Magnetoencephalography MEG

​A magnetoencephalography (MEG) is used to measure the magnetic fields caused by cerebral cortex activity outside the head. An MEG can locate brain activation areas to the accuracy of even a few millimetres. This method is used to locate epileptogenic foci in epileptic patients and to locate functionally vital brain areas prior to brain surgery. In addition, it can be used to measure the function of somatosensory pathways.

In the examination, the patient sits or lies in a small measuring room with his or her head under a helmet-shaped measuring device. The measurement is completely harmless and does not expose the patient to radiation. Depending on the grounds for the examination, it typically takes 1 to 3 hours. Several measurements are performed during the study and the patient has the possibility to stretch his or her legs between measurements. In most cases, one measurement takes 30 minutes at most, during which time the head should be as deep inside the measuring helmet as possible.

Since magnetic materials impede the examination, the patient should not wear any clothes containing metals during the study. If necessary, the patient can wear hospital clothes for the duration of the examination. In addition, some hair dyes and sprays, make-up and nail polish as well as metal piercings can cause magnetic disturbances, so these should be avoided if possible.