Autonomic dysfunction and treatment strategies in intracerebral hemorrhage

AIMS

Autonomic dysfunction with central autonomic network (CAN) damage occurs frequently after intracerebral hemorrhage (ICH) and contributes to a series of adverse outcomes. This review aims to provide insight and convenience for future clinical practice and research on autonomic dysfunction in ICH patients.

DISCUSSION

We summarize the autonomic dysfunction in ICH from the aspects of potential mechanisms, clinical significance, assessment, and treatment strategies. The CAN structures mainly include insular cortex, anterior cingulate cortex, amygdala, hypothalamus, nucleus of the solitary tract, ventrolateral medulla, dorsal motor nucleus of the vagus, nucleus ambiguus, parabrachial nucleus, and periaqueductal gray. Autonomic dysfunction after ICH is closely associated with neurological functional outcomes, cardiac complications, blood pressure fluctuation, immunosuppression and infection, thermoregulatory dysfunction, hyperglycemia, digestive dysfunction, and urogenital disturbances. Heart rate variability, baroreflex sensitivity, skin sympathetic nerve activity, sympathetic skin response, and plasma catecholamine concentration can be used to assess the autonomic functional activities after ICH. Risk stratification of patients according to autonomic functional activities, and development of intervention approaches based on the restoration of sympathetic-parasympathetic balance, would potentially improve clinical outcomes in ICH patients.

CONCLUSION

The review systematically summarizes the evidence of autonomic dysfunction and its association with clinical outcomes in ICH patients, proposing that targeting autonomic dysfunction could be potentially investigated to improve the clinical outcomes.

Data lake-driven analytics identify nocturnal non-dipping of heart rate as predictor of unfavorable stroke outcome at discharge

BACKGROUND

Post-stroke heart rate (HR) and heart rate variability (HRV) changes have been proposed as outcome predictors after stroke. We used data lake-enabled continuous electrocardiograms to assess post-stroke HR and HRV, and to determine the utility of HR and HRV to improve machine learning-based predictions of stroke outcome.

METHODS

In this observational cohort study, we included stroke patients admitted to two stroke units in Berlin, Germany, between October 2020 and December 2021 with final diagnosis of acute ischemic stroke or acute intracranial hemorrhage and collected continuous ECG data through data warehousing. We created circadian profiles of several continuously recorded ECG parameters including HR and HRV parameters. The pre-defined primary outcome was short-term unfavorable functional outcome after stroke indicated through modified Rankin Scale (mRS) score of > 2.

RESULTS

We included 625 stroke patients, 287 stroke patients remained after matching for age and National Institute of Health Stroke Scale (NIHSS; mean age 74.5 years, 45.6% female, 88.9% ischemic, median NIHSS 5). Both higher HR and nocturnal non-dipping of HR were associated with unfavorable functional outcome (p < 0.01). The examined HRV parameters were not associated with the outcome of interest. Nocturnal non-dipping of HR ranked highly in feature importance of various machine learning models.

CONCLUSIONS

Our data suggest that a lack of circadian HR modulation, specifically nocturnal non-dipping, is associated with short-term unfavorable functional outcome after stroke, and that including HR into machine learning-based prediction models may lead to improved stroke outcome prediction.

The Role of Arginine-Vasopressin in Stroke and the Potential Use of Arginine-Vasopressin Type 1 Receptor Antagonists in Stroke Therapy: A Narrative Review

Stroke is a life-threatening condition in which accurate diagnoses and timely treatment are critical for successful neurological recovery. The current acute treatment strategies, particularly non-invasive interventions, are limited, thus urging the need for novel therapeutical targets. Arginine vasopressin (AVP) receptor antagonists are emerging as potential targets to treat edema formation and subsequent elevation in intracranial pressure, both significant causes of mortality in acute stroke. Here, we summarize the current knowledge on the mechanisms leading to AVP hyperexcretion in acute stroke and the subsequent secondary neuropathological responses. Furthermore, we discuss the work supporting the predictive value of measuring copeptin, a surrogate marker of AVP in stroke patients, followed by a review of the experimental evidence suggesting AVP receptor antagonists in stroke therapy. As we highlight throughout the narrative, critical gaps in the literature exist and indicate the need for further research to understand better AVP mechanisms in stroke. Likewise, there are advantages and limitations in using copeptin as a prognostic tool, and the translation of findings from experimental animal models to clinical settings has its challenges. Still, monitoring AVP levels and using AVP receptor antagonists as an add-on therapeutic intervention are potential promises in clinical applications to alleviate stroke neurological consequences.

Integrative cerebral blood flow regulation in ischemic stroke

Optimizing cerebral perfusion is key to rescuing salvageable ischemic brain tissue. Despite being an important determinant of cerebral perfusion, there are no effective guidelines for blood pressure (BP) management in acute stroke. The control of cerebral blood flow (CBF) involves a myriad of complex pathways which are largely unaccounted for in stroke management. Due to its unique anatomy and physiology, the cerebrovascular circulation is often treated as a stand-alone system rather than an integral component of the cardiovascular system. In order to optimize the strategies for BP management in acute ischemic stroke, a critical reappraisal of the mechanisms involved in CBF control is needed. In this review, we highlight the important role of collateral circulation and re-examine the pathophysiology of CBF control, namely the determinants of cerebral perfusion pressure gradient and resistance, in the context of stroke. Finally, we summarize the state of our knowledge regarding cardiovascular and cerebrovascular interaction and explore some potential avenues for future research in ischemic stroke.

Autonomic Disturbances in Acute Cerebrovascular Disease

Autonomic disturbances often occur in patients with acute cerebrovascular disease due to damage of the central autonomic network. We summarize the structures of the central autonomic network and the clinical tests used to evaluate the functions of the autonomic nervous system. We review the clinical and experimental findings as well as management strategies of post-stroke autonomic disturbances including electrocardiographic changes, cardiac arrhythmias, myocardial damage, thermoregulatory dysfunction, gastrointestinal dysfunction, urinary incontinence, sexual disorders, and hyperglycemia. The occurrence of autonomic disturbances has been associated with poor outcomes in stroke patients. Autonomic nervous system modulation appears to be an emerging therapeutic strategy for stroke management in addition to treatments for sensorimotor dysfunction.

Lateral medullary infarction with cardiovascular autonomic dysfunction: an unusual presentation with review of the literature

PURPOSE

We report an unusual case of lateral medullary infarction presenting with orthostatic hypotension with pre-syncope without vertigo or Horner's syndrome.

METHODS

Case report with review of the literature.

RESULTS

A 67-year-old man presented with pre-syncope and ataxia without vertigo. Initial brain CT and MRI were normal. Neurological evaluation revealed right-beating nystagmus with left gaze, vertical binocular diplopia, right upper-extremity dysmetria, truncal ataxia with right axial lateropulsion, and right-facial and lower extremity hypoesthesia. Bedside blood pressure measurements disclosed orthostatic hypotension. He had normal sinus rhythm on telemetry and normal ejection fraction on echocardiogram. A repeat brain MRI disclosed an acute right dorsolateral medullary infarct. Autonomic testing showed reduced heart rate variability during paced deep breathing, attenuated late phase II and phase IV overshoot on Valsalva maneuver, and a fall of 25 mmHg of blood pressure at the end of a 10-min head-up tilt with no significant change in heart rate. These results were consistent with impaired sympathetic and parasympathetic cardiovascular reflexes. He was discharged to acute rehabilitation a week later with residual right dysmetria and ataxia.

CONCLUSION

Lateral medullary infarctions are usually reported as partial presentations of classical lateral medullary syndrome with accompanying unusual symptoms ranging from trigeminal neuralgias to hiccups. Pre-syncope from orthostatic hypotension is a rare presentation. In the first 3-4 days, absence of early DWI MRI findings is possible in small, dorsolateral medullary infarcts with sensory disturbances. Physicians should be aware of this presentation, as early diagnosis and optimal therapy are associated with good prognosis.

Blood Pressure Variability in Acute Ischemic Stroke: Influence of Infarct Location in the Insular Cortex

Background: The aim of this study was to elucidate the influence of insular infarction on blood pressure (BP) variability and outcomes according to the region of the insular cortex affected. Methods: A total of 90 patients diagnosed with acute unilateral ischemic stroke were registered. The BP variability was calculated over 24 h after admission (hyperacute) and for 2–3 days after admission (acute). Patients were classified into groups of right and left, and then right anterior, right posterior, left anterior, and left posterior insular infarction. Results: Patients with insular infarction showed a significantly larger infarct volume, higher modified Rankin scale scores, and lower SD and coefficient of variation (CV) of ­systolic BP in the hyperacute phase than shown by patients without insular infarction (p < 0.01, p < 0.01, p = 0.02, and p = 0.03, respectively). The SD and CV of systolic BP in the hyperacute phase showed significant differences among the 3 groups with right insular infarction, with left insular infarction, and without insular infarction (p < 0.05 and p < 0.05, respectively). There was a tendency for the systolic BP variability to be lower in patients with right anterior insular infarction than in patients with infarcts in other areas. Conclusion: The right insular cortex, especially the anterior part, might be a hub for autonomic nervous regulation.

Heart rate variability and baroreceptor sensitivity in acute stroke: a systematic review

BACKGROUND

Autonomic nervous system dysfunction is common after acute stroke and is associated with elevated risk of cardiac arrhythmia and mortality. Heart rate variability and baroreceptor sensitivity have been investigated as parameters of autonomic nervous system dysfunction for the prediction of stroke outcome.

SUMMARY

We performed a systematic literature review on heart rate variability and baroreceptor sensitivity as parameters for autonomic nervous function in acute stroke. Twenty-two studies were included. Associations between heart rate variability or baroreceptor sensitivity and stroke severity, early and late complications, dependency and mortality were reported. However, interpretability of most studies and extrapolation to general stroke population are limited due to many confounding factors such as varying methodology, small sample sizes, survival selection, and exclusion of patients with frequently occurring comorbidities in stroke. Key issues, such as the effect of thrombolytic therapy on autonomic function, autonomic nervous system dysfunction in the hyperacute phase of stroke, and correlation with the risk of recurrent stroke have not been investigated. Also, nonlinear techniques have remained largely unexplored in this domain, in spite of their advantage to provide more solid evaluation in the occurrence of arrhythmia.

KEY MESSAGES

Cardiac autonomic dysfunction, represented by reduced heart rate variability or impaired baroreceptor sensitivity, is associated with stroke severity, early and late complications, dependency, and mortality. Large-scale prospective studies applying internationally accepted standards of measures for analysis of heart rate variability and baroreceptor sensitivity are needed in patients with acute stroke.

Autonomic dysfunction in acute ischemic stroke: an underexplored therapeutic area?

Impaired autonomic function, characterized by a predominance of sympathetic activity, is common in patients with acute ischemic stroke. This review describes methods to measure autonomic dysfunction in stroke patients. It summarizes a potential relationship between ischemic stroke-associated autonomic dysfunction and factors that have been associated with worse outcome, including cardiac complications, blood pressure variability changes, hyperglycemia, immune depression, sleep disordered breathing, thrombotic effects, and malignant edema. Involvement of the insular cortex has been suspected to play an important role in causing sympathovagal imbalance, but its exact role and that of other brain regions remain unclear. Although sympathetic overactivity in patients with ischemic stroke appears to be a negative prognostic factor, it remains to be seen whether therapeutic strategies that reduce sympathetic activity or increase parasympathetic activity might improve outcome.

Interplay between brain stem angiotensins and monocyte chemoattractant protein-1 as a novel mechanism for pressor response after ischemic stroke

Pressor response after stroke commonly leads to early death or susceptibility to stroke recurrence, and detailed mechanisms are still lacking. We assessed the hypothesis that the renin-angiotensin system contributes to pressor response after stroke by differential modulation of the pro-inflammatory chemokine monocyte chemoattractant protein-1 (MCP-1) in the rostral ventrolateral medulla (RVLM), a key brain stem site that maintains blood pressure. We also investigated the beneficial effects of a novel renin inhibitor, aliskiren, against stroke-elicited pressor response. Experiments were performed in male adult Sprague-Dawley rats. Stroke induced by middle cerebral artery occlusion elicited significant pressor response, accompanied by activation of angiotensin II (Ang II)/type I receptor (AT1R) and AT2R signaling, depression of Ang-(1-7)/MasR and Ang IV/AT4R cascade, alongside augmentation of MCP-1/C-C chemokine receptor 2 (CCR2) signaling and neuroinflammation in the RVLM. Stroke-elicited pressor response was significantly blunted by antagonism of AT1R, AT2R or MCP-1/CCR2 signaling, and eliminated by applying Ang-(1-7) or Ang IV into the RVLM. Furthermore, stroke-activated MCP-1/CCR2 signaling was enhanced by AT1R and AT2R activation, and depressed by Ang-(1-7)/MasR and Ang IV/AT4R cascade. Aliskiren inhibited stroke-elicited pressor response via downregulating MCP-1/CCR2 activity and reduced neuroinflammation in the RVLM; these effects were potentiated by Ang-(1-7) or Ang IV. We conclude that whereas Ang II/AT1R or Ang II/AT2R signaling in the brain stem enhances, Ang-(1-7)/MasR or Ang IV/AT4R antagonizes pressor response after stroke by differential modulations of MCP-1 in the RVLM. Furthermore, combined administration of aliskiren and Ang-(1-7) or Ang IV into the brain stem provides more effective amelioration of stroked-induced pressor response.

Benefits of using dexmedetomidine during carotid endarterectomy: A review

As per current recommendation, patients with acute ischemic stroke should be offered carotid endarterectomy (CEA) within 24-72 hours. The same applies to patients with recurrent transient ischemic attacks (TIA). This time is usually less for hemodynamic optimization of patients who’ve suffered acute ischemic stroke. Hence’ they are hemodynamically labile and can have accelerated hypertension on induction/extubation. This can have disastrous outcomes. It is a common practice among anesthesiologists to avoid angiotensin converting enzyme(ACE) inhibitors or angiotensin receptor blockers on the day of surgery. This also adds to hypertensive issues perioperatively. Dexmedetomidine is a wonderful drug which can be used during CEA. Due to its centrally mediated sympatholytic effect, it confers good hemodynamic control during induction, intraoperatively, and during extubation. We did a search on PubMed and Google for carotid endarterectomies done under general and locoregional anesthesia during which dexmedetomidine was used. The keywords used by us during the search were as follows: anesthesia, carotid endarterectomy, anesthesia. We also searched for use of dexmedetomidine infusion to attenuate hypertensive response to intubation and for providing stability in major surgeries like CABG, craniotomies, bariatric surgeries, and valve replacements.

Blood pressure at hospital admission and outcome after primary intracerebral hemorrhage

INTRODUCTION

The importance of the admission blood pressure (BP) for intracerebral hemorrhage (ICH) outcome is not completely clear. Our objective was to analyze the clinical impact of BP at hospital arrival in patients with primary ICH.

MATERIAL AND METHODS

We studied 316 patients (50% women, mean age: 64 years, 75% with hypertension history) with acute primary ICH. The first BP reading at admission was evaluated for its association with neuroimaging findings and outcome. A Cox proportional hazards model and Kaplan-Meier analyses were constructed to evaluate factors associated with in-hospital mortality.

RESULTS

Intraventricular irruption occurred in 52% of cases. A high frequency of third ventricle extension was observed in patients with BP readings in the upper quartiles of the distribution (systolic, diastolic, or mean arterial pressure). Blood pressure readings did not correlate with hematoma volumes. In-hospital case fatality rate was 46% (63% among those with ventricular irruption). Systolic BP (SBP) > 190 mm Hg was independently associated with in-hospital mortality in supratentorial (n = 285) ICH (hazard ratio: 1.19, 95% confidence interval: 1.02-1.38, for the highest vs. the lowest quartile) even after adjustment for known strong predictors (age, ICH volume, Glasgow coma scale and ventricular extension). Blood pressure was not significantly associated with ventricular extension or outcome in patients with infratentorial ICH.

CONCLUSIONS

A high BP on admission is associated with an increased risk of intraventricular extension and early mortality in patients with supratentorial ICH. However, a significant proportion of patients with high BP readings without ventricular irruption still have an increased risk of death.

Effects of 24-Hour Blood Pressure and Heart Rate Recorded With Ambulatory Blood Pressure Monitoring on Recovery From Acute Ischemic Stroke

Background and Purpose—

This study used ambulatory blood pressure (BP) monitoring to generate BP and heart rate (HR) profiles soon after stroke onset and evaluated the association between determined values and 3-month stroke outcomes.

Methods—

We analyzed 24-hour ambulatory BP monitoring records from 104 patients with acute ischemic stroke. Ambulatory BP monitoring was attached at the second and eighth hospitalization days (Days 1 and 7). Both BP and HR were characterized using baseline, mean, maximum, and minimum values and coefficient of variation during 24-hour recording periods. Outcomes at 3 months were assessed as independence according to a modified Rankin Scale score of ≤2 and poor according to the score of ≥5.

Results—

Sixty-six (63%) patients achieved independence and 12 (11%) had poor outcomes. Mean ambulatory BP monitoring values changed from 150.5±19.5/85.7±11.3 mm Hg on Day 1 to 139.6±19.3/80.0±11.7 mm Hg on Day 7. After multivariate adjustment, mean values of systolic BP (OR, 0.63; 95% CI, 0.45–0.85), diastolic BP (0.61; 0.37–0.98), pulse pressure (0.55; 0.33–0.85), and HR (0.61; 0.37–0.98) recorded on Day 1 as well as mean HR on Day 7 (0.47; 0.23–0.87) were inversely associated with independence and mean values of systolic BP (1.92; 1.15–3.68), diastolic BP (5.28; 1.92–22.85), and HR (4.07; 1.83–11.88) on Day 1 as well as mean HR on Day 7 (4.92; 1.36–36.99) were positively associated with a poor outcome.

Conclusions—

All of systolic BP, diastolic BP, pulse pressure, and HR on Day 1 and HR on Day 7 assessed using ambulatory BP monitoring were associated with outcomes of patients with stroke at 3 months.

High NIHSS values predict impairment of cardiovascular autonomic control

BACKGROUND AND PURPOSE

Stroke is frequently associated with autonomic dysfunction, which causes secondary cardiovascular complications. Early diagnosis of autonomic imbalance prevents complications, but it is only available at specialized centers. Widely available surrogate markers are needed. This study tested whether stroke severity, as assessed by National Institutes of Health Stroke Scale (NIHSS) scores, correlates with autonomic dysfunction and thus predicts risk of autonomic complications.

METHODS

In 50 ischemic stroke patients, we assessed NIHSS scores and parameters of autonomic cardiovascular modulation within 24 hours after stroke onset and compared data with that of 32 healthy controls. We correlated NIHSS scores with parameters of total autonomic modulation (total powers of R-R interval [RRI] modulation; RRI standard deviation [RRI-SD], RRI coefficient of variation), parasympathetic modulation (square root of the mean squared differences of successive RRIs, RRI-high-frequency-powers), sympathetic modulation (normalized RRI-low-frequency-powers, blood pressure-low-frequency-powers), the index of sympatho-vagal balance (RRI-LF/HF-ratios), and baroreflex sensitivity.

RESULTS

Patients had significantly higher blood pressure and respiration, but lower RRIs, RRI-SDs, RRI coefficient of variation, square root of the mean squared differences of successive RRIs, RRI-low-frequency-powers, RRI-high-frequency-powers, RRI-total powers, and baroreflex sensitivity than did controls. NIHSS scores correlated significantly with normalized RRI-low-frequency-powers and RRI-LF/HF-ratios, and indirectly with RRIs, RRI-SDs, square root of the mean squared differences of successive RRIs, RRI-high-frequency-powers, normalized RRI-high-frequency-powers, RRI-total-powers, and baroreflex sensitivity. Spearman-Rho values ranged from 0.29 to 0.47.

CONCLUSIONS

Increasing stroke severity was associated with progressive loss of overall autonomic modulation, decline in parasympathetic tone, and baroreflex sensitivity, as well as progressive shift toward sympathetic dominance. All autonomic changes put patients with more severe stroke at increasing risk of cardiovascular complications and poor outcome. NIHSS scores are suited to predict risk of autonomic dysregulation and can be used as premonitory signs of autonomic failure.