The urinary catecholamine and plasma cortisol levels in patients with subarachnoid haemorrhage

Immune activation in irritable bowel syndrome: what is the evidence?

Irritable bowel syndrome (IBS) is a chronic functional gastrointestinal disorder that is characterized by abdominal pain and an altered defecation pattern. It affects between 5 and 20% of the general population and can seriously impact quality of life. The pathophysiology of IBS is rather complex and multifactorial including, for example, altered signalling by the gut-brain axis, dysbiosis, abnormal visceral pain signalling and intestinal immune activation. The latter has gained particular interest in recent years, with growing insight into the bidirectional communication between the nervous system and the immune system. In this Review, we detail the current evidence suggesting that immune activation contributes to the pathology seen in patients with IBS and discuss the potential mechanisms involved. Moreover, we describe how immune mediators, particularly those released by mast cells, can directly activate or sensitize pain-transmitting nerves, leading to increased pain signalling and abdominal pain. Finally, we discuss the potential of interventions targeting immune activation as a new therapeutic strategy for patients suffering from IBS.

Urinary dysfunction in acute brain injury: A narrative review

The frontal lobe urinary control center is an important regulator of urinary function. Neurologic injury often causes damage or temporary dysfunction of this center and other related urinary control pathways. Little has been reported about this topic in the literature although a majority of neurologic injury patients suffer from some type of urinary dysfunction. In this review, we highlight what is known about urinary dysfunction based on injury type (traumatic brain injury, hemorrhagic stroke, ischemic stroke, subarachnoid hemorrhage, subdural hematoma, and epilepsy). We discuss both clinical and pre-clinical data and pinpoint areas warranting further investigation. In the final section, we provide proposed practice suggestions for managing these patients clinically with the intended goal for refinement in these approaches following further clinical trials.

Association of Angiotensin-Converting Enzyme Inhibitors with Increased Mortality Among Patients with Isolated Severe Traumatic Brain Injury

BACKGROUND

Traumatic brain injury (TBI) is associated with one-third of all deaths from trauma. Preinjury exposure to cardiovascular drugs may affect TBI outcomes. Angiotensin-converting enzyme inhibitors (ACEIs) exacerbate brain cell damage and worsen functional outcomes in the laboratory setting. β-blockers (BBs), however, appear to be associated with reduced mortality among patients with isolated TBI.

OBJECTIVE

Examine the association between preinjury ACEI and BB use and clinical outcome among patients with isolated TBI.

METHODS

A retrospective cohort study of patients age ≥ 40 years admitted to an academic level 1 trauma center with isolated TBI between January 2010 and December 2014 was performed. Isolated TBI was defined as a head Abbreviated Injury Scale (AIS) score ≥ 3, with chest, abdomen, and extremity AIS scores ≤ 2. Preinjury medication use was determined through chart review. All patients with concurrent BB use were initially excluded. In-hospital mortality was the primary measured outcome.

RESULTS

Over the 5-year study period, 600 patients were identified with isolated TBI who were naive to BB use. There was significantly higher mortality (P = .04) among patients who received ACEI before injury (10 of 96; 10%) than among those who did not (25 of 504; 5%). A multivariate stepwise logistic regression analysis revealed a threefold increased risk of mortality in the ACEI cohort (P < .001), which was even greater than the twofold increased risk of mortality associated with an Injury Severity Score ≥ 16. A second analysis that included patients who received preinjury BBs (n = 98) demonstrated slightly reduced mortality in the ACEI cohort with only a twofold increased risk in multivariate analysis (P = .05).

CONCLUSIONS

Preinjury exposure to ACEIs is associated with an increase in mortality among patients with isolated TBI. This effect is ameliorated in patients who receive BBs, which provides evidence that this class of medications may provide a protective benefit.

Spontaneous Subarachnoid Hemorrhage: Assessment of Prognosis and Initial Management in the Intensive Care Unit

Spontaneous subarachnoid hemorrhage (SAH) is asso ciated with high morbidity and mortality. Primary con servative or preoperative management in the intensive care unit aims at prevention, early detection, and treat ment of complications. In this article we review the literature on the value of initial clinical and laboratory findings in predicting complications and outcome after SAH. Current conservative management of SAH is briefly discussed.

Potential adverse effects of norepinephrine on cortical somatosensory-evoked potentials during carotid endarterectomy: a case report

The cerebral metabolic and vascular effects of intravenous norepinephrine have been shown in an animal model using somatosensory-evoked potentials (SSEPs). A case of intravenous norepinephrine resulting in a decrease in SSEP amplitude (of greater than 50%) despite no significant change in blood pressure, prior to cross-clamping during a carotid endarterectomy is presented. This finding may have implications for the use of norepinephrine in the critical care unit as well as the operating room.

Cortisol and adrenocorticotropic hormone dynamics in the acute phase of subarachnoid haemorrhage

OBJECTIVE

An adequate response of hypothalamic-pituitary-adrenal (HPA) axis is important for survival and recovery after a severe disease. The hypothalamus and the pituitary glands are at risk of damage after subarachnoid haemorrhage (SAH). A better understanding of the hormonal changes would be valuable for optimising care in the acute phase of SAH.

PATIENTS

Fifty-five patients with spontaneous SAH were evaluated regarding morning concentrations of serum (S)-cortisol and P-adrenocorticotropic hormone (ACTH) 7 days after the bleeding. In a subgroup of 20 patients, the diurnal changes of S-cortisol and P-ACTH were studied and urine (U)-cortisol was measured. The relationships of hormone concentrations to clinical and radiological parameters and to outcome were assessed.

RESULTS

S-cortisol and P-ACTH were elevated the day of SAH. S-cortisol concentrations below reference range were uncommon. Early global cerebral oedema was associated with higher S-cortisol concentrations at admission and a worse World Federation of Neurological Surgeons (WFNS) and Reaction Level Scale 85 grade. Global cerebral oedema was shown to be a predictor of S-cortisol at admittance. Patients in better WFNS grade displayed higher U-cortisol. All patients showed diurnal variations of S-cortisol and P-ACTH. A reversed diurnal variation of S-cortisol was more frequently found in mechanically ventilated patients. Periods of suppressed P-ACTH associated with S-cortisol peaks occurred especially in periods of secondary brain ischaemia.

CONCLUSION

There was an HPA response acutely after SAH with an increase in P-ACTH and S-cortisol. Higher U-cortisol in patients in a better clinical grade may indicate a more robust response of the HPA system. Global cerebral oedema was associated with higher S-cortisol at admission and was a predictor of S-cortisol concentrations. Global cerebral oedema may be the result of the stress response initiated by the brain injury. Periods of suppressed P-ACTH occurred particularly in periods of brain ischaemia, indicating a possible connection between brain ischaemia and ACTH suppression.

Relation between brain interstitial and systemic glucose concentrations after subarachnoid hemorrhage

OBJECT

The aim in the present investigation was to study the relation between brain interstitial and systemic blood glucose concentrations during the acute phase after subarachnoid hemorrhage (SAH). The authors also evaluated the effects of insulin administration on local brain energy metabolism.

METHODS

Nineteen patients with spontaneous SAH were prospectively monitored with intracerebral microdialysis (MD). The relation between plasma glucose and MD-measured interstitial brain glucose concentrations as well as the temporal pattern of MD glucose, lactate, pyruvate, glutamate, and glycerol was studied for 7 days after SAH. Using a target plasma glucose concentration of 5-10 mmol/L, the effect of insulin injection was also evaluated.

RESULTS

The mean (± SD) correlation coefficient between plasma glucose and MD glucose was 0.27 ± 0.27 (p = 0.0005), with a high degree of individual variation. Microdialysis glucose, the MD/plasma glucose ratio, and MD glutamate concentrations decreased in parallel with a gradual increase in MD pyruvate and MD lactate concentrations. There were no significant changes in the MD L/P ratio or MD glycerol levels. Insulin administration induced a decrease in MD glucose and MD pyruvate.

CONCLUSIONS

After SAH, there was a positive correlation between plasma and MD glucose concentrations with a high degree of individual variation. A gradual decline in MD glucose and the MD/plasma glucose ratio and an increase in MD pyruvate and MD lactate concentrations during the 1st week after SAH suggest a transition to a hyperglycolytic state with increased cerebral glucose consumption. The administration of insulin was related to a lowering of MD glucose and MD pyruvate, often to low levels even though plasma glucose values remained above 6 mmol/L. After SAH, the administration of insulin could impede the glucose supply of the brain.

Increased cortisol levels are associated with delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

BACKGROUND

Physiological reactions of the stress hormone cortisol include hyperglycemia, hypertension, and endothelium dysfunction. In patients with aneurysmal subarachnoid hemorrhage (SAH), hyperglycemia, hypertension, and endothelium dysfunction are associated with the occurrence of delayed cerebral ischemia (DCI). Therefore, the purpose of the present study was to investigate whether increased serum cortisol levels after aneurysmal SAH are associated with DCI occurrence.

METHODS

Blood samples were obtained at standard intervals after SAH. DCI was defined as the gradual onset of new focal neurological impairment, and/or a decreased level of consciousness of at least 2 points as recorded on the Glasgow Coma Scale. Correlation coefficients were calculated to investigate the associations between cortisol and serum glucose levels, and between cortisol and von Willebrand factor levels.

RESULTS

Thirty-one patients were included. Eleven patients (35%) developed DCI. Signs of DCI started at a median of 6 days (range 4-10 days). Patients who developed DCI had significantly higher cortisol levels than patients without DCI (P = 0.006). Statistically significant, but weak, correlations were observed between cortisol and serum glucose levels (r = 0.216, P = 0.006), and cortisol and von Willebrand factor levels (r = 0.282, P < 0.001).

CONCLUSIONS

Increased serum cortisol levels after SAH are associated with DCI occurrence and might be the link between the associations of hyperglycemia and endothelium dysfunction with DCI. It remains to be investigated whether the association between cortisol levels and DCI is independent from known prognostic baseline factors, such as amount of blood on admission CT scan.

Changes in level of consciousness and association with hyperglycemia as tool for predicting and preventing re-bleeding after spontaneous subarachnoid hemorrhage

INTRODUCTION

It is crucial to predict and prevent re-bleeding from ruptured intracranial aneurysms in patients with subarachnoid hemorrhage (SAH). During the prehospital period and on arrival to the hospital, blood glucose and serum potassium levels, as well as changes in levels of consciousness were assessed in patients in the acute stage of spontaneous subarachnoid hemorrhage. These assessments were analyzed as possible risk factors for re-bleeding and as potential contributors to the prevention of re-bleeding, both in prehospital care and after hospital admission.

METHODS

Upon the arrival of 202 patients with spontaneous subarachnoid hemorrhage, the following indications were examined retrospectively: (1) presence/absence of re-bleeding; (2) time interval between the onset of SAH and re-bleeding; (3) level of consciousness using the Glasgow Coma Scale (GCS) score before and on arrival; (4) amount and distribution of subarachnoid blood using Fisher's Computerized Tomography Classification; (5) blood pressure; (6) blood glucose concentration; and (7) serum potassium concentration. The patients were hospitalized in the Yokohama City University Critical Care and Emergency Center (Yokohama, Japan) between January 1991 and December 2000. The re-bleeding rate was analyzed using the chi-square (chi2 test, and the averages and standard deviations of hematological data were compared using the Mann-Whitney U-test. The level of statistical significance was set at p < 0.05.

RESULTS

The overall re-bleeding rate was 20.8%. Among 119 patients with a GCS score of 3-7 before arrival, 42 (35.3%) had re-bleeding, but none of the 83 patients with a GCS score of 8-15 before arrival had re-bleeding. Of 105 patients with a GCS score of 13-15 on arrival, 14 (51.8%) of 27 patients whose consciousness level was a GCS score of 3-7 before arrival experienced re-bleeding. The re-bleeding rate of this group was high. Moreover, this rebleeding group had a significantly higher blood glucose concentration than did the patients whose GCS score was 13-15 both before and on arrival. Between the patients with or without re-bleeding, there was no significant difference in the blood pressure on arrival or in distribution according to Fisher's Computerized Tomography Classification

CONCLUSION

Since the re-bleeding rate is high in patients who have hyperglycemia and a history of a level of consciousness as low as a GCS score of 3-7, a detailed assessment of level of consciousness and blood glucose tests performed on arrival provide important information that will contribute to predicting and preventing re-bleeding. This may be extended to the prehospital phase, because blood glucose tests are simple and safe when performed by paramedics.

Changes in plasma catecholamine levels following injection of prostaglandin F2alpha into the basal cistern in rabbits

We measured plasma epinephrine and norepinephrine concentrations in a rabbit model simulating subarachnoid hemorrhage (SAH), following the injection of prostaglandin F(2alpha) (PGF(2alpha)) into the basal cistern. In this model, plasma epinephrine values increased significantly (to 4.2-fold those before injection), substantially more than norepinephrine (which increased 1.3-fold) at 5 minutes (min) after PGF(2alpha) injection. Dissection of autonomic outflow from the cervical spinal cord or ligation of the suprarenal veins reduced the changes in plasma catecholamine concentrations associated with PGF(2alpha) injection. These results suggest that the sympathetic discharge seen after PGF(2alpha) injection into the basal cistern in rabbits occurred through the sympatho-adrenal pathways.

Initial hyperglycemia as an indicator of severity of the ictus in poor-grade patients with spontaneous subarachnoid hemorrhage

An association between hyperglycemia and outcome in spontaneous subarachnoid hemorrhage (SAH) has been sporadically reported. Our hypothesis was that hyperglycemia is a sign of central metabolic disturbance linked with specific appearances on computerized tomography (CT) scans reflecting different degrees of corresponding brain injury. The admission plasma glucose level, initial CT findings, and outcome after 6 months were analysed in a cohort of 99 patients with SAH in Hunt & Hess Grade IV or V. The CT scans were quantitatively assessed for subarachnoid blood, intracerebral hematoma, intraventricular hemorrhage, hydrocephalus, midline shift and compression of the perimesencephalic cisterns. These findings were combined to determine a three-point CT severity score. All patients showed elevated (>5.8 mmol/l) plasma glucose levels on admission. Mortality among 33 patients with glucose concentration below 9.0 mmol/l was 33.3%, 71.1% for the 45 patients with glucose level between 9.0 and 13.0 mmol/l, and 95.2% for the 21 patients with concentration above 13.0 mmol/l (P<0.0001). Glucose level was higher in Grade V than in Grade IV patients (mean+/-SD) (11.8+/-3.2 vs 9.8+/-2.9 mmol/l; P=0.0012). Patients with mild CT findings (n=10) had the lowest glucose level (8.9+/-1.8 mmol/l; P=0.0082), whereas patients with severe findings (n=56) had the highest glucose (11.4+/-3.5 mmol/l; P=0.011). Despite association with clinical grade and extent of CT findings, logistic multiple regression revealed the admission plasma glucose level to be an independent prognosticator of outcome. The prognostic potential of the initial plasma glucose level may be beneficial in management protocols of poor-grade SAH patients.

Brain IL-1beta increases neutrophil and decreases lymphocyte counts through stimulation of neuroimmune pathways

Leukocytosis after cerebral injury is well described and may participate in the generation of cerebral damage. However, the mechanisms of brain-induced leukocytosis are still speculative. Since it is known that proinflammatory cytokines are involved in neuroimmunomodulation and since others and we have demonstrated high cytokine levels in the cerebrospinal fluid following injury, we supposed that brain cytokines may also influence leukocyte counts. In order to evaluate this hypothesis, we established an animal model using continuous intracerebroventricular (i.c.v.), intrahypothalamic (i.h.), or intravenous infusion of the proinflammatory cytokines tumor necrosis factor (TNF)-alpha and IL-1beta. Controls received vehicle solution. With this experimental paradigm we could show that i.c.v. and i.h. infusion of IL-1beta but not TNF-alpha dramatically increased neutrophil counts, whereas lymphocytes dropped. Blocking the hypothalamic-pituitary-adrenal (HPA) axis by hypophysectomy abolished the neutrophilia, whereas the lymphopenia remained unchanged. Furthermore, application of the beta2-adrenoreceptor antagonist propranolol prevented the decrease of lymphocytes and diminished the neutrophilia. All parameters normalized within 48 h after termination of infusion. So, our results demonstrate that brain IL-1beta can modify blood leukocyte counts through stimulation of both the sympathetic nervous system (SNS) and the HPA axis.

Clinical implications of poststroke hypothalamo-pituitary adrenal axis dysfunction: A critical literature review

Persistent hypothalamo-pituitary adrenal axis dysregulation occurs in up to 40% of patients who have suffered a stroke. The degree of hypercortisolemia is partly determined by the size and site of the vascular lesion. Adrenocortical hyperactivity begins almost immediately after a cerebrovasacular infarct but is persistent in an important subgroup of patients. In the early poststroke period (1 day to 1 month) high corticosteroid levels correlate with the presence of an acute confusional state. In the medium term (1 month to 1 year) hypercortisolemia is associated with the development of a major depressive episode and also relates to functional outcome and survival. Neuroanatomical deficits (particularly in the frontal or medial temporal lobes), age of onset, cognitive impairment, and reduced functional status may act as maintaining factors in both the poststroke depression and the adrenocortical hyperactivity. Patients with persisting hypercortisolemia, with or without depression or cognitive impairment, have a worse prognosis with an increased mortality rate. The mechanism for this effect may involve induced hyperglycemia or direct glucocorticoid neurotoxicity, which impairs the brain's capacity for recovery. It is suggested that the cautions use of antiglucocorticoid strategies may be of value in the medical management of the neuropsychiatric complications that follow cerebrovascular accidents.

Cushing's 'variant' response (acute hypotension) after subarachnoid hemorrhage. Association with moderate intracranial tensions and subacute cardiovascular collapse

BACKGROUND AND PURPOSE

Hypertension is considered common and appropriate with subarachnoid hemorrhage (SAH), maintaining cerebral perfusion. Hypotension, in contrast, is considered rare and detrimental. This study was designed to assess the frequency of each in both acute and subacute phases of primary SAH.

METHODS

SAH was created by arterial rupture in spontaneously breathing rats under urethane anesthesia without craniotomy (n = 32). Arterial pressure and intracranial pressure (ICP) were monitored invasively.

RESULTS

After extensive extravasation, the mean ICP rose acutely from 8 +/- 1 to 53 +/- 4 mm Hg over 2.4 +/- 0.3 minutes. Acute pressor changes occurred transiently in 71%. The most common acute response was hypotension (63%). Hypertension, in contrast, was rare (6%); the remainder was invariant (29%). Hypertension was associated with significantly lower maximum ICP values (39 +/- 4 versus 69 +/- 4 mm Hg, P < .001) with a negative correlation between hypotension and delta ICP (r = -.7, P < .01). Distinct and independent of acute responses, hypotension also occurred subacutely as a cardiovascular collapse (38%).

CONCLUSIONS

In contrast to popular belief, the most common acute response with SAH is hypotension; hypertension is rare. This, in fact, is in full agreement with Cushing: hypertension was seen only with gradual delta ICPs. In contrast, a "variant" to the classic response (hypotension) occurred with sudden delta ICPs. In the present study, hypotension stanched SAH at lower maximum ICP values, and thus with less cerebral compression. Despite this, cardiovascular collapse developed in a large proportion irrespective of acute change. Such collapse without prior hypertension (94%) implies a nonadrenergic etiology.

Delayed cerebral ischaemia: the pathological substrate

Ischaemic complications both at the level of the cortex and the hypothalamus are well recognised after an aneurysmal subarachnoid haemorrhage. We have studied histological changes in the cortex (53 patients) and hypothalamus (48 patients) in patients who died after an aneurysmal subarachnoid haemorrhage. Cortical ischaemic lesions were demonstrated in 41 of the 53 patients studied. These changes were more common in patients who had impaired control of systemic blood pressure (p = 0.0004) and in patients who died gradually (p = 0.0003). Hypothalamic lesions were found in 24 of 48 patients studied; 23 of these patients had widespread associated changes in the cerebral cortex. Patients with moderate/severe cortical changes tended to have hypothalamic lesions and it was uncommon for patients with no cortical lesions to have changes in the hypothalamus (p = 0.0007). We believe that these histological changes are due to diffuse microangiopathy which develops slowly after a subarachnoid haemorrhage and affects the cortex and hypothalamus. Because the cortical lesions are widespread we postulate that they may be implicated in the aetiology of the well described psychosocial or cognitive problems in patients who survive a subarachnoid haemorrhage.

Plasma glucose levels and outcome after aneurysmal subarachnoid hemorrhage

Plasma glucose levels were studied in 616 patients admitted within 72 hours after subarachnoid hemorrhage (SAH). Glucose levels measured at admission showed a statistically significant association with Glasgow Coma Scale scores, Botterell grade, deposition of blood on computerized tomography (CT) scans, and level of consciousness at admission. Elevated glucose levels at admission predicted poor outcome. A good recovery, as assessed by the Glasgow Outcome Scale at 3 months, occurred in 70.2% of patients with normal glucose levels (< or = 120 mg/dl) and in 53.7% of patients with hyperglycemia (> 120 mg/dl) (p = 0.002). The death rates for these two groups were 6.7% and 19.9%, respectively (p = 0.001). The association was still maintained after adjusting for age (> or < or = 50 years) and thickness of clot on CT scans (thin or thick) in the subset of patients who were alert/drowsy at admission. Increased mean glucose levels between Days 3 and 7 also predicted a worse outcome; good recovery was observed in 132 (73.7%) of 179 patients who had normal mean glucose levels (< or = 120 mg/dl) and 160 (49.7%) of 322 who had elevated mean glucose levels (> 120 mg/dl) (p < 0.0001). Death occurred in 6.7% and 20.8% of the two groups, respectively (p < 0.0001). It is concluded that admission plasma glucose levels can serve as an objective prognostic indicator after SAH. Elevated glucose levels during the 1st week after SAH also predict a poor outcome. However, a causal link between hyperglycemia and outcome after delayed cerebral ischemia, although suggested by experimental data, cannot be established on the basis of this study.

Serum cortisol and outcome of ischemic brain infarction

The predictive value of serum cortisol level on the prognosis in acute brain infarction of the carotid circulation territory was studied in 101 patients younger than 70 years. The levels of 7 a.m. and 7 p.m. serum cortisol were measured initially and at 1 week. All patients underwent a computed cerebral tomography (CT) within 2 days of the onset of symptoms, and a second CT 3 weeks or 3 month later. Serum cortisol values predicted the stroke outcome. Both the 7 a.m. and the 7 p.m. values in the initial and 1-week samples correlated positively with the severity of hemiparesis on the corresponding days. The 7 p.m. values predicted better than the 7 a.m. values the functional outcome and case fatality during the 3 month follow-up. Initially and at 1 week, the median 7 p.m. serum cortisol values were statistically significantly higher in those with frontally extending infarcts than in those with non-frontal infarcts. Both 7 a.m. fasting blood glucose and glycosylated hemoglobin (HbA1c) measurements were taken within 3 days of the onset in 95 cases. The patients were diagnosed to have prestroke normoglycemia (n = 73) and hyperglycemia (n = 22) on the basis of the HbA1c level. A highly significant (P = 0.0001) correlation was demonstrated between the initial 7 p.m. cortisol and 7 a.m. fasting blood glucose values in those with prestroke normoglycemia, suggesting that hyperglycemia during the acute phase of stroke is a stress response.

Levels of catecholamine in plasma and cerebrospinal fluid in aneurysmal subarachnoid hemorrhage

Despite intensive investigation into the cause of cerebral vasospasm (focal ischemic deficit) after subarachnoid hemorrhage, the morbidity and mortality associated with this condition remain high. Various studies have shown levels of catecholamine in plasma and cerebrospinal fluid (CSF) to be increased in subarachnoid hemorrhage, and it is possible that these vasoactive substances play an important role in the subsequent vasospasm. In an attempt to elucidate this possibility, the study presented here was undertaken to investigate the relationship between catecholamine levels in plasma and CSF and focal ischemic deficit (FID); the rupture of aneurysms on blood vessels supplying the hypothalamus as compared with the rupture of aneurysms on blood vessels supplying other areas of the brain; and the clinical outcome of the patients. Concentrations of adrenaline and noradrenaline in plasma and CSF samples obtained from 21 patients who had suffered aneurysmal subarachnoid hemorrhage were determined by a radioenzymatic technique. Significantly higher levels of adrenaline were found at the time of surgery in the CSF of patients with FID. A similar trend, though not statistically significant, was also observed for plasma. Patients with a rupture of aneurysms on blood vessels supplying the hypothalamus showed a tendency towards higher catecholamine levels in plasma and CSF. Subjects with a bad clinical outcome (i.e., those who were severely disabled or had died) had significantly higher levels of catecholamine in plasma than did those with a good clinical outcome (i.e., those with moderate or no disability). Further detailed analysis of the interrelationships showed that, within the group of patients with FID, those with rupture of aneurysms on blood vessels supplying the hypothalamus had significantly higher catecholamine levels in plasma than did those with rupture of aneurysms on other cerebral vessels. Furthermore, in the group of patients with rupture of aneurysms on blood vessels supplying the hypothalamus, those with a bad clinical outcome had significantly higher catecholamine levels in plasma than did those with a good clinical outcome. These findings lend support to the possibility that damage to the hypothalamus and subsequent elevations in catecholamine levels may be associated with FID and poor clinical outcome.

Autonomic and myocardial changes in middle cerebral artery occlusion: stroke models in the rat

Stroke models in larger animals such as the cat, dog and monkey are becoming increasingly more expensive and less readily available. However, the rat is an excellent model for focal cerebral ischemia. Rats are readily available, inexpensive and their neuroanatomy and brain function have been studied extensively. Increases in plasma catecholamines and myocardial damage have been observed in clinical stroke. We examined autonomic and myocardial changes in two rat stroke models. In one model only the middle cerebral artery was occluded (MCAO) while the other model involved occlusion of both the MCA and the common carotid artery (MCAO/CCAO). Arterial blood pressure and heart rate were monitored continuously in 25 male rats (326-430 g) that underwent one of the following procedures: (1) MCAO only; (2) MCAO/CCAO; (3) CCAO only; and (4) sham occlusions (SHAM). Arterial blood samples (0.5 ml) for radioenzymatic assay of norepinephrine (NE) and epinephrine (E) were taken twice before the occlusions and at 90 and 180 min after the occlusions. The animals were perfused at the end of the experiment and the heart removed and examined histologically. Tetrazolium salts were reacted with oxidative enzymes to delineate the region of inadequate perfusion. The mean blood pressure and pulse pressure of the SHAM, MCAO/CCAO and CCAO groups significantly declined from initial values (from an average of 78 to 53 mm Hg) during the course of the experiment. However, the mean blood pressure and pulse pressure of the MCAO rats did not change during the experiment, so that the final mean blood pressure and pulse pressure were significantly higher than in the other 3 groups. The levels of both NE and E increased significantly (NE, 1443 +/- 285.9 to 4095 +/- 929 pg/ml; E, 2402 +/- 623 to 3741 +/- 1166 pg/ml) following occlusion in the MCAO group only while the other 3 groups did not change. Four of 6 hearts in the MCAO group were abnormal, showing evidence of subendocardial hemorrhage, ischemic damage or subendocardial congestion. MCAO also resulted in a consistent region of the brain with inadequate perfusion including the insular cortex. These autonomic and myocardial changes appear to mimic some of the changes seen clinically in stroke patients and provide the first acute stroke model for studying autonomic dysfunction in the rat.

Blood pressure and both venous and urinary catecholamines after cerebral infarction

Blood pressure, both venous and urinary catecholamines and plasma renin activity (PRA) were studied in 10 patients (6 men and 4 women, mean age 70 +/- 10 years) on the first three days after cerebral infarction. Blood pressure fell significantly (p less than 0.02) on the second and third day after stroke. There was a small but significant (p less than 0.01) decrease in plasma epinephrine concentration on the third day. The norepinephrine values remained constant on the three days. The PRA showed a significant (p less than 0.01) rise on the third day. No significant correlation was detected between the course of the blood pressure and the plasma catecholamines or PRA. When blood pressure was correlated with the urinary catecholamines, however, a significant correlation with epinephrine (r = 0.45; p less than 0.05) and with norepinephrine (r = 0.44; p less than 0.05) was found. We conclude that the changes in blood pressure after stroke are at least partly mediated by the changes in catecholamine production.

Measurement of total circulating blood volume following subarachnoid haemorrhage: methodological aspects

The total circulating blood volume (TCBV) and total body/venous haematocrit ratio (Htb/Hv) was determined by simultaneous measurement of the red cell volume (RCV) and the plasma volume (PV) in 10 subarachnoid haemorrhage (SAH) patients, 10 supine bedresting control patients and 20 ambulant out-patients. The mean Htb/Hv of the SAH patients, 0.866, was found to be significantly lower than that of the supine controls, 0.908, and the ambulant patients, 0.909, (p less than 0.01). Using the ratio 0.866 the total circulating blood volume of the SAH patients was calculated from either their RCV or their PV and compared with their measured TCBV. Expressed as a percentage of measured TCBV the mean errors of these single volume determinations were 2.84% and 1.76% respectively. The significance of these changes in the Htb/Hv ratio of SAH patients is discussed in relation to the circulatory disturbances they suffer.

Catecholamines predict outcome in traumatic brain injury

Activation of the sympathetic nervous system attends traumatic brain injury, but the association of the severity of neurological impairment and recovery with the extent of sympathetic nervous system stimulation is poorly defined. In this study, plasma norepinephrine (NE), epinephrine (E), and dopamine (DA) levels were measured serially in 33 patients with traumatic brain injury and compared with the Glasgow Coma Score (GCS), which was obtained concurrently. A catecholamine gradient that reflected the extent of brain injury was demonstrated within 48 hours of the injury. In patients with a GCS of 3 to 4, NE and E levels increased four- to fivefold and the DA level increased threefold above normal (NE, 1686 +/- 416 pg/ml; E, 430 +/- 172 pg/ml; DA, 236 +/- 110 pg/ml), while patients with mild brain injury (GCS, greater than 11) had slightly elevated or normal levels. Patients with marked (GCS, 5 to 7) and moderate (GCS, 8 to 10) traumatic brain injuries had intermediate levels. The prognostic value of determining admission levels of NE was shown in patients with an admission GCS of 3 to 4 1 week after injury. Patients with severe and unchanging neurological impairment 1 week after injury had markedly elevated initial NE levels (2,176 +/- 531 pg/ml), whereas initial NE levels (544 +/- 89 pg/ml) were only mildly elevated in patients who improved to a GCS of greater than 11. These data indicate that markedly elevated NE levels predict outcome in patients with comparable neurological deficits. Thus levels of circulating catecholamines are excellent endogenous and readily quantifiable markers that appear to reflect the extent of brain injury and that may predict the likelihood of recovery.

Beta-adrenergic blockade after stroke. A preliminary closed cohort study

To collect background data for a prospective clinical trial of beta-blocking agents in the prevention of deaths after stroke, the long-term prognosis in 60 patients discharged from a stroke unit on beta-blocker therapy was compared with the outcome in 60 matched patients with stroke but without beta-blockers. Matching included sex, age, type of stroke, and presence or absence of hypertension and cardiac failure. Thirteen patients (22%) in the beta-blocker group died during a median followup of 41 months. Of the 60 patients not on beta-blockade at discharge, 21 (35%) died during a median followup of 36 months. By life-table technique and log-rank test, the relative risk for death was 0.60:1.00 (p = 0.14). During followup, 12 recurrent strokes were observed in patients on beta-blockers and 19 in patients without beta-blockers (relative risk 0.57:1.00; p = 0.12). It appeared that the reduction in mortality could only marginally be ascribed to fewer deaths from myocardial infarction; other causes of death were also less frequent in beta-blocker-treated patients. The results emphasize that supplementary information on the effect of beta-blocking agents on mortality after stroke is needed before a larger trial of beta-blocker therapy in patients with manifest cerebrovascular disease can be initiated.

Effect of selective lesions in the hypothalamic-pituitary region on the development of cerebral vasospasm following an experimental subarachnoid hemorrhage in the rat

Intracisternal injection of blood in the rat induced an angiographically demonstrable biphasic cerebral vasospasm with a maximal acute spasm at 10 min and a maximal late spasm at 2 days after the subarachnoid hemorrhage. Systemic administration of 6-hydroxydopamine, which destroys catecholamine fibers in the circumventricular areas characterized by the absence of a blood-brain barrier, prevented the development of both the acute and the late spasm. Isolation or removal of one of the circumventricular organs, the pituitary, from the brain via a stalk transection or a hypophysectomy did not affect the degree of vasospasm. Lesion of the median eminence, another region without a blood-brain barrier, prevented the development of both types of spasm. The median eminence receives projections from the A1 and A2 nuclei in the medulla oblongata. It is suggested that the projections of these nuclei to the internal layer of the median eminence underlie the development of spasm.

Adrenal enkephalin and catecholamine contents following subarachnoid hemorrhage in cats

A "closed space" subarachnoid hemorrhage (SAH) was produced experimentally in cats by rupture of the right middle cerebral artery to test the working hypothesis that a stressful event which provokes powerful sympathoadrenal discharge: causes a massive release of co-stored endogenous enkephalins together with catecholamines, induces an increased rate of opioid peptide precursor processing and/or synthesis, and eventually results in markedly elevated tissue levels of enkephalins relative to controls and to co-stored catecholamines. Adrenal medulla and other tissues were analyzed for met- and leu-enkephalins by RIAs and norepinephrine and epinephrine by HPLC-EC at 4 hrs, 3, 10, 16 and 30 days post-SAH. Catecholamines of adrenal medulla were already decreased at 4 hrs and by 3 days post-SAH depletion of epinephrine reached 86% and norepinephrine 53% compared to controls. Concurrently, at 4 hrs and 3 days post-SAH, the adrenal medulla was depleted 47% of met- and 53% of leu-enkephalins. By 10 days post-SAH, when catecholamines had regained control levels, met-enkephalin was elevated to 240% of control and 435% compared to the 3 day depletion; it remained elevated through 30 days post-SAH. In comparison, after 10 days reserpine treatment when catecholamines were markedly depleted, met-enkephalin rose to 970% and leu-enkephalin to 360% relative to controls, confirming recent reports in the literature. The data suggest that release of enkephalins originates primarily from epinephrine-type cells of the adrenal medulla in cat.

Activity of peripheral sympathetic efferent nerves in experimental subarachnoid haemorrhage. Part I: Observations at the time of intracranial hypertension

The origin and pathomechanism of vegetative disturbances in patients suffering from subarachnoid haemorrhage are not completely clarified. Since some of these alterations in vegetative functions may well be attributed to acute changes in sympathetic activity, we initiated a study to investigate this modality in experimentally induced subarachnoid haemorrhage. Experiments were performed on 51 cats, anaesthetized with alpha-chloralose and urethane, immobilized and artificially ventilated. Compound electrical discharges of the left vertebral, cardiac and renal sympathetic nerves, ECG, EEG, end-tidal CO2, systemic arterial blood pressure and intracranial pressure were recorded on a polygraph. Subarachnoid haemorrhage was simulated by the injection of 1-5 ml of fresh, autologous blood into the cisterna magna. Mock cerebrospinal fluid was also injected as a control. Our results showed that in induced subarachnoid haemorrhage, not the blood itself but the intracranial pressure elevation might be responsible for the strong increase in sympathetic efferent activity. With the direct recording of the electrical activity of the three sympathetic nerves, we were able to verify the sympathetic overactivity underlying the cardiovascular disturbances during intracranial pressure elevation. Regarding the mechanism of the overactivity, most probably not the ischaemia or hypoxia, but the mechanical distortion of the medulla could be the adequate stimulus of the sympathetic overactivity and the Cushing response during intracranial pressure elevation.

Characterization of beta adrenergic receptors in human cerebral arteries and alteration of the receptors after subarachnoid hemorrhage

The nature of beta adrenergic receptors in human cerebral arteries was characterized and alteration of these receptors after subarachnoid hemorrhage was examined using a radioligand binding assay. The specific 3H-dihydroalprenolol, a beta adrenergic antagonist, binding to human cerebral arteries was saturable and of high affinity (KD = 12.3 nM) with a Bmax of 790 fmol/mg protein. Ki values and Hill coefficients of adrenergic agents for 3H-dihydroalprenolol were as follows; propranolol, 4.1 X 10(-8)M, 1.01; isoproterenol, 1.7 X 10(-6)M, 0.80; epinephrine, 8.3 X 10(-6)M, 0.48; norepinephrine, 2.3 X 10(-5)M, 0.45; metoprolol, 6.8 X 10(-8)M and 7.9 X 10(-6)M, 0.62; butoxamine, 2.2 X 10(-8)M and 2.1 X 10(-6)M, 0.43. The analysis of inhibition of specific 3H-dihydroalprenolol binding by these adrenergic agents suggests that human cerebral arteries contain a high density of beta adrenergic receptors and that the receptors are classified into two types, namely beta 1 and beta 2 adrenergic receptors. The calculated beta 1/beta 2 ratio from Hofstee plots was approximately 4/6. KD and Bmax of 3H-dihydroalprenolol binding to the cerebral arteries after subarachnoid hemorrhage were compared with those of control group. KD and Bmax of 3H-dihydroalprenolol binding of subarachnoid hemorrhage group were 13.9 nM and 1140 fmol/mg protein, respectively. The calculated beta 1/beta 2 ratio was approximately 6/4. These data suggest that the density of total beta adrenergic receptors increased without any significant change in the affinity after subarachnoid hemorrhage and that the increase of beta 1 adrenergic receptors was dominant.

Direct evidence of hypertension and the possible role of post-menopause oestrogen deficiency in the pathogenesis of berry aneurysms

To determine the significance of hypertension in the pathogenesis of berry aneurysms, 113 patients with subarachnoid haemorrhage (SAH) and verified aneurysm and 63 patients with SAH without aneurysm were compared. Of those patients with angiographically verified aneurysms, 61.9% were found to have elevated blood pressure (greater than 160/95 mmHg) and 19.5% showed electrocardiographic signs of left ventricular hypertrophy (SV1 + RV5 (6) greater than 3.5 mV). The percentages for patients without aneurysm were 36.5% and 6.4% respectively. A significant correlation was found between anterior aneurysms and left ventricular hypertrophy (P less than 0.01). The mean Sokolow index values were also significantly elevated in cases of aneurysm (P less than 0.01). There was a complementary relationship between the extent of left ventricular hypertrophy and the percentage of females with regard to localization of an aneurysm and age group. The predominance of females in the total aneurysm population, in the 50- to 59-year-old age group, and among patients with internal carotid aneurysms indicates that a sex-specific hormonal factor may also play a role in the pathogenesis of aneurysms in addition to hypertension. The collagen wasting commonly observed in bone and skin in the post-menopausal period due to decreased oestrogen levels could possibly be responsible for the formation of aneurysms in the proximal segments of the cerebral arteries, as occurs in various connective tissue diseases.

Beta-blockade benefits patients following a subarachnoid haemorrhage

Previous studies have shown that ECG changes following a subarachnoid haemorrhage are associated with increased catecholamine levels, necrotic myocardial lesions, and a poor prognosis. Furthermore, beta-blockade using propranolol reverses some of the ECG changes and prevents necrotic myocardial lesions. This study was established to assess the affects of adrenergic blockade on morbidity and mortality following subarachnoid haemorrhage. Patients were admitted to the randomized double-blind between-patients study if they presented at the neurosurgical unit within 48 hours of a subarachnoid haemorrhage confirmed by lumbar puncture. Of 224 patients, the first 118 received an alpha-blocker, phentolamine 20 mg three-hourly, and either the beta-blocker propranolol 80 mg eight-hourly, or placebo. The last 106 patients received either propranolol or placebo. Treatment was continued for three weeks. Assessment at four weeks revealed significant improvements in the treated group for neurological deficit (p = 0.003) and death (p = 0.02). More treated patients underwent operation and those that did had a better outcome (p = 0.01). Assessment at one year showed that although patients had improved in both groups, patients in the treated group had significantly fewer neurological deficits (p = 0.003). There were fewer deaths in the treated group but this difference was not significant (p = 0.09). Possible mechanisms for this protective effect of propranolol may include a reduction in plasma renin activity, a reduction in pulmonary oedema, prevention of myocardial infarcts, and a reduction in cerebral oxygen requirements. It is concluded that early beta-blockade benefits patients with subarachnoid haemorrhage, in terms of fewer neurological deficits, for up to one year.

The angiopathy of subarachnoid hemorrhage I. Role of vessel wall catecholamines

Subarachnoid hemorrhage (SAH) due to rupture of the right middle cerebral artery (RMCA) produced specific anatomical and biophysiological responses in the involved feline vessels. The RMCA showed morphological alterations that became progressively more severe with time and were widespread within the cerebral vascular tree. SAH also resulted in an acute depletion of vessel catecholamine levels which remained depressed over a 30 day period. When the cerebral vessels of cats were severely depleted of catecholamines (using reserpine) prior to induced SAH, morphological alterations were significantly reduced both in severity and in degree of spread within the cerebral vascular network. The results of this study suggest that the concentration of norepinephrine within the vessel at the time of hemorrhage plays a significant role in the production of the angiopathy that follows SAH.

Cardiovascular response to severe head injury

The cardiovascular, pulmonary, and metabolic responses to severe head injury were studied clinically in the acute phase after severe head injury with the object of determining if a common response was present and, if so, its significance in the management of the patients' intracranial and systemic physiological states. Cardiac output, pulmonary capillary wedge pressure, arterial blood pressure, arterial and mixed venous blood gases, and arterial and mixed venous epinephrine (E) and norepinephrine (NE) levels were measured serially in 15 patients during the first 3 days after injury. A hyperdynamic state was found, characterized by increased cardiac output, cardiac work, moderate hypertension, tachycardia, decreased or normal systemic and pulmonary vascular resistance, increased pulmonary shunting, and increased oxygen delivery and utilization. Arterial E and NE levels correlated well with the cardiac output, cardiac work, blood pressure, heart rate, oxygen delivery, and oxygen utilization but not with vascular resistance or pulmonary shunt. The magnitude of the hyperdynamic state did not correlate with intracranial pressure, Glasgow Coma Scale score, or computerized tomography findings. It is concluded that a hyperdynamic cardiovascular state occurs after severe head injury, and that it is mediated in part by sympathetic nervous activity. The significance of this state for systemic management of patients with head injury is discussed.

Beneficial effects of adrenergic blockade in patients with subarachnoid haemorrhage

A total of 148 patients presenting within 48 hours of subarachnoid haemorrhage were assigned at random to receive standard management only or standard management and treatment with the adrenergic-blocking agents propranolol and phentolamine (or propranolol alone) for three weeks. One hundred and thirty-four patients completed the study. Assessment at four weeks showed a strong trend for less neurological deficit in the treated group, almost statistically significant (p=0.053) in the women. During the first month the treated group suffered fewer episodes of clinical deterioration consistent with cerebral arterial spasm: thus more treated patients underwent operation and those who did had a better outcome (p=0.030). At one year fewer were dead or disabled (unable to work) in the treated group; a significant difference for women (p=0.030). Possible mechanisms for these actions may include a reduction in pulmonary oedema, prevention of myocardial infarcts, a reduction in plasma renin activity, nd a reduction in cerebral oxygen requirements. It is concluded that early adrenergic blockade benefits patients (particularly women) with subarachnoid haemorrhage for up to one year in terms of lesser neurological deficit. Beta-blocker rather than alpha-blockade appears to be the useful component. A randomised, blind extension of the present study using long-acting propranolol and placebo has shown a significant (p=0.026) decrease in deaths and significantly (p=0.003) fewer poor results in the treatment group.

Electrocardiographic changes in acute ulcerative colitis

Two young women with acute ulcerative colitis were found to have electrocardiographic abnormalities which returned to normal with clinical improvement and corticosteroid therapy. Clinical and biochemical monitoring failed to reveal any cause for this previously unrecognized association and it is postulated that an aetiological agent or toxin produced by the inflammatory process may have damaged the myocardium or its autonomic supply.

Norepinephrine in cerebrospinal fluid of patients with cerebral vasospasm

The content of norepinephrine (NE) in the ventricular, basal cisternal, and lumbar cerebrospinal fluid (CSF) was determined in 19 patients with ruptured cerebral aneurysms at different intervals according to the presence or absence of vasospasm. Twelve were operated on within 3 days after subarachnoid hemorrhage (SAH), prior to the occurrence of vasospasm. Postoperatively, CSF was continuously drained from a basal cistern or lateral ventricle. Norepinephrine was assayed by the highly sensitive automated fluorometric method. The concentration of NE increased in all sites of CSF sampling along with the appearance of vasospasm. Above all, the cisternal CSF of patients with vasospasm contained significantly higher NE (0.246 +/- 0.049 ng/ml, mean +/- SEM) compared to those without vasospasm (0.075 +/- 0.001 ng/ml) (p less than 0.001). However, since this increase cannot be considered to be high enough locally to constrict cerebral arteries, this might be only a secondary phenomenon due to release of NE into CSF from various sources in the brain.

Plasma norepinephrine in stroke

Cardiac arrhythmias, myocardial necrosis and ECG abnormalities in stroke may result from abnormally high levels of sympathetic activity. To examine this possibility, plasma norepinephrine, epinephrine and dopamine were measured in 74 patients with cerebral infarction, 18 with transient ischemic attacks and 33 non-stroke controls. Mean norepinephrine, epinephrine and dopamine values (pg/ml) in cerebral infarction (433.2, 81.6, 75.6 were higher (p less than 0.01) than in controls (281.1, 60.1, 40.5, respectively). Transient ischemic attacks produced values intermediate to these two groups (391.3, 80.9, 54.9). The elevated catecholamine concentrations in cerebral infarction could not be explained by differences in age, blood pressure, heart rate, stress, type or severity of stroke. The high plasma norepinephrine in the stroke group is consistent with an increase in peripheral sympathetic activity which could produce the cardiac abnormalities of cerebral infarction.

A clinicopathological study of patients following a subarachnoid hemorrhage

The hypothalamus and myocardium of 54 patients (27 males and 27 females, age range 12 to 73 years) who died after subarachnoid hemorrhage (SAH) were examined histologically. In 42 patients, hypothalamic and myocardial lesions were found; in seven, hypothalamic lesions only; and in five, no hypothalamic nor myocardial lesions. A similar examination was performed on a control group of 25 patients (12 males and 13 females, age range 17 to 70 years) who had died from a variety of causes, all producing raised intracranial pressure. In these, no lesions were found in either the hypothalamus or the myocardium. The age of the patient, the site of the vascular pathology, and whether an operation was performed appeared to have no effect on the occurrence of hypothalamic and heart lesions; however, there was a correlation between these lesions, progressive neurological deterioration, and varying pulse rates and blood pressures. This study produces further evidence of the involvement of the autonomic nervous system in some of the deleterious effects of SAH, and a suggestion is made as to possible treatment.

Plasma catecholamine concentrations associated with cerebral vasospasm

Plasma concentrations of adrenaline and noradrenaline were measured sequentially over the immediate post-operative period following clipping of an intracranial aneurysm in 11 patients. Those patients who developed local cerebral vasospasm showed a sustained rise in plasma catecholamines, particularly noradrenaline, whilst those patients who developed generalised cerebral vasospasm showed early peaks of very high concentrations of adrenaline and noradrenaline which preceded radiological evidence of generalized vasospam.

Serum dopamine-beta-hydroxylase activity in acute stroke

Serum dopamine-beta-hydroxylase (DBH) activity was measured in 34 patients with acute cerebrovascular disease. The serum level of DBH activity showed its highest value soon after the onset of stroke and then gradually decreased over the next few days. After reaching its lowest level, the DBH activity again showed a slight increase. There was no direct relationship between serum DBH activity and total serum protein, or blood pressure. In 8 of 12 patients, DBH activity in the cerebral venous blood was higher than that in the arterial blood. These results suggest that rapid release of DBH into the circulating blood occurred after stroke, presumably from sympathetic nerve endings in the vessels or organs, including the brain.

Sympathetic nervous system activity in patients with subarachnoid hemorrhage

In patients with subarachnoid hemorrhage there were increased concentrations of plasma epinephrine and norepinephrine when compared with those concentrations in a group of patients admitted to hospital with other illness. Reassessment after a variable period showed that in patients whose eventual clinical result was poor the plasma epinephrine and norepinephrine concentrations increased further while in those with a good result those concentrations showed a decline. No such changes were evident in plasma dopamine-beta-hydroxylase activities which were within normal range. In a sub-group of patients who had neurosurgery after admission for clipping an aneurysm, the post-operative changes of plasma epinephrine and norepinephrine concentrations were related to the clinical condition of the patients.

Hypothalamic and myocardial lesions after subarachnoid haemorrhage

The hypothalamus and myocardium of 12 patients who had died after a subarachnoid haemorrhage, and of six patients who had died from other intracranial pathology were examined. Only in the patients who had died from subarachnoid haemorrhage were histological lesions found in both the hypothalamus and myocardium. The possible significance of these findings is discussed with particular reference to the sympathetic nervous system.

Brain energetics and circulatory control after subarachnoid hemorrhage

Ischemia-provoking factors such as vasospasm, decreased cerebral perfusion pressure, and intravascular thrombosis may be present after subarchnoid hemorrhage (SAH). When these factors were not present during controlled SAH, a primary depression of cerebral glycolysis associated with normal stores of energy-rich phosphates was found. Although cerebral blood flow usually changes in response to changes in cerebral metabolic needs, this influence on the circulation was not evident in the early hours after SAH. After 3 to 4 hours an erratic decrease in blood flow occurred, probably related to vasospasm, and there were measurable decreases in energy-rich phosphates similar to those occurring after more severe and prolonged ischemias. These findings are indicative of abnormally erratic vascular responses to metabolic cues and may play a role in producing the encephalopathy of SAH.

Paroxysmal hyperadrenergic state. A case during surgery for intracranial aneurysm

A case is reported of a patient with a cerebral aneurysm in whom it was difficult to induce hypotension. The hyperadrenergic state mimicked, in some respects, that seen in patients with neural crest lesions. Possible mechanisms are discussed and the anaesthetic management described.