A Network Analysis of 15O-H2O PET Reveals Deep Brain Stimulation Effects on Brain Network of Parkinson's Disease

PURPOSE: As Parkinson's disease (PD) can be considered a network abnormality, the effects of deep brain stimulation (DBS) need to be investigated in the aspect of networks. This study aimed to examine how DBS of the bilateral subthalamic nucleus (STN) affects the motor networks of patients with idiopathic PD during motor performance and to show the feasibility of the network analysis using cross-sectional positron emission tomography (PET) images in DBS studies. MATERIALS AND METHODS: We obtained [15O]H2O PET images from ten patients with PD during a sequential finger-to-thumb opposition task and during the resting state, with DBS-On and DBS-Off at STN. To identify the alteration of motor networks in PD and their changes due to STN-DBS, we applied independent component analysis (ICA) to all the cross-sectional PET images. We analysed the strength of each component according to DBS effects, task effects and interaction effects. RESULTS: ICA blindly decomposed components of functionally associated distributed clusters, which were comparable to the results of univariate statistical parametric mapping. ICA further revealed that STN-DBS modifies usage-strengths of components corresponding to the basal ganglia-thalamo-cortical circuits in PD patients by increasing the hypoactive basal ganglia and by suppressing the hyperactive cortical motor areas, ventrolateral thalamus and cerebellum. CONCLUSION: Our results suggest that STN-DBS may affect not only the abnormal local activity, but also alter brain networks in patients with PD. This study also demonstrated the usefulness of ICA for cross-sectional PET data to reveal network modifications due to DBS, which was not observable using the subtraction method.

El núcleo subtalámico en la fisiopatología de la enfermedad de Parkinson y su rol como diana quirúrgica / The subthalamic nucleus in the pathophysiology of Parkinson's disease and its role as a surgical target

Parkinson's disease is one of the most common causes of neurological disability, it caused by selective loss of neurons at the substantia nigra, which causes an imbalance in the functioning of the basal ganglia. In the pathophysiological events underlying this disease, hyperactivity of the subthalamic nucleus is more often associated with major clinical manifestations; this structure also plays a fundamental role in motor control, making it an excellent surgical target.

La enfermedad de Parkinson es una de las causas más frecuentes de discapacidad neurológica, se produce por la pérdida selectiva de neuronas a nivel de la sustancia nigra, lo que genera un desbalance en el funcionamiento de los ganglios basales. De los eventos fisiopatológicos subyacentes en esta enfermedad, la hiperactividad del núcleo Subtalámico es el que más se relaciona con las principales manifestaciones clínicas, además esta estructura juega un papel fundamental en el control motor, lo que la convierte en una excelente diana quirúrgica.

Imagens de ressonância magnética funcional em pacientes com doença de Parkinson submetidos à estimulação cerebral profunda / Functional Magnetic Resonance Imaging in patients with Parkinson’s disease with deep brain stimulation

A estimulação cerebral profunda (ECP) é usada para tratar a doença de Parkinson (DP) avançada. A estimulação do núcleo subtalâmico (NST) melhora o sintomas de parkinsonismo, mas seu mecanismo de ação permanece pouco compreendido. Dados comportamentais durante o exame e a evolução clínica foram analisados. RESULTADOS: Os pacientes não apresentaram complicações decorrentes dos exames de RMf. Com o estímulo elétrico ligado, nas sequências BL houve maior atividade em relação às RE, na área sensitivo-motora primária (SM1) esquerda. Durante o repouso, quando a estimulação elétrica foi ligada houve maior atividade das seguintes áreas: cerebelo direito, SM1 esquerda, Cgp, pM bilateral, mesencéfalo esquerdo e Cga. Houve melhora clínica dos pacientes e tanto a avaliação motora na primeira semana pós-operatória, na fase sem medicação, bem como a avaliação global em seis meses estiveram correlacionadas com os parâmetros motores aferidos durante os exames de RMf / Deep brain stimulation (DBS) is used to treat advanced Parkinson's disease (PD). Stimulation of the subthalamic nucleus (STN) is effective to improve the symptoms related to parkinsonism, but its mechanism of action remains poorly understood. Functional magnetic resonance imaging (fMRI) can be applied to study brain areas involved in motor activity, as a mean to better understand the effects of DBS. In this work we aimed to develop and test fMRI techniques to study DP patients treated with DBS. METHODS: We have initially performed tests to check the interference of the DBS in image quality and made adaptations that minimized the artifacts. After this initial phase PD patients were examined by fMRI in four different phases: during right hand movement (before surgery to implant DBS electrodes, after the surgery with the electrical stimulation turned off, and after the surgery with the electrical stimulation turned on the STN) and at rest with electrical stimulation turned on. In total, ten patients were examined, eight of them paired to matched normal volunteers...