An implantable lead assembly includes an outer jacket, first and second coiled conductors, and first and second electrodes. The outer jacket is elongated along a center axis and includes a body that radially extends between opposite interior and exterior surfaces. The interior surface defines an elongated lumen. The coiled conductors are held within the body of the outer jacket between the interior and exterior surfaces of the outer jacket and are wrapped around the lumen and the center axis. The electrodes are coupled with the outer jacket and electrically coupled to the coiled conductors in order to at least one of deliver stimulus pulses or sense electrical activity.