Before surgery can take place, the epileptic focus must be identified. To do this a range of diagnostic tests can be used. In the UK NHS, usual practice is to obtain details of the person's medical history, undertake a clinical examination, and perform an electroencephalogram (EEG) with electrodes applied to the scalp and a routine magnetic resonance imaging (MRI) scan. Individuals will usually go on to have continuous video and EEG recording with electrodes applied to the scalp in order to record seizures and identify the likely seizure focus. If these are unsuccessful in locating the epileptic focus three broad alternatives will need to be considered. Firstly, if there is a clear indication as to the site of the seizure focus the person may be admitted to hospital for continuous invasive EEG monitoring with electrodes inserted into, or across the surface of, the brain. Secondly, if there is no clear indication as to the site of the seizure focus, and it is considered unlikely that the patient will benefit from surgery, a decision might be made not to continue with the pre-surgical evaluation. Thirdly, and the most common, would be a decision to proceed with further, non-invasive, investigations such as specialised imaging scans or magnetoencephalography (MEG). The main aim of these investigations is to provide further information about the likely site of the seizure focus so that a decision can be made as to whether to proceed with invasive EEG monitoring, proceed to surgery, or to halt the pre-surgical evaluation.

We will undertake a systematic review to determine the added value of these non-invasive technologies in this decision making process and investigate the cost-effectiveness of these technologies. The cost of conducting further research will also be investigated.