Impact of physiological factors on longitudinal structural MRI measures of the brain

Zahid, Uzma; Hedges, Emily; Dimitrov, M; Murray, Robin M.; Barker, Gareth J.; Kempton, Matthew J.

doi:10.1016/j.pscychresns.2022.111446

Cited by 9 publications

(8 citation statements)

References 40 publications

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“…In a second recent paper [ 12 ], the King’s College investigators looked at physiological parameters, such as relative dehydration occurring diurnally, that might affect intra-brain structural relationships. They found none.…”

Section: Discussionmentioning

confidence: 99%

Acute Heart Failure, 90-Day Mortality, and Gravitational Ischemia in the Brain

Jaster

Ottaviani

2022

Diagnostics

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During the 90 days following hospitalization for acute heart failure, the ejection fraction and type of discharge medications have been shown in clinical trials to have little effect on mortality. We examined the recent literature addressing brain-related etiologies of sudden death following heart failure. Two mechanisms of sudden unexpected death have been suggested to possibly result from four significant influences on pathophysiology in the brain. The two causes of sudden death are (1) severe cardiac arrhythmia and (2) neurogenic pulmonary edema. They are both mediated through the brainstem autonomic nuclei generally and executed specifically through the dorsal motor nucleus of the vagus nerve. The four significant influences on pathophysiology, all contributing to ischemia in the brainstem autonomic nuclei, are: (1) Hyper-stimulation of neurons in the solitary tract nucleus, increasing their metabolic requirements; (2) Inadequate blood flow at a vascular watershed terminus, perfusing the autonomic nuclei; (3) Additionally decreased blood flow, globally throughout the brain, following vasoconstriction related to relative hyperventilation and decreased pCO2 levels; (4) Gravitational ischemia in the brainstem caused by the weight of the cerebral hemispheres sitting above the brainstem. Changes in head tilt release gravitational ischemia in the brain. There is no specific head position relative to gravity that is considered favorable or unfavorable for an extended period of time, longer than 24 h. Even a small degree of head elevation, used in managing pulmonary congestion, may increase gravitational ischemia in the posterior fossa and brainstem. In this paper, we suggest a new and important research avenue for intervening in cardiac arrhythmias and preventing their occurrence through the non-invasive use of head-tilting and other head repositioning maneuvers. This could potentially help many geriatric patients with heart failure, who have decreased mobility in bed, and who tend to stay in one position longer, thereby increasing gravitational ischemia in the brain.

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Section: Discussionmentioning

confidence: 99%

Acute Heart Failure, 90-Day Mortality, and Gravitational Ischemia in the Brain

Jaster

Ottaviani

2022

Diagnostics

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“…12 While cross-sectional structural MRI studies show reasonably large case-control effect sizes in volume in the range of up to 5%-10%, within-subject brain morphometry studies show smaller regional brain volume change in the range of up to 0.5% per year. 12 We used only MRI acquired following a standardized protocol and field strengths were equivalent in 4/6 patients, but the results of this retrospective case series might be limited by the comparison of MRI recorded at different scanners in some of the patients. Nevertheless, we observed a volume loss of clearly more than 5% in all patients for cerebral GM, which is considered more than the expected variation resulting from the use of different scanners or physiological factors.…”

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

“…The accuracy and reproducibility of brain volumetry depend on field strength and protocol changes 12 . While cross‐sectional structural MRI studies show reasonably large case–control effect sizes in volume in the range of up to 5%–10%, within‐subject brain morphometry studies show smaller regional brain volume change in the range of up to 0.5% per year 12 . We used only MRI acquired following a standardized protocol and field strengths were equivalent in 4/6 patients, but the results of this retrospective case series might be limited by the comparison of MRI recorded at different scanners in some of the patients.…”

Section: Discussionmentioning

confidence: 99%

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Valproate associated brain volume‐loss in pediatric epilepsy—A case series

et al. 2023

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Brain atrophy associated with valproate therapy is known from single case reports and frequently accompanied by cognitive deterioration. We present a case series of incidental finding of brain volume‐loss in children treated with valproate and employed automatic brain volumetry to assess the effect size of volume loss. 3D T1w datasets were automatically segmented into white matter, gray matter, and cerebrospinal fluid using the SPM‐12 algorithm. Respective volumes of cerebrum and cerebellum were read out and normalized to the total intracranial volume.We identified six patients (median age 148.5 (85‐178) months) who had received valproate for a median time of 5 (2‐23) months prior to MRI in which a loss of brain volume was noted. None had reported the occurrence of new clinical symptoms. Volumetry showed a volume loss of up to 28% for cerebral GM, 25% for cerebellar GM, 10% for cerebral WM and 20% for cerebellar WM. A volume loss of >5% in at least one of the subvolumes was found in all patients, with the more prominent volume loss in the cerebrum and in gray matter. In one patient, post‐valproate MRI was available and showed normalization of brain volume. Our case series indicates that valproate therapy might be associated with an asymptomatic volume loss of brain parenchyma in children with epilepsy and that this volume loss is assessable with automatic volumetry.

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“…In a second recent paper [18], the King's College Investigators looked at physiological parameters, such as relative dehydration, occurring diurnally, that might affect intrabrain structural relationships. They found none.…”

Section: Spatial Relationships Of Brain Componentsmentioning

confidence: 99%

Acute Heart Failure, 90-day Mortality—and Gravitational Ischemia in the Brain

Jaster¹,

Ottaviani²

2022

Preprint

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During the 90 days following hospitalization for acute heart failure, ejection fraction and type of discharge medications have been shown in clinical trials to have little effect on mortality. We examined the recent literature addressing brain-related etiologies of sudden death following heart failure. Two mechanisms of sudden unexpected death have been suggested to possibly result from 4 significant influences on pathophysiology in the brain. The two causes of death are severe cardiac arrhythmia, and neurogenic pulmonary edema. They are both mediated through the brainstem autonomic nuclei generally, and executed specifically through the dorsal motor nucleus of the vagus nerve. The four significant influences on pathophysiology in the brainstem autonomic nuclei are: 1) Hyper-stimulation of neurons in the solitary tract nucleus, increasing their metabolic requirements; 2) Inadequate blood flow at a vascular watershed terminus; 3) Additionally decreased blood flow following vasoconstriction related to relative hyperventilation and decreased pCO2 levels; 4) Gravitational ischemia in the brain—caused by the weight of the brain mass sitting above the brainstem. Changes in head tilt release gravitational ischemia in the brain. There is no specific head position (relative to gravity) that is considered favorable or unfavorable for an extended period of time (i.e. more than 24 hours). Even a small degree of head elevation, used in managing pulmonary congestion, may increase gravitational ischemia in the posterior fossa and brainstem. In this paper we suggest a new and important research avenue for intervening in cardiac arrhythmias, and preventing their occurrence, through the non-invasive use of head-tilting, and other head repositioning maneuvers. This could potentially help many geriatric patients with heart failure, who have decreased mobility in bed, and who tend to stay in one position longer, thereby increasing gravitational ischemia in the brain.

show abstract

Impact of physiological factors on longitudinal structural MRI measures of the brain

Cited by 9 publications

References 40 publications

Acute Heart Failure, 90-Day Mortality, and Gravitational Ischemia in the Brain

Acute Heart Failure, 90-Day Mortality, and Gravitational Ischemia in the Brain

Valproate associated brain volume‐loss in pediatric epilepsy—A case series

Acute Heart Failure, 90-day Mortality—and Gravitational Ischemia in the Brain

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