[Magnetoencephalography: a method for the study of brain function in neurosurgery].
Magnetoencephalography (MEG) is a non-invasive method for the study of electro-magnetic brain activity. Using multi-channel recordings the topography of the magnetic field can be recorded above the scalp with a temporal resolution of less than one millisecond. The method is suitable for the description and localization of cortical brain functions. The magnetic field strength that can be measured at up to 300 sensors is in the range of a few femto Tesla (10(-15) T) to somepico Tesla (10(-12) T). In order to measure these low magnetic fields highly sensitive SQUID-detectors are used on the one hand. On the other hand appropriate shielding equipment is employed to reduce effects of noise. Besides brain responses evoked by internal and external events (event-related magnetic fields), state-dependant oscillatory brain activity MEG can be recorded (spontaneous activity). Slow cortical oscillations in the range of 1 to 4 Hz are generated by damage of brain tissue and in the surrounding of brain tumors. In neurosurgery these activities can be used to monitor therapeutic success. Furthermore, oscillatory activities provide information about cortical regions involved in motor control. The measurement of motor related activities allows for the identification of recovery processes and reorganization after brain injury. Event-related magnetic brain responses are used in pre-surgical diagnosis and planning of treatment in epilepsy. In addition, they can be utilized to assess alterations in the functional organization of the cortex following injuries, tumor growth and neurosurgical interventions.
Braun
Christoph
C
Institut für Medizinische Psychologie und Verhaltensneurobiologie, Universität Tübingen, MEG-Zentrum der Universität Tübingen. christoph.braun@uni-tuebingen.de
D001921:Brain / Q000503:physiopathology* / Q000601:surgery*; D001931:Brain Mapping; D004569:Electroencephalography / Q000379:methods; D006801:Humans; D015225:Magnetoencephalography / Q000295:instrumentation / Q000379:methods*; D016343:Monitoring, Intraoperative / Q000379:methods; D019635:Neurosurgical Procedures / Q000379:methods*; D009991:Oscillometry