RESUMO
The frontal aslant tract (FAT) connects the supplementary motor area (SMA) with the pars opercularis. Its role in language and its implications in glioma surgery remain under discussion. We present an anatomosurgical study of three cases with surgical resolution. Three patients with gliomas in the left frontal lobe were operated on using an awake patient protocol with cortical and subcortical mapping techniques, conducting motor and language evaluations. Tractography was performed using DSI Studio software. All three patients showed intraoperative language inhibition through subcortical stimulation of the FAT. Resection involving the FAT correlated with language deficits in all cases and movement initiation deficits in two cases. All patients recovered from their deficits at six months postoperatively. In conclusion, the tract has been successfully reconstructed, showing both anatomical and functional complexity, supporting the idea of its mapping and preservation in glioma surgery. Future interdisciplinary studies are necessary to determine the transient or permanent nature of the deficits.
El tracto oblicuo frontal (TOF) conecta el área motora suplementaria (AMS) con la pars opercularis. Su rol en el lenguaje y su implicancia en la cirugía de gliomas siguen en discusión. Presentamos un estudio anatomoquirúrgico de tres casos con resolución quirúrgica. Se operaron tres pacientes con gliomas en el lóbulo frontal izquierdo utilizando protocolo de paciente despierto con técnicas de mapeo cortical y subcortical realizando evaluación motora y del lenguaje. Las tractografías fueron realizadas con el software DSI Studio. Los tres pacientes presentaron inhibición intraoperatoria del lenguaje mediante la estimulación subcortical de TOF. La resección en contacto con el TOF se correlacionó con déficits del lenguaje en todos los casos y en dos casos déficits en la iniciación del movimiento. Todos los pacientes recuperaron su déficit a los seis meses postoperatorios. En conclusión, se ha logrado reconstruir al tracto. Éste presenta una complejidad anatómica y funcional, que apoya la idea de su mapeo y preservación en la cirugía de gliomas. Futuros estudios interdisciplinarios son necesarios para determinar el carácter transitorio o permanente de los déficits.
Assuntos
Neoplasias Encefálicas , Lobo Frontal , Glioma , Humanos , Neoplasias Encefálicas/cirurgia , Neoplasias Encefálicas/diagnóstico por imagem , Neoplasias Encefálicas/patologia , Glioma/cirurgia , Glioma/diagnóstico por imagem , Glioma/patologia , Masculino , Lobo Frontal/cirurgia , Lobo Frontal/diagnóstico por imagem , Pessoa de Meia-Idade , Feminino , Adulto , Procedimentos Neurocirúrgicos/métodos , Mapeamento Encefálico/métodos , Córtex Motor/diagnóstico por imagem , Córtex Motor/cirurgia , Córtex Motor/anatomia & histologia , Imagem de Tensor de DifusãoRESUMO
The study of functional reorganization following stroke has been steadily growing supported by advances in neuroimaging techniques, such as functional magnetic resonance imaging (fMRI). Concomitantly, graph theory has been increasingly employed in neuroscience to model the brain's functional connectivity (FC) and to investigate it in a variety of contexts. The aims of this study were: 1) to investigate the reorganization of network topology in the ipsilesional (IL) and contralesional (CL) hemispheres of stroke patients with (motor stroke group) and without (control stroke group) motor impairment, and 2) to predict motor recovery through the relationship between local topological variations of the functional network and increased motor function. We modeled the brain's FC as a graph using fMRI data, and we characterized its interactions with the following graph metrics: degree, clustering coefficient, characteristic path length, and betweenness centrality (BC). For both patient groups, BC yielded the largest variations between the two analyzed time points, especially in the motor stroke group. This group presented significant correlations (P<0.05) between average BC changes and the improvements in upper-extremity Fugl-Meyer (UE-FM) scores at the primary sensorimotor cortex and the supplementary motor area for the CL hemisphere. These regions participate in processes related to the selection, planning, and execution of movement. Generally, higher increases in average BC over these areas were related to larger improvements in UE-FM assessment. Although the sample was small, these results suggest the possibility of using BC as an indication of brain plasticity mechanisms following stroke.
Assuntos
Córtex Motor , Reabilitação do Acidente Vascular Cerebral , Acidente Vascular Cerebral , Humanos , Imageamento por Ressonância Magnética/métodos , Córtex Motor/diagnóstico por imagem , Córtex Motor/patologia , Recuperação de Função Fisiológica , Acidente Vascular Cerebral/diagnóstico por imagem , Extremidade SuperiorRESUMO
The delta value of oxyhemoglobin (Δ-HbO) determined by functional near-infrared spectroscopy at prefrontal cortex (PFC) and motor cortex (MC) based on primary (25 °C) and secondary (5 °C) thermal stimuli presented a larger peak latency at left MC in fibromyalgia than in controls. The difference between HbO concentration 15 s after the thermal stimuli ending and HbO concentration before the thermal stimuli onset (Δ-HbO*) at left PFC increased 47.82% in fibromyalgia and 76.66% in controls. This value had satisfactory discriminatory properties to differentiate cortical activation in fibromyalgia versus controls. A receiver operator characteristics (ROC) analysis showed the Δ-HbO* cutoffs of - 0.175 at left PFC and - 0.205 at right PFC offer sensitivity and specificity of at least 80% in screening fibromyalgia from controls. In fibromyalgia, a ROC analysis showed that these cutoffs could discriminate those with higher disability due to pain and more severe central sensitization symptoms (CSS). The ROC with the best discriminatory profile was the CSS score with the Δ-HbO* at left PFC (area under the curve = 0.82, 95% confidence interval = 0.61-100). These results indicate that cortical activation based on Δ-HbO* at left PFC might be a sensitive marker to identify fibromyalgia subjects with more severe clinical symptoms.
Assuntos
Biomarcadores/análise , Mapeamento Encefálico/métodos , Fibromialgia/patologia , Córtex Motor/fisiopatologia , Córtex Pré-Frontal/fisiopatologia , Índice de Gravidade de Doença , Espectroscopia de Luz Próxima ao Infravermelho/métodos , Adolescente , Adulto , Idoso , Estudos de Casos e Controles , Feminino , Fibromialgia/diagnóstico por imagem , Humanos , Pessoa de Meia-Idade , Córtex Motor/diagnóstico por imagem , Oxiemoglobinas/análise , Córtex Pré-Frontal/diagnóstico por imagem , Adulto JovemRESUMO
BACKGROUND: Functional imaging studies have associated dystonia with abnormal activation in motor and sensory brain regions. Commonly used techniques such as functional magnetic resonance imaging impose physical constraints, limiting the experimental paradigms. Functional near-infrared spectroscopy (fNIRS) offers a new noninvasive possibility for investigating cortical areas and the neural correlates of complex motor behaviors in unconstrained settings. METHODS: We compared the cortical brain activation of patients with focal upper-limb dystonia and controls during the writing task under naturalistic conditions using fNIRS. The primary motor cortex (M1), the primary somatosensory cortex (S1), and the supplementary motor area were chosen as regions of interest (ROIs) to assess differences in changes in both oxyhemoglobin (oxy-Hb) and deoxyhemoglobin (deoxy-Hb) between groups. RESULTS: Group average activation maps revealed an expected pattern of contralateral recruitment of motor and somatosensory cortices in the control group and a more bilateral pattern of activation in the dystonia group. Between-group comparisons focused on specific ROIs revealed an increased activation of the contralateral M1 and S1 cortices and also of the ipsilateral M1 cortex in patients. CONCLUSIONS: Overactivity of contralateral M1 and S1 in dystonia suggest a reduced specificity of the task-related cortical areas, whereas ipsilateral activation possibly indicates a primary disorder of the motor cortex or an endophenotypic pattern. To our knowledge, this is the first study using fNIRS to assess cortical activity in dystonia during the writing task under natural settings, outlining the potential of this technique for monitoring sensory and motor retraining in dystonia rehabilitation.
Assuntos
Distonia/diagnóstico por imagem , Escrita Manual , Córtex Motor/diagnóstico por imagem , Adulto , Mapeamento Encefálico , Distonia/fisiopatologia , Feminino , Neuroimagem Funcional , Humanos , Masculino , Pessoa de Meia-Idade , Córtex Motor/fisiopatologia , Espectroscopia de Luz Próxima ao InfravermelhoRESUMO
Background. The primary motor cortex of the hand (M1-Hand) is a target used in transcranial magnetic stimulation (TMS) and in transcranial direct current stimulation (tDCS) for the treatment and evaluation of motor neurological diseases. Magnetic resonance imaging-guided neuronavigation locates the M1-Hand with high precision, but at a high cost. Although less accurate, the C3/C4 points of the international 10-20 system (IS 10-20) are routinely used to locate the M1-Hand. The international 10-5 system (IS 10-5) was developed with additional points (C3h/C4h), which could make it more accurate, but has not yet been tested on the location of the M1-Hand. Objective. To analyze and compare the accuracy of C1/C2, C3h/C4h and C3/C4 points in locating the M1-Hand correspondence on the scalp. Methods. The authors comparatively analyzed the distances from points C1/C2, C3h/C4h, and C3/C4 to the correspondence of the M1-Hand on the scalp in 30 MRI head exams. Results. In most cases, the M1-Hand was located between C1-C3h and C2-C4h in the left and right hemispheres of the brain, respectively. The C3h (0.98 ± 0.49 cm) and C4h (0.98 ± 0.51 cm) points presented the shortest distances from the M1-Hand, with a significant difference when compared with C3/C4. The accuracy between C1/C2 and C3h/C4h was not statistically significant. Conclusion. The C3h/C4h and C1/C2 points were more accurate when compared with the C3 and C4 points in locating the M1-Hand correspondence on the scalp.
Assuntos
Córtex Motor , Estimulação Transcraniana por Corrente Contínua , Eletroencefalografia , Potencial Evocado Motor , Mãos , Humanos , Imageamento por Ressonância Magnética , Córtex Motor/diagnóstico por imagem , Estimulação Magnética TranscranianaRESUMO
Gait initiation is a daily challenge even for healthy individuals as it requires the timely coupling between the automatic anticipatory postural adjustment (APA) and the voluntary step according to the context. Modulation of this motor event has been thought to involve higher level brain control, including cognitive inhibitory circuitries. Despite the known participation of the supplementary motor area (SMA) in the modulation of some parameters of APA, the participation of areas controlling inhibition during gait initiation still needs to be investigated. In this study, the hemodynamic responses of the SMA and dorsolateral prefrontal cortex (DLPFC) were assessed using functional near-infrared spectroscopy (fNIRS) during a gait initiation task under cognitive conflict to select the foot to step (congruent [CON] and incongruent [INC] conditions). The older group (OG) showed worse inhibitory control than the young group (YG) along with more impairments in APA parameters. OG also had a lower amplitude of hemodynamic responses in both areas than YG in the INC. The INC increased the correlation between SMA and DLPFC only in the YG. Aging seems to impair the interaction between the hemodynamic responses of SMA and DLPFC, which influences APA performance in gait initiation under cognitive conflict.
Assuntos
Envelhecimento/fisiologia , Envelhecimento/psicologia , Córtex Motor/irrigação sanguínea , Córtex Motor/fisiologia , Córtex Pré-Frontal/irrigação sanguínea , Córtex Pré-Frontal/fisiologia , Idoso , Fenômenos Biomecânicos , Cognição/fisiologia , Conflito Psicológico , Estudos Transversais , Feminino , Neuroimagem Funcional , Marcha/fisiologia , Hemodinâmica , Humanos , Masculino , Córtex Motor/diagnóstico por imagem , Equilíbrio Postural/fisiologia , Córtex Pré-Frontal/diagnóstico por imagem , Espectroscopia de Luz Próxima ao Infravermelho , Adulto JovemRESUMO
BACKGROUND: Decreased short-interval intracortical inhibition (SICI) to transcranial magnetic stimulation (TMS) of the primary motor cortex was described in subjects with restless legs syndrome/Willis-Ekbom disease (RLS/WED). It remained to be determined whether the magnitude of SICI decrease would be similar across levels of RLS/WED severity. Moreover, it was unknown whether, in addition to decreases in SICI, changes in cortical thickness or area could be detected in subjects with RLS/WED compared to controls. The objective of this study was to compare SICI, cortical thickness, and cortical area in subjects with idiopathic mild to moderate RLS/WED, severe to very severe RLS/WED, and controls. METHODS: The severity of RLS/WED was assessed by the International Restless Legs Syndrome Severity Scale (IRLSS). SICI and 3T magnetic resonance imaging (MRI) data of subjects with RLS/WED and controls were compared. A receiver operating characteristic curve for SICI was designed for discrimination of participants with RLS/WED from controls. Cortical thickness and area were assessed by automated surface-based analysis. RESULTS: SICI was significantly reduced in patients with mild to moderate and severe to very severe RLS/WED, compared to controls (one-way analysis of variance: F = 9.62, p < 0.001). Receiver operating characteristic curve analysis predicted RLS/WED when SICI was above 35% (area under the curve = 0.79, 95% CI 0.67-0.91, p < 0.001). Analyses of the whole brain and of regions of interest did not reveal differences in gray matter thickness or area between controls and subjects with RLS/WED. CONCLUSION: SICI is an accurate cortical biomarker that can support the diagnosis of RLS/WED even in subjects with mild symptoms, but cortical thickness and area were not useful for discriminating subjects with this condition from controls.
Assuntos
Encéfalo/diagnóstico por imagem , Córtex Motor/diagnóstico por imagem , Síndrome das Pernas Inquietas/terapia , Estimulação Magnética Transcraniana/efeitos adversos , Adulto , Encéfalo/fisiopatologia , Brasil/epidemiologia , Estudos de Casos e Controles , Excitabilidade Cortical , Potencial Evocado Motor , Feminino , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Córtex Motor/fisiopatologia , Qualidade de Vida , Receptores de GABA-A/fisiologia , Síndrome das Pernas Inquietas/diagnóstico , Síndrome das Pernas Inquietas/fisiopatologia , Sensibilidade e Especificidade , Índice de Gravidade de Doença , Estimulação Magnética Transcraniana/métodosRESUMO
BACKGROUND: Amyotrophic lateral sclerosis (ALS) is a devastating disease that targets motor neurons. Upper motor neurons degeneration is pathologically characterized by brain iron accumulation. Signal attenuation in the shape of a ribbon at the posterior border of the precentral gyrus can be observed on conventional magnetic resonance imaging (MRI) sequences including T2-weighted sequence. METHODS: With the aim to know the qualities of this potential marker of ALS, we conducted a prospective study. Patients with definite ALS in the age range of 40-70 years and healthy controls underwent 3T brain MRI using a standardized sequence. A second MRI was performed 18 months later under the same conditions in the patients with ALS. RESULTS: Most of the patients with ALS (91.66%) exhibited a "black ribbon" (BR) with an average area of 79.98 mm3. Signal attenuation discriminated ALS with a mean value of 63.97 arbitrary units (AU) on the left BR (95% CI: 60.67-67.27), a mean value of 59.15 AU (95% CI: 54.78-63.53) on the right BR, and a significant difference with control subjects presenting a mean value of 107.85 AU (p < 0.001). The optimal cut-off point for differentiating patients with ALS from controls (sensitivity, 0.92; specificity, 0.93) was 83 AU. Forced vital capacity and muscle strength in the contralateral upper extremity were significantly correlated with the ribbon intensity in ALS. Patients who underwent a second study exhibited significant changes in the BR related to the rapid evolution of the disease. CONCLUSIONS: This marker represents a valuable tool for the selection of candidates and their follow-up in clinical trials.
Assuntos
Esclerose Lateral Amiotrófica/diagnóstico por imagem , Imageamento Tridimensional/métodos , Imageamento por Ressonância Magnética/métodos , Córtex Motor/diagnóstico por imagem , Adulto , Idoso , Estudos de Coortes , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos ProspectivosRESUMO
BACKGROUND: Mirror therapy (MT) is becoming an alternative rehabilitation strategy for various conditions, including stroke. Although recent studies suggest the positive benefit of MT in chronic stroke motor recovery, little is known about its neural mechanisms. PURPOSE: To identify functional brain changes induced by a single MT intervention in ischemic stroke survivors, assessed by both transcranial magnetic stimulation (TMS) and functional magnetic resonance imaging (fMRI). MATERIALS AND METHODS: TMS and fMRI were used to investigate 15 stroke survivors immediately before and after a single 30-min MT session. RESULTS: We found statistically significant increase in post-MT motor evoked potential (MEP) amplitude (increased excitability) from the affected primary motor cortex (M1), when compared to pre-MT MEP. Post-MT fMRI maps were associated with a more organized and constrained pattern, with a more focal M1 activity within the affected hemisphere after MT, limited to the cortical area of hand representation. Furthermore, we find a change in the balance of M1 activity toward the affected hemisphere. In addition, significant correlation was found between decreased fMRI ß-values and increased MEP amplitude post-MT, in the affected hemisphere. CONCLUSION: Our study suggests that a single MT intervention in stroke survivors is related to increased MEP of the affected limb, and a more constrained activity of the affected M1, as if activity had become more constrained and limited to the affected hemisphere.