic antioxidant blood plasma profile in the period of high training loads of elite speed skaters in the altitude.

At the altitude, hypoxia and training load are key factors in the development of oxidative stress. Altitude-induced oxidative stress is developed due to the depletion of antioxidant potential. In the current study, we examined the non-enzymatic antioxidant profile of blood plasma in 7 males and 5 females specializing in speed skating at a 21-day training camp at 1 850 â€‹m above sea level. Training included: cycling, roller skating, ice skating, strength training, and special training. At the start point and the endpoint, total hemoglobin mass (tHb-mass), hemoglobin concentration, and circulating blood volume were determined. Antioxidant profiles, hypoxic doses, hypoxic impulses, and training impulses were assessed at 3, 6, 10, 14, and 18 days. Antioxidant profiles consisting of "urate" and "thiol" parts were registered with chemiluminometry. In the training dynamics, antioxidant parameters changed individually, but in total there was a decrease in the "urate" capacity by a factor of 1.6 (p â€‹= â€‹0.001) and an increase in the "thiol" capacity by a factor of 1.8 (p â€‹= â€‹0.013). The changes in "urate" capacity positively correlated (rS â€‹= â€‹0.40) and the changes in "thiol" capacity negatively correlated (rS â€‹= â€‹-0.45) with changes in tHb-mass. Both exercise and hypoxic factors affect the antioxidant parameters bidirectionally. They correlated with a decrease in thiol capacity and with an increase in urate capacity. The assessment of the non-enzymatic antioxidant profile can be a simple and useful addition to screening the reactive oxygen species homeostasis and can help choose the personalized training schedule, individualize recovery and ergogenic support.

NIRS-Based Study of Local Cerebral Oxygenation During Transcranial Direct Current Stimulation in Patients with Mild Traumatic Brain Injury.

The purpose of our study was to assess the dynamics of local cerebral oxygenation (LCO) by near-infrared spectroscopy (NIRS) during transcranial direct current stimulation (tDCS) in the acute stage of mild traumatic brain injury (mTBI). Fifty-seven mTBI patients (18 women and 39 men, 35 ± 11.7 years old, GCS 13.7 ± 0.7) were treated by tDCS at 3-5 days after head injury. Stimulation parameters were: 1 mA, 9 V, duration-20 min. A cerebral oximeter was used to assess LCO-values in the frontotemporal lobes. Anodal and cathodal LCO values were compared before tDCS and every 2 min until the tDCS end. Significance was preset to p < 0.05. Results: A significant decrease in LCO values on the anodal side was observed at the 8th to 12th minutes of stimulation, compared to the cathodal side (at 8th minute - p = 0.011; at 12th minute - p < 0.00000001) and compared to LCO values before tDCS (p < 0.00001). The LCO on the cathodal side was not significantly different during the whole tDCS. At the end of the procedure, the interhemispheric LCO differences were not statistically significant (p = 0.757). Conclusions: Transcranial DCS in 3-5 days of mTBI leads to a significant decrease in the LCO value on the anodal side between 8 and 12 min and subsequent recovery to baseline values by the end of the procedure.

Eye Tracking Parameters Correlate with the Level of Cerebral Oxygen Saturation in Mild Traumatic Brain Injury: A Preliminary Study.

AIM: The aim of this study was to assess the relationship between oculomotor synergies and brain oxygen status at mild traumatic brain injury (mTBI) using simultaneous comparison of eye-tracking (ET) parameters and cerebral oxygen saturation. MATERIAL AND METHODS: This non-randomised single-centre prospective study included 77 patients with mTBI (mean age was 36.3 ± 4.8 years, 48 men, 29 women, median GCS 13.7 ± 0.7). Cerebral oximetry was used to detect oxygen saturation level (SctO2) in the frontal lobe pole (FLP) region. Eye movements were measured simultaneously using the EyeTracker. Calculated parameters were: vertical and horizontal angular eyeball velocity (AV); left vertical speed (LVS); right vertical speed (RVS); left horizontal speed (LHS); and right horizontal speed (RHS). The indices of vertical and horizontal eye version (version index, Vx) were calculated as the Pearson correlation coefficient between the corresponding AV of the right and left eyes. Significance was pre-set to p < 0.05. RESULTS: SctO2 in the FLP varied from 62% to 79%. The average SctO2 values were 69.26 ± 6.96% over the left FLP and 70.25 ± 7.58% over the right FLP (p = 0.40). The total analysis of the eye-tracking data revealed the following values of gaze parameters: LVS - 0.327 ± 0.263 rad/sec; LHS - 0.201 ± 0.164 rad/sec; RVS - 0.361 ± 0.269 rad/sec; and RHS - 0.197 ± 0.124 rad/sec. The calculated vertical version index (VVx) was 0.80 ± 0.12. The calculated horizontal version index (HVx) was 0.82 ± 0.11. The VVx and HVx were correlated with SctO2 levels in the FLP (p = 0.038; r = 0.235; p = 0.048; r = 0.218, respectively p = 0.035; r = 0.241; p = 0.039; r = 0.235, respectively). CONCLUSIONS: VVx and HVx correlate with the SctO2 level in the FLP (p < 0.01) in mTBI. No significant correlation was detected between the level of the SctO2 level and vertical and horizontal AV of the eyeballs. Eye tracking can help quantify the severity of ocular conjugation impairments after mTBI, as well as explore the contribution that cerebral oxygen status disorders make to this process.

The Changes in Brain Oxygenation During Transcranial Alternating Current Stimulation as Consequences of Traumatic Brain Injury: A Near-Infrared Spectroscopy Study.

The aim was to evaluate the changes in brain tissue oxygenation, assessed by near-infrared spectroscopy (NIRS), during transcranial alternating current stimulation (tACS) in patients with mild and moderate traumatic brain injury (TBI). Nineteen patients with diffuse, blunt, non-severe TBI (mean age 32.7 ± 11.4 years; 4 women and 15 men; Glasgow Coma Score before tACS 14.1 ± 0.5) were treated by 10 Hz in-phase tACS applied for 30 minutes to the left and right lateral prefrontal cortex at 21 days after TBI. Regional cerebral tissue oxygen saturation (SctO2) in the frontal lobes was measured simultaneously by the cerebral oximeter. Significance was preset to P < 0.05. The SctO2 values before tACS were not different between hemispheres ~65%. After 15 minutes of tACS, a significant (p < 0.05) decrease in regional SctO2 was observed with the minimum at the eighth minute of 53.4 ± 3.2% and 53.4 ± 3.2% in the left and right hemispheres, respectively. At the end of the stimulation (30 minutes), the hemispheric differences in cerebral oxygen saturation became statistically insignificant again (p > 0.05). Therefore, tACS causes a significant decrease in SctO2, probably, due to neuronal activation. Our data indicate that tACS may need to be supplemented with oxygen therapy. Further research is required.

Microcirculatory Biomarkers of Secondary Cerebral Ischemia in Traumatic Brain Injury.

AIM: The purpose of this study was to study changes in cerebral microcirculation parameters in the development of secondary cerebral ischemia (SCI). METHODS: A total of 202 patients with a Glasgow Coma Scale score ≤ 12 after experiencing a traumatic brain injury (TBI) were recruited for the study within 6 h of the injury. All patients were subjected to perfusion computed tomography. The cerebral blood flow velocity was recorded using transcranial Doppler ultrasound. The arterial blood pressure was measured noninvasively. The cerebrovascular resistance (CVR), cerebral arterial compliance (CAC), cerebrovascular time constant (CTC), and critical closing pressure (CCP) were measured using the neuromonitoring complex. All patients had unilateral foci of posttraumatic ischemia. Statistical analysis was performed using a paired Student's t test and factor analysis. RESULTS AND CONCLUSION: The CVR and CCP were significantly increased in patients who developed SCI after TBI, whereas the CAC and CTC were significantly decreased (P < 0.05). Factor analyses revealed that the CVR, CAC, and CTC were significantly associated with development of posttraumatic ischemia (P < 0.05). The changes in the CVR and CCP in patients with TBI were significantly associated with SCI development (P < 0.05).

Secondary Cerebral Ischemia at Traumatic Brain Injury Is More Closely Related to Cerebrovascular Reactivity Impairment than to Intracranial Hypertension.

The purpose of this study was to investigate the relationship between the development of secondary cerebral ischemia (SCI), intracranial pressure (ICP) and cerebrovascular reactivity (CVR) after traumatic brain injury (TBI). METHODS: 89 patients with severe TBI with ICP monitoring were studied retrospectively. The mean age was 36.3 ± 4.8 years, 53 men, 36 women. The median Glasgow Coma Score (GCS) was 6.2 ± 0.7. The median Injury Severity Score was 38.2 ± 12.5. To specify the degree of impact of changes in ICP and CVR on the SCI progression in TBI patients, logistic regression was performed. Significant p-values were <0.05. RESULTS: The deterioration of CVR in combination with the severity of ICP has a significant impact on the increase in the prevalence rate of SCI. A logistic regression analysis for a model of SCI dependence on intracranial hypertension and CVR was performed. The results of the analysis showed that CVR was the most significant factor affecting SCI development in TBI. CONCLUSIONS: The development of SCI in severe TBI depends largely on CVR impairment and to a lesser extent on ICP level. Treatment for severe TBI patients with SCI progression should not be aimed solely at intracranial hypertension correction but also at CVR recovery.

NIRS-Based Assessment of Cerebral Oxygenation During High-Definition Anodal Transcranial Direct Current Stimulation in Patients with Posttraumatic Encephalopathy.

The aim was to evaluate the changes in brain tissue oxygenation, assessed by near-infrared spectroscopy (NIRS) during high-definition transcranial direct current stimulation (HD-tDCS) in patients with posttraumatic encephalopathy (PTE). Fifty-two patients with PTE after diffuse, blunt, non-severe traumatic brain injury (TBI) (14 women and 38 men, 31.8 ± 12.5 years, Glasgow Coma Score before tDCS 13.2 ± 0.3) were treated with HD-tDCS at 21 days after TBI. The parameters were as follows: 1 mA, 9 V, and current density ~0.15 mA/cm2. The duration of HD-tDCS was 30 min. The anodal and cathodal electrodes were placed over the left M1 and contralateral supraorbital region, respectively. HD-tDCS was delivered by a direct current stimulator with a pair of surface sponge electrodes (S = 3 cm2). Regional cerebral oxygen saturation (SctO2) in the frontal lobes was measured simultaneously and bilaterally by the cerebral oximeter. SctO2 values were compared before stimulation, by the 15th minute and at the end of the tDCS. Significance was preset to p < 0.05. Results. Before the stimulation, SctO2 values varied between 53% and 86% (74 ± 7.1%) without significant difference between hemispheres (p = 0.135). After 15 min, a significant (p < 0.0000001) decrease in regional SctO2 on the anodal side was observed (mean 54.5 ± 5.6%). On the cathodal side, SctO2 remained unchanged. At the end of the stimulation (30 min), differences between the hemispheres in SctO2 remained statistically significant (p < 0.05). Conclusions. In patients with PTE complicated by TBI, HD-tDCS causes a statistically significant (p < 0.05) decrease in regional SctO2 on the anodal side.

Comparative Analysis of Simultaneous Transcranial Doppler and Perfusion Computed Tomography for Cerebral Perfusion Evaluation in Patients with Traumatic Brain Injury.

The aim was to investigate the feasibility of simultaneous comparison of cerebral circulation in major vessels and microvasculature in patients suffering traumatic brain injury (TBI) with or without intracranial hematomas (IH). METHODS: 170 patients were divided into two groups: Group 1 - diffuse TBI (75 patients); and Group 2 - TBI with IH (95 patients: 18 epidural, 65 subdural and 12 multiple). Perfusion computed tomography (PCT) for assessment of volumetric cerebral blood flow (CBF) was done 2-15 days after admission to hospital. Simultaneous assessment of cerebral blood flow velocity (CBFV) in both middle cerebral arteries was done by transcranial Doppler. RESULTS: In patients with diffuse TBI, CBF had statistically valid correlations with CBFV (r = 0.28, p = 0.0149 on the left side; r = 0.382, p = 0.00075 on the right side). In patients with TBI and IH, the analysis did not reveal any reliable correlations between the CBFV and CBF velocity in the temporal lobes, either on the side of the removed IH or on the opposite side. CONCLUSION: The greatest linear correlation was noted in patients with diffuse TBI without the development of a coarse shift of the midline structures and dislocation syndrome. This correlation decreases with the increase in injury severity and development of secondary complications in the acute period, which probably reflects impairment of the coupling of oxygen consumption by brain tissue and cerebral microcirculation.

The Сerebrovascular Time Constant in Patients with Head Injury and Posttraumatic Cerebral Vasospasm.

The aim of the study was to assess the time constant of cerebral arterial bed in TBI patients with cerebral vasospasm (CVS) with and without intracranial hematomas (ICH).We examined 84 patients with severe TBI (mean 35 ± 15 years, 53 men and 31 women). The first group included 41 patients without ICH and the second group included 43 patients with epidural (7) and subdural (36) hematomas.Perfusion computed tomography (PCT) was performed in 1-12 days after TBI in the first group and in 2-8 days after craniotomy in the second group. Arteriovenous amplitude of regional cerebral blood volume oscillation was calculated as the difference of arterial and venous blood volume in the "region of interest." Mean arterial pressure was measured and the flow rate of middle cerebral artery was recorded with Transcranial Doppler after PCT. Time constant was calculated by the formula modificated by M. Kasprowicz. Results and Conclusion: The τ was shorter (p < 0.005) in both first and second group in comparison with normal values. The τ in the second group on ipsilateral side former hematoma with CVS was shorter than in the first group and in the second group on contralateral side former hematoma without CVS (р = 0.024).