Systems and methods for controlled sympathectomy procedures for neuromodulation are disclosed. A system for controlled micro ablation procedures is disclosed. A guidewire including one or more sensors or electrodes for accessing and recording physiologic information from one or more anatomical sites within the parenchyma of an organ as part of a physiologic monitoring session, a diagnostic test, or a neuromodulation procedure is disclosed. A guidewire including one or more sensors and/or a means for energy delivery, for performing a neuromodulation procedure within a small vessel within a body is disclosed.