Transcranial Doppler sonography at the early stage of acute central nervous system infections in adults

Müller, Martin; Merkelbach, S.; Hermes, M.; Schimrigk, К.

doi:10.1016/0301-5629(95)02029-2

Cited by 29 publications

(29 citation statements)

References 33 publications

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“…[16][17][18][19][20] Blood flow velocities (systolic, diastolic, and mean velocities) and the pulsatility and resistive indexes, which derive from the flow velocities, are the most common measurements used. Blood flow velocity increases and the pulsatility and resistive index decrease with arteriolar vasoconstriction.…”

Section: Discussionmentioning

confidence: 99%

Increased cerebrovascular resistance in cirrhotic patients with ascites

et al. 1998

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Studies assessing regional hemodynamics in patients with cirrhosis and ascites have shown vasodilation in the splanchnic circulation and vasoconstriction in the renal circulation and in the brachial and femoral artery vascular territories. The aim of this study was to assess the cerebral vascular resistance in cirrhotic patients with ascites. The resistive index in the middle cerebral artery (an index of the cerebral vascular resistance) and in a renal interlobar artery were measured by Doppler ultrasonography in 7 healthy subjects: 13 patients with compensated cirrhosis and 24 patients with ascites (13 with renal failure). The arterial blood pressure and the activity of the renin-angiotensin and sympathetic nervous systems, as estimated by plasma renin activity and plasma norepinephrine concentration, respectively, were also measured. The resistive index in the middle cerebral artery was significantly increased in patients with ascites (0.68 ؎ 0.05, mean ؎ SD) as compared with patients without ascites (0.60 ؎ 0.01, P F .05) and with healthy patients (0.52 ؎ 0.01, P F .01). Renal resistive index was also increased in patients with ascites (0.77 ؎ 0.01) compared with the other two groups (0.68 ؎ 0.02 and 0.62 ؎ 0.00, respectively; P F .001). The resistive index in the middle cerebral artery showed a direct correlation with renal resistive index (r ‫؍‬ .73, P F .01), plasma renin activity (r ‫؍‬ .61, P F .01), and norepinephrine (r ‫؍‬ .53, P F .01). The resistive index in the middle cerebral artery showed an inverse correlation with mean arterial pressure (r ‫,54.؊؍‬ P F .01). These results indicate that in patients with cirrhosis and ascites there is a cerebral vasoconstriction which is probably related with the arterial hypotension and the overactivity of vasoconstrictor systems. (HEPATOL-OGY 1998;28:39-44.)Portal hypertension in cirrhosis is associated with a hyperdynamic circulation, which is characterized by hypervolemia, high cardiac output, arterial hypotension, and low peripheral vascular resistance. 1 These circulatory abnormalities are thought to be secondary to a splanchnic arteriolar vasodilation related to the increase in portal pressure. Portal hypertension in experimental animals is associated with a generalized splanchnic arteriolar vasodilation. 2,3 There is indirect evidence that this also occurs in human cirrhosis, as hepatic blood flow is usually normal or increased in these patients, even though 60% to 80% of portal flow is shunted through the collateral circulation. 4 In addition, the mean transit time in the splanchnic vascular bed is substantially reduced in alcoholic cirrhotic patients, which indicates a hyperkinetic splanchnic circulation in these patients. 5 Finally, studies using echo-Doppler have documented increased splenic and mesenteric blood flow in patients with cirrhosis. 6,7 Investigations assessing regional circulations in human cirrhosis are also consistent with that concept. Renal blood flow is reduced and renal vascular resistance is increased in most patients with cirrhosi...

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Section: Discussionmentioning

confidence: 99%

Increased cerebrovascular resistance in cirrhotic patients with ascites

et al. 1998

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“…Contrast transfer efficiency was defined on a logarithmic scale as follows (Ponnekanti et al , 1996):

η (d B) = ∣ C_{o} (d B) ∣ - ∣ C_{t} (d B) ∣

where C o and C t represent the estimated and true elasticity contrasts, respectively. Therefore, η = 0 represents 100 % elasticity contrast-transfer-efficiency, and η < 0 represents a contrast transfer efficiency that is less than 100 %.…”

Section: Methodsmentioning

confidence: 99%

Investigating the impact of spatial priors on the performance of model-based IVUS elastography

Richards

Doyley

2011

Phys. Med. Biol.

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This paper describes methods that provide pre-requisite information for computing circumferential stress in modulus elastograms recovered from vascular tissue—information that could help cardiologists detect life-threatening plaques and predict their propensity to rupture. The modulus recovery process is an ill-posed problem; therefore additional information is needed to provide useful elastograms. In this work, prior geometrical information was used to impose hard or soft constraints on the reconstruction process. We conducted simulation and phantom studies to evaluate and compare modulus elastograms computed with soft and hard constraints versus those computed without any prior information. The results revealed that (1) the contrast-to-noise ratio of modulus elastograms achieved using the soft prior and hard prior reconstruction methods exceeded those computed without any prior information; (2) the soft prior and hard prior reconstruction methods could tolerate up to 8 % measurement noise; and (3) the performance of soft and hard prior modulus elastogram degraded when incomplete spatial priors were employed. This work demonstrates that including spatial priors in the reconstruction process should improve the performance of model-based elastography, and the soft prior approach should enhance the robustness of the reconstruction process to errors in the geometrical information.

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“…Among the complications, the inflammatory changes of the large and small intracranial vessels seem to be an important outcome prediction factor as indicated by pathological and angiographic findings [16,29,34,39]. The use of MBV measurements to indicate arterial narrowing of the large basal cerebral arteries in bacterial meningitis is complicated by other factors increasing MBV: first, inflammatory hyperaemia [25,28,35,38]; and second, the decrease of an increased intracranial pressure [22]. However, the upper limit of MBV as a sign of hyperaemia or restoring cerebral blood flow is unknown.…”

Section: Discussionmentioning

confidence: 99%

Relationship between short-term outcome and occurrence of cerebral artery stenosis in survivors of bacterial meningitis

Müller

Merkelbach

Hermes³

et al. 1998

Journal of Neurology

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To evaluate the influence of cerebral artery stenosis on the outcome of patients with bacterial meningitis we examined prospectively 47 consecutive patients [33 men, 14 women, mean (SD) age, 53 (17) years, range 18-81] with bacterial meningitis caused by various bacterial pathogens. The patients were examined with the use of the Glasgow Coma Scale (GCS) on days 1, 3, 5, 8, 14 and with the use of the Glasgow Outcome Scale (GOS) on day 21 after admission. In addition, focal cerebral signs were recorded separately. At each clinical examination, the patients underwent transcranial Doppler sonography recordings of the mean blood velocity (MBV) and the pulsatility index in all of the main intracranial arteries and in the submandibular internal carotid artery (ICA). A stenosis of the middle cerebral artery (MCA) was diagnosed by an MBV of > or = 120 cm/s or by an MBV ratio > 3 between the MCA and the ICA. An anterior cerebral artery (ACA) stenosis was indicated by an MBV > or = 100 cm/s, a posterior cerebral artery (PCA) stenosis by an MBV of > or = 85 cm/s, and a basilar artery (BA) stenosis by an MBV of > or = 95 cm/s. Twenty-five patients developed stenosis of the cerebral arteries (apart from 1, all within 8 days), 22 patients remained without stenosis. Of 29 focal cerebral signs, 27 occurred within 8 days. For outcome analysis, outcome was classified into two groups: not handicapped (GOS 5) versus handicapped (GOS 2-4) and dead (GOS 1). Based on the disease course up to day 8, risk factors for a handicapped/dead outcome after day 8 were advancing age (odds ratio per year, 1.06; 95% confidence interval (CI), 1.01-1.11; P = 0.03) and the presence of arterial stenosis (odds ratio, 7.3; 95% CI, 1.1-45) using a multivariate logistic regression analysis model. GCS on day 1, cerebrospinal fluid total protein content and the presence of focal cerebral signs were not significantly related to outcome in this series. The patients with stenosis exhibited significantly more frequently a poorer GCS on days 1-5 (Mann-Whitney U test; P < 0.05). In conclusion, the early occurrence of stenosis of the cerebral arteries in bacterial meningitis predicted a worse clinical course of the disease and a poorer short-term outcome of the survivors.

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Transcranial Doppler sonography at the early stage of acute central nervous system infections in adults

Cited by 29 publications

References 33 publications

Increased cerebrovascular resistance in cirrhotic patients with ascites

Increased cerebrovascular resistance in cirrhotic patients with ascites

Investigating the impact of spatial priors on the performance of model-based IVUS elastography

Relationship between short-term outcome and occurrence of cerebral artery stenosis in survivors of bacterial meningitis

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