A method of identifying a change in the health of a nerve during a surgical procedure includes determining a sensitivity of the nerve at a first time, determining a sensitivity of the nerve at a second time, and providing an indication to a user corresponding to a change in the sensitivity of the nerve from the first time to the second time. In each instance, the sensitivity of the nerve is determined by providing an electrical stimulus via an electrode disposed on a distal end portion of an elongate medical instrument, and monitoring a magnitude of a mechanical response of a muscle innervated by the nerve.