Reversible Cerebral Vasoconstriction Syndrome and Female Sex: A Narrative Review.

Reversible cerebral vasoconstriction syndrome (RCVS) refers to segmental, multifocal constriction of intracranial arteries along with acute headache and resolves within weeks. It occurs more commonly in women, and 1 well-known manifestation of RCVS is postpartum angiopathy. Furthermore, the female sex is included in scoring systems designed to assist with diagnosing RCVS. Nonetheless, the literature is mixed regarding the true role of female and pregnancy-related factors in the pathophysiology of RCVS, and it is similarly unclear whether management of this disorder differs by sex. Given the association of RCVS with female sex and the importance of highlighting, recognizing, and managing stroke etiologies in women, herein, the author reviews what is currently known and unknown about the topic of RCVS in women.

Dynamic changes in glymphatic function in reversible cerebral vasoconstriction syndrome.

BACKGROUND: The pathophysiology of the reversible cerebral vasoconstriction syndrome (RCVS) remains enigmatic and the role of glymphatics in RCVS pathophysiology has not been evaluated. We aimed to investigate RCVS glymphatic dynamics and its clinical correlates. METHODS: We prospectively evaluated the glymphatic function in RCVS patients, with RCVS subjects and healthy controls (HCs) recruited between August 2020 and November 2023, by calculating diffusion-tensor imaging along the perivascular space (DTI-ALPS) index under a 3-T MRI. Clinical and vascular (transcranial color-coded duplex sonography) investigations were conducted in RCVS subjects. RCVS participants were separated into acute (≤ 30 days) and remission (≥ 90 days) groups by disease onset to MRI interval. The time-trend, acute stage and longitudinal analyses of the DTI-ALPS index were conducted. Correlations between DTI-ALPS index and vascular and clinical parameters were performed. Bonferroni correction was applied to vascular investigations (q = 0.05/11). RESULTS: A total of 138 RCVS patients (mean age, 46.8 years ± 11.8; 128 women) and 42 HCs (mean age, 46.0 years ± 4.5; 35 women) were evaluated. Acute RCVS demonstrated lower DTI-ALPS index than HCs (p < 0.001) and remission RCVS (p < 0.001). A continuously increasing DTI-ALPS trend after disease onset was demonstrated. The DTI-ALPS was lower when the internal carotid arteries resistance index and six-item Headache Impact test scores were higher. In contrast, during 50-100 days after disease onset, the DTI-ALPS index was higher when the middle cerebral artery flow velocity was higher. CONCLUSIONS: Glymphatic function in patients with RCVS exhibited a unique dynamic evolution that was temporally coupled to different vascular indices and headache-related disabilities along the disease course. These findings may provide novel insights into the complex interactions between glymphatic transport, vasomotor control and pain modulation.

Assessing the pulmonary vascular responsiveness to oxygen with proton MRI.

Ventilation-perfusion matching occurs passively and is also actively regulated through hypoxic pulmonary vasoconstriction (HPV). The extent of HPV activity in humans, particularly normal subjects, is uncertain. Current evaluation of HPV assesses changes in ventilation-perfusion relationships/pulmonary vascular resistance with hypoxia and is invasive, or unsuitable for patients because of safety concerns. We used a noninvasive imaging-based approach to quantify the pulmonary vascular response to oxygen as a metric of HPV by measuring perfusion changes between breathing 21% and 30%O2 using arterial spin labeling (ASL) MRI. We hypothesized that the differences between 21% and 30%O2 images reflecting HPV release would be 1) significantly greater than the differences without [Formula: see text] changes (e.g., 21-21% and 30-30%O2) and 2) negatively associated with ventilation-perfusion mismatch. Perfusion was quantified in the right lung in normoxia (baseline), after 15 min of 30% O2 breathing (hyperoxia) and 15 min normoxic recovery (recovery) in healthy subjects (7 M, 7 F; age = 41.4 ± 19.6 yr). Normalized, smoothed, and registered pairs of perfusion images were subtracted and the mean square difference (MSD) was calculated. Separately, regional alveolar ventilation and perfusion were quantified from specific ventilation, proton density, and ASL imaging; the spatial variance of ventilation-perfusion (σ2V̇a/Q̇) distributions was calculated. The O2-responsive MSD was reproducible (R2 = 0.94, P < 0.0001) and greater (0.16 ± 0.06, P < 0.0001) than that from subtracted images collected under the same [Formula: see text] (baseline = 0.09 ± 0.04, hyperoxia = 0.08 ± 0.04, recovery = 0.08 ± 0.03), which were not different from one another (P = 0.2). The O2-responsive MSD was correlated with σ2V̇a/Q̇ (R2 = 0.47, P = 0.007). These data suggest that active HPV optimizes ventilation-perfusion matching in normal subjects. This noninvasive approach could be applied to patients with different disease phenotypes to assess HPV and ventilation-perfusion mismatch.NEW & NOTEWORTHY We developed a new proton MRI method to noninvasively quantify the pulmonary vascular response to oxygen. Using a hyperoxic stimulus to release HPV, we quantified the resulting redistribution of perfusion. The differences between normoxic and hyperoxic images were greater than those between images without [Formula: see text] changes and negatively correlated with ventilation-perfusion mismatch. This suggests that active HPV optimizes ventilation-perfusion matching in normal subjects. This approach is suitable for assessing patients with different disease phenotypes.

Reversible cerebral vasoconstriction syndrome in Guillain-Barre syndrome: a case report and literature review.

BACKGROUND: Reversible cerebral vasoconstriction syndrome (RCVS) is characterized by transient constriction of cerebral arteries, leading to severe headache and potential complications. The association between RCVS and Guillain-Barre syndrome (GBS) is rare and poorly understood and warrants further investigation. METHODS: A detailed case of RCVS in a patient with GBS was presented, followed by a comprehensive literature review. PubMed, Embase, and Google Scholar were searched for relevant cases and studies. RESULTS: The case involved a 62-year-old woman with GBS who developed RCVS. The literature review identified three additional reported cases. RCVS in GBS primarily affected middle-aged women and presented with a variety of neurological symptoms. Neuroimaging showed reversible vasoconstriction in the cerebral arteries, along with other complications such as posterior reversible encephalopathy syndrome, subarachnoid hemorrhage, and infarcts. While the treatment for GBS consisted mainly of intravenous immunoglobulin, specific treatments for RCVS remain unclear. CONCLUSIONS: The coexistence of RCVS and GBS is a rare occurrence. RCVS in GBS may result from the disruption of cerebral vascular tone regulation, possibly influenced by GBS-related dysautonomia and consequent high blood pressure. Recognizing RCVS in GBS patients is critical for appropriate management.

A new model for evaluating pressure-induced vascular tone in small cerebral arteries.

The capacity of small cerebral arteries (SCAs) to adapt to pressure fluctuations has a fundamental physiological role and appears to be relevant in different pathological conditions. Here, we present a new computational model for quantifying the link, and its contributors, between luminal pressure and vascular tone generation in SCAs. This is assembled by combining a chemical sub-model, representing pressure-induced smooth muscle cell (SMC) signalling, with a mechanical sub-model for the tone generation and its transduction at tissue level. The devised model can accurately reproduce the impact of luminal pressure on different cytoplasmic components involved in myogenic signalling, both in the control case and when combined with some specific pharmacological interventions. Furthermore, the model is also able to capture and predict experimentally recorded pressure-outer diameter relationships obtained for vessels under control conditions, both in a Ca 2 + -free bath and under drug inhibition. The modularity of the proposed framework allows the integration of new components for the study of a broad range of processes involved in the vascular function.

Hybrid Photoacoustic Ultrasound Imaging System for Cold-Induced Vasoconstriction and Vasodilation Monitoring.

Lewis hunting reaction refers to the alternating cold-induced vasoconstriction and dilation in extremities, whose underlying mechanism is complex. While numerous studies reported this intriguing phenomenon by measuring cutaneous temperature fluctuation under cold exposure, few of them tracked peripheral vascular responses in real-time, lacking a non-invasive and quantitative imaging tool. To better monitor hunting reaction and diagnose relevant diseases, we developed a hybrid photoacoustic ultrasound (PAUS) tomography system to monitor finger vessels' dynamic response to cold, together with simultaneous temperature measurement. We also came out a standard workflow for image analysis with self-defined indices. In the small cohort observational study, vascular changes in the first cycle of hunting reaction were successfully captured by the image series and quantified. Time difference between vasodilation and temperature recovery was noticed and reported for the first time, thanks to the unique capability of the PAUS imaging system in real-time and continuous vascular monitoring. The developed imaging system and indices enabled more objective and quantitative monitoring of peripheral vascular activities, indicating its great potential in numerous clinical applications.

Scoping Review: Integration of the Major Mechanisms Underlying the Regulation of Arteriolar Tone.

BACKGROUND: Cardiovascular diseases remain the leading cause of morbidity and mortality worldwide. Arteriolar tone regulation plays a critical role in maintaining appropriate organ blood flow and perfusion distribution, which is vital for both vascular and overall health. SUMMARY: This scoping review aimed to explore the interplay between five major regulators of arteriolar tone: metabolism (adenosine), adrenergic control (norepinephrine), myogenic activation (intravascular pressure), perivascular oxygen tension, and intraluminal flow rates. Specifically, the aim was to address how arteriolar reactivity changes in the presence of other vasoactive stimuli and by what mechanisms. The review focused on animal studies that investigated the impact of combining two or more of these stimuli on arteriolar diameter. Overall, 848 articles were identified through MEDLINE and EMBASE database searches, and 38 studies were included in the final review. KEY MESSAGES: The results indicate that arteriolar reactivity is influenced by multiple factors, including competitive processes, structural limitations, and indirect interactions among stimuli. Additionally, the review identified a lack of research involving female animal models and limited insight into the interaction of molecular signaling pathways, which represent gaps in the literature.

A case report on concomitant reversible cerebral vasoconstriction syndrome and transient global amnesia.

Reversible Cerebral Vasoconstriction Syndrome clinically presents as severe headaches with or without neurological deficits accompanied by multilocal caliber variation of the cerebral arteries on imaging studies. Transient Global Amnesia is a benign neurological condition that implies sudden temporary antero- and retrograde amnesia. The exact pathophysiological mechanisms involved in transient global amnesia and reversible cerebral vasoconstriction syndrome remain unclear but suggest similar pathways as both can be triggered by factors that activate the sympathetic nervous system. We herein discuss a potential relationship of the two conditions in a 65-year-old woman that initially presented herself to the emergency department with temporary memory impairment, indicating Transient Global Amnesia. Four days later, the patient revealed a thunderclap headache accompanied by a subarachnoid hemorrhage with transient segmental narrowing of the arteries of the anterior circulation on neuroimaging. In this case report we hypothesize that Reversible Cerebral Vasoconstriction Syndrome might be a potential cause for the clinical symptoms and imaging patterns with Transient Global Amnesia as a possible prodromal stage of Reversible Cerebral Vasoconstriction Syndrome.

Association between impaired dynamic cerebral autoregulation and BBB disruption in reversible cerebral vasoconstriction syndrome.

BACKGROUND: Half of the sufferers of reversible cerebral vasoconstriction syndrome (RCVS) exhibit imaging-proven blood-brain barrier disruption. The pathogenesis of blood-brain barrier disruption in RCVS remains unclear and mechanism-specific intervention is lacking. We speculated that cerebrovascular dysregulation might be associated with blood-brain barrier disruption in RCVS. Hence, we aimed to evaluate whether the dynamic cerebral autoregulation is altered in patients with RCVS and could be associated with blood-brain barrier disruption. METHODS: A cross-sectional study was conducted from 2019 to 2021 at headache clinics of a national tertiary medical center. Dynamic cerebral autoregulation was evaluated in all participants. The capacity of the dynamic cerebral autoregulation to damp the systemic hemodynamic changes, i.e., phase shift and gain between the cerebral blood flow and blood pressure waveforms in the very-low- and low-frequency bands were calculated by transfer function analysis. The mean flow correlation index was also calculated. Patients with RCVS received 3-dimensional isotropic contrast-enhanced T2 fluid-attenuated inversion recovery imaging to visualize blood-brain barrier disruption. RESULTS: Forty-five patients with RCVS (41.9 ± 9.8 years old, 29 females) and 45 matched healthy controls (41.4 ± 12.5 years old, 29 females) completed the study. Nineteen of the patients had blood-brain barrier disruption. Compared to healthy controls, patients with RCVS had poorer dynamic cerebral autoregulation, indicated by higher gain in very-low-frequency band (left: 1.6 ± 0.7, p = 0.001; right: 1.5 ± 0.7, p = 0.003; healthy controls: 1.1 ± 0.4) and higher mean flow correlation index (left: 0.39 ± 0.20, p = 0.040; right: 0.40 ± 0.18, p = 0.017; healthy controls: 0.31 ± 0.17). Moreover, patients with RCVS with blood-brain barrier disruption had worse dynamic cerebral autoregulation, as compared to those without blood-brain barrier disruption, by having less phase shift in very-low- and low-frequency bands, and higher mean flow correlation index. CONCLUSIONS: Dysfunctional dynamic cerebral autoregulation was observed in patients with RCVS, particularly in those with blood-brain barrier disruption. These findings suggest that impaired cerebral autoregulation plays a pivotal role in RCVS pathophysiology and may be relevant to complications associated with blood-brain barrier disruption by impaired capacity of maintaining stable cerebral blood flow under fluctuating blood pressure.

Impaired intracellular Ca2+ signaling contributes to age-related cerebral small vessel disease in Col4a1 mutant mice.

Humans and mice with mutations in COL4A1 and COL4A2 manifest hallmarks of cerebral small vessel disease (cSVD). Mice with a missense mutation in Col4a1 at amino acid 1344 (Col4a1+/G1344D) exhibit age-dependent intracerebral hemorrhages (ICHs) and brain lesions. Here, we report that this pathology was associated with the loss of myogenic vasoconstriction, an intrinsic vascular response essential for the autoregulation of cerebral blood flow. Electrophysiological analyses showed that the loss of myogenic constriction resulted from blunted pressure-induced smooth muscle cell (SMC) membrane depolarization. Furthermore, we found that dysregulation of membrane potential was associated with impaired Ca2+-dependent activation of large-conductance Ca2+-activated K+ (BK) and transient receptor potential melastatin 4 (TRPM4) cation channels linked to disruptions in sarcoplasmic reticulum (SR) Ca2+ signaling. Col4a1 mutations impair protein folding, which can cause SR stress. Treating Col4a1+/G1344D mice with 4-phenylbutyrate, a compound that promotes the trafficking of misfolded proteins and alleviates SR stress, restored SR Ca2+ signaling, maintained BK and TRPM4 channel activity, prevented loss of myogenic tone, and reduced ICHs. We conclude that alterations in SR Ca2+ handling that impair ion channel activity result in dysregulation of SMC membrane potential and loss of myogenic tone and contribute to age-related cSVD in Col4a1+/G1344D mice.

[A case of acute bilateral blindness presumably caused by reversible cerebral vasoconstriction syndrome after traumatic brain injury].

A 62-year-old man was admitted to our hospital for acute bilateral blindness two days after a head injury. Hemorrhagic cerebellar infarction was found on the initial MRI, and peripheral arteries were poorly visualized on MRA. On the follow-up MRA nine days later, peripheral arteries were clearly depicted. These imaging findings suggested reversible cerebral vasoconstriction syndrome (RCVS). We started steroid pulse therapy for suspected optic neuritis with no clear response. The initial fundoscopic examination revealed no abnormalities in the optic disc, but optic nerve atrophy developed one month later. Based on the course of events, we diagnosed the patient with posterior ischemic optic neuropathy triggered by RCVS.

A case report of reversible cerebral vasoconstriction syndrome with thunderclap headache significantly exacerbated in the supine position and alleviated in the standing position.

BACKGROUND: Reversible cerebral vasoconstriction syndrome (RCVS) is characterized by sudden onset thunderclap headache and multiple segmental reversible cerebral vasoconstrictions that improve within 3 months. The postpartum period is a well-known precipitating factor for the onset of RCVS. Cerebral venous thrombosis (CVT) causes thunderclap headaches in the postpartum period. While headache in CVT is sometimes exacerbated in the supine position, the severity of the headache in RCVS is usually independent of body position. In this study, we report a case of RCVS with thunderclap headache exacerbated in the supine position, and headache attacks that resolved quickly in the standing position during the postpartum period. CASE PRESENTATION: A 33-year-old woman presented with a sudden increase in blood pressure and thunderclap headache on the fifth postpartum day (day 1: the first sick day). The headache was severe and pulsatile, with onset in the supine position in bed, and peaked at approximately 10 s. It was accompanied by nausea and chills but there were no scintillating scotomas or ophthalmic symptoms. The headache resolved in the standing or sitting position but was exacerbated and became unbearable within a few seconds when the patient was in the supine position. Therefore, she was unable to lie supine at night. Computed tomography angiography (CTA) of the head on day 2 and magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) on day 3 showed no abnormalities. However, considering the possibility of RCVS, verapamil was initiated on day 3. The headache resolved the following day. MRA of the head on day 10 revealed diffuse and segmental stenoses in the bilateral middle and posterior cerebral arteries and basilar artery. Therefore, the patient was diagnosed with RCVS. The headache gradually resolved and disappeared completely on day 42. Cerebral vasoconstriction was also improved on MRA on day 43. CONCLUSIONS: This postpartum RCVS case was notable for the exacerbation of headaches in the supine position. For the diagnosis of thunderclap headache in the postpartum period, RCVS should be considered in addition to CVT when the patient presents with a headache that is exacerbated in the supine position.

The Pulmonary Vasculature.

The pulmonary circulation is a low-pressure, low-resistance circuit whose primary function is to deliver deoxygenated blood to, and oxygenated blood from, the pulmonary capillary bed enabling gas exchange. The distribution of pulmonary blood flow is regulated by several factors including effects of vascular branching structure, large-scale forces related to gravity, and finer scale factors related to local control. Hypoxic pulmonary vasoconstriction is one such important regulatory mechanism. In the face of local hypoxia, vascular smooth muscle constriction of precapillary arterioles increases local resistance by up to 250%. This has the effect of diverting blood toward better oxygenated regions of the lung and optimizing ventilation-perfusion matching. However, in the face of global hypoxia, the net effect is an increase in pulmonary arterial pressure and vascular resistance. Pulmonary vascular resistance describes the flow-resistive properties of the pulmonary circulation and arises from both precapillary and postcapillary resistances. The pulmonary circulation is also distensible in response to an increase in transmural pressure and this distention, in addition to recruitment, moderates pulmonary arterial pressure and vascular resistance. This article reviews the physiology of the pulmonary vasculature and briefly discusses how this physiology is altered by common circumstances.

Evidence of impaired functional sympatholysis in patients with heart failure with preserved ejection fraction.

Exercising muscle blood flow is reduced in patients with heart failure with a preserved ejection fraction (HFpEF), which may be related to disease-related changes in the ability to overcome sympathetic nervous system (SNS)-mediated vasoconstriction during exercise, (i.e., "functional sympatholysis"). Thus, in 12 patients with HFpEF (69 ± 7 yr) and 11 healthy controls (Con, 69 ± 4 yr), we examined forearm blood flow (FBF), mean arterial pressure (MAP), and forearm vascular conductance (FVC) during rhythmic handgrip exercise (HG) at 30% of maximum voluntary contraction with or without lower-body negative pressure (LBNP, -20 mmHg) to increase SNS activity and elicit peripheral vasoconstriction. SNS-mediated vasoconstrictor responses were determined as LBNP-induced changes (%Δ) in FVC, and the "magnitude of sympatholysis" was calculated as the difference between responses at rest and during exercise. At rest, the LBNP-induced change in FVC was significantly lesser in HFpEF compared with Con (HFpEF: -9.5 ± 5.5 vs. Con: -21.0 ± 8.0%; P < 0.01). During exercise, LBNP-induced %ΔFVC was significantly attenuated in Con compared with rest (HG: -5.8 ± 6.0%; P < 0.05) but not in HFpEF (HG: -9.9 ± 2.5%; P = 0.88). Thus, the magnitude of sympatholysis was lesser in HFpEF compared with Con (HFpEF: 0.4 ± 4.7 vs. Con: -15.2 ± 11.8%; P < 0.01). These data demonstrate a diminished ability to attenuate SNS-mediated vasoconstriction in HFpEF and provide new evidence suggesting impaired functional sympatholysis in this patient group.NEW & NOTEWORTHY Data from the current study suggest that functional sympatholysis, or the ability to adequately attenuate sympathetic nervous system (SNS)-mediated vasoconstriction during exercise, is impaired in patients with heart failure with preserved ejection fraction (HFpEF). These observations extend the current understanding of HFpEF pathophysiology by implicating inadequate functional sympatholysis as an important contributor to reduced exercising muscle blood flow in this patient group.

Intrapulmonary arterial contraction assay reveals region-specific deregulation of vasoreactivity to lung injuries.

Intrapulmonary arteries located in the proximal lung differ from those in the distal lung in size, cellular composition, and the surrounding microenvironment. However, whether these structural variations lead to region-specific regulation of vasoreactivity in homeostasis and following injury is unknown. Herein, we employ a two-step method of precision-cut lung slice (PCLS) preparation, which maintains almost intact intrapulmonary arteries, to assess contractile and relaxation responses of proximal preacinar arteries (PaAs) and distal intraacinar arteries (IaAs) in mice. We found that PaAs exhibited robust vasoconstriction in response to contractile agonists and significant nitric oxide (NO)-induced vasodilation. In comparison, IaAs were less contractile and displayed a greater relaxation response to NO. Furthermore, in a mouse model of pulmonary arterial hypertension (PAH) induced by chronic exposure to ovalbumin (OVA) allergen and hypoxia (OVA-HX), IaAs demonstrated a reduced vasocontraction despite vascular wall thickening with the emergence of new αSMA+ cells coexpressing markers of pericytes. In contrast, PaAs became hypercontractile and less responsive to NO. The reduction in relaxation of PaAs was associated with decreased expression of protein kinase G, a key component of the NO pathway, following chronic OVA-HX exposure. Taken together, the PCLS prepared using the modified preparation method enables functional evaluation of pulmonary arteries in different anatomical locations and reveals region-specific mechanisms underlying the pathophysiology of PAH in a mouse model.NEW & NOTEWORTHY Utilizing mouse precision-cut lung slices with preserved intrapulmonary vessels, we demonstrated a location-dependent structural and contractile regulation of pulmonary arteries in health and on noxious stimulations. For instance, chronic ovalbumin and hypoxic exposure increased pulmonary arterial pressure (PAH) by remodeling intraacinar arterioles to reduce vascular wall compliance while enhancing vasoconstriction in proximal preacinar arteries. These findings suggest region-specific mechanisms and therapeutic targets for pulmonary vascular diseases such as PAH.

Pericytes Are Not Associated With Reduced Capillary Perfusion After Experimental Subarachnoid Hemorrhage.

BACKGROUND: Subarachnoid hemorrhage (SAH) is characterized by an acute reduction of cerebral blood flow and subsequent cortical infarcts, but the underlying mechanisms are not well understood. Since pericytes regulate cerebral perfusion on the capillary level, we hypothesize that pericytes may reduce cerebral perfusion after SAH. METHODS: Pericytes and vessel diameters of cerebral microvessels were imaged in vivo using NG2 (neuron-glial antigen 2) reporter mice and 2-photon microscopy before and 3 hours after sham surgery or induction of SAH by perforating the middle cerebral artery with an intraluminal filament. Twenty-four hours after, SAH pericyte density was assessed by immunohistochemistry. RESULTS: SAH caused pearl-string-like constrictions of pial arterioles, slowed down blood flow velocity in pial arterioles by 50%, and reduced the volume of intraparenchymal arterioles and capillaries by up to 70% but did not affect pericyte density or induce capillary constriction by pericytes. CONCLUSIONS: Our results suggest that perfusion deficits after SAH are not induced by pericyte-mediated capillary constrictions.

Reversible cerebral vasoconstriction syndrome: A review of pathogenesis, clinical presentation, and treatment.

Reversible segmental narrowing of the intracranial arteries has been described since several decades in numerous clinical settings, using variable nosology. Twenty-one years ago, we tentatively proposed the unifying concept that these entities, based on similar clinical-imaging features, represented a single cerebrovascular syndrome. This "reversible cerebral vasoconstriction syndrome" or RCVS has now come of age. A new International Classification of Diseases code, (ICD-10, I67.841) has been established, enabling larger-scale studies. The RCVS2 scoring system provides high accuracy in confirming RCVS diagnosis and excluding mimics such as primary angiitis of the central nervous system. Several groups have characterized its clinical-imaging features. RCVS predominantly affects women. Recurrent worst-ever (thunderclap) headaches are typical at onset. While initial brain imaging is often normal, approximately one-third to half develop complications such as convexity subarachnoid hemorrhages, lobar hemorrhages, ischemic strokes located in arterial "watershed" territories and reversible edema, alone or in combination. Vasoconstriction evolves over hours to days, first affecting distal and then the more proximal arteries. An overlap between RCVS and primary thunderclap headache, posterior reversible encephalopathy syndrome, Takotsubo cardiomyopathy, transient global amnesia, and other conditions has been recognized. The pathophysiology remains largely unknown. Management is mostly symptomatic: headache relief with analgesics and oral calcium-channel blockers, removal of vasoconstrictive factors, and avoidance of glucocorticoids that can significantly worsen outcome. Intra-arterial vasodilator infusions provide variable success. Overall, 90-95% of admitted patients achieve complete or major resolution of symptoms and clinical deficits within days to weeks. Recurrence is exceptional, although 5% can later develop isolated thunderclap headaches with or without mild cerebral vasoconstriction.

Sudden-onset headache due to reversible cerebral vasoconstriction syndrome.

Reversible cerebral vasoconstriction syndrome (RCVS) is characterized by reversible segmental vasoconstriction of the cerebral arteries that spontaneously resolve within 3 months. Occurrence of RCVS peaks at around 40 years and the syndrome is common in women. Here, we report an adolescent boy case of RCVS.

Reversible cerebral vasoconstriction syndrome: strategies to early diagnosis and the role of transcranial color-coded doppler ultrasonography (TCCD).

BACKGROUND: Reversible cerebral vasoconstriction syndrome (RCVS) is a cerebrovascular transitory condition characterized by severe headache, possible concomitant acute neurological symptoms, evidence of diffuse multifocal segmental constriction of cerebral arteries, and usually spontaneously resolving within 3 months. Putative causes and/or precipitating factors are vasoactive drugs-e.g., antidepressants, α-sympathomimetics, triptans-post-partum, and immunosuppressants. CASE PRESENTATION: We report the case of a middle-aged woman referred to the emergency room (ER) with a 7-day long intense headache and vomit. Cerebral non-contrast computed tomography (CT) was negative for acute ischemic lesions or intracranial bleedings. She was again referred to ER 7 days later with additional fluctuating episodes of weakness in left arm and both lower limbs. A new brain CT was negative. Due to worsening headache, a transcranial color-coded Doppler (TCCD) was performed, which showed diffuse multifocal blood flow acceleration in all principal intracranial vessels, and particularly on the right hemisphere. These findings were subsequently confirmed at MR angiogram and digital subtraction angiography. CONCLUSION: TCCD imaging is a non-invasive and relatively inexpensive tool which provides real-time information on cerebrovascular function, blood flow velocities, and hemodynamic changes. TCCD may be a powerful tool in the early detection of acute infrequent cerebrovascular conditions, as well as in monitoring their course and the therapeutic response.

Vasoconstriction during non-hypotensive hypovolemia is not associated with activation of baroreflex: A causality-based approach.

Non-hypotensive hypovolemia simulated with oscillatory lower body negative pressure in the range of -10 to -20 mmHg is associated with vasoconstriction {increase in total peripheral vascular resistance (TPVR)}. Due to the mechanical stiffening of vessels, there is a disjuncture of mechano-neural coupling at the level of arterial baroreceptors which has not been investigated. The study was designed to quantify both the cardiac and vascular arms of the baroreflex using an approach based on Wiener-Granger causality (WGC) - partial directed coherence (PDC). Thirty-three healthy human volunteers were recruited and continuous heart rate and blood pressure {systolic (SBP), diastolic (DBP), and mean (MBP)} were recorded. The measurements were taken in resting state, at -10 mmHg (level 1) and -15 mmHg (level 2). Spectral causality - PDC was estimated from the MVAR model in the low-frequency band using the GMAC MatLab toolbox. PDC from SBP and MBP to RR interval and TPVR was calculated. The PDC from MBP to RR interval showed no significant change at -10 mmHg and -15 mmHg. No significant change in PDC from MBP to TPVR at -10 mmHg and -15 mmHg was observed. Similar results were obtained for PDC estimation using SBP as input. However, a significant increase in TPVR from baseline at both levels of oscillatory LBNP (p-value <0.001). No statistically significant change in PDC from blood pressure to RR interval and blood pressure to TPVR implies that vasoconstriction is not associated with activation of the arterial baroreflex in ≤-15 mmHg LBNP. Thereby, indicating the role of cardiopulmonary reflexes during the low level of LBNP simulated non-hypotensive hypovolemia.