Magnetic pulses help diagnose consciousness

Science : In medical cases where someone has suffered a traumatic brain injury (TBI) or has fallen into a coma, it is important to be able to determine what level of consciousness the person retains, if any. Currently, doctors are limited to attempting to stimulate the patient’s senses and looking for slight movements of the eyes or fingers. But an estimated 40% of patients judged to have no consciousness are later found to have some level of it. Attempts to use brain imaging or monitoring of electrical activity have also been found to be unreliable. Now Marcello Massimini of the University of Milan in Italy and his colleagues believe they have found a viable method for measuring consciousness. An electroencephalograph (EEG) is used to measure electrical activity stimulated by pulses from a magnetic coil held to the skull, and a variety of characteristics of the EEG readings are used to rank the response on a scale between 0 and 1. The system was calibrated with healthy people fully awake, in deep sleep, and under different types of anesthesia. It was then tested on people who had suffered a variety of TBIs with relatively well-understood levels of consciousness. The system works without requiring any input from the patient, so it holds considerable promise as a diagnostic tool, but it struggles with some ambiguous cases, especially for patients with intermittent consciousness.