Clinical neurophysiologyHead: PD Dr. O. Pogarell
Every year, well over 4000 brain functional studies (electroencephalography/EEG and evoked potentials/EP) are performed in the Department of Clinical Neurophysiology. In addition, approx. 3000 electrocardiograms (ECGs) are recorded every year.
The most frequently performed examination is electroencephalography (EEG), which is recorded in all inpatients at least once during their hospital stay. The EEG is a non-invasive procedure that directly measures electrical brain activity, which is conducted from the scalp by surface electrodes via an ‘electrode cap’. An EEG recording is made in a state of ‘relaxed alertness’ (wakefull resting state) with closed eyes, lasting approx. 40 minutes. In order to increase the informative value of the examination, towards the end of the measurement, the EEG is recorded while the patient is hyperventilating (increased rate of breathing). Certain abnormal EEG changes (e.g. in case of epilepsy) can appear more clearly during this stage (see figure). Further ‘provocation methods’ include sleep deprivation and photic stimulation, which are applied in special cases.
Figure: EEG of a patient with epilepsy: intermittent appearance of generalised epileptiform discharges indicating increased cerebral excitability