The invention consists of a device to evaluate hemodynamic response generated by the spinal cord in response to a suprasensorial stimulus applied to a peripheral nerve (medium or posterior tibial) by the use of functional near-infrared spectroscopy (fNIRS). The device consists of 3 main components, an electrical stimulator, an optical recording unit and a signal processing and control module. The device allows non-invasive, comfortable, harmless, portable, home-based, and low-cost evaluation of changes in local hemodynamic parameters in response to neuronal activation of the spinal cord by electrical stimulation of a peripheral nerve. The invention also includes a corresponding method of using the device and monitoring the spinal function.