Autonomic dysfunction affects cerebral neurovascular coupling

Azevedo, Elsa; Castro, Pedro; Santos, Rosa; Freitas, João; Coelho, Teresa; Rosengarten, Bernhard; Panerai, Ronney B.

doi:10.1007/s10286-011-0129-3

Cited by 41 publications

(31 citation statements)

References 29 publications

(40 reference statements)

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“…Of note, these same fTCD parameters are known to be disturbed in patients with vascular dementia, diabetes mellitus and migraine attacks [29,30,31]. Although it is plausible that these fTCD results are related to endothelial dysfunction, we cannot exclude an autonomic nervous system involvement in the cerebrovascular regulation, as shown in other diseases associated with autonomic failure [32]. …”

Section: Discussionmentioning

confidence: 99%

Functional Transcranial Doppler: Presymptomatic Changes in Fabry Disease

Azevedo

Mendes²,

Seixas³

et al. 2012

Eur Neurol

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Background and Aim: Cerebrovascular disease may progress asymptomatically in the early stages of Fabry disease (FD). Our aim was to test whether functional transcranial Doppler (fTCD) could provide useful data in the evaluation of these presymptomatic FD patients. Methods: A cohort of 12 adult FD patients from families with the classical phenotype of the disease was evaluated with fTCD in the posterior cerebral artery. Results: Compared to healthy controls, resting blood velocities were significantly lower in the FD cohort (p = 0.032 for systolic, p = 0.021 for diastolic). FTCD suggested a disturbed neurovascular coupling in the visual cortex of FD patients, with lower gain (p = 0.007) and rate time (p = 0.019). Men had a significantly higher attenuation (p = 0.013) and lower natural frequency (p = 0.046) than the heterozygous women. Conclusion: These data are the first to suggest that patients with FD may develop cortical vascular dysfunction in the territory of the posterior circulation, early in the natural history of the disease. If the present findings are confirmed in larger, prospective studies, fTCD will be useful for assessing stroke risk in as yet asymptomatic FD patients, improving preventive therapeutic management.

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Section: Discussionmentioning

confidence: 99%

Functional Transcranial Doppler: Presymptomatic Changes in Fabry Disease

Azevedo

Mendes²,

Seixas³

et al. 2012

Eur Neurol

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“…Both the P1 and P2 segments have been utilized with similar results, however a consistent segment should be maintained throughout a given study. 52,55,73,92,93 Lastly, often only the posterior window is suitable for insonating intracranial vessels in the elderly, due to skull thickening with advancing age. 94 Some studies have reported that 10À15% of individuals will have inadequate windows for insonating intracranial cerebral vessels; 95 as such, it may be advantageous to utilize other techniques such as NIRS (see next section) in addition to TCD for studies in the elderly or those with related cerebrovascular pathology.…”

Section: Transcranial Dopplermentioning

confidence: 99%

“…52 The selective activation of the occipital lobe is achieved using repeatable and reliable stimuli involving an eyes-open task against a bright visual stimuli (reading, flashing screen, eyes tracking tester's moving hand, etc.). The visual stimulation provides a strong mechanistic model of neurovascular coupling that is somewhat independent of variable neuronal activation schemes (i.e., a variety of different visual spatial tasks elicit similar PCA hyperemic responses); 73 however, less is understood about the hyperemia response in MCA or anterior cerebral arteries to tasks of varying difficulties or under different states of motivation. Conventionally, after a 10À15 min period of quiet rest (to allow stabilization of blood volume and hemodynamic signals), 5À10 cycles are repeated where each cycle consists of a 20À30 s period of eyes-closed time followed by 30À40 s of eyes-open time.…”

Section: Eliciting the Neurovascular Coupling Responsementioning

confidence: 99%

“…Conventionally, after a 10À15 min period of quiet rest (to allow stabilization of blood volume and hemodynamic signals), 5À10 cycles are repeated where each cycle consists of a 20À30 s period of eyes-closed time followed by 30À40 s of eyes-open time. 52,73 The greater the number of cycles, the higher the signal-to-noise ratio; however, this obviously must be balanced with the time constraints of the study and the impact on the participants whom may be from a clinical population.…”

Section: Eliciting the Neurovascular Coupling Responsementioning

confidence: 99%

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Neurovascular coupling in humans: Physiology, methodological advances and clinical implications

Phillips

Chan

Zheng

et al. 2015

J Cereb Blood Flow Metab

319

364

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Neurovascular coupling reflects the close temporal and regional linkage between neural activity and cerebral blood flow. Although providing mechanistic insight, our understanding of neurovascular coupling is largely limited to nonphysiological ex vivo preparations and non-human models using sedatives/anesthetics with confounding cerebrovascular implications. Herein, with particular focus on humans, we review the present mechanistic understanding of neurovascular coupling and highlight current approaches to assess these responses and the application in health and disease. Moreover, we present new guidelines for standardizing the assessment of neurovascular coupling in humans. To improve the reliability of measurement and related interpretation, the utility of new automated software for neurovascular coupling is demonstrated, which provides the capacity for coalescing repetitive trials and time intervals into single contours and extracting numerous metrics (e.g., conductance and pulsatility, critical closing pressure, etc.) according to patterns of interest (e.g., peak/minimum response, time of response, etc.). This versatile software also permits the normalization of neurovascular coupling metrics to dynamic changes in arterial blood gases, potentially influencing the hyperemic response. It is hoped that these guidelines, combined with the newly developed and openly available software, will help to propel the understanding of neurovascular coupling in humans and also lead to improved clinical management of this critical physiological function.

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“…Due to technical reasons the postural condition of the patients varies with these approaches. A recent focus on a disturbed NVC has been outlined in stroke [6], Alzheimer [7], and autonomic failure [8] diseases. For these reasons, a better understanding of NVC mechanism in different orthostatic conditions can have an impact both in scientific and clinical grounds.…”

Section: Introductionmentioning

confidence: 99%

Adaptation of cerebral pressure-velocity hemodynamic changes of neurovascular coupling to orthostatic challenge

Castro

Santos

Freitas

et al. 2012

Perspectives in Medicine

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Neurovascular coupling (NVC), analysed by a control system approach, was shown to be unaffected by orthostatic challenge, but data is lacking regarding the mechanism of this interplay and the behaviour of other cerebrovascular reactivity parameters. We investigated the changes in different pressure-velocity models during functional transcranial Doppler (TCD), under different orthostatic conditions.Thirteen healthy volunteers performed a reading test stimulation task in sitting, supine and head-up tilt (HUT) positions. CBF velocity was monitored with TCD in the posterior cerebral artery, and blood pressure was monitored with Finapres. Cerebrovascular resistance index (CVRi) was compared to a two-parameter model including resistance-area product (RAP) and critical closing pressure (CrCP), in the maximal and in the stable phases of flow response to visual stimulation.All cerebrovascular resistance parameters decreased with visual stimulation but the magnitude of their variation in each orthostatic condition was not similar. From supine to HUT, CrCP variation decreased (both maximal and stable phase p = 0.001). CVRi variation increased from sitting to HUT positions (maximal p = 0.039; stable phase p = 0.033). RAP variation to visual stimulation did not change between the three positions (maximal p = 0.077; stable phase p = 0.188).A 2-parameter model of vascular resistance provided better discrimination for the effects of posture on NVC as shown by the adaptive changes in CrCP with orthostatic challenge, in comparison with the classical use of CVRi. These findings suggest that although NVC seemed unaffected by orthostatic challenge, more complex vasoregulative mechanisms are activated in different orthostatic conditions that could potentially be of diagnostic or prognostic value.

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Autonomic dysfunction affects cerebral neurovascular coupling

Abstract: These results demonstrate that cerebrovascular regulation is affected in FAP subjects with AF, and that it worsens with orthostasis.

Cited by 41 publications

References 29 publications

Functional Transcranial Doppler: Presymptomatic Changes in Fabry Disease

Functional Transcranial Doppler: Presymptomatic Changes in Fabry Disease

Neurovascular coupling in humans: Physiology, methodological advances and clinical implications

Adaptation of cerebral pressure-velocity hemodynamic changes of neurovascular coupling to orthostatic challenge

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