The incidence of neurological complications, including stroke and cognitive dysfunction, is elevated in patients with heart failure (HF) with reduced ejection fraction. We hypothesized that the cerebrovascular response to isometric handgrip (iHG) is altered in patients with HF. Adults with HF and healthy volunteers were included. Cerebral blood velocity (CBV; transcranial Doppler, middle cerebral artery) and arterial blood pressure (BP; Finometer) were continuously recorded supine for 6 min, corresponding to 1 min of baseline and 3 min of iHG exercise, at 30% maximum voluntary contraction, followed by 2 min of recovery. The resistance-area product was calculated from the instantaneous BP-CBV relationship. Dynamic cerebral autoregulation (dCA) was assessed with the time-varying autoregulation index estimated from the CBV step response derived by an autoregressive moving-average time-domain model. Forty patients with HF and 23 BP-matched healthy volunteers were studied. Median left ventricular ejection fraction was 38.5% (interquartile range: 0.075%) in the HF group. Compared with control subjects, patients with HF exhibited lower time-varying autoregulation index during iHG, indicating impaired dCA ( P < 0.025). During iHG, there were steep rises in CBV, BP, and heart rate in control subjects but with different temporal patterns in HF, which, together with the temporal evolution of resistance-area product, confirmed the disturbance in dCA in HF. Patients with HF were more likely to have impaired dCA during iHG compared with age-matched control subjects. Our results also suggest an impairment of myogenic, neurogenic, and metabolic control mechanisms in HF. The relationship between impaired dCA and neurological complications in patients with HF during exercise deserves further investigation. NEW & NOTEWORTHY Our findings provide the first direct evidence that cerebral blood flow regulatory mechanisms can be affected in patients with heart failure during isometric handgrip exercise. As a consequence, eventual blood pressure modulations are buffered less efficiently and metabolic demands may not be met during common daily activities. These deficits in cerebral autoregulation are compounded by limitations of the systemic response to isometric exercise, suggesting that patients with heart failure may be at greater risk for cerebral events during exercise.

Background: Circulatory shock is a life-threatening disorder that is associated with high mortality, with a state of systemic and tissue hypoperfusion that can lead to organ failure, including the brain, where altered mental state is often observed. We hypothesized that cerebral autoregulation (CA) is impaired in patients with circulatory shock. Methods: Adult patients with circulatory shock and healthy controls were included. Cerebral blood flow velocity (CBFV, transcranial Doppler ultrasound) and arterial blood pressure (BP, Finometer or intra-arterial line) were continuously recorded during 5 min in both groups. Autoregulation Index (ARI) was estimated from the CBFV response to a step change in BP, derived by transfer function analysis; ARI ≤ 4 was considered impaired CA. The relationship between organ dysfunction, assessed with the Sequential Organ Failure Assessment (SOFA) score and the ARI, was assessed with linear regression. Results: Twenty-five shock patients and 28 age-matched healthy volunteers were studied. The mean ± SD SOFA score was 10.8 ± 4.3. Shock patients compared with control subjects had lower ARI values (4.0 ± 2.1 vs. 5.9 ± 1.5, P = 0.001). Impaired CA was more common in shock patients (44.4% vs. 7.1%, P = 0.003). There was a significant inverse relationship between the ARI and the SOFA score (R = −0.63, P = 0.0008). Conclusions: These results suggest that circulatory shock is often associated with impaired CA and that the severity of CA alterations is correlated with the degree of multiple organ failure, reinforcing the need to monitor cerebral hemodynamics in patients with circulatory shock.

In this article, the authors evaluated the diagnostic utility of FLAIR imaging in the detection of microadenomas in patients with Cushing's disease (CD). All 23 patients (24 pituitary adenomas) underwent volumetric gradient recalled echo (3D-GRE) MRI and FLAIR scanning preoperatively. Compared with intraoperative findings and postoperative histopathology, 3D-GRE sequences correctly confirmed 18 location-concordant tumors and were unable to identify 4 tumors (MRI-negative CD). In contrast, FLAIR sequences only correctly confirmed 12 tumors (noted incorrectly as 13 in the abstract) and were unable to identify 10 tumors. In the past decade, many researchers have explored the usefulness of FLAIR imaging in brain tumors, while few highlighted the significance of it in the diagnosis of pituitary adenomas. 3,4 Exactly as the data showed in this study, compared with that of 3D-GRE MRI, the accuracy of FLAIR in detecting CD microadenomas was much lower, which means the diagnostic value of FLAIR imaging is very limited.Chatain et al. also found all 5 patients with negative 3D-GRE MRI displayed FLAIR hyperintensity. Among them, 4 patients had location-concurrent positive histopathological findings, and in 1 patient (case 7) the concordance of imaging with histopathology was unable to be identified because the foci of FLAIR hyperintensity was not removed during surgery. The authors concluded that FLAIR helps 3D-GRE determine MRI-negative CD for surgical planning, which we think is quite debatable. The standalone specificity of 3D-GRE and FLAIR in this study was equal, but is impossible in real life. Considering the innate instability of specificity/sensitivity as well as the rather small sample size of this study, statistical errors undoubtedly existed. In addition, the positive and negative likelihood ratios (more statistically stable than specificity/sensitivity) of 3D-GRE were 1.64 and 0.36, while those of FLAIR were 1.1 and 0.9. This indicates that the possibility of confirming the foci of FLAIR hyperintensity as tumors was just 52.4%.Even though the authors used T2-weighted sequences to screen for cysts within the pituitary gland or the adenoma, it is still difficult to differentiate. 6 As for the localization, small Rathke cleft cysts (RCCs) usually lie within the central posterior aspect of the anterior lobe adjacent to the posterior lobe, similar to CD microadenomas. The signals of cysts on MR images are diverse due to their different compositions of cystic fluid. When protein components are in the majority, RCCs will present T2 signal hypo-/isointensity, precontrast FLAIR isointensity, and postcontrast FLAIR hyperintensity, which are similar to the radiological appearances of microadenomas. When MRI-negative microadenomas and hyperintense cysts on FLAIR coexist in the same pituitary gland, the authors may regard the cysts as tumors and then select incorrect surgical sites. In conclusion, we can use FLAIR as an auxiliary sequence in CD, but the diagnostic value of it cannot be overestimated. Further studies with a s...

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