Systems for determining structural integrity of a bone within the spine of a patient, the bone having a first aspect and a second aspect, wherein the second aspect separated from the first aspect by a width and located adjacent to a spinal nerve. A stimulator is configured to generate an electrical stimulus to be applied to the first aspect of the bone. A monitor is configured to electrically monitor a muscle myotome associated with the spinal nerve to detect if an onset neuro-muscular response occurs in response to the application of the electrical stimulus to the first aspect of the bone. An adjuster is configured to automatically increase the magnitude of the electrical stimulus to until the onset neuro-muscular response is detected. Lastly, a communicator is configured to communicate to a user via at least one of visual and audible means information representing the magnitude of the electrical stimulus which caused the onset neuro-muscular response.