Hypertensive Cerebral Microinfarction and Cerebrovascular Reactivity

Dinsdale, Henry B.; Robertson, David; Chiang, Terrance; Mukherjee, Suranjan

doi:10.1159/000114461

Cited by 20 publications

(10 citation statements)

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“…He concluded that these changes were all functional, since they disappeared within a short time after the relief of hypertension [16]. The response of CNS vasculature to acute rises in blood pressure was intensely investigated in the following decades [17][18][19]. When the acute rises in blood pressure exceed the auto-regulatory capacity of the CNS vessel network, regions of vasoconstriction and vasodilatation develop, typically at the arterial boundary zones.…”

Section: Discussionmentioning

confidence: 99%

Posterior reversible encephalopathy syndrome in the pediatric renal population

et al. 2007

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Posterior reversible leukoencephalopathy syndrome (PRES) clinically presents with seizures, severe headaches, and mental and visual changes. Our goal was to describe the clinical features, triggering factors, neuro-imaging findings, and electroencephalogram (EEG) findings in a pediatric cohort with renal disease. We retrospectively analyzed the records of 18 children with the diagnosis of PRES between January 2001 and June 2006 at the University of Miami/Holtz Children's Hospital, USA. There were 22 PRES episodes. The most common clinical presentation was generalized tonic-clonic seizures in 59% (13/22). The most common identified trigger of PRES was hypertensive crisis in 59% (13/22). Almost half of the children had no evidence of on-going uncontrolled hypertension; 44% (8/18) had normal funduscopic examination findings, and 50% (9/18) had no or mild left ventricular hypertrophy. Two of the 18 patients had recurrent PRES episodes, three episodes each. Diffuse slowing was the most common finding on the EEGs. Atypical magnetic resonance imaging (MRI) findings were more prevalent in the imaged cases (62% vs 25%, P < 0.05). All the computerized tomography (CT) scans were normal, despite the positive MRI findings in four cases when both types of imaging was used. All the episodes had total clinical resolution. In conclusion, despite the diverse initial trigger, acute hypertension seems to be the common pathogenic pathway for pediatric PRES. MRI seems superior to CT, with better sensitivity due to its high resolution and diffusion-weighted imaging. The lesions do not necessarily have to be in the posterior white matter and may not be totally reversible.

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Section: Discussionmentioning

confidence: 99%

Posterior reversible encephalopathy syndrome in the pediatric renal population

et al. 2007

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“…It has been suggested that in this vascular crisis the arterioles react to extreme elevations in blood pressure either with spasm (uncontrolled vasoconstriction) or with the opposite response, forced vasodilation. Evidence for this possibility has been obtained from three different experimental approaches: direct observation of pial vessels (16)(17)(18)(19)(20), blood-brain barrier studies (5-7, 16, 17, 21, 22), and cerebral blood flow studies (2)(3)(4).…”

Section: Strandgaard Mackenzie Sengupta Rowan Lassen Harpermentioning

confidence: 99%

“…In the previous work of Byrom (17) on experimental hypertensive encephalopathy in the rat and in other later experiments (18)(19)(20), the constricted segments were regarded as being in vasospasm. This vasospasm was thought to damage the brain by hypoxia, causing neurological symptoms and local blood-brain barrier lesions and edema.…”

Section: Strandgaard Mackenzie Sengupta Rowan Lassen Harpermentioning

confidence: 99%

Upper Limit of Autoregulation of Cerebral Blood Flow in the Baboon

Strandgaard

MacKenzie

Sengupta

et al. 1974

Circulation Research

166

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The upper limit of autoregulation of cerebral blood flow was studied in ten young baboons. Blood pressure was increased by infusing angiotensin, and cerebral blood flow was measured by the intracarotid 133 xenon injection method. Autoregulation was maintained until blood pressure was 30-40% above resting values. At this blood pressure level, cerebrovascular resistance reached a maximum. Any additional increase in blood pressure resulted in an increase in cerebral blood flow and a decrease in cerebrovascular resistance; this situation is designated the "breakthrough of autoregulation." In four baboons subjected to unilateral sympathetic denervation, autoregulation of cerebral blood flow was studied bilaterally; no difference in the upper limit of autoregulation was found between the intact and the sympathectomized hemisphere. The breakthrough of autoregulation supposedly plays an important role in the pathogenesis of acute hypertensive encephalopathy. The old concept of hypertensive cerebral vasospasm has been revised in recent years, and it is now generally recognized that acute hypertensive encephalopathy is caused by focal overdistention of brain arterioles with lesions of the blood-brain barrier. However, whether this condition is associated with a high cerebral blood flow in the clinical syndrome has not been investigated. KEY WORDSinduced hypertension breakthrough of autoregulation hypertensive encephalopathy cerebrovascular resistance angiotensin 133 xenon clearance• When blood pressure rises, cerebral blood flow is held constant by autoregulatory constriction of the cerebral resistance vessels. Some recent communications have described the existence of an upper limit of autoregulation. When blood pressure rises beyond this limit, autoregulation is exhausted; a forced arteriolar dilation and an increase in cerebral blood flow occur. This situation is called the "breakthrough of autoregulation" (l) and has been observed in hypercapnic dogs (2), in man by the arteriovenous oxygen difference method (3), and, in a limited study, in man by the intracarotid criticism because of the unphysiological experimental conditions (2), the use of an indirect method for assessment of cerebral blood flow (3), and the limited number of experiments performed (4). The present study was undertaken to obtain conclusive evidence on the upper limit of autoregulation. Normocapnic baboons were used, and cerebral blood flow was measured by the intracarotid 133 Xe injection method. The involvement of sympathetic nerves in the regulation of cerebral blood flow during acutely induced hypertension was also evaluated. MethodsThe study was carried out in ten young adult baboons {Papio cynocephalus or Papio anubis) weighing 10-14 kg. Three of the baboons were studied 2 weeks after a unilateral cervical sympathectomy, and one baboon was studied immediately after an acute cervical sympathetic block. The baboons were anesthetized with phencyclidine (12 mg, im) and sodium thiopental (7.5 mg/kg, iv). They were intubated and connected to ...

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“…These experiments have thus not demonstrated significant spasm of the brain arterioles under high blood pressure. A number of studies report on direct observation of pial vessels at high blood pressure (1,2,12,13). The arterioles here display a "sausage-string" appearance, with constricted and dilated segments intermingled.…”

Section: Discussionmentioning

confidence: 99%

The Lower and Upper Limits for Autoregulation of Cerebral Blood Flow

Strandgaard¹,

Sengupta²,

MacKenzie³

et al. 1975

Cerebral Circulation and Metabolism

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The existence of a lower blood pressure limit for autoregulation has been recognized since 1959 (9). A shift upward of the lower end of the autoregulation curve in chronic arterial hypertension was suggested by Gottstein (6) on the basis of data from the literature, but has never been demonstrated in the individual patient. The existence of an upper blood pressure limit for autoregulation was demonstrated by Ekstrom-Jodal et al. (4) in hypercapnic dogs, but was not found at normocapnia. The present communication deals with the blood pressure limits for autoregulation in hypertensive and normotensive man and the upper limit for autoregulation in the baboon. Furthermore, the possible role of the sympathetic nerves for CBF regulation at high blood pressure has been studied in the baboon. Material and MethodsIn the majority of patients autoregulation was studied by the arteriovenous oxygen difference method, based on the assumption of a constant CMRO". A total of 31 hypertensive and 13 normotensive subjects was studied. The jugular vein was catheterized either from an arm vein or by puncture at the neck. The brachial or femoral arteries were catheterized. Blood pressure was elevated by angiotensin infusion and reduced by trimethaphan infusion combined with head-up tilt. At various blood pressure levels blood samples were drawn and analyzed for cerebral A VDO" and P aCO".

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Hypertensive Cerebral Microinfarction and Cerebrovascular Reactivity

Cited by 20 publications

References 0 publications

Posterior reversible encephalopathy syndrome in the pediatric renal population

Posterior reversible encephalopathy syndrome in the pediatric renal population

Upper Limit of Autoregulation of Cerebral Blood Flow in the Baboon

The Lower and Upper Limits for Autoregulation of Cerebral Blood Flow

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