Breath-holding Index Research Articles

Assessment of cerebral hemodynamics in multiple sclerosis patients

BackgroundMultiple sclerosis (MS) is the most common demyelinating disease of the central nervous system. Autonomic dysfunction is present in a wide range of patients (15–80%) that might present with abnormalities in the regulation of the cardiovascular system, sleep disturbance, urinary symptoms, sexual problems, and temperature regulation problem. Although the predominant view is that of an autoimmune inflammatory condition, changes in brain vasculature can occur and contribute to pathophysiology.ObjectivesThe aim of this study was to evaluate cerebral hemodynamics and assess autonomic dysfunction in patients with MS and explore its relationship with disease status.MethodsEighty patients diagnosed with MS according to McDonald criteria 2017 were recruited to this comparative cross-sectional study. All participants underwent assessment of cerebral hemodynamics through transcranial Doppler ultrasonography. Cerebral vasomotor reactivity (CVR) to hypercapnia was measured by the breath-holding index (BHI). They were also assessed for autonomic dysfunction by autonomic questionnaire and blood pressure measurements in both erect and supine positions.ResultsBHI values showed decreased CVR and were significantly lower in SPMS than in RRMS patients. Autonomic functions were more affected in SPMS than RRMS with total score 2.58 ± 1.13 for the RRMS group and 4.05 ± 1.04 for the SPMS group.ConclusionsCerebrovascular hemodynamic insufficiency in MS may be secondary to the downstream effects of neuro-inflammatory cascades.

Blood markers of endothelial dysfunction and their correlation to cerebrovascular reactivity in patients with chronic hepatitis C infection

Although liver cirrhosis and hepatocellular carcinoma are major consequences of hepatitis C (HCV), there has been an increasing number of studies examining extrahepatic manifestations, especially those caused by systemic chronic inflammation and metabolic complications that might predispose HCV patients to atherosclerosis and ischemic cerebrovascular disease (CVD). The aim of our study was to assess E-selectin, VCAM-1, ICAM-1 and VEGF-A serum levels in patients with chronic HCV infection and to correlate them with cerebrovascular reactivity. A blood sample was taken from eighteen patients with chronic hepatitis C infection and from the same number of healthy blood donors in the control group. The aim was to analyse markers of endothelial dysfunction and to correlate them with cerebrovascular reactivity expressed as breath-holding index (BHI) determined using transcranial color Doppler. The obtained results revealed significant differences between the groups in all endothelial markers except for the E selectin. While the ICAM-1 and sVCAM-1 were significantly increased in the hepatitis group, VEGF-A was significantly decreased. A significant reduction of 0.5 (95% CI 0.2, 0.8) in the mean BHI was found in the hepatitis group (mean BHI 0.64) compared to controls (mean BHI 1.10). No significant association between the BHI and any of the endothelial markers was found in the control group, while in the hepatitis group, the scatter plot of ICAM-1 vs BHI suggested that the association might be present. In conclusion, the results of this study confirm an association between a chronic HCV infection and altered cerebrovascular reactivity as well as higher levels of markers of endothelial activation (ICAM-1, VCAM-1) as possible indicators of an increased CVD risk.

Impact of mandibular advancement device therapy on cerebrovascular reactivity in patients with carotid atherosclerosis combined with OSAHS.

Obstructive sleep apnea-hypopnea syndrome (OSAHS) may affect cerebrovascular reactivity (CVR), representing cerebrovascular endothelial function, through complex cerebral functional changes. This study aimed to evaluate the change of CVR after 1-month and 6-month mandibular advancement device (MAD) treatment of patients withcarotid atherosclerosis (CAS) combined with OSAHS. Patients with carotid atherosclerosis combined withOSAHS who voluntarily accepted Silensor-IL MAD therapy were prospectively enrolled. All patients underwent polysomnographic (PSG) examinations and CVR evaluation by breath-holding test using transcranial Doppler ultrasound at baseline (T0), 1month (T1), and 6months (T2) of MAD treatment. Of 46 patients(mean age 54.4± 12.4 years, mean body mass index [BMI] 27.5± 4.5 kg/m2), 41 patients (responsive group) responded to the 1-month and 6-month treatment of MAD, an effective treatment rate of 89%. The remaining 5 patients (non-responsive group) were younger (47.4 ± 13.5years) and had ahigher BMI (35.8 ± 1.8kg/m2). The responsive group had an improvement of apnea-hypopnea index (AHI) (events/h) from 33.0 ± 25.0 (T0) to 12.4 ± 10.4 (T1) and 8.7 ± 8.8 (T2), P < 0.001; minimum arterial oxygen saturation (minSpO2) (%) increasedfrom 79.8 ± 9.1 (T0) to 81.8 ± 9.4 (T1) and 85.2 ± 5.4 (T2), P < 0.01; longest apnea (LA) (s) decreasedfrom 46.5 ± 23.1 (T0) to 33.3 ± 22.7 (T1) and 29.4 ± 18.5 (T2), P < 0.001; T90 (%) decreasedfrom 10.3 ± 14.9 (T0) to 6.1 ± 11.8 (T1) and 3.3 ± 7.5 (T2), P < 0.05. Sleep architecture of these patients also improved significantly. The responsive group had a significant increase in left, right, and mean breath-holding index (BHI): left BHI(/s) from 0.52 ± 0.42 (T0) to 0.94 ± 0.56 (T1) and 1.04 ± 0.64 (T2), P < 0.01; right BHI(/s) from 0.60 ± 0.38 (T0) to 1.01 ± 0.58 (T1) and 1.11 ± 0.60 (T2), P < 0.01; mean BHI(/s) from 0.56 ± 0.38 (T0) to 0.97 ± 0.55 (T1) and 1.07 ± 0.59 (T2), P < 0.01), suggesting improved CVR. Effective MAD therapy is beneficial for restoring cerebrovascular endothelial function in patients with CAS and OSAHS in a short period (1month and 6months). Clinical trial registration number: NCT03665818. September 11, 2018.

Repetitive Head Impact Exposure and Cerebrovascular Function in Adolescent Athletes.

The purpose of this study was to determine how subconcussive head impact exposure in high school collision sport student-athletes influenced cerebrovascular function. Transcranial Doppler was used to assess pre- to post-season changes in: (1) resting middle (MCA) and posterior cerebral arteries (PCA), (2) cerebrovascular reactivity (CVR) via breath-holding index (BHI), vasomotor reactivity response (VMRr) and overall MCA response curve, and (3) neurovascular coupling (NVC) via NVC response magnitude and overall PCA response curve. Fifty-three high school-aged athletes (age = 15.8 ± 1.2years, height = 175.8 ± 8.1cm, mass = 69.4 ± 13.5kg) were recruited into two groups (collision vs. non-collision sport). All participants completed a pre-season cerebrovascular function assessment. Following a 4- to 5-month window (118.6 ± 12.2 days), 48 athletes from the original sample (age = 16.0 ± 1.2 years, height = 175.5 ± 8.1 cm, mass = 68.6 ± 4.0 kg) repeated the cerebrovascular assessment. There were no group differences in any cerebrovascular measures at pre-season testing (p > 0.05). At post-season testing, collision sport athletes demonstrated greater positive change in BHI (t44 = -2.21, p = 0.03) while non-collision sport athletes demonstrated greater negative change in the NVC response magnitude to the reading task (t44 = 1.98, p = 0.048), and lower overall PCA response curve to the reading task (F1,2710 = 101.54, p < 0.001). All other pre- to post-season change values were non-significant (p > 0.05). Our data indicate that single-season changes in cerebrovascular outcomes may differ between collision and non-collision sport athletes. Although the clinical interpretation is still unclear, our study demonstrates that CVR and NVC assessments may be sensitive to the dynamic cerebrovascular changes occurring in adolescent athletes. Future research should continue to assess these outcomes following both subconcussive head impact exposure and throughout the recovery trajectory following concussion.

Assessment of Cerebral Vasomotor Reactivity in Patients With Primary Open-angle Glaucoma and Ocular Hypertension Using the Breath-Holding Index.

Patients with ocular hypertension (OHT) do not show impaired cerebral vasodilation responses to hypercapnia but patients with primary open-angle glaucoma (POAG) do. Impaired vasoreactivity in patients with POAG may have neuronal or vascular origins and increase stroke risk. To investigate changes in cerebral blood flow and cerebral vasomotor reactivity using the breath-holding index in patients with POAG and OHT, to examine whether these parameters contribute to the risk of ischemic stroke. Thirty patients with POAG, 30 patients with OHT, and 30 age- and sex-matched healthy control subjects were included in this university hospital-based, cross-sectional, and observational study. Eyes with a greater degree of visual field loss and/or more severe optic disc damage were selected for the study in patients with POAG, whereas in patients with OHT and controls, the study eye was chosen randomly. The mean blood flow velocity and breath-holding index were measured in the middle cerebral artery ipsilaterally in patient and control groups, by using transcranial Doppler ultrasonography. The mean blood flow velocity and breath-holding indexes were significantly lower in patients with POAG than in the control group (all P<0.05). In the OHT group, the mean blood flow velocity and breath-holding indexes were not different from those in the control group. Patients with POAG have impaired vasodilation response to hypercapnia. Presumably, the neuronal changes and deterioration of the endothelium-mediated vasodilatation in patients with glaucoma may disrupt the regulation of arteries and potentially present functional insufficiency on vasoreactivity. Moreover, impaired cerebral vascular regulation may contribute to the increased risk of stroke in patients with POAG.

Which repetitive transcranial magnetic stimulation modality affects vasomotor reactivity in healthy subjects and how long does it last?

Objectives The aim of our study was to evaluate the effects of low and high-frequency repetitive transcranial magnetic stimulation (rTMS) on hypoxia-induced changes in bilateral cerebrovascular reserve up to 24 h in the same individuals. Methods Right-handed ten healthy male individuals participated in the study. All participants had neither drug therapy nor a concomitant disease and none of them had a variation in the circle of Willis, intracranial stenosis, arteriovenous malformation, or aneurysm which may have an impact on transcranial doppler ultrasound (TCD) examination and transcranial magnetic stimulation (TMS) recording. Results There was a statistically significant difference in the breath‐holding index (BHI) between before and after 0, 15, 30 min after 1 Hz repetitive stimulation (p < 0.05). When applying 5 Hz repetitive stimulation there was no difference before and after BHI values (p > 0.05). There were no differences in bilateral, ipsilateral, or contralateral middle cerebral artery (MCA) mean cerebral blood flow velocity (CBFV) after low or high-frequency rTMS application (p > 0.05). Conclusion The main result of the study was that low-frequency rTMS reduced vasomotor reactivity (VMR) for the very first 30 min and then this effect disappears. And the high-frequency rTMS did not affect VMR at all. Significance The effect of rTMS on VMR may continue up to 30 min but then return to the baseline and can be used safely.

Cerebral Hemodynamic Response To Menstrual Cycle In Migraine

Objective: Menstrually related migraine (MRM) occurs in relation to menstrual cycles. We investigated the cerebral hemodynamic response to the menstrual cycle in nonmenstrually related migraines (nMRM), MRM and healthy controls.&#x0D; Methods: 22 nMRM, 20 MRM patients in an attack-free interval and 20 healthy volunteers were included in our study. TCD recordings were made during the follicular and luteal phases of the hormonal cycle and mean flow velocity values of middle and posterior cerebral arteries were studied. Cerebral vasomotor reactivity (CVR) was evaluated by breath holding index (BHI) and visually evoked blood flow (VEBF) changes in both phases of the same menstrual cycle.&#x0D; Results: Mean flow veloticities and hormone levels were not different between groups. Right BHI and bilateral VEBF values were significantly lower in both of the migraine groups. The physiological elevation of CVR in the luteal phase was detected in the control and nMRM groups, but not in the MRM group.&#x0D; Conclusion: The cerebral hemaodynamics were affected in both MRM and nMRM. Additionally the physiological CVR to menstrual cycle was impaired in MRM. The impairment in cerebral hemodynamic response to the menstrual cycle in MRM needs further research to discover the underlying pathophysiology.

A Breath-Holding Index Applied to the Internal Carotid Artery Siphon in Transcranial Doppler Studies.

The breath-holding index (BHI) is a useful method to assess cerebrovascular reactivity. It is calculated based on the mean flow velocities of the middle cerebral artery (MCA) using transcranial Doppler (BHIMCA ). Therefore, it is not feasible in patients with poor temporal windows. This study tested the feasibility of a BHI using the internal carotid artery (ICA) siphon flow velocity (BHIICA ). Twenty-four patients (aged 38-79 years) with unilateral or bilateral stenosis of the cervical ICAs were prospectively recruited. The 48 examined bilateral ICAs were divided into three groups according to the stenosis degree: <50%, 50-99%, and occlusion. We investigated the reproducibility of both BHI methods (BHIMCA and BHIICA ), the correlation between the two BHI methods, and the tendency for the BHIs to decrease with increasing degree of cervical ICA stenosis. For the BHIMCA , we found a good reproducibility (intraclass correlation coefficient, rI > .9) and a significantly decreased BHI with increasing stenosis of the ICA (P = .001). For the BHIICA , good reproducibility was demonstrated (rI > or ≒ .9), but there was no significant decrease in the BHI related to the increasing degree of ICA stenosis (P = .952). Furthermore, the correlation between the two BHI methods was not robust (kappa coefficient, right .259; left .619). Our study suggests that the BHIICA is not a feasible alternative method to the BHIMCA.

Transcranial Doppler Evaluation of the Cerebral Vasculature in Women Patients who Have Migraine with Aura.

Previous studies suggest that increased cerebrovascular reactivity might be a feature of patients who have migraine with aura (MwA). The correlation between the clinical presentation of migraine with aura and transcranial Doppler parameters remains unclear. The main aim of this study was to explore cerebral blood flow, vascular resistance, and cerebrovascular reactivity in women MwA. Also, the relationships between hemodynamic conditions and aura characteristics are examined. Cross-sectional study. Headache Center, Neurology Clinic, Clinical Center of Serbia. Fifty-four women MwA and 49 healthy controls (HCs). Transcranial Doppler sonography examination was used to determine blood flow mean velocity (MV) and pulsatility index (PI), as well as breath-holding index (BHI), in 15 arterial segments comprising the circle of Willis. A total of 54 women MwA and 49 HCs were studied. The PIs of all segments of the left and right middle cerebral arteries and the left and right anterior cerebral arteries were significantly higher in MwA with regards to HCs. Also, both the left and right BHIs were significantly higher in MwA than HCs. In addition, MVs of the right vertebral artery and the first segment of the basilar artery were significantly lower in MwA than HCs. Longer duration of migraine aura showed a weak negative correlation with the PI of the left posterior cerebral artery. Our findings suggest increased vessel pulsatility, abnormal cerebrovascular reactivity, and decreased cerebral blood flow velocity in several arterial segments of the Willis circle in women MwA.

Carotid occlusion: Impact of cerebral hemodynamic impairment on cognitive performances.

The aim of this study was to investigate whether the presence of carotid artery occlusion (CO) may be associated with different cognitive performances in relation to the side of the occlusion and its hemodynamic consequences. During a 12-month period, 61 asymptomatic patients, 32 with right and 29 with left CO, were enrolled. Each patient underwent an assessment of cerebrovascular reactivity (CVR) to hypercapnia with transcranial Doppler (TCD) ultrasonography using the breath-holding index (BHI). Neuropsychological assessment evaluating performances of the hemisphere ipsilateral to CO were administered at entry (T0 ) and then repeated after 2 years (T1 ). Scores obtained at colored progressive matrices (CPM) and Rey Complex Figure Copy Test were significantly lower at T0 in patients with reduced BHI values ipsilateral to CO. Multivariate models showed that reduced BHI values were also associated to a significant decrease from T0 to T1 in scores obtained for CPM and Categorical Verbal Fluency tests, respectively, in patients with right (P = 0.002) or left CO (P = 0.004). These findings suggest that hemodynamic alterations could be involved in the reduction in cognitive function regulated by the hemisphere ipsilateral to CO. The assessment of CVR with TCD ultrasonography may be a reliable approach for the individuation of asymptomatic patients with CO at increased risk of cognitive deterioration.

Incomplete circle of Willis and cerebrovascular reactivity in asymptomatic patients before and after carotid endarterectomy

Introduction/Objective. Circle of Willis (CoW) provides the most significant collateral flow in the presence of significant stenosis or occlusion of internal carotid artery. In terms of collateral flow ?incomplete? type and ?complete? type of CoW can be recognized. Patients with carotid artery disease with incomplete CoW have lower cerebrovascular reactivity and higher risk for stroke. Cerebrovascular reactivity refers to the residual capacity of dilatation of cerebral blood vessels in the condition of insufficient blood flow. In this study we analyzed changes in cerebrovascular reactivity after carotid endarterectomy in asymptomatic patients with respect to complete and incomplete CoW morphology. Methods. In this study in 97 patients with asymptomatic carotid artery disease we measured cerebrovascular reactivity before and after carotid endarterectomy by using method of ?apnea test? and ?breathholding index? (BHI). Patients were divided into two following groups: patients with ?complete? CoW and ?incomplete? CoW based on non-contrast magnetic resonance angio performed previously to the operation. Descriptive statistics, univariate analysis, and ANOVA for comparison of BHI values between groups were used. Results. The results showed significant increase in cerebrovascular reactivity at the side of stenosis in both groups of patients with complete CoW (BHI value increased from 0.897 to 1.090; F (1.65) = 30.788, p &lt; 0.0005, parc. ?2 = 0.321) and incomplete CoW (BHI value increased from 0.690 to 1.010; F (1.27) = 62.318, p &lt; 0.0005, parc. ?2 = 0.698) and the more significant increase in the group of incomplete CoW compared to the group with complete CoW (F (1.92) = 4.557, p = 0.035, parc. ?2 = 0.047) Conclusion. In most asymptomatic patients, cerebrovascular reactivity restores to normal following carotid endarterectomy. Parameters of cerebrovascular reactivity are lower in patients with incomplete CoW and the increase after carotid endarterectomy is more significant in such patients.

Erenumab does not alter cerebral hemodynamics and endothelial function in migraine without aura.

To assess whether erenumab influences cerebral vasomotor reactivity and flow-mediated dilation in migraine patients. Consecutive migraineurs prescribed erenumab at our Headache Centre and age and sex-matching controls were invited to participate in this observational longitudinal study. Patients were evaluated for cerebral vasomotor reactivity to hypercapnia (breath-holding index) in middle and posterior cerebral arteries and for brachial corrected flow mediated dilation at baseline (T0), after 2 weeks from the first erenumab injection (T2) and after 2 weeks from the fourth Erenumab injection (T18). Patients displaying a reduction of at least 50% in monthly migraine days after completing the fourth month of therapy were classified as responders. Sixty patients and 25 controls agreed to participate. Middle and posterior cerebral artery mean flow velocities, breath-holding index and flow-mediated dilation did not differ at T0 and from T0 to T2 in patients and controls. In patients, we neither observed a variation of the explored variables from T0 to T18 nor an interaction between evaluation times (T0-T2 or T0-T18) and chronic condition at T0, responder state or erenumab fourth dose. Our findings demonstrate that erenumab preserves cerebral vasomotor reactivity and flow-mediated dilation in migraineurs without aura.

Transcranial Doppler as a Predictor of Ischemic Events in Vertebral Artery Dissection.

Transcranial Doppler (TCD) helps identify patients with carotid dissections at risk of ischemic events (IEs). There is paucity of data identifying independent predictors of IE in vertebral arterial dissection (VAD). We sought to investigate the clinical and ultrasound predictors of IE. Patients with VAD admitted between June 2017 and February 2020 were evaluated clinically and with TCD; sonographic curves, microembolic signals (MES), and the breath-holding index (BHI) test were applied. Covariates found on univariate screen (P < .25) were included in a multivariable linear regression to identify independent predictors of IEs. Of 88 patients with 100 VAD, 75 (85.2%) were females with a mean age 37.9 ± 7.5 years. All patients received antiplatelet treatment. TCD monitoring lasted an average of 21 ± 2.1 minutes. TCD was abnormal in 23 cases (26.1%); 21 patients had abnormal sonographic curves in the vertebral/basilar arteries, while in 4 cases, MES were present and in 5 (4.5%), BHI was abnormal. None of the patients with a normal TCD had an IE. Six strokes occurred during follow up. On univariate analysis, male sex, diabetes, dyslipidemia, a previous myocardial infarct, migraine, time of consultation to the ER, bilateral VAD, MES, BHI abnormalities, post stenotic flow in the basilar artery (PFB), and basilar/vertebral velocities were significantly associated with the risk of IEs. In the multivariate analysis, only the presence of PFB was a significant predictor of IE (OR: 68.6, 95% CI 5-937, <.001). TCD in VAD predicts patients at high risk of IE.

Cerebral vasoreactivity, a surrogate marker of cerebrovascular disease, is not impaired in subjects with lifetime, untreated, congenital isolated GH deficiency.

Cerebrovascular disease (CeVD) is a major cause of death and disability. The role of the GH/IGF-I axis on CeVD risk is controversial. Patients with GH deficiency (GHD) in the setting of hypopituitarism often exhibit CeVD predisposing factors, like low nitric oxide generation, endothelial dysfunction, increased visceral fat mass, increased levels of LDL cholesterol, and increased intima-media thickness, a surrogate marker of atherosclerosis. However, several confounders such as the primary hypothalamic-pituitary lesion, hormonal replacement therapies, consequences of surgery and radiotherapy, may influence this relationship. Therefore, we decided to assess cerebral vasoreactivity, a surrogate marker of CeVD, in adult subjects with untreated isolated GHD (IGHD) due to the same homozygous null mutation in the GHRH receptor gene. A cross-sectional study was carried out in 25 adult IGHD subjects and 25 age- and gender-matched controls. Interview, physical examination, laboratory data, intima-media thickness measurement, and transcranial Doppler were performed. The intracranial hemodynamics (mean flow velocity, pulsatility and resistance indexes) were measured, and the response to the vasodilatory stimulus by breath-holding maneuver (breath-holding index) was calculated. IGHD and control groups were similar in Framingham risk score and intima-media thickness. Similarly, there was no difference in mean flow velocity, pulsatility, resistance, and breath-holding index. Lifetime, untreated IGHD does not cause impaired cerebral vasoreactivity.

Mechanisms Involved in Lacunar Infarction and Their Role in Early Neurological Deterioration

Background The mechanisms of lacunar infarction are still unclear and may be heterogenous. We aimed to investigate the presence of parent artery atheroma, cerebral vasodilatory function, and blood-brain barrier (BBB) breakdown and their role in the development of early neurological deterioration (END) in patients with acute lacunar infarction. Methods Patients with acute lacunar infarction prospectively underwent transcranial Doppler breath-holding test, contrast-enhanced f luid-attenuated inversion recovery magnetic resonance imaging, and magnetic resonance angiography with/without high-resolution vessel wall imaging to determine the cerebral vasomotor reactivity to carbon dioxide (CO2-CVR) of the symptomatic artery, BBB breakdown, and the presence of branch atheromatous disease in the parent artery, respectively, before the development of END. We compared the presence of each mechanism between patients who developed END and those without END and the role in predicting END between mechanisms. Results Among the 41 patients included, three (7.3%) experienced END. Reduced CO2-CVR, branch atheromatous disease, and widespread BBB breakdown were observed in eight (19.5%), 10 (24.4%), and 11 patients (26.8%), respectively. Among these factors, CO2-CVR was significantly lower in patients with END than in those without END (breath-holding index, 0.64 [interquartile range, 0.47–0.70] vs. 1.05 [0.81–1.33], p=0.028) and best predicted END (area under the curve=0.889; 95% confidence interval, 0.779–0.999; p<0.001). Conclusion Cerebral vasodilatory dysfunction is associated with END in patients with acute lacunar infarction. Our study suggests that CO2-CVR testing has a role in the risk stratification of lacunar infarction, and a confirmatory study is required in the future. Key words: Stroke; Lacunar infarction; Cerebral small vessel diseases; Transcranial Doppler ultrasonography; Blood-brain barrier

Magnetic resonance markers of bilateral neuronal metabolic dysfunction in patients with unilateral internal carotid artery occlusion.

To evaluate cerebral hemodynamic, metabolic and anatomic changes occurring in patients with unilateral occlusion of the internal carotid artery (ICA). Twenty-two patients with unilateral occlusion of ICA and twenty age and sex matched healthy subjects were included in the study. Single voxel proton magnetic resonance spectroscopy (1H-MRS) of the centrum semiovale, semi-automated hippocampal volumetry in T1-weighted scans and transcranial Doppler examination (TCD) with calculation of Breath Holding Index (BHI) were performed in both groups. Metabolic, anatomic, and hemodynamic features were compared between the two groups. The N-acetylaspartate (NAA)/choline (Cho) ratio was significantly lower in both hemispheres of enrolled patients compared to controls (p = 0.005 for the side with occlusion, p = 0.04 for the side without occlusion). The hippocampus volume was significantly reduced bilaterally in patients compared to healthy subjects (p = 0.049). A statistically significant difference in BHI values was observed between the side with occlusion and without occlusion (p = 0.037) of the patients, as well as between BHI values of the side with occlusion and healthy volunteers (p = 0.014). Patients with unilateral ICA occlusion have reduced NAA/Cho ratio in the white matter of both hemispheres and have bilateral atrophy of hippocampus. The alteration of hemodynamics alone cannot explain these changes.

Cerebral hemodynamics in patients with multiple sclerosis

Background and PurposeMultiple sclerosis (MS) is a demyelinating disease of the central nervous system. Although the currently predominant view is that of an autoimmune inflammatory condition, changes in brain vasculature can occur and contribute to pathophysiology. The aim of this study was to evaluate cerebral hemodynamics in patients with MS and explore its relationship with disease status. MethodsPatients with MS and age- and sex- matched healthy controls were recruited. All participants underwent assessment of cerebral hemodynamics through transcranial Doppler ultrasonography. Cerebral vasomotor reactivity (CVR) to hypercapnia was measured by the breath-holding index (BHI). ResultsA total of 80 patients with MS and 80 healthy controls were recruited. BHI values obtained in healthy controls, relapsing-remitting (RR)-MS and secondary progressive (SP)-MS patients were 1.15±0.11, 0.87±0.18 and 0.51±0.20, respectively (p<0.001). Group-wise, patients showed decreased CVR in comparison to controls and BHI values were significantly lower in SP-MS than in RR-MS patients. At linear regression analysis, the disease form was significantly associated with cerebral hemodynamics being the SP phenotype an independent predictor of lower BHI values [β=-0.36, 95% confidence interval (CI): -0.44 to -0.27, p<0.001; adjusted β=-0.37, 95% CI: -0.50 to -0.23, p<0.001). ConclusionsCerebrovascular hemodynamic insufficiency in MS may be secondary to the downstream effects of neuro-inflammatory cascades.

Cerebral vasomotor reactivity in migraine: effect of patent foramen ovale and aerogenic microembolism

ABSTRACT Objective The first data on the effect of presence of patent foramen ovale (PFO) with high-volume right-to-left shunt (RLS) on cerebral vasomotor reactivity (CVMR) in migraineurs are herein presented. In addition, the immediate effect of air microbubbles on CVMR has been determined. Methods Breath-holding index (BHI) and percent velocity decrease during hyperventilation (HPV) tests were performed before and after agitated saline injections in bilateral middle and posterior cerebral arteries (MCA and PCA) in 38 migraineurs (19 with aura) and 18 control subjects. Results Presence of PFO correlated with a significant decrease of MCA BHI (1.43 ± 0.39 vs 1.04 ± 0.67, p = 0.032) and marginal reduction of PCA BHI (1.25 ± 0.46 vs. 1.01 ± 0.39, p = 0.090) in migraineurs. After agitated saline injection, PCA BHI significantly decreased from 1.03 to 0.78 (p = 0.007) in patients with PFO, from 1.15 to 0.91 (p = 0.014) in those without PFO, and from 1.01 to 0.76 (p = 0.023) in subjects with migraine and PFO. No significant MCA BHI difference was noted soon after bubble injection. Conclusions The presence of high grade RLS is associated with reduced vasodilatory CVMR in migraineurs. Further decrease of CVMR of PCA upon aerogenic microemboli passage may support the mechanism of ‘facilitation with subclinical cerebral ischemia caused by microembolism’, hypothesis explaining the onset of migraine. Abbreviations BHI: Breath-holding index; BHT: Breath Holding Test; CVMR: Cerebral vasomotor reactivity; EDV: End-diastolic velocity; HIT-6: Headache Impact Test; HPV: Hyperventilation; MCA: Middle cerebral artery; MIDAS: migraine disability Assessment score; PCA: Posterior cerebral artery; PFO: Patent foramen ovale; PI: Pulsatility index; PSV: Peak systolic velocity; RLS: Right-to-left shunt; TCD: Transcranial Doppler; Vmean: Mean velocity.

Cerebrovascular reactivity in young and old patients with obstructive sleep apnea

ObjectiveImpaired cerebrovascular reactivity (CVR) in patients with obstructive sleep apnea syndrome (OSAS) increases the risk of ischemic stroke. CVR also decreases with age in normal individuals. However, it is unclear whether OSAS affects CVR differently in young and old patients. The aim of this study was to compare CVR in old and young patients with OSAS via transcranial Doppler (TCD) measurements of changes in cerebral blood flow velocity in the middle cerebral artery (MCAmv) during breath holding and hyperventilation. MethodsA total of 20 old patients (≥65 y) and 40 young patients (<65 y) with similar distributions of sex and OSAS severity were recruited for this study. The breath-holding index (BHI) and the hyperventilation index (HVI) were calculated to measure CVR. ResultsNo differences were found in MCAmv at baseline, apnea or hyperventilation between the two groups with different OSAS severities. However, reduced BHI (P < 0.01) and HVI (P < 0.01) were found in the young group with increasing severity of OSAS. Notably, the decline in BHI and HVI associated with OSAS severity was steeper in young patients than in old patients (P < 0.01). ConclusionsThese findings suggest that CVR in young patients is more impacted by OSAS severity than that in old patients, suggesting the existence of age-related cerebrovascular susceptibility to OSAS.

Cerebrovascular Reactivity in Special Operations Forces Combat Soldiers.

The purpose of this study was to investigate how concussion history affects cerebrovascular reactivity (CVR) in Special Operations Forces (SOF) combat soldiers. We studied 104 SOF soldiers [age = 33.5 ± 4.3years; height = 179.7 ± 6.3cm; 59 (56.7%) with self-reported concussion history]. We employed transcranial Doppler (TCD) ultrasound to measure middle cerebral artery (MCA)velocity. Baseline TCD data were collected for 2min. Changes in MCAvelocity were measured in response to five breath-holding trials and five hyperventilation trials. Cerebrovascular reactivity was quantified by the breath-holding index (BHI), vasomotor reactivity reserve (VMRr), and percent change in overall response curves. Independent t tests were employed to assess group differences in BHI, and VMRr values. We employed mixed effects models with quadratic mean structures to assess group differences in percent change MCAvelocity response curves. There were no significant group differences in BHI (t102 = 0.04, p = 0.97) or VMRr (t102 = -0.33, p = 0.75). There were no group differences in relative MCAvelocity response curves during the breath-holding task (F1,5092 = 0.19, p = 0.66) or during the hyperventilation task (F1,5092 = 0.41, p = 0.52) between SOF soldiers with and without a self-reported concussion history. If CVR deficits exist immediately post-concussion, our study suggests that these deficits recover over time in this population. While long-term neurophysiological effects of blast-related injury are currently unknown, assessing CVR response may provide further insight into cerebrovascular function and overall physiological health following blast exposure.