Beta-blockade in acute aneurysmal subarachnoid haemorrhage

Beta-Blockade in Aneurysmal Subarachnoid Hemorrhage: a Systematic Review and Meta-Analysis

BACKGROUND/OBJECTIVE

Sympathetic nervous system activation after aneurysmal subarachnoid hemorrhage (aSAH) is associated with complications and poor outcome. In this systematic review and meta-analysis, we investigate the effect of beta-blockers on outcome after aSAH.

METHODS

The review was prospectively registered with PROSPERO (CRD42019111784). We performed a systematic literature search of MEDLINE, EMBASE, the Cochrane Library, published conference proceedings, and abstracts. Eligible studies included both randomized controlled trials and observational studies up to October 2018, reporting the effect of beta-blocker therapy on the following outcomes in aSAH: mortality, vasospasm, delayed cerebral ischemia, infarction or stroke, cardiac dysfunction, and functional outcomes. Studies involving traumatic SAH were excluded. Citations were reviewed, and data extracted independently by two investigators using a standardized proforma.

RESULTS

We identified 819 records with 16 studies (four were randomized controlled trials) including 6702 patients selected for analysis. Exposure to beta-blockade either before or after aSAH was associated with a significant reduction in unadjusted mortality (RR 0.63, 95% CI 0.42-0.93, p = 0.02). A significant reduction in unadjusted mortality was also seen in prospective trials of post-event beta-blockade (RR 0.51, 95% CI 0.28-0.93, p = 0.03). Statistically significant differences were not seen for other outcomes investigated.

CONCLUSIONS

In adult patients with aSAH, beta-blocker therapy is associated with a mortality benefit. Studies are generally of a low quality with considerable clinical heterogeneity. Prospective large interventional trials with patient centered outcomes are required to validate this finding.

Metabolische Störungen

Im folgenden Kapitel werden die verschiedenen metabolischen Störungen betrachtet. Zunächst wird auf die allgemeinen und spezifischen neurologischen Komplikationen bei Organtransplantation eingegangen. Dann geht es um die metabolischen Enzephalopathien: Störungen der Gehirntätigkeit bei angeborenen und erworbenen Stoffwechselerkrankungen im engeren Sinn, Elektrolytstörungen, Hypovitaminosen, zerebrale Folgen einzelner Organdysfunktionen, zerebrale Hypoxien, Endotheliopathien und Mitochondropathien. Anschließend werden das Alkoholdelir und die Wernicke-Enzephalopathie erörtert. Bei zahlreichen akuten Erkrankungen von Gehirn, Rückenmark und peripherem Nervensystem treten typische Störungen vegetativer Systeme auf, deren Erkennung und Therapie insbesondere bei Intensivpatienten eine vitale Bedeutung haben kann: die autonomen Störungen. Bei der zentralen pontinen Myelinolyse kommt es zu einer akuten, vorwiegend fokal-symmetrischen Demyelinisierung im Hirnparenchym. Auch Basalganglienerkrankungen können intensivmedizinisch relevant werden. Und schließlich wird die akute Stressreaktion betrachtet, die aufgrund der vielfältigen metabolischen und endokrinen Veränderungen bei kritischen Erkrankungen entsteht. Gerade das RCVS als neuere Krankheitsentität und wichtige Differenzialdiagnose zur Vaskulitis des ZNS verdient einen eigenen Platz, in diesem Unterkapitel werden ebenfalls verwandte Syndrome wie die hypertensive Enzephalopathie und das PRES abgehandelt.

Metoprolol treatment decreases tissue myeloperoxidase activity after spinal cord injury in rats

Neutrophil infiltration has been reported to play an important role in spinal cord injury (SCI). In addition to their cardioprotective effects, beta-blockers have been found to have neuroprotective effects on the central nervous system, but their effect on SCI has not yet been studied. In the current study, we investigated the effect of metoprolol on myeloperoxidase (MPO) activity, a marker of neutrophil activation, in the spinal cord after experimental SCI in rats. Rats were divided into six groups: controls received only laminectomy and spinal cord samples were taken immediately; the sham operated group received laminectomy, and spinal cord samples were taken 4h after laminectomy; the trauma only group underwent a 50g/cm contusion injury but received no medication; and three other groups underwent trauma as for the trauma group, and received 30mg/kg methylprednisolone, 1mg/kg metoprolol, or 1mL saline, respectively. All the medications were given intraperitoneally as single doses, immediately after trauma. Spinal cord samples were taken 4h after trauma and studied for MPO activity. The results showed that tissue MPO activity increased after injury. Both metoprolol and methylprednisolone treatments decreased MPO activity, indicating a reduction in neutrophil infiltration in damaged tissue. The effect of metoprolol on MPO activity was found to be similar to methylprednisolone. In view of these data, we conclude that metoprolol may be effective in protecting rat spinal cord from secondary injury.

Aneurysmal subarachnoid haemorrhage in a patient with thyrotoxicosis

A case of subarachnoid haemorrhage secondary to rupture of an intracranial aneurysm occurring in a patient with new-onset, frank thyrotoxicosis is described. This unusual case highlights the dilemma of whether to continue beta-blockers such as propanolol for frank thyrotoxicosis, or whether to assign higher priority to maintaining adequate cerebral perfusion pressure in established ischaemic deficit due to vasospasm. In a complicated case such as this, the Maudsley Mentation Test score and perfusion CT scanning are two useful adjuncts for the early detection and evaluation of the course of ischaemic deficit.

Attenuation of cerebral vasospasm in rabbits using clonidine hydrochloride, a central adrenergic agonist

The aim of this study was to assess, firstly, if exclusion of central noradrenergic areas in the hypothalamus and brain stem with the central sympathetic blocker clonidine hydrochloride could prevent the development of chronic vasospasm following experimental subarachnoid haemorrhage in rabbits and, secondly, if, parallel with the effect on cerebral arteries, changes in dopamine beta-hydroxylase concentration in the hypothalamus and brain stem could also be detected. Experimental subarachnoid haemorrhage, in concentrations of 1 ml of autologous arterial blood/1 kg of body weight was carried out on 18 New Zealand rabbits. Histological specimens were obtained by the method of perfusion fixation after the rabbits were sacrificed on day 8 after subarachnoid haemorrhage. The spastic effect of experimentally induced subarachnoid haemorrhage was determined by assessing the intensity of corrugation of the intima of the rabbit basilar artery by the previously developed method of corrugation coefficient and computer image analysis. The concentration and localization of dopamine beta-hydroxylase in noradrenaline-containing neurons was immunohistochemically assessed (semiquantitatively as 0, 1 and 2) with anti-dopamine beta-hydroxylase, at precisely defined sites of the hypothalamus and brain stem of the same rabbit. The results revealed less corrugated and smoother intima in the basilar artery and significantly lower dopamine beta-hydroxylase concentration in the control group of rabbits with sham subarachnoid haemorrhage and without any additional interventions (mean corrugation coefficient=1.123+/-0.024, P=0.35 x 10(-3); mean dopamine beta-hydroxylase=0.350+/-0.071, P=0.22 x 10(-3)), and smoother intima in the basilar artery with significantly lower concentration of dopamine beta-hydroxylase in the clonidine group (rabbits with subarachnoid haemorrhage and central alpha(2)-blocker clonidine hydrochloride at a daily dose of 0.03 mg/kg of body weight for 8 days; mean corrugation coefficient=1.177+/-0.058, P=1.7 x 10(-3); mean dopamine beta-hydroxylase=0.583+/-0.175, P=1.1 x 10(-3)). In comparison, the haemorrhage only group (rabbits with subarachnoid haemorrhage and without medication; mean corrugation coefficient=1.370+/-0.101; mean dopamine beta-hydroxylase=1.214+/-0.313) displayed intensive corrugation of the intima of the basilar artery and a significantly more intensive accumulation of dopamine beta-hydroxylase than did the control group and the clonidine group. The results of this study demonstrated that the central alpha(2)-blocker clonidine hydrochloride effectively prevents vasospasm, and diminishes the concentration of cerebral dopamine beta-hydroxylase in the hypothalamus and brain stem after experimental subarachnoid haemorrhage in rabbits.

Monoamine metabolism and sympathetic nervous activation following subarachnoid haemorrhage: influence of gender and hydrocephalus

Subarachnoid haemorrhage is a serious condition, often accompanied by cerebral vasospasm and hydrocephalus, which may result in delayed cerebral ischaemia and neurological deterioration. While the mechanisms responsible remain unknown, activation of the sympathetic nervous system, leading to elevated levels of circulating catecholamines is, at least in part, implicated. In this study, we sought to examine the importance of sympathetic nervous activation and its relation to brain monoaminergic neurotransmission in 25 patients following subarachnoid haemorrhage by examining plasma and cerebrospinal fluid levels of the catecholamines noradrenaline, adrenaline and dopamine, and their metabolites. Total body sympathetic activity was concurrently assessed using isotope dilution methodology. In the early phase following subarachnoid haemorrhage patients exhibited markedly elevated rates of spillover of noradrenaline to plasma (9.11 +/- 1.12 vs. 3.39 +/- 0.26 nmol/min, p < 0.01), with rates being higher in those patients in whom hydrocephalus developed (11.15 +/- 1.40 vs. 7.90 +/- 1.41 nmol/min, p = 0.05). The degree of sympathetic nervous activation tended to be higher in females compared with males. Lower cerebral perfusion pressures were observed in those patients in whom cerebrospinal fluid concentrations of noradrenaline and dopamine metabolites were high. A marked sympathetic nervous activation, more pronounced in women and in those with hydrocephalus, occurs following subarachnoid haemorrhage. The diminished cerebral perfusion seen following subarachnoid bleeding may occur as a result of activation of central catecholaminergic neurones.

Subarachnoid haemorrhage-induced sympathoexcitation in rats is reversed by bosentan or sodium nitroprusside

1. The roles played by nitric oxide (NO) and endothelin (ET) in the genesis of sympathetic nervous activation following experimental subarachnoid haemorrhage was investigated using spectral analysis of blood pressure rhythms. 2. Subarachnoid haemorrhage was induced in conscious rats by injecting 0.3 mL homologous blood via a catheter placed along the surface of the brain and directed towards the circle of Willis. Three hours after the insult and after sympathetic activation was evident, animals received either an acute injection of the ET antagonist bosentan (5 mg/kg, i.v.; n = 7), an infusion of the NO donor sodium nitroprusside (SNP; 18 microg/h; n = 7) or no treatment (n = 7). 3. Three hours following the induction of subarachnoid haemorrhage, the mid-frequency components of systolic blood pressure were markedly elevated, indicating a pronounced sympathoexcitation. However, blood pressure and heart rate levels remained unchanged at this time. In the absence of treatment, the mid-frequency components of blood pressure remained elevated for a subsequent 2 h. Treatment with a non-hypotensive dose of SNP reversed the sympathoexcitation within 1 h. Treatment with bosentan was also effective in reducing the mid-frequency oscillations in blood pressure associated with subarachnoid haemorrhage. 4. Our results indicate that subarachnoid haemorrhage is associated with an acute activation of the sympathetic nervous system. The degree of sympathoexcitation can be reversed by the use of either bosentan or SNP.

Central autonomic dysorganization in the early stages of experimental meningitis in rabbits induced by complement-C5A-fragment: a pathophysiological validation of the largest lyapunov exponent of heart rate dynamics

In a study of central autonomic organization in early stages of experimental meningitis in rabbits, the temporal oscillations of the momentary heart rate (heart rate dynamics) were measured. In 10 anesthetized rabbits an experimental meningitis was induced by intracisternal injection of complement-C5a-fragment in a carrier solution of sodium chloride and bovine serum albumin. 10 rabbits were injected with the above carrier solution only and served as controls. The temporal structure of the heart rate dynamics was operationalized phase-space analytically through the estimation of the largest Lyapunov exponent. Without exception, positive Lyapunov exponents of the heart rate dynamics were found, which revealed chaotic oscillations. In contrast to the controls, the intracisternal injection of C5a caused a significant decrease of the analytical index and reduced its reproducibility significantly. This result suggests a subtle central-autonomic dysfunction and a loss of the autonomic steady-state induced by the acute inflammatory process.