A mains electricity (AC-powered) device assembly designed to continuously measure the electrical signals produced by a patient's brain and display/record them as an electroencephalogram (EEG) to evaluate brain function. It may be capable of monitoring various other physiological paramenters such as electromyogram (EMG), respiration wave forms, blood pressure, ocular motility, and/or haemoglobin oxygen saturation (SpO2) and carbon dioxide (CO2) in relation to EEG. It includes a control unit, electrodes, and components (e.g., amplifier, cables, probes); it is designed to be easily moved and is commonly used at the patient's bedside, in an intensive care unit (ICU), or an examination room.