Middle Cerebral Artery Flow Velocity Research Articles

TP10.1.12Personal Protective Equipment impairs pulmonary gas exchange causing systemic hypercapnia-hypoxaemia and cerebral hyperperfusion-induced cephalalgia

Abstract Aims To what extent Personal Protective Equipment (PPE) impacts integrated cardiopulmonary-cerebrovascular function has not been examined. The hypothesis tested was that PPE adversely influences pulmonary gas exchange, resulting in systemic hypercapnic-hypoxaemia and cerebral hyperperfusion-induced cephalalgia. Methods Eight male Higher Surgical Trainees (aged 33 ± 2y) participated in a repeated measures crossover study, completing two-hour laparoscopic simulation tasks, on two separate occasions (separate days), once in standard operating attire, and once in full PPE (including FFP3 mask). Results Following two hours of simulation, full PPE (compared with standard operating attire) was associated with increased FICO2 (7.9% (±0.8%) vs. 7.1% (±1.2%); p = 0.025), decreased FIO2 (16.0% (±0.4%) vs. 16.6% (±0.5%); p = 0.011), and decreased peripheral O2 saturation (95% (± 1%) vs. 98% (±1%); p = 0.001). Headaches were reported by three participants in PPE (Chi2 3.692, p = 0.055), and was associated with increased Middle Cerebral Artery flow velocity; 82 (±4) cm/s, compared with 63 (±9) cm/s in the remaining five participants (p = 0.008). Skin temperature increased by 1.3 °C during simulation in PPE (p = 0.001), with an equal mean insensible fluid loss of 300ml under both conditions (p = 0.049). Conclusions Collectively, these findings highlight the integrated cardiopulmonary-cerebrovascular complications associated with PPE-induced impairment in pulmonary gas exchange. Protective countermeasures should be designed to prevent risk to healthcare staff and patients alike.

Leptomeningeal collateral flow in patients with middle cerebral artery occlusion assessed by transcranial Doppler.

To explore the application value and clinical significance of transcranial Doppler(TCD)in assessing leptomeningeal collateral flow (LMF) status in patients with unilateral middle cerebral artery (MCA) occlusion. Medical records of patients with unilateral MCA occlusion confirmed by digital subtraction angiography (DSA) were analyzed retrospectively. The patients were divided into three groups according to LMF status, and the laboratory and imaging results were collected. Cerebral blood flow velocity (CBFV) of MCA, anterior cerebral artery (ACA), and posterior cerebral artery (PCA) on the affected side (ipsilateral, i) and the healthy side (contralateral, c) were measured and recorded by TCD. The results of CBFV changes detected by TCD were compared with those of DSA, and the correlation between CBFV changes and LMF status was analyzed. Eighty-four patients with unilateral MCA occlusion were included. CBFViACA and CBFViPCA were significantly faster than CBFVcACA and CBFVcPCA in patients with good LMF status (p<.05). There was a significant positive correlation between CBFViACA and LMF status (r = 0.697, p<.001). There was statistical significance in receiver operating characteristic curve analysis of CBFViACA and CBFViPCA (p<.05). The area under the curve of CBFViACA and CBFViPCA, respectively, was 0.879 and 0.678, and the best cutoff value was 82 and 60.5 cm/s. TCD can assess LMF status by detecting the changes of flow velocity of intracranial vessels. CBFV of ACA and PCA in patients with MCA occlusion is significantly correlated with LMF status by DSA. Assessing LMF status, CBFViACA, CBFViACA/CBFVcACA, and CBFViACA/CBFViMCA has the great diagnostic value, which is of great significance in guiding MCA occlusion patients to choose individualized treatment.

Relation of middle cerebral artery flow velocity and risk of cognitive decline: A prospective community-based study

Hemodynamic parameters measured by the Transcranial Doppler Ultrasound (TCD) are related to cognitive impairment in many cross-sectional studies, but the longitudinal evidence is scarce. This study aimed to verify the association between flow velocity of Middle Cerebral Artery (MCA) and the longitudinal cognitive decline in community dwelling older adults.

Transcranial Doppler study in acute spontaneous intracerebral hemorrhage: The role of pulsatility index.

ObjectivePulsatility index (PI) is a parameter calculated by transcranial Doppler sonography (TCD), which is commonly used for patients with subarachnoid hemorrhage or ischemic stroke. However, we performed a retrospective analysis of patients with acute spontaneous intracerebral hemorrhage (ICH) to assess the function of TCD, particularly the PI.MethodsThis study involved a total of 46 patients with acute ICH who received treatment at a single center between May 2013 and December 2014. Medical records of baseline characteristics, except for the modified Rankin scale, were obtained at initial evaluation in the emergency room, and TCD was used to calculate middle cerebral artery flow velocity (MFV) and PI at admission (baseline), 24 h, and 7 days. The PI and MFV values on the affected middle cerebral artery were compared with those on the contralateral side. Linear regression analysis was used for statistical analyses (SPSS 21.0, IBM Corp., Armonk, NY, USA).ResultsStatistical analysis indicated that sex, age, Glasgow coma scale, intraventricular hemorrhage, and hematoma size were not correlated with PI (p＞0.05); however, only PI was positively correlated with functional outcome at 6 months after treatment (R=0.846, p=0.002).ConclusionsThese results provide evidence that the parameter of PI is an independent determinant prognostic factor in acute spontaneous ICH. Further research is needed to investigate the influence of cerebral blood flow dynamics on a larger, more controlled, and more randomized basis.

Effect of early acupuncture on cognitive function in patients with vascular dementia after cerebral infarction

To observe the clinical efficacy of early acupuncture for vascular dementia (VD) after cerebral infarction, and explore its possible mechanism. A total of 120 patients with VD after cerebral infarction were randomized into an acupuncture combined with medication group (60 cases, 1 case dropped off) and a western medication group (60 cases, 1 case dropped off). In the western medication group, oxiracetam capsules were given orally, 2 capsules each time, 3 times a day. On the basis of the treatment as the western medication group, Bupi Peiyuan Yizhi acupuncture was applied at Baihui (GV 20), Sishencong (EX-HN 1), Zhongwan (CV 12), Wailing (ST 26), Xiawan (CV 10), Qihai (CV 6), Guanyuan (CV 4), etc. in the acupuncture combined with medication group, 30 min each time, once a day, 5 days a week. The treatment was given 8 weeks in both groups. Before and after treatment，the scores of mini-mental state examination (MMSE), Alzheimer's disease assessment scale cognitive part (ADAS-Cog), clock drawing test (CDT), Barthel index were observed, blood flow velocity of middle cerebral artery (MCA) was detected, and the clinical efficacy was evaluated in the two groups. The total effective rate was 89.8% (53/59) in the acupuncture combined with medication group, which was superior to 76.3% (45/59) in the western medication group (P<0.01). Compared before treatment, the subitem scores and total scores of MMSE, ADAS-Cog score, CDT score and Barthel index score after treatment were improved in the two groups (P<0.01, P<0.05), and the scores in the acupuncture combined with medication group were superior to those in the western medication group (P<0.05, P<0.01). After treatment, the blood flow velocity of bilateral MCA was increased in the acupuncture combined with medication group (P<0.05), which was faster than the western medication group (P<0.05). Early acupuncture could improve cognitive function and activities of daily living in patients with VD after cerebral infarction, its mechanism may be related to improving the blood flow velocity of MCA, promoting blood circulation, and improving cerebral perfusion.

Improvement in neurological outcome and brain hemodynamics after late cranioplasty.

Early cranioplasty has been encouraged after decompressive craniectomy (DC), aiming to reduce consequences of atmospheric pressure over the opened skull. However, this practice may not be often available in low-middle-income countries (LMICs). We evaluated clinical improvement, hemodynamic changes in each hemisphere, and the hemodynamic balance between hemispheres after late cranioplasty in a LMIC, as the institution's routine resources allowed. Prospective cohort study included patients with bone defects after DC evaluated with perfusion tomography (PCT) and transcranial Doppler (TCD) and performed neurological examinations with prognostic scales (mRS, MMSE, and Barthel Index) before and 6months after surgery. A final sample of 26 patients was analyzed. Satisfactory improvement of neurological outcome was observed, as well as significant improvement in the mRS (p = 0.005), MMSE (p < 0.001), and Barthel Index (p = 0.002). Outpatient waiting time for cranioplasty was 15.23 (SD 17.66) months. PCT showed a significant decrease in the mean transit time (MTT) and cerebral blood volume (CBV) only on the operated side. Although most previous studies have shown an increase in cerebral blood flow (CBF), we noticed a slight and nonsignificant decrease, despite a significant increase in the middle cerebral artery flow velocity in both hemispheres on TCD. There was a moderate correlation between the MTT and contralateral muscle strength (r = - 0.4; p = 0.034), as well as between TCD and neurological outcomes ipsilateral (MMSE; r = 0.54, p = 0.03) and contralateral (MRS; p = 0.031, r = - 0.48) to the operated side. Even 1year after DC, cranioplasty may improve cerebral perfusion and neurological outcomes and should be encouraged.

Transcranial Doppler Assessment of Cerebrovascular Reactivity in Migraine Patients

Background: Migraine is considered as a neurovascular coupling disorder where the cerebral vascular reactivity is malfunctioning and measuring hemodynamic changes during migraine without causing more disturbances has always been a challenge. Objective: This study aimed to detect the role of transcranial Doppler ultrasound in assessing the vasomotor reactivity of cerebral blood vessels in migraine patients. Patients and Methods: This case control study included thirty-two migraine patients and thirty-two healthy individuals that were recruited from Neurology Department at Zagazig University Hospital and Neuropsychiatry Department at El-Sahel Teaching Hospital Outpatient Clinics during the period from April to December 2020. We performed Transcranial Doppler (TCD) on all participants and Breath Holding Index (BHI) was measured on both sides from the middle cerebral artery (MCA). Results: There was a significant decrease in breath holding index in patients of migraine. There was a statistical significance decrease in BHI and Maximum flow velocity in the left MCA (Max. FV Lt MCA) among severe patients compared to moderate patients. Conclusion: Migraineurs have significantly lower BHI compared to control group. The noninvasiveness of TCD and the possibility it provides for obtaining instantaneous information about cerebral blood flow changes indicates its usefulness in the study of vascular changes in different types of migraine.

Hemodynamic Response, Coughing and Incidence of Cerebrospinal Fluid Leakage on Awakening with an Endotracheal Tube or Laryngeal Mask Airway in Place after Transsphenoidal Pituitary Surgery: A Randomized Clinical Trial.

We aimed to compare systemic and cerebral hemodynamics and coughing during emergence after pituitary surgery after endotracheal tube (ETT) extubation or after replacing ETT with a laryngeal mask airway (LMA). Patients were randomized to awaken with an ETT in place or after replacing it with an LMA. We recorded mean arterial pressure (MAP), heart rate, middle cerebral artery (MCA) flow velocity, regional cerebral oxygen saturation (SrO2), cardiac index, plasma norepinephrine, need for vasoactive drugs, coughing during emergence, and postoperative cerebrospinal fluid (CSF) leakage. The primary endpoint was postoperative MAP; secondary endpoints were SrO2 and coughing incidence. Forty-five patients were included. MAP was lower during emergence than at baseline in both groups. There were no significant between-group differences in blood pressure, nor in the number of patients that required antihypertensive drugs during emergence (ETT: 8 patients (34.8%) vs. LMA: 3 patients (14.3%); p = 0.116). MCA flow velocity was higher in the ETT group (e.g., mean (95% CI) at 15 min, 103.2 (96.3–110.1) vs. 89.6 (82.6–96.5) cm·s−1; p = 0.003). SrO2, cardiac index, and norepinephrine levels were similar. Coughing was more frequent in the ETT group (81% vs. 15%; p < 0.001). CSF leakage occurred in three patients (13%) in the ETT group. Placing an LMA before removing an ETT during emergence after pituitary surgery favors a safer cerebral hemodynamic profile and reduces coughing. This strategy may lower the risk for CSF leakage.

Age corrected changes in intracranial hemodynamics after carotid endarterectomy.

Transcranial Doppler ultrasound (TCD) is a frequently used method to monitor brain perfusion during and following carotid endarterectomy (CEA). Our aim was to define the normally occurring changes of intracranial hemodynamics in patients undergoing CEA measuring recently developed TCD parameters. A retrospective, single-center cohort study was performed. Patients undergoing CEA were evaluated pre- and postoperatively from day 0 to day 3 measuring middle cerebral artery flow velocity (MCAFV). The following parameters were analyzed: the first systolic peak (Sys1), the second systolic peak (Sys2) and diastolic flow velocity at a fixed time after heartbeat onset (Dias@560). These parameters linearly decrease with age and were, therefore, transformed to Z-scores. Three hundred eighteen patients were included with a mean age of 70.8 years. Most patients were male (71%). Compared to preoperatively, the Z-scores of Sys1 and Sys2 were larger on postoperative day 3: +1.12 standard deviation (SD) or 16.0 cm/s (CI: 0.93 to 1.32; P<0.001) and +0.55 SD or 7.8 cm/s (CI: 0.35 to 0.74; P<0.001), respectively. The Z-score for Dias@560 was smaller than preoperatively: -0.23 SD or -1.9 cm/s (CI: -0.41 to -0.05, P=0.015). Under normal circumstances Sys1 profits more from CEA than Sys2, whilst diastolic flow velocity decreases. This indicates a return to normal arteriolar vascular resistance. Carefully describing normal changes in MCAFV, may in future enable discrimination of abnormalities, such as hyperperfusion syndrome.

Effects of different ventilation on cerebral oxygen saturation and cerebral blood flow before and after modified ultrafiltration in infants during ventricular septal defect repair.

To analyse the changes of different ventilation on regional cerebral oxygen saturation and cerebral blood flow in infants during ventricular septal defect repair. Ninety-two infants younger than 1 year were enrolled in the study. End-expiratory tidal pressure of carbon dioxide was maintained at 40-45 and 35-39mmHg in relative low and high ventilation groups. Regional cerebral oxygen saturation and flow velocity of the middle cerebral artery were recorded after anaesthesia (T0), cut pericardium (T1), separation from cardiopulmonary bypass (T2), the end of modified ultrafiltration, (T3) and at the end of operation (T4). The relative low ventilation group exhibited a significantly high regional cerebral oxygen saturation at each time point except for T2 (T0:77 ± 4, T1:76 ± 5, T3:76 ± 8, T4:76 ± 8, respectively, p < 0.001). Flow velocity of the middle cerebral artery in the relative low ventilation group was higher compared to the relative high ventilation group at each time point except for T2 (T0:53 ± 14, T1:54 ± 15, T3:53 ± 17, T4:52 ± 16, respectively, p < 0.001). Between the two groups, T2 showed the lowest middle cerebral artery flow velocity (relative low ventilation: 39 ± 15, relative high ventilation: 39 ± 11, p < 0.001). The infants' regional cerebral oxygen saturation and middle cerebral artery flow velocity performed better in the range of 40-45mmHg end-expiratory tidal pressure of carbon dioxide during CHD surgery. Modified ultrafiltration increased cerebral oxygen saturation. It was important to regulate ventilation in order to balance cerebral oxygen in infants.

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

BackgroundThere 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. MethodsA 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. ResultsONSD 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. ConclusionsThis 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.

Decrase in cerebral blood flow during maximal handgrip isometric contraction – a brief report

Findings of the studies on the relationship between isometric handgrip contraction and changes in cerebral blood flow (CBF) are contradictory. The aim of the study was to evaluate CBF changes during one minute of a maximal handgrip isometric contraction. Our main hypothesis was that the maximal handgrip test will cause a decrease in CBF related to the decrease in handgrip strength. The study protocol included a transcranial Doppler ultrasound measurement of middle cerebral arterial mean flow velocity (Vmean) with the concomitant measurement of the sustained maximal handgrip strength over a period of one minute in 12 healthy subjects of both sexes. The main findings indicate that a maximal handgrip exercise causes a significant decrease in cerebral blood flow that is slightly more prominent on the contralateral side. This decrease is accompanied by a significant but transient increase in heart rate and also by an important (16%) increase in mean arterial pressure. The maximal isometric contraction may result in an considerable decrease in cerebral blood flow that in certain cases may become even clinically relevant. In the light of our findings, we suggest that maximal isometric contractions should be better avoided as a therapeutic tool and that isometric exercises of intensities up to 60% of maximal voluntary contraction are better used.

Inner Ear Complications in Children and Adolescents with Sickle Cell Disease

Hearing impairment is a reported complication of sickle cell disease, yet inner ear pathology is not fully understood. The study purpose was to examine the patterns of inner ear involvement in patients with sickle cell disease by magnetic resonance imaging (MRI) and to assess its association with auditory functions. A cross-sectional study included 22 children with sickle cell disease examined for inner ear pathology by audiogram, MRI inner ear and transcranial Doppler (TCD) with revision of their hospital records for transfusion, chelation and hydroxyurea (HU) therapy. Abnormal MRI in the form of intrinsic T1 hyperintensity within the lumen of inner ear structures and cochlear neuropathy was found in five (22.7%) patients; left middle cerebral artery (MCA) flow velocity was higher in patients with abnormal MRI (83.4 ± 5.3 cm/sec) compared to normal MRI (68.2 ± 11.1 cm/sec) (p = 0.015), however, none of the patients had TCD of >170 cm/sec. There was no significant difference between patients with normal and abnormal MRI as regards hearing level and speech audiometry. Sensorineural hearing loss (SNHL) was present in two (9.1%) and conductive hearing loss (CHL) in two (9.1%) patients. There was a significant negative correlation between right ear mean hearing level and right MCA flow velocity and significant negative correlation between left ear mean hearing level and basilar artery (BA) flow velocity. We concluded that inner ear pathology is not uncommon in asymptomatic patients with sickle cell anemia, yet it did not correlate with hearing impairment and may occur with normal TCD results.

Cerebral hemodynamics in patients with arterial hypertension of the older age groups with orthostatic hypotensive reactions

Abstract Objective To study cerebrovascular autoregulation in pts with arterial hypertension (AH) with orthostatic hypotensive reactions (OHR) during an active orthostatic test (AOT). 50 pts with AH (40 g, 10 m), 68.5±5.3 years, I-III gr. were examined. Blood pressure monitoring (BPM) by “BP Lab”, Russia. AOT was performed with continuous measurement of systolic blood pressure (SBP) and diastolic blood pressure (DBP) in the digital artery (“Task Force Monitor”, “CNSystems” Austria). The criteria for the OHR were evaluated according to guidelines ESC, 2018. Cerebral hemodynamics in the middle cerebral artery (MCA) was monitored during the AOT (Angiodin-2K (BIOSS company, Russia), using a transcranial sensor with a freq. of 2 MHz. In the MCA, systolic (Vs), diastolic (Vd), average cerebral blood flow velocity (Vm), pulsation index (Pi), and vascular resistance index (Ri), the difference ΔVm30s,% and ΔVm30s, were recorded. Statistical analysis was performed using the non-parametric Mann-Whitney method using Statistica 6.0 Results In 17 (34%) pts with AH, OHR was detected. BP in pts with OHR compared with pts without OHR (mmHg), SBP: 131.7±12.2 vs 131.3±13.8, p&amp;gt;0.05; DBP 74.3±11.8 vs 75.3±8.9, p&amp;gt;0.05). In AOT in pts with OHR, the Vm in the orthostasis significantly decreased compared to pts without OHR, both in the first 30 s. and at 3 min. (Tabl.1). Conclusions In pts with AH of older age groups with OHR, in comparison with the same category of pts without OHR, there is a change in cerebral autoregulation in the form of a more pronounced decrease in cerebral blood flow velocity in MCA in the orthostatic position. Funding Acknowledgement Type of funding source: None

Cerebral autoregulation is heterogeneous in different stroke mechanism of ischemic stroke caused by intracranial atherosclerotic stenosis

Background and PurposeIntracranial atherosclerotic stenosis (ICAS) is the most common cause of ischemic stroke (IS) and is associated with stroke recurrence. It results in IS due to a variety of mechanisms. However, the influence of brain reserve mechanism on different stroke mechanism is still unclear. Cerebral autoregulation (CA) is an important brain reserve mechanism and is impaired after IS. This study aimed to explore the impaired pattern of CA and assess the association between CA and stroke risk factors in different stroke mechanism caused by ICAS.MethodsIS patients with ICAS (50%–99% stenosis/occlusion) in middle cerebral artery (MCA) or internal carotid artery were enrolled to receive CA examinations within 7 days after onset. Healthy volunteers were also recruited as controls. CA was recorded from spontaneous fluctuations of blood pressure and MCA flow velocity. Transfer function analysis was used to derive CA parameters, including phase difference (PD) and coherence in the low‐frequency range (0.06–0.12 Hz).ResultsA total of 89 IS patients and 90 healthy controls were included. Compared with controls, CA was impaired ipsilaterally in patients with parent artery atherosclerosis occluding penetrating artery (POPA) while CA was bilaterally impaired in other stroke mechanisms. And CA on ipsilateral hemisphere was correlated with hypertension/hyperlipidemia in patients with POPA (r = −0.481, p = .008; r = −0.484, p = .008). While CA on ipsilateral hemisphere was correlated with perfusion parameter including the arterial spin‐labeling (ASL) parameter cerebral blood flow (CBF) (r = 0.893, p = .007) and collateral circulation status the American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology (ASITN/SIR) (r = 0.610, p = .021) in patients with hypoperfusion mechanism.ConclusionIn IS patients, CA was impaired heterogeneously and was correlated with different risk factors in varied stroke mechanism. CA can be as an informative determinant of stroke risk in patients with ICAS and to help improving individualized treatment strategies in the presence of ischemic stroke caused by ICAS.

Middle cerebral artery velocity is associated with the severity of MRI brain injury in neonates received therapeutic hypothermia

BackgroundNo previous study has investigated the relationship between middle cerebral artery (MCA) flow velocity and the severity of hypoxic ischemic encephalopathy (HIE) evaluated by magnetic resonance imaging (MRI). The aim of this study was to assess the correlation between cerebral blood flow as assessed by transcranial Doppler sonography and the severity of MRI brain injury in asphyxiated neonates with clinical HIE who received therapeutic hypothermia. MethodsThis retrospective cohort study was conducted in the neonatal intensive care unit at Chang Gung Memorial Hospital between April 2011 and May 2014. All neonates with HIE who received therapeutic hypothermia, transcranial Doppler examinations, and brain MRI were eligible. Brain MRI was performed at 11 days of age (interquartile range: 8.5–15 days) and the severity of MRI brain injuries was evaluated using the MR scoring system proposed by Barkovich et al. Serial transcranial Doppler examinations were performed in pre-hypothermia, hypothermia, and post-hypothermia phases. ResultsTwenty-six neonates met the eligibility criteria for this study. Neonates with an abnormal MCA mean flow velocity (MFV) during the hypothermia phase had a higher risk of brain MRI abnormalities (77.8% vs. 22.2%, p = 0.017) and neonates with abnormal high MFV of MCA had higher MR scores of basal ganglia (p = 0.022). However, there were no statistical differences between abnormal MFV of MCA and brain MRI abnormalities during pre- and post-hypothermia phases. ConclusionsDuring therapeutic hypothermia, mean cerebral blood flow velocity of the MCA was associated with the severity of MRI brain injury in the neonates with clinical HIE.

Neuromonitoring Using Neurosonography and Pupillometry in A Weaning and Early Neurorehabilitation Unit.

Long-term surveillance of intracranial pressure (ICP) in neurological/neurosurgical patients during ventilator weaning and early neurorehabilitation currently relies on clinical observation because neuroimaging is rarely readily available. In this prospective study, multimodal neurosonography and pupillometry are evaluated for follow-up monitoring. Sonographic neuromonitoring was used to noninvasively examine patients' ICP during weaning and early neurorehabilitation. It allowed assessments of third ventricle width, possible midline shift, middle cerebral artery flow velocities, and bilateral optic nerve sheath diameters. Quantitative pupillometry was used to determine pupil size and reactivity. Other neuroimaging findings, spinal tap ICP measurements, and clinical follow-up data served as controls. Seventeen patients-11 suffering from intracranial hemorrhage, four from encephalopathies, and two from ischemic stroke-were examined for ICP changes by using neurosonography and pupillometry during a mean observation period of 21 days. In total, 354 of 980 analyses (36.1%) yielded pathological results. In 15 of 17 patients (88.2%), pathological values were found during follow-up without a clear clinical correlate. In two patients (11.8%), clinically relevant changes in ICP occurred and were identified using neurosonography. Abnormal pupillometry findings displayed a high predictive value for absent clinical improvement. Multimodal neurosonography may be a noninvasive means for long-term ICP assessment, whereas pupillometry may only detect rapid ICP changes during acute neurointensive care. The study also illustrates common pitfalls in neuromonitoring in general, with large numbers of pathological albeit nonsignificant findings. Additional controlled studies should validate the influence of detected subtle changes in ICP on neurological outcome.

Arterial and Venous Cerebral Blood Flow Velocities and Their Correlation in Healthy Volunteers and Traumatic Brain Injury Patients.

Few studies have explored the cerebral venous compartment or the correlation between venous and arterial cerebral blood flows. We aimed to correlate cerebral blood flow velocities in the arterial (middle cerebral artery) and venous (straight sinus) compartments in healthy volunteers and traumatic brain injury (TBI) patients. In addition, we determined the normative range of these parameters. A total of 122 healthy volunteers and 95 severe TBI patients of both sexes were included and stratified into 3 age groups as follows: group 1 (aged, 18 to 44 y); group 2 (aged, 45 to 64 y); group 3 (older than 65 y). Transcranial Doppler systolic cerebral blood flow velocity, diastolic cerebral blood flow velocity, and mean cerebral blood flow velocity (FVs, FVd, FVm, respectively) were measured in the middle cerebral artery and peak cerebral venous blood flow velocity (FVVs) was measured in the straight sinus. The arteriovenous correlation was assessed on the basis of a positive relationship between FVs and FVVs. There was an arteriovenous correlation (FVs vs. FVVs) in healthy volunteers (R=0.39, P<0.0001). We found no arteriovenous correlation in the TBI cohort overall, but FVs and FVVs were correlated in age group 1 (R=0.28, P=0.05) and in males (R=0.29, P=0.01). In healthy volunteers, FVs and FVm were significantly higher in males compared with females; and FVs, FVm, FVd, FVVs all increased across the age spectrum. There were no significant differences in any of these parameters in TBI patients. There are age and sex differences in arterial and venous cerebral blood flow velocities in healthy volunteers. Arteriovenous correlation is present in healthy volunteers but absent in TBI patients.

Dynamic cerebral autoregulation is an independent outcome predictor of acute ischemic stroke after endovascular therapy

BackgroundEndovascular therapy (EVT) is increasingly used to improve cerebral reperfusion after moderate-to-severe acute ischemic stroke (AIS). However, the influence of hemodynamic factors on clinical outcome is still unclear after EVT. Dynamic cerebral autoregulation (dCA) is an important brain reserve mechanism and is impaired after AIS. This study aimed to explore the role of dCA in predicting the outcome of AIS patients after EVT.MethodsAIS patients with severe stenosis/occlusion of unilateral middle cerebral artery (MCA) or internal carotid and treatment with EVT were enrolled to receive dCA examinations at the 24 h, 72 h and 7th day after stroke onset. Healthy volunteers were also recruited as controls. DCA was recorded from spontaneous fluctuations of blood pressure and MCA flow velocity. Transfer function analysis was used to derive dCA parameters, including phase difference (PD) and coherence in the low-frequency range (0.06–0.12 Hz). The clinical outcome was measured using the modified Rankin Scale (mRS) at 90 days after onset. Multivariate logistic regression was performed to reveal the correlation between dCA and clinical outcomes. The receiver operation characteristics (ROC) curve was performed to determine the cut-off point of PD.ResultsA total of 62 AIS patients and 77 healthy controls were included. Compared with controls, dCA were impaired bilaterally till to 7th day after onset in patients, presenting as much lower PD value on the ipsilateral side. During follow-up, we found that PD on the ipsilateral side at 24 h after onset was significantly lower in patients with unfavourable outcome (n = 41) than those with favourable outcome (n = 21), even after adjustment of confounding factors (p = 0.009). ROC curve analysis revealed that PD < 26.93° was an independent predictor of unfavourable-outcome.ConclusionIn AIS patients after EVT, dCA was impaired on both sides over the first 7 days. PD on the ipsilateral side at 24 h after onset is an independent unfavourable-outcome predictor for AIS after EVT.

The effect of age on cerebral blood flow responses during repeated and sustained stand to sit transitions.

IntroductionAging is associated with impaired cerebrovascular blood flow and function, attributed to reduced vasodilatory capacity of the cerebrovascular network. Older adults may also have an impaired relationship between changes in blood pressure and cerebral blood flow; however, previous reports conflict. This study aimed to compare the blood pressure and cerebral blood flow responses to both repeated and sustained stand‐to‐sit transitions in young and older adults, and to assess the relationship with cerebrovascular reactivity.MethodsIn 20 young (age: 24 ± 4 years) and 20 older (age: 71 ± 7 years) adults we compared middle cerebral artery flow velocity (MCAv), end‐tidal partial pressure of carbon dioxide (PETCO2), and blood pressure (mean arterial blood pressure [MAP]) during repeated stand‐to‐sit (10 s standing and 10 s sitting) and sustained stand‐to‐sit (3 min standing followed by 2 min sitting) transitions. Cerebrovascular reactivity to changes in carbon dioxide levels was assessed using a repeated breath‐hold test.ResultsThe % change in MCAv per % change in MAP (%∆MCAv/%∆MAP) was higher in the older adults than in the young adults during repeated stand‐to‐sit transitions. During the sustained protocol the %∆MCAv/%∆MAP response was similar in both age groups. A high %∆MCAv/%∆MAP response during the repeated stand‐to‐sit protocol was associated with low cerebrovascular reactivity to CO2 (r = −.39; p < .01), which was significantly lower in the older adults.ConclusionThese findings suggest that the higher %∆MCAv/%∆MAP during repeated stand–sit transitions was associated with impaired cerebrovascular reactivity. Impairments in endothelial function and vascular stiffness with age may contribute to the altered transient cerebral pressure–flow responses in older adults.