Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 186
Filtrar
1.
Invest Ophthalmol Vis Sci ; 60(7): 2773-2780, 2019 06 03.
Artigo em Inglês | MEDLINE | ID: mdl-31247084

RESUMO

Purpose: Explore in vivo whether there is direct communication between the cerebrospinal fluid (CSF) and extravascular compartment of human visual pathway structures. Methods: A prospective and observational study included 10 subjects who underwent intrathecal gadolinium-enhanced magnetic resonance imaging (MRI) for suspected CSF circulation disorder, but with a negative result and with no known ophthalmic diseases. After precontrast T1-weighted MRI, 0.5 mL of gadobutrol (Gadovist, 1.0 mmol/mL) was injected intrathecally. Gadobutrol distributes in the extravascular space, and served as a CSF tracer. Consecutive MRI scans were obtained throughout 24 to 48 hours. To assess gadobutrol contrast enrichment, regions of interest (ROIs) were placed at multiple locations along the visual pathway, from the primary visual cortex to the eye's vitreous body. CSF tracer dependent T1 signal was measured in each ROI. A linear mixed-model was used for statistical analyses. Results: CSF tracer enrichment was found within the optic nerve, optic chiasm, optic tract, and primary visual cortex (P < 0.001). Peak tracer enrichment in the visual pathway generally occurred after 24 hours and was preceded by peak enhancement in the prechiasmatic cistern after 4 to 6 hours. Conclusions: The results indicate direct communication between CSF of subarachnoid space and the extravascular space of the human visual pathway. Extravascular entry of the CSF tracer is a prerequisite for a glymphatic system, the present findings may suggest its presence. The existence of a glymphatic system in the human visual pathway could bring novel perspectives on the pathophysiology and treatment of ophthalmic diseases.


Assuntos
Espaço Subaracnóideo/fisiologia , Vias Visuais/fisiologia , Adulto , Líquido Cefalorraquidiano/fisiologia , Meios de Contraste/administração & dosagem , Feminino , Sistema Glinfático/fisiologia , Humanos , Injeções Espinhais , Imagem por Ressonância Magnética , Masculino , Quiasma Óptico/diagnóstico por imagem , Quiasma Óptico/fisiologia , Nervo Óptico/diagnóstico por imagem , Nervo Óptico/fisiologia , Trato Óptico/diagnóstico por imagem , Trato Óptico/fisiologia , Compostos Organometálicos/administração & dosagem , Estudos Prospectivos , Espaço Subaracnóideo/diagnóstico por imagem , Córtex Visual/diagnóstico por imagem , Córtex Visual/fisiologia , Vias Visuais/diagnóstico por imagem
2.
Trop Anim Health Prod ; 51(5): 1179-1186, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30685834

RESUMO

This study aimed to evaluate the impact of subarachnoid anesthesia with ketamine during transcervical artificial insemination (TCAI) on the welfare of ewes and on subsequent pregnancy rates. Ninety Suffolk adult ewes were randomized into three treatment groups: control group (CG), which underwent the TCAI procedure as established by cervical traction (CG; n = 30) and two groups that received subarachnoid anesthesia with ketamine at a dose of either 0.75 mg/kg (KE0.75; n = 30) or 1.5 mg/kg (KE1.5; n = 30) 5 min before the cervical traction procedure. Intrauterine insemination was performed using frozen semen from three males previously analyzed and approved for fertility. The use of subarachnoid anesthesia decreased ewes' vocalizations (P = 0.0001) and abdominal contraction (P = 0.0150) during cervical manipulations. The CG had more groans and vocalizations at the moment of cervix clamping and applicator passage through the cervix (P = 0.001). The cervix traction was facilitated by anesthesia. For the control group, most of the cervical traction was done just up to the middle of the vagina (P = 0.0021). Pregnancy rates increased significantly with anesthesia (P = 0.04) as shown by the rates of 40.0%, 56.7%, and 66.7% for CG, KE1.5, and KE0.75, respectively. The CG showed behaviors associated with absolute immobility, which is suggestive of distress. In brief, the use of ketamine in subarachnoid anesthesia for transcervical artificial insemination in ewes facilitated cervical traction, increased the pregnancy rate, and improved animal welfare.


Assuntos
Anestesia/veterinária , Anestésicos Dissociativos/administração & dosagem , Bem-Estar do Animal , Inseminação Artificial , Ketamina/administração & dosagem , Taxa de Gravidez , Ovinos/fisiologia , Animais , Colo do Útero/fisiologia , Feminino , Inseminação Artificial/métodos , Gravidez , Distribuição Aleatória , Sêmen/fisiologia , Preservação do Sêmen/métodos , Espaço Subaracnóideo/fisiologia
3.
Adv Exp Med Biol ; 1133: 9-18, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30324588

RESUMO

The aim of the study was to assess blood pressure-subarachnoid space (BP-SAS) width coupling properties using time-frequency bispectral analysis based on wavelet transforms during handgrip and cold tests. The experiments were performed on a group of 16 healthy subjects (F/M; 7/9) of the mean age 27.2 ± 6.8 years and body mass index of 23.8 ± 4.1 kg/m2. The sequence of challenges was first handgrip and then cold test. The handgrip challenge consisted of a 2-min strain, indicated by oral communication from the investigator, at 30% of maximum strength. The cold test consisted of 2 min of hand immersion to approximately wrist level in cold water of 4 °C, verified by a digital thermometer. Each test was preceded by 10 min at baseline and was followed by 10-min recovery recordings. BP and SAS were recorded simultaneously. Three 2-min stages of the procedure, baseline, test, and recovery, were analyzed. We found that BP-SAS coupling was present only at cardiac frequency, while at respiratory frequency both oscillators were uncoupled. Handgrip and cold test failed to affect BP-SAS cardiac-respiratory coupling. We showed similar handgrip and cold test cardiac bispectral coupling for individual subjects. Further studies are required to establish whether the observed intersubject variability concerning the BP-SAS coupling at cardiac frequency has any potential clinical predictive value.


Assuntos
Pressão Sanguínea , Força da Mão , Espaço Subaracnóideo/fisiologia , Adulto , Temperatura Baixa , Feminino , Frequência Cardíaca , Humanos , Masculino , Análise de Ondaletas , Adulto Jovem
4.
J Biomech Eng ; 140(8)2018 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-30003260

RESUMO

Cerebrospinal fluid (CSF) dynamics are thought to play a vital role in central nervous system (CNS) physiology. The objective of this study was to investigate the impact of spinal cord (SC) nerve roots (NR) on CSF dynamics. A subject-specific computational fluid dynamics (CFD) model of the complete spinal subarachnoid space (SSS) with and without anatomically realistic NR and nonuniform moving dura wall deformation was constructed. This CFD model allowed detailed investigation of the impact of NR on CSF velocities that is not possible in vivo using magnetic resonance imaging (MRI) or other noninvasive imaging methods. Results showed that NR altered CSF dynamics in terms of velocity field, steady-streaming, and vortical structures. Vortices occurred in the cervical spine around NR during CSF flow reversal. The magnitude of steady-streaming CSF flow increased with NR, in particular within the cervical spine. This increase was located axially upstream and downstream of NR due to the interface of adjacent vortices that formed around NR.


Assuntos
Líquido Cefalorraquidiano/metabolismo , Hidrodinâmica , Modelos Anatômicos , Raízes Nervosas Espinhais/anatomia & histologia , Raízes Nervosas Espinhais/fisiologia , Feminino , Humanos , Imagem por Ressonância Magnética , Modelagem Computacional Específica para o Paciente , Raízes Nervosas Espinhais/diagnóstico por imagem , Espaço Subaracnóideo/anatomia & histologia , Espaço Subaracnóideo/diagnóstico por imagem , Espaço Subaracnóideo/fisiologia , Adulto Jovem
5.
Adv Exp Med Biol ; 1070: 37-47, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29435957

RESUMO

In the cerebrospinal fluid (CSF) circulation, two components can be distinguished: bulk flow (circulation) and pulsatile flow (back and forth motion). CSF pulsatile flow is generated by both cardiac and respiratory cycles. Recent years have seen increased interest in cardiac- and respiratory-driven CSF pulsatility as an important component of cerebral homeostasis. CSF pulsatility is affected by cerebral arterial inflow and jugular outflow and potentially linked to white matter abnormalities in various diseases, such as multiple sclerosis or hypertension. In this review, we discuss the physiological mechanisms associated with CSF pulsation and its clinical significance. Finally, we explain the concept of using the oscillations of subarachnoid space width as a surrogate for CSF pulsatility.


Assuntos
Líquido Cefalorraquidiano/fisiologia , Fluxo Pulsátil/fisiologia , Espaço Subaracnóideo/fisiologia , Humanos
6.
Sci Rep ; 8(1): 3057, 2018 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-29449606

RESUMO

Abnormal cerebrospinal fluid (CSF) pulsatility has been implicated in patients suffering from various diseases, including multiple sclerosis and hypertension. CSF pulsatility results in subarachnoid space (SAS) width changes, which can be measured with near-infrared transillumination backscattering sounding (NIR-T/BSS). The aim of this study was to combine NIR-T/BSS and wavelet analysis methods to characterise the dynamics of the SAS width within a wide range of frequencies from 0.005 to 2 Hz, with low frequencies studied in detail for the first time. From recordings in the resting state, we also demonstrate the relationships between SAS width in both hemispheres of the brain, and investigate how the SAS width dynamics is related to the blood pressure (BP). These investigations also revealed influences of age and SAS correlation on the dynamics of SAS width and its similarity with the BP. Combination of NIR-T/BSS and time-frequency analysis may open up new frontiers in the understanding and diagnosis of various neurodegenerative and ageing related diseases to improve diagnostic procedures and patient prognosis.


Assuntos
Líquido Cefalorraquidiano/fisiologia , Fluxo Pulsátil , Espaço Subaracnóideo/fisiologia , Adolescente , Adulto , Velocidade do Fluxo Sanguíneo , Pressão Sanguínea/fisiologia , Circulação Cerebrovascular/fisiologia , Feminino , Voluntários Saudáveis , Frequência Cardíaca/fisiologia , Humanos , Hipertensão/líquido cefalorraquidiano , Hipertensão/diagnóstico , Masculino , Esclerose Múltipla/líquido cefalorraquidiano , Esclerose Múltipla/diagnóstico , Espectroscopia de Luz Próxima ao Infravermelho/métodos , Análise de Ondaletas
7.
Am J Obstet Gynecol ; 218(4): 440.e1-440.e36, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29353032

RESUMO

BACKGROUND: Congenital Zika virus (ZIKV) infection can be detected in both the presence and absence of microcephaly and manifests as a number of signs and symptoms that are detected clinically and by neuroimaging. However, to date, qualitative and quantitative measures for the purpose of diagnosis and prognosis are limited. OBJECTIVES: Main objectives of this study conducted on fetuses and infants with confirmed congenital Zika virus infection and detected brain abnormalities were (1) to assess the prevalence of microcephaly and the frequency of the anomalies that include a detailed description based on ultrasound and magnetic resonance imaging in fetuses and ultrasound, magnetic resonance imaging, and computed tomography imaging postnatally, (2) to provide quantitative measures of fetal and infant brain findings by magnetic resonance imaging with the use of volumetric analyses and diffusion-weighted imaging, and (3) to obtain additional information from placental and fetal histopathologic assessments and postnatal clinical evaluations. STUDY DESIGN: This is a longitudinal cohort study of Zika virus-infected pregnancies from a single institution in Colombia. Clinical and imaging findings of patients with laboratory-confirmed Zika virus infection and fetal brain anomalies were the focus of this study. Patients underwent monthly fetal ultrasound scans, neurosonography, and a fetal magnetic resonance imaging. Postnatally, infant brain assessment was offered by the use of ultrasound imaging, magnetic resonance imaging, and/or computed tomography. Fetal head circumference measurements were compared with different reference ranges with <2 or <3 standard deviations below the mean for the diagnosis of microcephaly. Fetal and infant magnetic resonance imaging images were processed to obtain a quantitative brain volumetric assessment. Diffusion weighted imaging sequences were processed to assess brain microstructure. Anthropometric, neurologic, auditory, and visual assessments were performed postnatally. Histopathologic assessment was included if patients opted for pregnancy termination. RESULTS: All women (n=214) had been referred for Zika virus symptoms during pregnancy that affected themselves or their partners or if fetal anomalies that are compatible with congenital Zika virus syndrome were detected. A total of 12 pregnant patients with laboratory confirmation of Zika virus infection were diagnosed with fetal brain malformations. Most common findings that were assessed by prenatal and postnatal imaging were brain volume loss (92%), calcifications (92%), callosal anomalies (100%), cortical malformations (89%), and ventriculomegaly (92%). Results from fetal brain volumetric assessment by magnetic resonance imaging showed that 1 of the most common findings associated with microcephaly was reduced supratentorial brain parenchyma and increased subarachnoid cerebrospinal fluid. Diffusion weighted imaging analyses of apparent diffusion coefficient values showed microstructural changes. Microcephaly was present in 33.3-58.3% of the cases at referral and was present at delivery in 55.6-77.8% of cases. At birth, most of the affected neonates (55.6-77.8%) had head circumference measurements >3 standard deviations below the mean. Postnatal imaging studies confirmed brain malformations that were detected prenatally. Auditory screening results were normal in 2 cases that were assessed. Visual screening showed different anomalies in 2 of the 3 cases that were examined. Pathologic results that were obtained from 2 of the 3 cases who opted for termination showed similar signs of abnormalities in the central nervous system and placental analyses, including brain microcalcifications. CONCLUSION: Congenital microcephaly is not an optimal screening method for congenital Zika virus syndrome, because it may not accompany other evident and preceding brain findings; microcephaly could be an endpoint of the disease that results from progressive changes that are related to brain volume loss. Long-term studies are needed to understand the clinical and developmental relevance of these findings.


Assuntos
Encéfalo/anormalidades , Encéfalo/diagnóstico por imagem , Complicações Infecciosas na Gravidez/epidemiologia , Infecção por Zika virus/epidemiologia , Adolescente , Adulto , Calcinose/diagnóstico por imagem , Líquido Cefalorraquidiano/fisiologia , Estudos de Coortes , Colômbia/epidemiologia , Diagnóstico por Imagem , Potenciais Evocados Auditivos , Potenciais Evocados Visuais , Feminino , Humanos , Hidrocefalia/diagnóstico por imagem , Recém-Nascido , Estudos Longitudinais , Microcefalia/virologia , Gravidez , Espaço Subaracnóideo/fisiologia , Adulto Jovem , Infecção por Zika virus/congênito
8.
Neurol Med Chir (Tokyo) ; 58(1): 23-31, 2018 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-29142154

RESUMO

The advent of magnetic resonance imaging (MRI) enables noninvasive measurement of cerebrospinal fluid (CSF) motion, and new information about CSF motion has now been acquired. The driving force of the CSF has long been thought to be choroid plexus (CP) pulsation, but to investigate whether this phenomenon actually occurs, CSF motion was observed in the ventricular system and subarachnoid space using MRI. Eleven healthy volunteers, ranging in age from 23 to 58 years, participated in this study. The MRI sequences used were four-dimensional phase-contrast (4D-PC) and time-spatial labeling inversion pulse (t-SLIP). The 4D-PC images included sagittal images in the cranial midline, coronal images focusing on the foramen of Monro (FOM), and oblique coronal images of the trigone to quantify CSF velocity and acceleration. These values were compared and analyzed as non-parametric data using the Kolmogorov-Smirnov test and the Mann-Whitney U test. 4D-PC showed that the median CSF velocity was significantly lower in the posterior part of the lateral ventricle than in other regions. The quantitative analysis of velocity and acceleration showed that they were decreased around the CP in the trigone. Image analysis of both velocity mapping and t-SLIP showed suppressed CSF motion around the CP in the trigone. These findings cast doubt on CP pulsation being the driving force for CSF motion.


Assuntos
Líquido Cefalorraquidiano/fisiologia , Plexo Corióideo/efeitos dos fármacos , Plexo Corióideo/fisiologia , Ventrículos Laterais/diagnóstico por imagem , Ventrículos Laterais/fisiologia , Fluxo Pulsátil/fisiologia , Adulto , Ventrículos Cerebrais/diagnóstico por imagem , Ventrículos Cerebrais/fisiologia , Feminino , Humanos , Imagem por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Valores de Referência , Espaço Subaracnóideo/diagnóstico por imagem , Espaço Subaracnóideo/fisiologia , Adulto Jovem
9.
J Cereb Blood Flow Metab ; 38(4): 719-726, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29039724

RESUMO

Clearance of waste products from the brain is of vital importance. Recent publications suggest a potential clearance mechanism via paravascular channels around blood vessels. Arterial pulsations might provide the driving force for paravascular flow, but its flow pattern remains poorly characterized. In addition, the relationship between paravascular flow around leptomeningeal vessels and penetrating vessels is unclear. In this study, we determined blood flow and diameter pulsations through a thinned-skull cranial window. We observed that microspheres moved preferentially in the paravascular space of arteries rather than in the adjacent subarachnoid space or around veins. Paravascular flow was pulsatile, generated by the cardiac cycle, with net antegrade flow. Confocal imaging showed microspheres distributed along leptomeningeal arteries, while their presence along penetrating arteries was limited to few vessels. These data suggest that paravascular spaces around leptomeningeal arteries form low resistance pathways on the surface of the brain that facilitate cerebrospinal fluid flow.


Assuntos
Encéfalo/fisiologia , Líquido Cefalorraquidiano/fisiologia , Animais , Velocidade do Fluxo Sanguíneo/fisiologia , Volume Sanguíneo , Encéfalo/anatomia & histologia , Artérias Cerebrais/fisiologia , Circulação Cerebrovascular/fisiologia , Pressão Intracraniana/fisiologia , Masculino , Meninges/irrigação sanguínea , Camundongos , Camundongos Endogâmicos C57BL , Microscopia Confocal , Microesferas , Espaço Subaracnóideo/irrigação sanguínea , Espaço Subaracnóideo/fisiologia
10.
J Neurosci Methods ; 290: 125-132, 2017 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-28780368

RESUMO

BACKGROUND: Catheterization has been widely used in neuroscience and pain research for local drug delivery. Though different modifications were developed, the use of young animals for spinal catheterization remains limited because of a little success rate. A reliable technique is needed to catheterize young animals aimed for in vivo testing combined with spinal cord electrophysiology, often limited by animal age, to facilitate pain research. NEW METHODS: We describe intrathecal catheterization of young rats (3-week-old) through atlanto-occipical approach for long-lasting drug delivery into the lumbar subarachnoid space. The technique represents a surgical approach of minimized invasiveness that requires PE-10 catheter and few equipment of standard laboratory use. RESULTS: Behavioral assessments revealed that spinal catheterization does not change peripheral sensitivity of different modalities (thermal and mechanical) and gives no rise to locomotive deficit or anxiety-like behavior in young rats. The long-term administration of genetic material (oligodeoxynucleotides given up to 4days), examined both in vivo and in situ, produced no adverse effects on basal peripheral sensitivity, but changed the AMPA receptor-mediated currents in sensory interneurons of the spinal cord. COMPARISON WITH EXISTING METHODS: Dissimilar to already described methods, the method is designed for the use of young rats for behavioral testing in vivo and/or spinal cord electrophysiology in situ. CONCLUSIONS: A practical method for spinal catheterization of young animals designed for studies in vivo and in situ is proposed. The method is rapid and effective and should facilitate investigation of therapeutic effects on both systemic and subcellular levels, as an advantage over the existing methods.


Assuntos
Articulação Atlantoccipital/fisiologia , Cateterismo/métodos , Sistemas de Liberação de Medicamentos/instrumentação , Sistemas de Liberação de Medicamentos/métodos , Neurônios/fisiologia , Medula Espinal/citologia , Potenciais de Ação/efeitos dos fármacos , Potenciais de Ação/fisiologia , Animais , Articulação Atlantoccipital/efeitos dos fármacos , Cateterismo/instrumentação , Agonistas de Aminoácidos Excitatórios/farmacologia , Comportamento Exploratório , Corantes Fluorescentes/administração & dosagem , Técnicas In Vitro , Injeções Espinhais , Masculino , Neurônios/efeitos dos fármacos , Oligodesoxirribonucleotídeos/farmacologia , Proteína Quinase C/química , Ratos , Ratos Wistar , Bloqueadores dos Canais de Sódio/farmacologia , Medula Espinal/efeitos dos fármacos , Espaço Subaracnóideo/fisiologia , Tetrodotoxina/farmacologia , Ácido alfa-Amino-3-hidroxi-5-metil-4-isoxazol Propiônico/farmacologia
11.
PLoS One ; 12(6): e0179503, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28654638

RESUMO

BACKGROUND AND OBJECTIVE: Respiration is known to affect cerebrospinal fluid (CSF) movement. We hypothesised that increased inspiratory resistance would affect the dynamic relationship between blood pressure (BP) changes and subarachnoid space width (SAS) oscillations. METHODS: Experiments were performed in a group of 20 healthy volunteers undergoing controlled intermittent Mueller Manoeuvres (the key characteristic of the procedure is that a studied person is subjected to a controlled, increased inspiratory resistance which results in marked potentiation of the intrathoracic negative pressure). BP and heart rate (HR) were measured using continuous finger-pulse photoplethysmography; oxyhaemoglobin saturation with an ear-clip sensor; end-tidal CO2 with a gas analyser; cerebral blood flow velocity (CBFV), pulsatility and resistive indices with Doppler ultrasound. Changes in SAS were recorded with a new method i.e. near-infrared transillumination/backscattering sounding. Wavelet transform analysis was used to assess the BP and SAS oscillations coupling. RESULTS: Initiating Mueller manoeuvres evoked cardiac SAS component decline (-17.8%, P<0.001), systolic BP, diastolic BP and HR increase (+6.3%, P<0.001; 6.7%, P<0.001 and +2.3%, P<0.05, respectively). By the end of Mueller manoeuvres, cardiac SAS component and HR did not change (+2.3% and 0.0%, respectively; both not statistically significant), but systolic and diastolic BP was elevated (+12.6% and +8.9%, respectively; both P<0.001). With reference to baseline values there was an evident decrease in wavelet coherence between BP and SAS oscillations at cardiac frequency in the first half of the Mueller manoeuvres (-32.3%, P<0.05 for left hemisphere and -46.0%, P<0.01 for right hemisphere) which was followed by subsequent normalization at end of the procedure (+3.1% for left hemisphere and +23.1% for right hemisphere; both not statistically significant). CONCLUSIONS: Increased inspiratory resistance is associated with swings in the cardiac contribution to the dynamic relationship between BP and SAS oscillations. Impaired cardiac performance reported in Mueller manoeuvres may influence the pattern of cerebrospinal fluid pulsatility.


Assuntos
Velocidade do Fluxo Sanguíneo/fisiologia , Pressão Sanguínea/fisiologia , Circulação Cerebrovascular/fisiologia , Respiração , Espaço Subaracnóideo/fisiologia , Adolescente , Adulto , Feminino , Voluntários Saudáveis , Frequência Cardíaca/fisiologia , Humanos , Masculino , Espaço Subaracnóideo/diagnóstico por imagem , Ultrassonografia Doppler Transcraniana , Adulto Jovem
12.
World Neurosurg ; 97: 523-531, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27474454

RESUMO

BACKGROUND: Many studies have shown that cerebrospinal fluid (CSF) behaves irregularly, rather than with laminar flow, in the various CSF spaces. We adapted a modified previously known magnetic resonance imaging technique to visualize irregular CSF motion. Subsequently, we assessed the usefulness and clinical significance of the present method. MATERIALS AND METHODS: Normal CSF motion in 10 healthy volunteers was visualized with the dynamic improved, motion-sensitized, driven-equilibrium steady-state free precession technique. Subsequently, CSF motion visualization with a modified sequence was applied to 3 patients. RESULTS: In healthy volunteers, we achieved visualization of the irregularity of CSF flow in the ventricles and spinal canal, whereas CSF motion was diminished in the peripheral part of the intracranial subarachnoid space. In one case, we confirmed the patency of the patient's third ventriculostomy fenestration site. In the other, we verified the usefulness of the proposed sequence for determining the communication between the ventricle or subarachnoid space and the cyst. CONCLUSIONS: Using the present sequence, we obtained images that accentuated CSF motion, which is largely composed of irregular motion. This method does not require pulse triggering or complex post-processing of images and allows visualization of CSF motion in a short period of time in selected whole imaging planes. It can therefore be applied clinically to diagnose various diseases that cause abnormalities in the CSF space.


Assuntos
Ventrículos Cerebrais/diagnóstico por imagem , Líquido Cefalorraquidiano/diagnóstico por imagem , Líquido Cefalorraquidiano/fisiologia , Imagem por Ressonância Magnética/métodos , Reologia/métodos , Espaço Subaracnóideo/diagnóstico por imagem , Adulto , Ventrículos Cerebrais/fisiologia , Humanos , Interpretação de Imagem Assistida por Computador/métodos , Masculino , Pessoa de Meia-Idade , Neuroimagem/métodos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Espaço Subaracnóideo/fisiologia , Adulto Jovem
13.
PLoS One ; 11(10): e0162938, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27727298

RESUMO

PURPOSE: Previous computational fluid dynamics (CFD) studies have demonstrated that the Chiari malformation is associated with abnormal cerebrospinal fluid (CSF) flow in the cervical part of the subarachnoid space (SAS), but the flow in the SAS of the posterior cranial fossa has received little attention. This study extends previous modelling efforts by including the cerebellomedullary cistern, pontine cistern, and 4th ventricle in addition to the cervical subarachnoid space. METHODS: The study included one healthy control, Con1, and two patients with Chiari I malformation, P1 and P2. Meshes were constructed by segmenting images obtained from T2-weighted turbo spin-echo sequences. CFD simulations were performed with a previously verified and validated code. Patient-specific flow conditions in the aqueduct and the cervical SAS were used. Two patients with the Chiari malformation and one control were modelled. RESULTS: The results demonstrated increased maximal flow velocities in the Chiari patients, ranging from factor 5 in P1 to 14.8 in P2, when compared to Con1 at the level of Foramen Magnum (FM). Maximal velocities in the cervical SAS varied by a factor 2.3, while the maximal flow in the aqueduct varied by a factor 3.5. The pressure drop from the pontine cistern to the cervical SAS was similar in Con1 and P1, but a factor two higher in P2. The pressure drop between the aqueduct and the cervical SAS varied by a factor 9.4 where P1 was the one with the lowest pressure jump and P2 and Con1 differed only by a factor 1.6. CONCLUSION: This pilot study demonstrates that including the posterior cranial fossa is feasible and suggests that previously found flow differences between Chiari I patients and healthy individuals in the cervical SAS may be present also in the SAS of the posterior cranial fossa.


Assuntos
Malformação de Arnold-Chiari/fisiopatologia , Líquido Cefalorraquidiano/fisiologia , Fossa Craniana Posterior/fisiologia , Espaço Subaracnóideo/fisiologia , Adulto , Algoritmos , Malformação de Arnold-Chiari/líquido cefalorraquidiano , Malformação de Arnold-Chiari/diagnóstico por imagem , Fossa Craniana Posterior/diagnóstico por imagem , Feminino , Humanos , Hidrodinâmica , Imagem por Ressonância Magnética , Pessoa de Meia-Idade , Projetos Piloto , Pressão , Espaço Subaracnóideo/diagnóstico por imagem
14.
Comput Biol Med ; 77: 49-58, 2016 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-27518326

RESUMO

Lumbar drainage is considered a therapeutic measure in treatment of subarachnoid hemorrhage. However, the evidence on the effectiveness of this method is still inconclusive. In this study, a subject-specific three dimensional model of the cerebrospinal fluid (CSF) pathways and compartments was developed. The ventricular and the cranial and spinal subarachnoid spaces were reconstructed using magnetic resonance images. Occurrence of subarachnoid hemorrhage was modeled. Since the presence of blood in the CSF spaces is known to be the cause of complications such as cerebral vasospasm, concentration of blood in these spaces was investigated. Two cases of lumbar drains that were different in the drainage rate were studied. Temporal variations of concentration of blood in CSF spaces were calculated. It was observed that lumbar drainage accelerates the clearance of blood and, thereby, the spasmogens present in the cranial and spinal subarachnoid space. Higher clearance rates were observed at higher drainage rates.


Assuntos
Líquido Cefalorraquidiano/fisiologia , Simulação por Computador , Drenagem , Hemorragia Subaracnóidea/terapia , Adulto , Biologia Computacional , Feminino , Humanos , Hidrodinâmica , Modelos Biológicos , Espaço Subaracnóideo/fisiologia
15.
Neurol Res ; 38(8): 725-32, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27308842

RESUMO

OBJECTIVES: Intrathecal catheterization and drug delivery in rats has always been a very important method for neuroscience and pain research. Although the technique has been continually improved since the first report, the experience gained over the years suggested that some defects remained unsolved. On the basis of modification of the standard epidural needle, lumbar needle, and intrathecal tube, we aimed to develop a simple and practical technique for intrathecal catheterization, which was similar to the 'needle-through-needle technique' used in combined spinal-epidural (CSE) anesthesia. METHODS: For comparison, rats received intrathecal catheterization via either laminectomy at L3-4 (control group) or our modified method (modification group). The operation time, success rate, and the incidence of postoperative complication were recorded. Thermal paw withdrawal latency, mechanical paw withdrawal threshold, Rota-rod, and body weight were measured on pre-operative day 1 and postoperative day 1-3, 5, 7, 14, 21, respectively. RESULTS: Compared with control group, our modified method was more practical to grasp and could bring about higher success rate, firmer catheters immobility, less weight loss, and minimal mortality. There was no difference between the two groups in spinal cord injury, hematoma, location of lumbar enlargement, and lateral location of the catheters tip. The procedure itself did not interfere with behavioral tests and motor coordination. CONCLUSION: We suggest that the modified method of intrathecal catheterization is well suitable for long-term behavior and pharmacology research on spinal cord.


Assuntos
Cateterismo/métodos , Sistemas de Liberação de Medicamentos , Injeções Espinhais/métodos , Medula Espinal/cirurgia , Anestésicos Locais/administração & dosagem , Anestésicos Locais/farmacologia , Animais , Condicionamento Operante , Lidocaína/administração & dosagem , Lidocaína/farmacologia , Masculino , Exame Neurológico , Complicações Pós-Operatórias/fisiopatologia , Ratos , Ratos Sprague-Dawley , Medula Espinal/efeitos dos fármacos , Medula Espinal/fisiologia , Espaço Subaracnóideo/efeitos dos fármacos , Espaço Subaracnóideo/fisiologia , Fatores de Tempo
16.
Brain Res ; 1635: 201-8, 2016 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-26794252

RESUMO

PURPOSE: Because a lowered intracranial pressure (ICP) is a possible mechanism of optic neuropathy, we wished to study the CSF dynamics in the optic nerve chamber by recording possible changes in the optic nerve subarachnoid space pressure (ONSP) and the impact on it when acutely lowering ICP. METHODS: In eight normal dogs pressure probes were implanted in the left brain ventricle, lumbar cistern, optic nerve subarachnoid space and in the anterior eye chamber. Following CSF shunting from the brain ventricle we monitored changes of ICP, lumbar cistern pressure (LCP), ONSP and intraocular pressure (IOP). RESULTS: At baseline, the pressures were different with ICP>LCP>ONSP but correlated with each other (P<0.001). The "trans-lamina cribrosa pressure gradient" (TLPG) was highest for IOP-ONSP, lower for IOP-LCP, and lowest for IOP-ICP (P<0.001). During CSF shunting the ICP gradually decreased in a linear fashion together with the ONSP ("ICP-depended zone"). But when the ICP fell below a critical breakpoint, ICP and ONSP became uncoupled and ONSP remained constant despite further ICP decline ("ICP-independent zone"). CONCLUSIONS: Because the parallel decline of ICP and ONSP breaks down when ICP decreases below a critical breakpoint, we interpret this as a sign of CSF communication arrest between the intracranial and optic nerve SAS. This may be caused by obstructions of either CSF inflow through the optic canal or outflow into the intra-orbital cavity. This CSF exchange arrest may be a contributing factor to optic nerve damage and the optic nerve chamber syndrome which may influence the loss of vision or its restoration.


Assuntos
Pressão Intracraniana , Pressão Intraocular/fisiologia , Nervo Óptico/fisiologia , Espaço Subaracnóideo/fisiologia , Animais , Pequim , Cães , Hidrodinâmica
17.
Med Hypotheses ; 85(6): 958-61, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26362731

RESUMO

Most hypotheses trying to explain the pathophysiology of idiopathic syringomyelia involve mechanisms whereby CSF is pumped against a pressure gradient, from the subarachnoid space into the cord parenchyma. On review, these theories have universally failed to explain the disease process. A few papers have suggested that the syrinx fluid may originate from the cord capillary bed itself. However, in these papers, the fluid is said to accumulate due to impaired fluid drainage out of the cord. Again, there is little evidence to substantiate this. This proffered hypothesis looks at the problem from the perspective that syringomyelia and normal pressure hydrocephalus are almost identical in their manifestations but only differ in their site of effect within the neuraxis. It is suggested that the primary trigger for syringomyelia is a reduction in the compliance of the veins draining the spinal cord. This reduces the efficiency of the pulse wave dampening, occurring within the cord parenchyma, increasing arteriolar and capillary pulse pressure. The increased capillary pulse pressure opens the blood-spinal cord barrier due to a direct effect upon the wall integrity and interstitial fluid accumulates due to an increased secretion rate. An increase in arteriolar pulse pressure increases the kinetic energy within the cord parenchyma and this disrupts the cytoarchitecture allowing the fluid to accumulate into small cystic regions in the cord. With time the cystic regions coalesce to form one large cavity which continues to increase in size due to the ongoing interstitial fluid secretion and the hyperdynamic cord vasculature.


Assuntos
Hidrocefalia de Pressão Normal/diagnóstico , Siringomielia/diagnóstico , Adulto , Malformação de Arnold-Chiari/fisiopatologia , Barreira Hematoencefálica , Pressão do Líquido Cefalorraquidiano/fisiologia , Feminino , Humanos , Hidrocefalia de Pressão Normal/fisiopatologia , Imagem por Ressonância Magnética , Medula Espinal/irrigação sanguínea , Medula Espinal/fisiologia , Espaço Subaracnóideo/fisiologia , Siringomielia/fisiopatologia
18.
PLoS One ; 10(8): e0135429, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26285143

RESUMO

PURPOSE: The aim of the study was to assess changes in subarachnoid space width (sas-TQ), the marker of intracranial pressure (ICP), pial artery pulsation (cc-TQ) and cardiac contribution to blood pressure (BP), cerebral blood flow velocity (CBFV) and cc-TQ oscillations throughout the maximal breath hold in elite apnoea divers. Non-invasive assessment of sas-TQ and cc-TQ became possible due to recently developed method based on infrared radiation, called near-infrared transillumination/backscattering sounding (NIR-T/BSS). METHODS: The experimental group consisted of seven breath-hold divers (six men). During testing, each participant performed a single maximal end-inspiratory breath hold. Apnoea consisted of the easy-going and struggle phases (characterised by involuntary breathing movements (IBMs)). Heart rate (HR) was determined using a standard ECG. BP was assessed using the photoplethysmography method. SaO2 was monitored continuously with pulse oximetry. A pneumatic chest belt was used to register thoracic and abdominal movements. Cerebral blood flow velocity (CBFV) was estimated by a 2-MHz transcranial Doppler ultrasonic probe. sas-TQ and cc-TQ were measured using NIR-T/BSS. Wavelet transform analysis was performed to assess cardiac contribution to BP, CBFV and cc-TQ oscillations. RESULTS: Mean BP and CBFV increased compared to baseline at the end of the easy phase and were further augmented by IBMs. cc-TQ increased compared to baseline at the end of the easy phase and remained stable during the IBMs. HR did not change significantly throughout the apnoea, although a trend toward a decrease during the easy phase and recovery during the IBMs was visible. Amplitudes of BP, CBFV and cc-TQ were augmented. sas-TQ and SaO2 decreased at the easy phase of apnoea and further decreased during the IBMs. CONCLUSIONS: Apnoea increases intracranial pressure and pial artery pulsation. Pial artery pulsation seems to be stabilised by the IBMs. Cardiac contribution to BP, CBFV and cc-TQ oscillations does not change throughout the apnoea.


Assuntos
Apneia , Velocidade do Fluxo Sanguíneo/fisiologia , Artérias Cerebrais/fisiologia , Circulação Cerebrovascular/fisiologia , Espaço Subaracnóideo/fisiologia , Adolescente , Adulto , Pressão Sanguínea , Suspensão da Respiração , Estudos de Casos e Controles , Feminino , Voluntários Saudáveis , Frequência Cardíaca , Humanos , Masculino , Análise de Ondaletas
19.
J Hypertens ; 33(9): 1811-7; discussion 1817-8, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26248322

RESUMO

BACKGROUND: Little is known about intracranial pressure (ICP)-cerebral haemodynamic interplay during repetitive apnoea. A recently developed method based on near-infrared transillumination/backscattering sounding (NIR-T/BSS) noninvasively measures changes in pial artery pulsation (cc-TQ) as well as subarachnoid width (sas-TQ) in humans. METHOD: We tested the complex response of the pial artery and subarachnoid width to apnoea using this method. The pial artery and subarachnoid width response to consecutive apnoeas lasting 30, 60 s and maximal breath-hold (91.1 ±â€Š23.1 s) were studied in 20 healthy volunteers. The cc-TQ and sas-TQ were measured using NIR-T/BSS; cerebral blood flow velocity (CBFV), pulsatility index and resistive index were measured using Doppler ultrasound of the left internal carotid artery; heart rate (HR) and beat-to-beat SBP and DBP blood pressure were recorded using a Finometer; end-tidal CO2 (EtCO2) was measured using a medical gas analyser. RESULTS: Apnoea evoked a multiphasic response in blood pressure, pial artery compliance and ICP. First, SBP declined, which was accompanied by an increase in cc-TQ and sas-TQ. Directly after these changes, SBP exceeded baseline values, which was followed by a decline in cc-TQ and the return of sas-TQ to baseline. During these initial changes, CBFV remained stable. Towards the end of the apnoea, BP, cc-TQ and CBFV increased, whereas pulsatility index, resistive index and sas-TQ declined. Changes in sas-TQ were linked to changes in EtCO2, HR and SBP. CONCLUSION: Apnoea is associated with ICP swings, closely reflecting changes in EtCO2, HR and peripheral BP. The baroreflex influences the pial artery response.


Assuntos
Apneia/fisiopatologia , Artérias Cerebrais/fisiologia , Espaço Subaracnóideo/anatomia & histologia , Espaço Subaracnóideo/fisiologia , Adolescente , Adulto , Barorreflexo , Pressão Sanguínea/fisiologia , Artéria Carótida Interna/diagnóstico por imagem , Circulação Cerebrovascular/fisiologia , Feminino , Voluntários Saudáveis , Frequência Cardíaca/fisiologia , Humanos , Pressão Intracraniana/fisiologia , Masculino , Tamanho do Órgão , Ultrassonografia Doppler , Adulto Jovem
20.
Neuromodulation ; 18(6): 448-59; discussion 459, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26095007

RESUMO

INTRODUCTION: Motion of the spinal cord relative to a spinal cord stimulator epidural electrode array can cause suboptimal stimulation: either noxious, inefficient, or insufficient. Adaptive stimulation attempts to mitigate these effects by modulating stimulation parameters in a position-dependent fashion. Near-infrared (NIR) reflectometry is demonstrated to provide real-time direct measurement of spinal cord position at the site of stimulation, which can facilitate closed-loop adaptive stimulation during static and dynamic motion states. METHODS: A miniature sensor array consisting of an NIR light emitting diode flanked by phototransistors potted in epoxy was placed in the dorsal epidural space of a human cadaver at the T8 level via laminotomy. Turgor of the subarachnoid space was maintained by intrathecal infusion of saline. NIR reflectance was measured as the cadaver was rotated about its longitudinal axis on a gantry. NIR reflectance was correlated with gantry position and velocity. RESULTS: NIR reflectometry suggests gravitational force is the primary determinant of cord position in static, ordinal positions. Under dynamic motion conditions, there was statistically significant cross-correlation between reflectometry data and the tangential velocity squared, suggesting that centripetal force was the primary determinant of cord position as the gantry was rotated. Reflectometry data strongly correlated with a simple geometric model of anticipated spinal cord precession within the spinal canal. CONCLUSIONS: Spinal cord position during dynamic motion has been shown to differ from static predictions due to additional influences such as centripetal force. These findings underscore limitations in extrapolating spinal cord position from surrogates such as body position or body acceleration at sites remote from the stimulating electrodes. NIR reflectometry offers a real-time direct measure of spinal cord position in both static and dynamic motion states, which may facilitate closed-loop adaptive stimulation applications.


Assuntos
Postura/fisiologia , Espectroscopia de Luz Próxima ao Infravermelho , Estimulação da Medula Espinal/métodos , Espaço Subaracnóideo/fisiologia , Cadáver , Humanos , Dinâmica não Linear , Espectroscopia de Luz Próxima ao Infravermelho/métodos , Medula Espinal/fisiologia , Tomógrafos Computadorizados , Tomografia Computadorizada por Raios X
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA