1
|
Panerai RB, Hanby MF, Robinson TG, Haunton VJ. Alternative representation of neural activation in multivariate models of neurovascular coupling in humans. J Neurophysiol 2019; 122:833-843. [DOI: 10.1152/jn.00175.2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Neural stimulation leads to increases in cerebral blood flow (CBF), but simultaneous changes in covariates, such as arterial blood pressure (BP) and [Formula: see text], rule out the use of CBF changes as a reliable marker of neurovascular coupling (NVC) integrity. Healthy subjects performed repetitive (1 Hz) passive elbow flexion with their dominant arm for 60 s. CBF velocity (CBFV) was recorded bilaterally in the middle cerebral artery with transcranial Doppler, BP with the Finometer device, and end-tidal CO2 (EtCO2) with capnography. The simultaneous effects of neural stimulation, BP, and [Formula: see text] on CBFV were expressed with a dynamic multivariate model, using BP, EtCO2, and stimulation [ s( t)] as inputs. Two versions of s( t) were considered: a gate function [ sG( t)] or an orthogonal decomposition [ sO( t)] function. A separate CBFV step response was extracted from the model for each of the three inputs, providing estimates of dynamic cerebral autoregulation [CA; autoregulation index (ARI)], CO2 reactivity [vasomotor reactivity step response (VMRSR)], and NVC [stimulus step response (STIMSR)]. In 56 subjects, 224 model implementations produced excellent predictive CBFV correlation (median r = 0.995). Model-generated sO( t), for both dominant (DH) and nondominant (NDH) hemispheres, was highly significant during stimulation (<10−5) and was correlated with the CBFV change ( r = 0.73, P = 0.0001). The sO( t) explained a greater fraction of CBFV variance (~50%) than sG( t) (44%, P = 0.002). Most CBFV step responses to the three inputs were physiologically plausible, with better agreement for the CBFV-BP step response yielding ARI values of 7.3 for both DH and NDH for sG( t), and 6.9 and 7.4 for sO( t), respectively. No differences between DH and NDH were observed for VMRSR or STIMSR. A new procedure is proposed to represent the contribution from other aspects of CBF regulation than BP and CO2 in response to sensorimotor stimulation, as a tool for integrated, noninvasive, assessment of the multiple influences of dynamic CA, CO2 reactivity, and NVC in humans. NEW & NOTEWORTHY A new approach was proposed to identify the separate contributions of stimulation, arterial blood pressure (BP), and arterial CO2 ([Formula: see text]) to the cerebral blood flow (CBF) response observed in neurovascular coupling (NVC) studies in humans. Instead of adopting an empirical gate function to represent the stimulation input, a model-generated function is derived as part of the modeling process, providing a representation of the NVC response, independent of the contributions of BP or [Formula: see text]. This new marker of NVC, together with the model-predicted outputs for the contributions of BP, [Formula: see text] and stimulation, has considerable potential to both quantify and simultaneously integrate the separate mechanisms involved in CBF regulation, namely, cerebral autoregulation, CO2 reactivity and other contributions.
Collapse
Affiliation(s)
- Ronney B. Panerai
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
- National Institute for Health Research Leicester Biomedical Research Centre, University of Leicester, Leicester, United Kingdom
| | - Martha F. Hanby
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
| | - Thompson G. Robinson
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
- National Institute for Health Research Leicester Biomedical Research Centre, University of Leicester, Leicester, United Kingdom
| | - Victoria J. Haunton
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
- National Institute for Health Research Leicester Biomedical Research Centre, University of Leicester, Leicester, United Kingdom
| |
Collapse
|
2
|
Panerai RB, Haunton VJ, Hanby MF, Salinet ASM, Robinson TG. Statistical criteria for estimation of the cerebral autoregulation index (ARI) at rest. Physiol Meas 2016; 37:661-72. [DOI: 10.1088/0967-3334/37/5/661] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
3
|
Hanby MF, Al-Bachari S, Makin F, Vidyasagar R, Parkes LM, Emsley HCA. Structural and physiological MRI correlates of occult cerebrovascular disease in late-onset epilepsy. Neuroimage Clin 2015; 9:128-33. [PMID: 26413475 PMCID: PMC4556750 DOI: 10.1016/j.nicl.2015.07.016] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Late-onset epilepsy (LOE), with onset after 50 years of age, is often attributed to underlying occult cerebrovascular disease. LOE is associated with a three-fold increase in subsequent stroke risk, therefore it is important to improve our understanding of pathophysiology. In this exploratory study, we aimed to determine whether established structural magnetic resonance imaging markers and novel physiological imaging markers of occult cerebrovascular disease were more common in patients with LOE than age-matched controls. Sixteen patients with LOE (mean age ± SD: 67.6 ± 6.5 years) and 15 age-matched control subjects (mean age: 65.1 ± 3.9 years) underwent a 3 T MRI scan protocol. T1-weighted images and T2-weighted fluid attenuated inversion recovery (FLAIR) images were used to determine cortical grey matter volume and white matter hyperintensity (WMH) volume respectively, whilst multiple delay time arterial spin labelling (ASL) images were collected at rest and during a hypercapnic challenge. Cerebral blood flow (CBF) and arterial arrival time (AAT) were calculated from ASL data under both normocapnic and hypercapnic conditions. Cerebrovascular reactivity was also calculated for both CBF and AAT relative to the change in end-tidal CO2. Patients with LOE were found to have significantly lower cortical volume than control subjects (33.8 ± 3.8% of intracranial volume vs. 38.0 ± 5.5%, p = 0.02) and significantly higher WMH volume (1339 ± 1408 mm3 vs. 514 ± 481 mm3, p = 0.047). Baseline whole brain AAT was found to be significantly prolonged in patients with LOE in comparison to control subjects (1539 ± 129 ms vs. 1363 ± 167 ms, p = 0.005). Voxel-based analysis showed the significant prolongation of AAT to be predominantly distributed in the frontal and temporal lobes. Voxel-based morphometry showed the lower cortical volume to be localised primarily to temporal lobes. No significant differences in CBF or cerebrovascular reactivity were found between the two groups. Baseline whole brain AAT and cortical volume differences persisted upon further analysis to take account of differences in smoking history between patients and control subjects. These findings suggest that occult cerebrovascular disease is relevant to the pathophysiology of LOE. LOE patients were found to have increased WMHs and reduced GM volume on MRI imaging in comparison to HC. Baseline arterial arrival time was significantly longer in LOE patients than HC. Baseline cerebral blood flow did not differ between LOE patients and HC. Cerebrovascular reactivity did not differ between LOE patients and HC.
Collapse
Key Words
- AAT, arterial arrival time
- ASL, arterial spin labelling
- Arterial spin labelling
- CBF, cerebral blood flow
- CT, computerised tomography
- CVD, cerebrovascular disease
- CVR, cerebrovascular reactivity
- Cerebral blood flow
- Cerebrovascular disease
- EEG, electroencephalogram
- ETCO2, end-tidal CO2
- FLAIR, fluid attenuated inversion recovery image
- FWHM, full width half maximum
- GM, grey matter
- ICV, intracranial volume
- LOE, late-onset epilepsy
- Late-onset epilepsy
- MRI, magnetic resonance imaging
- MoCA, Montreal cognitive assessment
- SVD, small vessel disease
- Seizures
- VBA, voxel-based analysis
- VBM, voxel-based morphometry.
- Voxel-based morphometry
- WMH, white matter hyperintensity
- oCVD, occult cerebrovascular disease
Collapse
Affiliation(s)
- Martha F Hanby
- Centre for Imaging Science, Institute of Population Health, Faculty of Medical and Human Sciences, University of Manchester, Manchester, UK ; Department of Neurology, Royal Preston Hospital, Preston, UK
| | - Sarah Al-Bachari
- Centre for Imaging Science, Institute of Population Health, Faculty of Medical and Human Sciences, University of Manchester, Manchester, UK
| | - Fadiyah Makin
- Centre for Imaging Science, Institute of Population Health, Faculty of Medical and Human Sciences, University of Manchester, Manchester, UK
| | - Rishma Vidyasagar
- Centre for Imaging Science, Institute of Population Health, Faculty of Medical and Human Sciences, University of Manchester, Manchester, UK
| | - Laura M Parkes
- Centre for Imaging Science, Institute of Population Health, Faculty of Medical and Human Sciences, University of Manchester, Manchester, UK
| | - Hedley C A Emsley
- Department of Neurology, Royal Preston Hospital, Preston, UK ; Faculty of Medical and Human Sciences, University of Manchester, Manchester, UK
| |
Collapse
|
4
|
Al-Bachari S, Parkes LM, Vidyasagar R, Hanby MF, Tharaken V, Leroi I, Emsley HCA. Arterial spin labelling reveals prolonged arterial arrival time in idiopathic Parkinson's disease. Neuroimage Clin 2014; 6:1-8. [PMID: 25379411 PMCID: PMC4215519 DOI: 10.1016/j.nicl.2014.07.014] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 07/24/2014] [Accepted: 07/29/2014] [Indexed: 12/30/2022]
Abstract
Idiopathic Parkinson's disease (IPD) is the second most common neurodegenerative disease, yet effective disease modifying treatments are still lacking. Neurodegeneration involves multiple interacting pathological pathways. The extent to which neurovascular mechanisms are involved is not well defined in IPD. We aimed to determine whether novel magnetic resonance imaging (MRI) techniques, including arterial spin labelling (ASL) quantification of cerebral perfusion, can reveal altered neurovascular status (NVS) in IPD. Fourteen participants with IPD (mean ± SD age 65.1 ± 5.9 years) and 14 age and cardiovascular risk factor matched control participants (mean ± SD age 64.6 ± 4.2 years) underwent a 3T MRI scan protocol. ASL images were collected before, during and after a 6 minute hypercapnic challenge. FLAIR images were used to determine white matter lesion score. Quantitative images of cerebral blood flow (CBF) and arterial arrival time (AAT) were calculated from the ASL data both at rest and during hypercapnia. Cerebrovascular reactivity (CVR) images were calculated, depicting the change in CBF and AAT relative to the change in end-tidal CO2. A significant (p = 0.005) increase in whole brain averaged baseline AAT was observed in IPD participants (mean ± SD age 1532 ± 138 ms) compared to controls (mean ± SD age 1335 ± 165 ms). Voxel-wise analysis revealed this to be widespread across the brain. However, there were no statistically significant differences in white matter lesion score, CBF, or CVR between patients and controls. Regional CBF, but not AAT, in the IPD group was found to correlate positively with Montreal cognitive assessment (MoCA) scores. These findings provide further evidence of alterations in NVS in IPD. Investigation of neurovascular status (NVS) in IPD using arterial spin labelling Diffuse prolonged arterial arrival time in IPD compared to controls Reduced regional CBF in the IPD group correlated with cognitive impairment. Clinical evidence of altered NVS in IPD warrants further research.
Collapse
Key Words
- 3T, 3 Tesla
- AAT, arterial arrival time
- AD, Alzheimer’s disease
- ASL, arterial spin labelling
- Arterial arrival time
- Arterial spin labelling
- CBF, cerebral blood flow
- CO2, carbon dioxide
- CV, cerebrovascular
- CVD, cerebrovascular disease
- CVR, cerebrovascular reactivity
- CVRAAT, cerebrovascular reactivity measures of arterial arrival time
- CVRCBF, cerebrovascular reactivity measures of cerebral blood flow
- Cerebral blood flow
- Cerebrovascular reactivity
- DS, digit span
- DSST, digit symbol substitution test
- DWMH, deep white matter hyperintensity
- EPI, echo planar imaging
- ETCO2, end-tidal carbon dioxide
- FAS, (verbal) fluency assessment scale
- FLAIR, fluid attenuation inversion recovery
- FWE, family-wise error
- HAM-D, Hamilton depression rating scale
- IPD, idiopathic Parkinson's disease
- Idiopathic Parkinson's disease
- L-dopa, levodopa
- LARS, Lille apathy rating scale
- LEDD, levodopa equivalent daily dose
- MCI, mild cognitive impairment
- MRI, magnetic resonance imaging
- MoCA
- MoCA, Montreal cognitive assessment
- NPI, neuropsychiatric inventory
- NVU, Neurovascular unit
- O2−, oxygen
- PET, positron emission tomography
- PIGD, Postural instability and gait disorder
- PL, parietal lobe
- PVH, periventricular hyperintensity
- ROI, region of interest
- SPECT, single positron emission computed tomography
- SPM, statistical parametric mapping
- STAR, signal targeting with alternating radiofrequency
- TD, tremor dominant
- TE, echo time
- TI, inversion time
- TL, temporal lobe
- TMT-B, trail making test B
- TR, repetition time
- UKPDS BB, United Kingdom Parkinson's Disease Society Brain Bank
- UPDRS, Unified Parkinson's disease Rating Scale
- WAIS-R, Wechsler adult intelligence scale-revised
- WML, white matter lesion
- fMRI, functional magnetic resonance imaging
Collapse
Affiliation(s)
- Sarah Al-Bachari
- Department of Neurology, Royal Preston Hospital, Preston, UK ; Centre for Imaging Science, Institute of Population Health, University of Manchester, UK
| | - Laura M Parkes
- Centre for Imaging Science, Institute of Population Health, University of Manchester, UK
| | - Rishma Vidyasagar
- Centre for Imaging Science, Institute of Population Health, University of Manchester, UK
| | - Martha F Hanby
- Department of Neurology, Royal Preston Hospital, Preston, UK
| | - Vivek Tharaken
- Institute of Brain, Behaviour and Mental Health, University of Manchester, UK
| | - Iracema Leroi
- Institute of Brain, Behaviour and Mental Health, University of Manchester, UK
| | - Hedley C A Emsley
- Department of Neurology, Royal Preston Hospital, Preston, UK ; School of Medicine, University of Manchester, UK
| |
Collapse
|
5
|
Gibson LM, Hanby MF, Al-Bachari SM, Parkes LM, Allan SM, Emsley HCA. Late-onset epilepsy and occult cerebrovascular disease. J Cereb Blood Flow Metab 2014; 34:564-70. [PMID: 24517978 PMCID: PMC3982095 DOI: 10.1038/jcbfm.2014.25] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 01/13/2014] [Indexed: 11/09/2022]
Abstract
The interface between cerebrovascular disease (CVD) and epilepsy is complex and multifaceted. Late-onset epilepsy (LOE) is increasingly common and is often attributed to CVD, and is indeed associated with an increased risk of stroke. This relationship is easily recognizable where there is a history of stroke, particularly involving the cerebral cortex. However, the relationship with otherwise occult, subcortical CVD is currently less well established yet causality is often invoked. In this review, we consider the diagnosis of LOE in clinical practice--including its behaviour as a potential mimic of acute ischemic stroke and transient ischemic attack; evidence for an association between occult CVD and LOE; and potential mechanisms of epileptogenesis in occult CVD, including potential interrelationships between disordered cerebral metabolism and perfusion, disrupted neurovascular unit integrity, blood-brain barrier dysfunction, and inflammation. We also discuss recently recognized issues concerning antiepileptic drug treatment and vascular risk and consider a variety of less common CVD entities associated with seizures.
Collapse
Affiliation(s)
- Lorna M Gibson
- Division of Clinical Neurosciences, Western General Hospital, Edinburgh, UK
| | | | - Sarah M Al-Bachari
- 1] Department of Neurology, Royal Preston Hospital, Preston, UK [2] University of Manchester, Manchester, UK
| | - Laura M Parkes
- Biomedical Imaging Institute, University of Manchester, Manchester, UK
| | - Stuart M Allan
- Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - Hedley C A Emsley
- 1] Department of Neurology, Royal Preston Hospital, Preston, UK [2] School of Medicine, University of Manchester, Manchester, UK
| |
Collapse
|
6
|
|
7
|
Hanby MF, Scott KM, Scotton W, Wijesekera L, Mole T, Ellis CE, Leigh PN, Shaw CE, Al-Chalabi A. The risk to relatives of patients with sporadic amyotrophic lateral sclerosis. Brain 2011; 134:3454-7. [PMID: 21933809 PMCID: PMC3235555 DOI: 10.1093/brain/awr248] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis is a neurodegenerative disease of motor neurons with a median survival of 2 years. Most patients have no family history of amyotrophic lateral sclerosis, but current understanding of such diseases suggests there should be an increased risk to relatives. Furthermore, it is a common question to be asked by patients and relatives in clinic. We therefore set out to determine the risk of amyotrophic lateral sclerosis to first degree relatives of patients with sporadic amyotrophic lateral sclerosis attending a specialist clinic. Case records of patients with sporadic amyotrophic lateral sclerosis seen at a tertiary referral centre over a 16-year period were reviewed, and pedigree structures extracted. All individuals who had originally presented with sporadic amyotrophic lateral sclerosis, but who subsequently had an affected first degree relative, were identified. Calculations were age-adjusted using clinic population demographics. Probands (n = 1502), full siblings (n = 1622) and full offspring (n = 1545) were identified. Eight of the siblings and 18 offspring had developed amyotrophic lateral sclerosis. The unadjusted risk of amyotrophic lateral sclerosis over the observation period was 0.5% for siblings and 1.0% for offspring. Age information was available for 476 siblings and 824 offspring. For this subset, the crude incidence of amyotrophic lateral sclerosis was 0.11% per year (0.05-0.21%) in siblings and 0.11% per year (0.06-0.19%) in offspring, and the clinic age-adjusted incidence rate was 0.12% per year (0.04-0.21%) in siblings. By age 85, siblings were found to have an 8-fold increased risk of amyotrophic lateral sclerosis, in comparison to the background population. In practice, this means the risk of remaining unaffected by age 85 dropped from 99.7% to 97.6%. Relatives of people with sporadic amyotrophic lateral sclerosis have a small but definite increased risk of being affected.
Collapse
Affiliation(s)
- Martha F Hanby
- MRC Centre for Neurodegeneration Research, Institute of Psychiatry P 041, London SE5 8AF, UK
| | | | | | | | | | | | | | | | | |
Collapse
|
8
|
Abstract
BACKGROUND Causative gene mutations have been identified in about 2% of those with amyotrophic lateral sclerosis (ALS), often, but not always, when there is a strong family history. There is an assumption that there is a genetic component to all ALS, but genome-wide association studies have yet to produce a robustly replicated result. A definitive estimate of ALS heritability is therefore required to determine whether ongoing efforts to find susceptibility genes are worth while. METHODS The authors performed two twin studies, one population- and one clinic-based. The authors used structural equation modelling to perform a meta-analysis of data from these studies and an existing twin study to estimate ALS heritability, and identified 171 twin pairs in which at least one twin had ALS. RESULTS AND DISCUSSION Five monozygotic twin pairs were concordant-affected, and 44 discordant-affected. No dizygotic twin pairs were concordant-affected, and 122 discordant-affected. The heritability of sporadic ALS was estimated as 0.61 (0.38 to 0.78) with the unshared environmental component 0.39 (0.22 to 0.62). ALS has a high heritability, and efforts to find causative genes should continue.
Collapse
Affiliation(s)
- A Al-Chalabi
- King's College London, MRC Centre for Neurodegeneration Research, Institute of Psychiatry, London, UK.
| | | | | | | | | | | | | |
Collapse
|