Vestibular effects on cerebral blood flow

Serrador, Jorge M.; Black, F. Owen; Schlegel, Todd T.; Wood, Scott J.

doi:10.1038/npre.2008.2413.2

Cited by 6 publications

(8 citation statements)

References 8 publications

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“…It is also possible that the vestibular system played a role in the postural effect on cerebrovascular CO 2 reactivity. The vestibular system can affect cerebral flow velocity and cerebrovascular resistance when upright, likely an adaptive mechanism to help dilate the cerebral vessels [27]. However, given that we observed greater vasodilation (i.e., hypercapnic slope) when supine when there is no hydrostatic gradient, it seems unlikely the vestibular system had a significant impact on our findings.…”

Section: Effect Of Body Posture On Cerebrovascular Co 2 Reactivitymentioning

confidence: 56%

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Cerebrovascular reactivity and cerebral autoregulation are improved in the supine posture compared to upright in healthy men and women

et al. 2020

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Cerebrovascular reactivity and cerebral autoregulation are two major mechanisms that regulate cerebral blood flow. Both mechanisms are typically assessed in either supine or seated postures, but the effects of body position and sex differences remain unclear. This study examined the effects of body posture (supine vs. seated vs. standing) on cerebrovascular reactivity during hyper and hypocapnia and on cerebral autoregulation during spontaneous and slow-paced breathing in healthy men and women using transcranial Doppler ultrasonography of the middle cerebral artery. Results indicated significantly improved cerebrovascular reactivity in the supine compared with seated and standing postures (supine = 3.45±0.67, seated = 2.72±0.53, standing = 2.91±0.62%/mmHg, P<0.0167). Similarly, cerebral autoregulatory measures showed significant improvement in the supine posture during slow-paced breathing. Transfer function measures of gain significantly decreased and phase significantly increased in the supine posture compared with seated and standing postures (gain: supine = 1.98±0.56, seated = 2.37±0.53, standing = 2.36±0.71%/mmHg; phase: supine = 59.3±21.7, seated = 39.8±12.5, standing = 36.5±9.7˚; all P<0.0167). In contrast, body posture had no effect on cerebral autoregulatory measures during spontaneous breathing. Men and women had similar cerebrovascular reactivity and similar cerebral autoregulation during both spontaneous and slow-paced breathing. These data highlight the importance of making comparisons within the same body position to ensure there is not a confounding effect of posture.

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Section: Effect Of Body Posture On Cerebrovascular Co 2 Reactivitymentioning

confidence: 56%

“…Seven women had natural menstrual cycles. Three women were tested during the follicular phase (range: days 6-14) and four were tested in the luteal phase (range: days [24][25][26][27][28][29][30][31][32][33][34][35]. All women were confirmed not pregnant immediately prior to laboratory testing.…”

Section: Participantsmentioning

confidence: 99%

Cerebrovascular reactivity and cerebral autoregulation are improved in the supine posture compared to upright in healthy men and women

et al. 2020

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“…In humans, caloric vestibular stimulation (Cui et al, ), head pitch (Ray and Carter, ; Ray et al, ), and GVS (Bent et al, ; Grewal et al, ; James and Macefield, ; Voustianiouk et al, ) have all been demonstrated to alter sympathetic nerve activity (SNA) (for review, see Yates and Bronstein, ). Similarly, linear acceleration causes transient changes in blood pressure and blood flow (Cui et al, ; Serrador et al, ) that are attenuated in patients with bilateral vestibular deficits (Yates et al, ). Otolith activation by off‐vertical‐axis rotation produces an increase in muscle SNA in‐phase with the component associated with head‐up tilt and a decrease in this activity corresponding to the head‐down tilt component (Kaufmann et al, ).…”

Section: Discussionmentioning

confidence: 99%

“…This pathway maintains homeostasis through constant negative feedback activity. In contrast, the vestibular system appears to influence blood pressure through a more direct and feed‐forward mechanism that modulates blood pressure during changes in posture with respect to gravity (e.g., when rising from a seated or lying position) in order to maintain adequate blood flow to the brain (Dieterich and Brandt, ; Serrador et al, ). The existence of a functional connection between the vestibular system and blood pressure control mechanisms was hypothesized almost a century ago (Bradbury and Eggleston, ) and is now supported by a body of basic and clinical research (Fig.…”

mentioning

confidence: 99%

Projection neurons of the vestibulo‐sympathetic reflex pathway

Holstein

Friedrich

Martinelli

2014

J of Comparative Neurology

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Changes in head position and posture are detected by the vestibular system and are normally followed by rapid modifications in blood pressure. These compensatory adjustments, which allow humans to stand up without fainting, are mediated by integration of vestibular system pathways with blood pressure control centers in the ventrolateral medulla. Orthostatic hypotension can reflect altered activity of this neural circuitry. Vestibular sensory input to the vestibulo-sympathetic pathway terminates on cells in the vestibular nuclear complex, which in turn project to brainstem sites involved in the regulation of cardiovascular activity, including the rostral and caudal ventrolateral medullary regions (RVLM and CVLM, respectively). In the present study, sinusoidal galvanic vestibular stimulation was used to activate this pathway, and activated neurons were identified through detection of c-Fos protein. The retrograde tracer FluoroGold was injected into the RVLM or CVLM of these animals, and immunofluorescence studies of vestibular neurons were conducted to visualize c-Fos protein and FluoroGold concomitantly. We observed activated projection neurons of the vestibulo-sympathetic reflex pathway in the caudal half of the spinal, medial and parvocellular medial vestibular nuclei. Approximately two-thirds of the cells were ipsilateral to FluoroGold injection sites in both RVLM and CVLM and the remainders were contralateral. As a group, cells projecting to RVLM were located slightly rostral to those with terminals in CVLM. Individual activated projection neurons were multipolar, globular or fusiform in shape. This study provides the first direct demonstration of the central vestibular neurons that mediate the vestibulo-sympathetic reflex.

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“…Future research on the relationship between vestibular system integrity and symptoms of postural hypotension in older age is needed to verify this hypothesis. Nevertheless, recent work has demonstrated that activation of the vestibular system, especially the otolith organs, directly affects cerebral blood flow independently of blood pressure and end tidal carbon dioxide . Deficient otolith organs could therefore contribute to cerebral hypoperfusion, and it is well documented that cerebral hypoperfusion leads to symptoms of light‐headedness.…”

Section: Discussionmentioning

confidence: 99%