Plasma 3-methoxy-4-hydroxyphenylethyleneglycol and homovanillic acid concentrations in patients with subarachnoid hemorrhage

Blood pressure changes after aneurysmal subarachnoid hemorrhage and their relationship to cerebral vasospasm and clinical outcome

OBJECTIVE

Cerebral vasospasm (VS) and resulting delayed ischemic brain injury constitute the most severe secondary complication after subarachnoid hemorrhage (SAH). Identification of early clinical predictors of developing vasospasm and poor outcome has remained a major challenge in neurointensive care medicine. Aim of the present study was analyze the relevance of spontaneous changes in blood pressures and their predictive value for predicting vasospasm as well as adverse clinical outcome.

METHODS

98 aneurysmal SAH patients were analyzed retrospectively. Patients were divided into two study groups: (1) VS+ (developing VS) and (2) VS- (not developing VS). Repeat-angiography was routinely performed on day 8 after SAH or earlier if clinical signs were suggestive for overt vasospasm. Systolic, diastolic and mean blood pressures were averaged hourly and plotted over time. Secondly, blood pressure (BP)-progression was analyzed with respect to clinical outcomes as assessed by the Glasgow outcome scale.

RESULTS

Mean, systolic, and diastolic blood pressure values progressed in both VS- and VS+ cohorts over time. However, as early as 4 days after SAH a significant dissociation of RR curves was observed between the groups with patients in the VS+ group displaying a significantly higher slope coefficient of blood pressure elevation. An increase of mean arterial pressure >20% within the first 4 days was predictive of developing vasospasm. Elevation of mean arterial blood pressure in the VS+ group was mainly attributable to changes in diastolic pressure. Elevation of mean arterial blood pressure >25% within the first week after SAH was associated with unfavorable outcome.

CONCLUSIONS

SAH leads to spontaneous and progressive elevations in mean arterial blood pressure. Vasospasm might be anticipated by identifying early elevations of mean arterial blood pressure. Finally, spontaneous elevations of mean arterial blood pressure correlate with poorer outcomes.

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.

Cisternal MHPG level inversely correlates with Glasgow coma scale after aneurysmal subarachnoid hemorrhage

We measured the concentrations of monoamines and amino acids in the cisternal cerebrospinal fluid obtained from 15 patients after aneurysmal subarachnoid hemorrhage. Based on the Glasgow Coma Scale (GCS), the patients were divided into two conscious (GCS always 14 or better from the third post-operative day to Day 12; n = 8) and unconscious groups (n = 7). We examined the concentrations of monoamines and amino acids between the two groups and evaluated the correlation between the concentrations and the GCS at CSF sampling. The concentration of MHPG was significantly higher in the unconscious than in the conscious group from Days 4 to 12. A significant inverse correlation was observed between the MHPG concentration and the GCS (r = approximately 0.635, p < 0.0001). Measuring the cisternal MHPG concentration may be useful for estimating convalescence after subarachnoid hemorrhage.

Noradrenaline synthesis, release and vesicular transport in the rat brain following subarachnoid haemorrhage

The present study was designed to estimate the release of noradrenaline, and to evaluate the efficiency of noradrenaline vesicular transport, as indicated from measures of dihydroxyphenylglycol (DHPG), and synthesis in the medulla and hypothalamus following subarachnoid haemorrhage in rats. Subarachnoid haemorrhage was induced by the injection of homologous blood into the cisterna magna (n = 11). Sham operated animals served as controls (n = 11). Three days following subarachnoid haemorrhage, medulla and hypothalamus were dissected and placed in an in vitro superfusion system. Exposure to K(+) (50 mM) for 2 min served as a stimulus for the release of the neurotransmitter noradrenaline, its precursor (dihydroxyphenylalanine [DOPA]) and intraneuronal metabolite, DHPG. Basal noradrenaline overflow from both the medulla and hypothalamus were similar in the two groups of rats but basal DOPA overflow from the medulla was significantly reduced in the subarachnoid haemorrhage animals (0.97 +/- 0.15 vs. 1.97 +/- 0.38 pg/10 min/mg, p < 0.01). Administration of K(+) induced the release of noradrenaline, the response from the medulla in the subarachnoid haemorrhage group being attenuated (p < 0.01) compared with the sham operated animals (174% and 240%, respectively). K(+) induced a similar release of noradrenaline from the hypothalamus in both groups of rats (239% in sham animals and 283% in the subarachnoid haemorrhage group). The overflow of DHPG from both the hypothalamus and medulla was similar in both groups of animals. Our results suggest that the diminution in noradrenaline release from the medulla occurs as a result of a reduction in the rate of noradrenaline synthesis and release.

Time-course alterations of monoamine levels and cerebral blood flow in brain regions after subarachnoid hemorrhage in rats

To investigate the possible correlation between changes in monoaminergic neuronal activity and cerebral blood flow (CBF) in the same brain region after subarachnoid hemorrhage (SAH), monoamine levels were analyzed by both HPLC-ECD and fluorohistochemistry techniques, and CBF was measured by using colored microspheres. At the second day of SAH, significant and nonsignificant reductions in blood flow were seen in the examined brain regions with a marked increase in CBF appearing in the telencephalon and hypothalamus on the third day. Significant reductions of monoamine levels in most brain regions were also observed on the second day after SAH, whereas norepinephrine (NE) levels in midbrain increased to 1.5 times compared to the normal level. These reductions were sustained until the fourth day of SAH, although at the third day, serotonin (5-HT) and dopamine levels in the hippocampus and 5-HT levels in the cerebelium were significantly elevated. In fluorohistochemical studies, the fluoro-intensities of monoamines, particularly catecholamines, in the midbrain dorsal NE bundle were enhanced at the second day after SAH. These NE neurons originated from the A5 cell group close to the area where homologous blood was applied through the cisterna magna. The results obtained after SAH show an apparent correlation between changes in monoamine levels and CBF in norepinephrine (NE)-rich areas. These results suggest that SAH-induced neuronal dysfunctions, particularly with NE neurons, are caused not only by reductions of blood flow but also by hemorrhage.