Needle guidance system

A system and device to determine the location of a needle as it penetrates through a tissue and into a desired site, such as the epidural space, are described. The system (1000) contains a light guide (1020), a light source (1040), a light sensor (1050), and a logic unit (1060). When the tip of the needle (1010) traverses the relatively dense Ligamantum Flavum, the reflecting plane of the ligament is positioned at or near zero distance relative to the tip of the device. Once the tip enters a less dense epidural space the distance to the reflecting plane becomes greater than zero thus producing a drop in intensity of the reflected light. That drop in the intensity of the reflected light is measured by the light sensor and interpreted by a logic unit to be consistent with entry into the epidural space, allowing the system to provide a signal indicating entry into the epidural space.