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Autonomic Dysfunction Contributes to Impairment of Cerebral Autoregulation in Patients with Epilepsy.

ABSTRACT: Patients with epilepsy frequently experience autonomic dysfunction and impaired cerebral autoregulation. The present study investigates autonomic function and cerebral autoregulation in patients with epilepsy to determine whether these factors contribute to impaired autoregulation. A total of 81 patients with epilepsy and 45 healthy controls were evaluated, assessing their sudomotor, cardiovagal, and adrenergic functions using a battery of autonomic nervous system (ANS) function tests, including the deep breathing, Valsalva maneuver, head-up tilting, and Q-sweat tests. Cerebral autoregulation was measured by transcranial Doppler examination during the breath-holding test, the Valsalva maneuver, and the head-up tilting test. Autonomic functions were impaired during the interictal period in patients with epilepsy compared to healthy controls. The three indices of cerebral autoregulation-the breath-holding index (BHI), an autoregulation index calculated in phase II of the Valsalva maneuver (ASI), and cerebrovascular resistance measured in the second minute during the head-up tilting test (CVR_2-min)-all decreased in patients with epilepsy. ANS dysfunction correlated significantly with impairment of cerebral autoregulation (measured by BHI, ASI, and CVR_2-min), suggesting that the increased autonomic dysfunction in patients with epilepsy may augment the dysregulation of cerebral blood flow. Long-term epilepsy, a high frequency of seizures, and refractory epilepsy, particularly temporal lobe epilepsy, may contribute to advanced autonomic dysfunction and impaired cerebral autoregulation. These results have implications for therapeutic interventions that aim to correct central autonomic dysfunction and impairment of cerebral autoregulation, particularly in patients at high risk for sudden, unexplained death in epilepsy.

SUBMITTER: Chen SF

PROVIDER: S-EPMC8073240 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:We examined whether the efficacy of steady-state cerebral autoregulation (CA) is reduced in older adults with amnestic mild cognitive impairment (aMCI), a prodromal stage of clinical Alzheimer disease (AD). Forty-two patients with aMCI and 24 cognitively normal older adults (NC) of similar age, sex, and education underwent stepwise decreases and increases in mean arterial pressure (MAP) induced by intravenous infusion of sodium nitroprusside and phenylephrine, respectively. Changes in cerebral blood flow (CBF) were measured repeatedly in the internal carotid and vertebral artery. Linear mixed modeling, including random effects of both individual intercept and regression slope, was used to quantify the MAP-CBF relationship accounting for nonindependent, repeated CBF measures. Changes in end-tidal CO2 (EtCO2) associated with changes in MAP were also included in the model to account for their effects on CBF. Marginal mean values of MAP were reduced by 13-14 mmHg during sodium nitroprusside and increased by 20-24 mmHg during phenylephrine infusion in both groups with similar doses of drug infusion. A steeper slope of changes in CBF in response to changes in MAP was observed in aMCI relative to NC, indicating reduced efficacy of CA (MAP × Group, P = 0.040). These findings suggest that cerebrovascular dysfunction may occur early in the development of AD.NEW & NOTEWORTHY Cerebral autoregulation is a fundamental regulatory mechanism to protect brain perfusion against changes in blood pressure that, if impaired, may contribute to the development of Alzheimer's disease. Using a linear mixed model, we demonstrated that the efficacy of cerebral autoregulation, assessed during stepwise changes in arterial pressure, was reduced in individuals with amnestic mild cognitive impairment, a prodromal stage of Alzheimer's disease. These findings support the hypothesis that cerebrovascular dysfunction may be an important underlying pathophysiological mechanism for the development of clinical Alzheimer's disease.

Project description:Clinical monitoring of cerebral blood flow (CBF) autoregulation in patients undergoing liver transplantation may provide a means for optimizing blood pressure to reduce the risk of brain injury. The purpose of this pilot project is to test the feasibility of autoregulation monitoring with transcranial Doppler (TCD) and near-infrared spectroscopy (NIRS) in patients undergoing liver transplantation and to assess changes that may occur perioperatively.We performed a prospective observational study in 9 consecutive patients undergoing orthotopic liver transplantation. Patients were monitored with TCD and NIRS. A continuous Pearson's correlation coefficient was calculated between mean arterial pressure (MAP) and CBF velocity and between MAP and NIRS data, rendering the variables mean velocity index (Mx) and cerebral oximetry index (COx), respectively. Both Mx and COx were averaged and compared during the dissection phase, anhepatic phase, first 30 min of reperfusion, and remaining reperfusion phase. Impaired autoregulation was defined as Mx ? 0.4.Autoregulation was impaired in one patient during all phases of surgery, in two patients during the anhepatic phase, and in one patient during reperfusion. Impaired autoregulation was associated with a MELD score >15 (p = 0.015) and postoperative seizures or stroke (p < 0.0001). Analysis of Mx categorized in 5 mmHg bins revealed that MAP at the lower limit of autoregulation (MAP when Mx increased to ? 0.4) ranged between 40 and 85 mmHg. Average Mx and average COx were significantly correlated (p = 0.0029). The relationship between COx and Mx remained when only patients with bilirubin >1.2 mg/dL were evaluated (p = 0.0419). There was no correlation between COx and baseline bilirubin (p = 0.2562) but MELD score and COx were correlated (p = 0.0458). Average COx was higher for patients with a MELD score >15 (p = 0.073) and for patients with a neurologic complication than for patients without neurologic complications (p = 0.0245).These results suggest that autoregulation is impaired in patients undergoing liver transplantation, even in the absence of acute, fulminant liver failure. Identification of patients at risk for neurologic complications after surgery may allow for prompt neuroprotective interventions, including directed pressure management.

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Autonomic Dysfunction Contributes to Impairment of Cerebral Autoregulation in Patients with Epilepsy.

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