A method and a device for diagnosing brain injury (e.g. concussion) based on analysis of electromyogram (EMG) signals and presence of neurological modulation impairment of motor activity are described. The method consists of recording specific EMG signals under defined conditions, processing the acquired EMG signals, extracting the relevant information, and making diagnosis of brain injury and disorders that are associated with brain pathology. Specifically, the steps and device involved in the method include placing an EMG electrode set on the subject's body area, acquiring EMG signals from a subject's muscle(s) undergoing contraction, processing the acquired EMG signals using a signal processing algorithm that includes Fourier transformation. The resulting EMG data with a frequency domain (frequency power spectra) are then analyzed in comparison with databases stored in the device and used to determine anomaly of diagnostic value in the EMG power spectra from subjects. A diagnosis can be made based the altered EMG frequency power spectra that reflect the neurological modulation impairment of motor neurons. The diagnostic value, determination, management suggestions are displayed on the device.
