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1.
Front Neurol ; 14: 1280015, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38152645

RESUMO

The human vestibular system is crucial for motion perception, balance control, and various higher cognitive functions. Exploring how the cerebral cortex responds to vestibular signals is not only valuable for a better understanding of how the vestibular system participates in cognitive and motor functions but also clinically significant in diagnosing central vestibular disorders. Near-infrared spectroscopy (NIRS) provides a portable and non-invasive brain imaging technology to monitor cortical hemodynamics under physical motion. Objective: This study aimed to investigate the cerebral cortical response to naturalistic vestibular stimulation induced by real physical motion and to validate the vestibular cerebral cortex previously identified using alternative vestibular stimulation. Approach: Functional NIRS data were collected from 12 right-handed subjects when they were sitting in a motion platform that generated three types of whole-body passive translational motion (circular, lateral, and fore-and-aft). Main results: The study found that different cortical regions were activated by the three types of motion. The cortical response was more widespread under circular motion in two dimensions compared to lateral and fore-and-aft motions in one dimensions. Overall, the identified regions were consistent with the cortical areas found to be activated in previous brain imaging studies. Significance: The results provide new evidence of brain selectivity to different types of motion and validate previous findings on the vestibular cerebral cortex.

2.
Stroke ; 54(6): 1548-1557, 2023 06.
Artigo em Inglês | MEDLINE | ID: mdl-37216445

RESUMO

BACKGROUND: Major intracerebral hemorrhage (ICH) trials have largely been unable to demonstrate therapeutic benefit in improving functional outcomes. This may be partly due to the heterogeneity of ICH outcomes based on their location, where a small strategic ICH could be debilitating, thus confounding therapeutic effects. We aimed to determine the ideal hematoma volume cutoff for different ICH locations in predicting ICH outcomes. METHODS: We retrospectively analyzed consecutive ICH patients enrolled in the University of Hong Kong prospective stroke registry from January 2011 to December 2018. Patients with premorbid modified Rankin Scale score >2 or who underwent neurosurgical intervention were excluded. ICH volume cutoff, sensitivity, and specificity in predicting respective 6-month neurological outcomes (good [modified Rankin Scale score 0-2], poor [modified Rankin Scale score 4-6], and mortality) for specific ICH locations were determined using receiver operating characteristic curves. Separate multivariate logistic regression models were also conducted for each location-specific volume cutoff to determine whether these cutoffs were independently associated with respective outcomes. RESULTS: Among 533 ICHs, the volume cutoff for good outcome according to ICH location was 40.5 mL for lobar, 32.5 mL for putamen/external capsule, 5.5 mL for internal capsule/globus pallidus, 6.5 mL for thalamus, 17 mL for cerebellum, and 3 mL for brainstem. ICH smaller than the cutoff for all supratentorial sites had higher odds of good outcomes (all P<0.05). Volumes exceeding 48 mL for lobar, 41 mL for putamen/external capsule, 6 mL for internal capsule/globus pallidus, 9.5 mL for thalamus, 22 mL for cerebellum, and 7.5 mL for brainstem were at greater risk of poor outcomes (all P<0.05). Mortality risks were significantly higher for volumes that exceeded 89.5 mL for lobar, 42 mL for putamen/external capsule, and 21 mL for internal capsule/globus pallidus (all P<0.001). All receiver operating characteristic models for location-specific cutoffs had good discriminant values (area under the curve >0.8), except in predicting good outcome for cerebellum. CONCLUSIONS: ICH outcomes differed with location-specific hematoma size. Location-specific volume cutoff should be considered in patient selection for ICH trials.


Assuntos
Hemorragia Cerebral , Acidente Vascular Cerebral , Humanos , Estudos Retrospectivos , Hemorragia Cerebral/diagnóstico por imagem , Hemorragia Cerebral/cirurgia , Globo Pálido , Hematoma/diagnóstico por imagem , Hematoma/cirurgia
3.
Stroke ; 54(1): 78-86, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36321455

RESUMO

BACKGROUND: Intracerebral hemorrhage (ICH) survivors are at high risk for recurrent stroke and cardiovascular events. Blood pressure (BP) control represents the most potent intervention to lower these risks, but optimal treatment targets in this patient population remain unknown. We sought to determine whether survivors of ICH achieving more intensive BP control than current guideline recommendations (systolic BP <130 mmHg and diastolic BP <80 mmHg) were at lower risk of major adverse cardiovascular and cerebrovascular events and mortality. METHODS: We analyzed data for 1828 survivors of spontaneous ICH from 2 cohort studies. Follow-up BP measurements were recorded 3 and 6 months after ICH, and every 6 months thereafter. Outcomes of interest were major adverse cardiovascular and cerebrovascular events (recurrent ICH, incident ischemic stroke, myocardial infarction), vascular mortality (defined as mortality attributed to recurrent ICH, ischemic stroke, or myocardial infarction), and all-cause mortality. RESULTS: During a median follow-up of 46.2 months, we observed 166 recurrent ICH, 68 ischemic strokes, 69 myocardial infarction, and 429 deaths. Compared with survivors of ICH with systolic BP 120 to 129 mmHg, participants who achieved systolic BP <120 mmHg displayed reduced risk of recurrent ICH (adjusted hazard ratio [AHR], 0.74 [95% CI, 0.59-0.94]) and major adverse cardiovascular and cerebrovascular events (AHR, 0.69 [95% CI, 0.53-0.92]). All-cause mortality (AHR, 0.76 [95% CI, 0.57-1.03]) and vascular mortality (AHR, 0.68 [95% CI, 0.45-1.01]) did not differ significantly. Among participants aged >75 years or with modified Rankin Scale score 4 to 5, systolic BP <120 mmHg was associated with increased all-cause mortality (AHR, 1.38 [95% CI, 1.02-1.85] and AHR, 1.36 [95% CI, 1.03-1.78], respectively), but not vascular mortality. We found no differences in outcome rates between survivors of ICH with diastolic BP <70 versus 70 to 79 mmHg. CONCLUSIONS: Targeting systolic BP <120 mmHg in select groups of survivors of ICH could result in decreased major adverse cardiovascular and cerebrovascular events risk without increasing mortality. Our findings warrant investigation in dedicated randomized controlled trials.


Assuntos
AVC Isquêmico , Infarto do Miocárdio , Acidente Vascular Cerebral , Humanos , Pressão Sanguínea/fisiologia , Hemorragia Cerebral/epidemiologia , Infarto do Miocárdio/complicações , Estudos de Coortes , AVC Isquêmico/complicações , Acidente Vascular Cerebral/complicações
4.
J Am Heart Assoc ; 11(6): e024158, 2022 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-35253479

RESUMO

Background Survivors of intracranial hemorrhage (ICH) are at increased risk for major adverse cardiovascular and cerebrovascular events (MACCE), in the form of recurrent stroke and myocardial Infarction. We investigated whether long-term blood pressure (BP) variability represents a risk factor for MACCE after ICH, independent of average BP. Methods and Results We analyzed data from prospective ICH cohort studies at Massachusetts General Hospital and the University of Hong Kong. We captured long-term (ie, visit-to-visit) BP variability, quantified as individual participants' variation coefficient. We explored determinants of systolic and diastolic BP variability and generated survival analyses models to explore their association with MACCE. Among 1828 survivors of ICH followed for a median of 46.2 months we identified 166 with recurrent ICH, 68 with ischemic strokes, and 69 with myocardial infarction. Black (coefficient +3.8, SE 1.3) and Asian (coefficient +2.2, SE 0.4) participants displayed higher BP variability. Long-term systolic BP variability was independently associated with recurrent ICH (subhazard ratio [SHR], 1.82; 95% CI, 1.19-2.79), ischemic stroke (SHR, 1.62; 95% CI, 1.06-2.47), and myocardial infarction (SHR, 1.54; 95% CI, 1.05-2.24). Average BP during follow-up did not modify the association between long-term systolic BP variability and MACCE. Conclusions Long-term BP variability is a potent risk factor for recurrent hemorrhage, ischemic stroke, and myocardial infarction after ICH, even among survivors with well-controlled hypertension. Our findings support the hypothesis that combined control of average BP and its variability after ICH is required to minimize incidence of MACCE.


Assuntos
Hipertensão , AVC Isquêmico , Infarto do Miocárdio , Acidente Vascular Cerebral , Pressão Sanguínea/fisiologia , Hemorragia Cerebral/etiologia , Humanos , Hipertensão/complicações , Hipertensão/epidemiologia , Infarto do Miocárdio/complicações , Infarto do Miocárdio/epidemiologia , Estudos Prospectivos , Fatores de Risco , Acidente Vascular Cerebral/diagnóstico , Acidente Vascular Cerebral/epidemiologia , Acidente Vascular Cerebral/etiologia
5.
J Am Heart Assoc ; 10(11): e020392, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33998241

RESUMO

Background Survivors of intracerebral hemorrhage (ICH) are at high risk for recurrent stroke, which is associated with blood pressure control. Because most recurrent stroke events occur within 12 to 18 months of the index ICH, rapid blood pressure control is likely to be crucial. We investigated the frequency and prognostic impact of uncontrolled short-term hypertension after ICH. Methods and Results We analyzed data from Massachusetts General Hospital (n=1305) and the University of Hong Kong (n=523). We classified hypertension as controlled, undertreated, or treatment resistant at 3 months after ICH and determined the following: (1) the risk factors for uncontrolled hypertension and (2) whether hypertension control at 3 months is associated with stroke recurrence and mortality. We followed 1828 survivors of ICH for a median of 46.2 months. Only 9 of 234 (4%) recurrent strokes occurred before 3 months after ICH. At 3 months, 713 participants (39%) had controlled hypertension, 755 (41%) had undertreated hypertension, and 360 (20%) had treatment-resistant hypertension. Black, Hispanic, and Asian race/ethnicity and higher blood pressure at time of ICH increased the risk of uncontrolled hypertension at 3 months (all P<0.05). Uncontrolled hypertension at 3 months was associated with recurrent stroke and mortality during long-term follow-up (all P<0.05). Conclusions Among survivors of ICH, >60% had uncontrolled hypertension at 3 months, with undertreatment accounting for the majority of cases. The 3-month blood pressure measurements were associated with higher recurrent stroke risk and mortality. Black, Hispanic, and Asian survivors of ICH and those presenting with severe acute hypertensive response were at highest risk for uncontrolled hypertension.


Assuntos
Pressão Sanguínea/fisiologia , Hemorragia Cerebral/etiologia , Hipertensão/complicações , Idoso , Hemorragia Cerebral/epidemiologia , Hemorragia Cerebral/fisiopatologia , Feminino , Seguimentos , Hong Kong/epidemiologia , Humanos , Hipertensão/fisiopatologia , Incidência , Masculino , Recidiva , Estudos Retrospectivos , Taxa de Sobrevida/tendências , Fatores de Tempo
6.
Stroke ; 51(7): 2228-2231, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32432998

RESUMO

BACKGROUND AND PURPOSE: The current coronavirus disease 2019 (COVID-19) pandemic represents a global public health crisis, disrupting emergency healthcare services. We determined whether COVID-19 has resulted in delays in stroke presentation and affected the delivery of acute stroke services in a comprehensive stroke center in Hong Kong. METHODS: We retrospectively reviewed all patients with transient ischemic attack and stroke admitted via the acute stroke pathway of Queen Mary Hospital, Hong Kong, during the first 60 days since the first diagnosed COVID-19 case in Hong Kong (COVID-19: January 23, 2020-March 24, 2020). We compared the stroke onset to hospital arrival (onset-to-door) time and timings of inpatient stroke pathways with patients admitted during the same period in 2019 (pre-COVID-19: January 23, 2019-March 24, 2019). RESULTS: Seventy-three patients in COVID-19 were compared with 89 patients in pre-COVID-19. There were no significant differences in age, sex, vascular risk factors, nor stroke severity between the 2 groups (P>0.05). The median stroke onset-to-door time was ≈1-hour longer in COVID-19 compared with pre-COVID-19 (154 versus 95 minutes, P=0.12), and the proportion of individuals with onset-to-door time within 4.5 hours was significantly lower (55% versus 72%, P=0.024). Significantly fewer cases of transient ischemic attack presented to the hospital during COVID-19 (4% versus 16%, P=0.016), despite no increase in referrals to the transient ischemic attack clinic. Inpatient stroke pathways and treatment time metrics nevertheless did not differ between the 2 groups (P>0.05 for all comparisons). CONCLUSIONS: During the early containment phase of COVID-19, we noted a prolongation in stroke onset to hospital arrival time and a significant reduction in individuals arriving at the hospital within 4.5 hours and presenting with transient ischemic attack. Public education about stroke should continue to be reinforced during the COVID-19 pandemic.


Assuntos
Betacoronavirus , Infecções por Coronavirus , Ataque Isquêmico Transitório/epidemiologia , Pandemias , Pneumonia Viral , Acidente Vascular Cerebral/epidemiologia , Tempo para o Tratamento/estatística & dados numéricos , Doença Aguda , Idoso , Idoso de 80 Anos ou mais , COVID-19 , Atenção à Saúde/estatística & dados numéricos , Serviços Médicos de Emergência , Serviço Hospitalar de Emergência/estatística & dados numéricos , Feminino , Hong Kong/epidemiologia , Hospitais Especializados/estatística & dados numéricos , Hospitais Urbanos/estatística & dados numéricos , Humanos , Ataque Isquêmico Transitório/terapia , Masculino , Pessoa de Meia-Idade , Proteínas Recombinantes/uso terapêutico , Estudos Retrospectivos , Fatores de Risco , SARS-CoV-2 , Acidente Vascular Cerebral/prevenção & controle , Acidente Vascular Cerebral/terapia , Trombectomia/estatística & dados numéricos , Terapia Trombolítica/estatística & dados numéricos , Ativador de Plasminogênio Tecidual/uso terapêutico
7.
J Rehabil Med ; 49(6): 475-481, 2017 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-28612077

RESUMO

OBJECTIVE: There are potential benefits of repetitive transcranial magnetic stimulation (rTMS) in improving swallowing functions after stroke; however, few studies have been performed in the chronic stroke population. This study aims to distil the key effects of rTMS on swallowing functions and swallowing-related quality of life. METHODS: Twenty-two participants with chronic post-stroke dysphagia were randomly assigned into active or sham rTMS groups. Seven participants withdrew from the study, thus data from 15 participants (mean age 64.6 years) were analysed. Participants received 3,000 pulses of 5 Hz rTMS (active: n = 11; sham: n = 4) on the tongue area of the motor cortex for 10 days over a period of 2 weeks. All participants were assessed 1 week before, and 2 months, 6 months and 12 months after stimulation. Outcomes were measured by a videofluoroscopic swallowing study, swallowing-related quality-of-life questionnaire and Iowa Oral Performance Instrument. RESULTS: No statistically significant effects were identified for any outcome measures. CONCLUSION: This study indicates that 5 Hz rTMS applied over the tongue area of the motor cortex is not effective for improving swallowing function in individuals with chronic post-stroke dysphagia. Possible explanations for these non-significant results are dis cussed. Future studies should explore the potential of the current protocol in conjunction with conventional dysphagia therapy.


Assuntos
Transtornos de Deglutição/etiologia , Qualidade de Vida/psicologia , Acidente Vascular Cerebral/complicações , Estimulação Magnética Transcraniana/métodos , Doença Crônica , Transtornos de Deglutição/patologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Córtex Motor/fisiopatologia , Acidente Vascular Cerebral/fisiopatologia
8.
World Neurosurg ; 106: 85-91, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28606579

RESUMO

BACKGROUND: Antiplatelet resumption in patients who developed intracerebral hemorrhage (ICH) while on antiplatelet therapy (antiplatelet-related ICH) represents an important medical dilemma. We aimed to study the long-term cardiovascular outcomes of antiplatelet-related ICH survivors, and the risk of recurrent ICH with antiplatelet resumption. METHODS: This was an observational study of 109 antiplatelet-related ICH survivors. The clinical end points were recurrent ICH, ischemic vascular events, and vascular death (fatal ICH or ischemic vascular events). Predictors of recurrent ICH and vascular death were derived using a multivariable Cox regression model. RESULTS: The median duration of follow-up was 3.5 years (interquartile range, 1.6-5.8 years). Ischemic vascular events were more common than recurrent ICHs (6.8 per 100 patient-years vs. 2.6 per 100 patient-years; P = 0.028). Antiplatelet use was not associated with an elevated risk of recurrent ICH (hazard ratio [HR], 1.11, 95% confidence interval [CI], 0.27-4.62). A mean follow-up systolic blood pressure of >140 mmHg increased the risk of both recurrent ICH (HR, 4.28; 95% CI, 1.01-18.11) and vascular death (HR, 11.14; 95% CI, 2.72-45.62). Cerebral amyloid angiopathy (CAA) was an independent predictor for recurrent ICH (HR, 24.34; 95% CI, 2.80-211.47). CONCLUSIONS: Antiplatelet resumption after antiplatelet-related ICH did not appear to carry a clinically significant risk of recurrent ICH, whereas inadequate blood pressure control and CAA contributed to a more robust risk. Antiplatelet resumption should be considered, especially in survivors with adequate blood pressure control and without CAA.


Assuntos
Hemorragia Cerebral/induzido quimicamente , Inibidores da Agregação Plaquetária/efeitos adversos , Idoso , Hemorragia Cerebral/mortalidade , Substituição de Medicamentos , Feminino , Humanos , Isquemia/etiologia , Isquemia/mortalidade , Masculino , Recidiva , Estudos Retrospectivos , Fatores de Risco , Sobreviventes
9.
Appl Ergon ; 63: 1-8, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28502398

RESUMO

This study examines the correlations between optokinetic after-nystagmus (OKAN) parameters and individual susceptibility to visually induced motion sickness (VIMS). Twenty-seven participants were exposed to vertical black-and-white stripes drifting along the yaw axis at 60° per second for 30 min to collect individual VIMS data (Phase 1). Two weeks after the exposure, OKANs were measured (Phase 2). 19 out of 27 participants (i.e., 70%) exhibited consistent OKAN patterns. Significant correlations between the time constants of OKAN and levels of VIMS experienced by the same viewers were found. Four months later, these 27 participants were invited back for a second OKAN measurement (Phase 3). Twenty-one participants came back. Their two OKAN measurements were significantly correlated (r = 0.69, p = 0.001). Rated levels of VIMS in phase 1 significantly correlated with the time constant of OKAN in both Phase 2 (r = 0.51, p = 0.044) and Phase 3 (r = 0.74, p = 0.006). The implications of the correlation results are discussed.


Assuntos
Enjoo devido ao Movimento/fisiopatologia , Nistagmo Optocinético/fisiologia , Estimulação Luminosa/efeitos adversos , Adulto , Feminino , Humanos , Masculino , Enjoo devido ao Movimento/etiologia , Fatores de Tempo , Adulto Jovem
10.
Int J Lang Commun Disord ; 50(3): 389-96, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25588767

RESUMO

BACKGROUND: There is growing evidence of potential benefits of repetitive transcranial magnetic stimulation (rTMS) in the rehabilitation of dysphagia. However, the site and frequency of stimulation for optimal effects are not clear. AIMS: The aim of this pilot study is to investigate the short-term effects of high-frequency 5 Hz rTMS applied to the tongue region of the motor cortex on swallowing functions and the quality of life of post-stroke individuals with dysphagia. METHODS & PROCEDURES: Two male and two female participants were assigned randomly to active and sham groups. The participants in the active group received 10 sessions of active rTMS for 2 weeks, whereas the sham participants received 10 sessions of sham rTMS for 2 weeks. Each participant received a total of 3000 pulses of 5 Hz active or sham rTMS per day for 10 days. Outcome measures were taken at baseline, 1 week and 1 month post-rTMS. OUTCOMES & RESULTS: Participants who received active rTMS had improved swallowing functions and swallowing-related quality of life at 1 week and 1 month post-stimulation. CONCLUSIONS & IMPLICATIONS: The study showed that excitatory rTMS applied over the tongue motor cortex is a feasible approach in individuals with chronic post-stroke dysphagia. Further investigation with larger sample population is warranted to support the benefit of this stimulation protocol.


Assuntos
Transtornos de Deglutição/terapia , Disartria/terapia , Acidente Vascular Cerebral/complicações , Acidente Vascular Cerebral/terapia , Estimulação Magnética Transcraniana , Idoso , Doença Crônica , Transtornos de Deglutição/diagnóstico , Transtornos de Deglutição/fisiopatologia , Disartria/diagnóstico , Disartria/fisiopatologia , Feminino , Humanos , Masculino , Córtex Motor/fisiopatologia , Acidente Vascular Cerebral/fisiopatologia , Língua/inervação
11.
Am J Hypertens ; 27(12): 1486-94, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24842389

RESUMO

BACKGROUND: Blood pressure (BP) variability (BPV) is a novel risk factor for the development of atherosclerotic diseases. High BPV has recently been shown to predict all-cause and cardiovascular mortality in patients with lacunar infarct. Whether BPV has prognostic implications in patients with ischemic stroke subtypes, other than those due to small-vessel occlusion, remains uncertain. METHODS: We prospectively followed up the clinical outcome of 632 consecutive ischemic stroke patients without atrial fibrillation. The average BP and BPV, as determined by the coefficient of variation of the systolic and diastolic BP, were recorded during a mean 12 ± 6 outpatient clinic visits. RESULTS: The average age of the population was 71 ± 11 years. After a mean of 76 ± 18 months of follow-up, 161 patients died (26%); 35% (n = 56 of 161) of these deaths were due to cardiovascular causes. Sixteen percent and 5% developed recurrent stroke and acute coronary syndrome (ACS), respectively. After adjusting for mean systolic BP and confounding variables, patients with high systolic BPV were at significantly greater risk of cardiovascular mortality (hazards ratio (HR) = 2.36; 95% confidence interval (CI) = 1.02-5.49; P < 0.05). High systolic BPV also predicted all-cause mortality after adjusting for mean systolic BP (HR = 1.79; 95% CI = 1.16-2.75; P < 0.05). There was no association between systolic BPV and nonfatal recurrent stroke or nonfatal ACS. Raised diastolic BPV did not predict recurrent nonfatal stroke, nonfatal ACS, or mortality. CONCLUSIONS: Visit-to-visit systolic BPV predicts long-term all-cause and cardiovascular mortality in patients with ischemic stroke without atrial fibrillation, independent of other conventional risk factors, including average BP control.


Assuntos
Pressão Sanguínea/fisiologia , Isquemia Encefálica/fisiopatologia , Hipertensão/fisiopatologia , Visita a Consultório Médico , Idoso , Determinação da Pressão Arterial , Isquemia Encefálica/etiologia , Isquemia Encefálica/mortalidade , Causas de Morte/tendências , Feminino , Seguimentos , Hong Kong/epidemiologia , Humanos , Hipertensão/complicações , Hipertensão/mortalidade , Masculino , Prognóstico , Estudos Prospectivos , Fatores de Risco , Taxa de Sobrevida/tendências , Fatores de Tempo
12.
PLoS One ; 9(4): e90307, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24694731

RESUMO

The integrity of structural connectivity in a functional brain network supports the efficiency of neural processing within relevant brain regions. This study aimed to quantitatively investigate the short- and long-range fibers, and their differential roles in the lower cognitive efficiency in aging and dementia. Three groups of healthy young, healthy older adults and patients with Alzheimer's disease (AD) participated in this combined functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) study on prospective memory (PM). Short- and long-range fiber tracts within the PM task engaged brain networks were generated. The correlation between the fMRI signal change, PM performance and the DTI characters were calculated. FMRI results showed that the PM-specific frontal activations in three groups were distributed hierarchically along the rostrocaudal axis in the frontal lobe. In an overall PM condition generally activated brain network among the three groups, tractography was used to generate the short-range fibers, and they were found impaired in both healthy older adults and AD patients. However, the long-range fiber tracts were only impaired in AD. Additionally, the mean diffusivity (MD) of short-range but not long-range fibers was positively correlated with fMRI signal change and negatively correlated with the efficiency of PM performance. This study suggests that the disintegrity of short-range fibers may contribute more to the lower cognitive efficiency and higher compensatory brain activation in healthy older adults and more in AD patients.


Assuntos
Envelhecimento , Doença de Alzheimer/fisiopatologia , Encéfalo/fisiopatologia , Cognição , Fibras Nervosas , Rede Nervosa , Adulto , Fatores Etários , Idoso , Doença de Alzheimer/diagnóstico por imagem , Encéfalo/diagnóstico por imagem , Imagem de Tensor de Difusão/métodos , Feminino , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Radiografia
13.
J Clin Neurosci ; 19(4): 607-8, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22285113

RESUMO

Guillain-Barré syndrome (GBS) is a neurological emergency that warrants prompt diagnosis and treatment. Occasionally, the clinical, laboratory and electrophysiological features are neither typical nor diagnostic. It requires a high index of suspicion and clinical judgement for early diagnosis and commencement of treatment in those scenarios. Some pathogens are potential triggers of this serious neurological disease, including: Campylobacter jejuni, Mycoplasma pneumoniae and cytomegalovirus. Although uncommon, hepatotrophic viruses (hepatitis A, B and C) are increasingly recognized to be triggering microbes. Here, we report a patient with unusual GBS triggered by an atypical microbe, hepatitis E virus, in a Chinese patient, via a common route of transmission in this locality.


Assuntos
Síndrome de Guillain-Barré/microbiologia , Hepatite E/complicações , Doença Aguda , Feminino , Síndrome de Guillain-Barré/fisiopatologia , Síndrome de Guillain-Barré/terapia , Humanos , Pessoa de Meia-Idade , Plasmaferese
15.
J Cereb Blood Flow Metab ; 29(9): 1538-46, 2009 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-19536072

RESUMO

Neurogenesis and angiogenesis in the subventricular zone and peri-infarct region have been confirmed. However, newly formed neuronal cells and blood vessels that appear in the nonischemic ipsilateral ventroposterior nucleus (VPN) of the thalamus with secondary damage after stroke has not been previously studied. Twenty-four stroke-prone renovascular hypertensive rats were subjected to distal right middle cerebral artery occlusion (MCAO) or sham operation. 5'-Bromo-2'-deoxyuridine (BrdU) was used to label cell proliferation. Rats were killed at 7 or 14 days after the operation. Neuronal nuclei (NeuN), OX-42, BrdU, nestin, laminin(+), BrdU(+)/nestin(+), BrdU(+)/NeuN(+), nestin(+)/GFAP(+)(glial fibrillary acidic protein), and BrdU(+)/laminin(+) immunoreactive cells were detected within the ipsilateral VPN. The primary infarction was confined to the right somatosensory cortex. Within the ipsilateral VPN of the ischemic rats, the number of NeuN(+) neurons decreased, the OX-42(+) microglia cells were activated, and BrdU(+) and nestin(+) cells were detected at day 7 after MCAO and increased in number at day 14. Moreover, BrdU(+)/nestin(+) cells and BrdU(+)/NeuN(+) cells were detected at day 14 after MCAO. In addition, the ischemic rats showed a significant increase in vascular density in the ipsilateral VPN compared with the sham-operated rats. These results suggest that secondary damage with neurogenesis and angiogenesis of the ipsilateral VPN of the thalamus occurs after focal cortical infarction.


Assuntos
Córtex Cerebral , Infarto Cerebral , Hipertensão , Neovascularização Fisiológica/fisiologia , Neurogênese/fisiologia , Tálamo , Animais , Antimetabólitos/metabolismo , Bromodesoxiuridina/metabolismo , Proliferação de Células , Córtex Cerebral/anatomia & histologia , Córtex Cerebral/patologia , Infarto Cerebral/patologia , Infarto Cerebral/fisiopatologia , Hipertensão/patologia , Hipertensão/fisiopatologia , Infarto da Artéria Cerebral Média , Proteínas de Filamentos Intermediários/metabolismo , Laminina/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Nestina , Ratos , Ratos Sprague-Dawley , Tálamo/anatomia & histologia , Tálamo/patologia , Tálamo/fisiologia
16.
J Peripher Nerv Syst ; 14(1): 14-21, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19335535

RESUMO

Charcot-Marie-Tooth (CMT) neuropathy is inherited with genetic and clinical heterogeneity. The X-linked form (CMTX) is linked to mutations in the GJB1 gene. However, the genotype-phenotype correlation between variants in the non-coding region of GJB1 gene and CMTX is unclear. We found two structural variants (-459C>T and -713G>A) in the 5' non-coding region of a transcript (Ref seq ID: NM_000166) of the GJB1 gene and explored its association with CMTX in two Chinese families. All family members who carried the -459C>T variant either were symptomatic or had abnormal electrophysiological studies compatible with CMTX, whereas all the non-symptomatic family members who had normal electrophysiological studies and 10 healthy unrelated controls did not have this variant. The other variant in the 5'-flanking region of the gene was found to be a benign polymorphism, although it had been earlier reported to be associated with CMTX in a Taiwanese family. Secondary structure prediction analysis of mutant mRNA using M fold and RNA structure softwares indicates that the -459C>T mutation may reduce translation efficiency of the GJB1 gene by changing its 5'-untranslated region secondary structure and abolishing the internal ribosome entry site at the initialization of its translation in Schwann cells. Our study can help clarify the causal mutations of CMTX in the non-protein coding region of GJB1.


Assuntos
Regiões 5' não Traduzidas/genética , Doença de Charcot-Marie-Tooth/genética , Conexinas/genética , Saúde da Família , Mutação Puntual/genética , Adolescente , Adulto , Idoso , Povo Asiático/etnologia , Doença de Charcot-Marie-Tooth/patologia , Doença de Charcot-Marie-Tooth/fisiopatologia , Criança , Análise Mutacional de DNA , Eletromiografia , Feminino , Doenças Genéticas Ligadas ao Cromossomo X/genética , Humanos , Masculino , Microscopia Eletrônica de Transmissão , Pessoa de Meia-Idade , Condução Nervosa/genética , Condução Nervosa/fisiologia , Nervos Periféricos/patologia , Nervos Periféricos/fisiopatologia , Nervos Periféricos/ultraestrutura , Análise de Sequência , Adulto Jovem , Proteína beta-1 de Junções Comunicantes
18.
Hum Factors ; 51(5): 739-51, 2009 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-20196298

RESUMO

OBJECTIVE: This study investigates isolated effects of vection and optokinetic nystagmus (OKN) on visually induced motion sickness (VIMS) provoked by rotating optokinetic drum patterns. BACKGROUND: VIMS was the subject of recent standardization activities, but the effects of OKN have not been studied in the absence ofvection. METHOD: Experiment 1 suppressed OKN by eye fixation and examined VIMS severity (both ordinal and ratio scale) and time spent in saturated vection at four pattern rotating velocities of 0, 2, 14, and 34 degrees per second (dps). Experiment 2 suppressed vection by adding a peripheral visual field rotating in the opposite direction to the rotating patterns. VIMS severity and OKN slow-phase velocity were studied at four rotating velocities of 0, 30, 60, and 90 dps. RESULTS: Results from Experiment 1 indicated that VIMS severity increased as the pattern velocity increased from 0 dps to 34 dps. Results from Experiment 2 indicated that as the velocity of the rotating pattern increased, the slow-phase velocity of OKN and the severity of VIMS increased and peaked in the 60-dps condition. In both experiments, ratio-scaled nausea data significantly correlated with ordinal-scaled nausea ratings. CONCLUSION: VIMS can still occur in the absence of either vection or OKN. Interestingly, the profile of the summed results of the two experiments matches nicely with the profile reported by Hu et al. in which neither OKN nor vection were controlled. APPLICATION: Potential applications include modeling and reduction of VIMS in computer gaming environments.


Assuntos
Percepção de Movimento , Enjoo devido ao Movimento/etiologia , Nistagmo Optocinético/fisiologia , Reconhecimento Visual de Modelos , Rotação/efeitos adversos , Adulto , Feminino , Hong Kong , Humanos , Nistagmo Patológico/fisiopatologia , Adulto Jovem
20.
Hong Kong Med J ; 13(4): 314-8, 2007 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-17664536

RESUMO

'Mah-jong epilepsy' is a rare reflex epilepsy syndrome, manifesting as recurrent epileptic seizures triggered by either playing or just watching mah-jong. We present three patients with this condition and review all the reported cases. Mah-jong-induced seizures can be considered a subtype of cognition-induced epilepsy. Nonetheless, these patients have distinctive clinical and electrophysiological features: late age of onset, different seizure patterns, single seizure-trigger, lack of spontaneous seizures, and electroencephalographic findings not supportive of idiopathic generalised epilepsy. The pathophysiological mechanism underlying mah-jong-induced seizures may be different from the other cognition-associated reflex epileptic phenomena.


Assuntos
Epilepsia Reflexa/etiologia , Recreação , Adulto , Feminino , Humanos , Masculino
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