Flexible apparatus for ablating unhealthy spinal tissue. A housing includes a distal end and a proximal end. Multiple thermocouples mounted on the housing measure spinal tissue temperatures at locations between the proximal end and the distal end. A sensor measures spinal tissue impedance. The measured spinal tissue impedance corresponds to various physical state data of the spinal tissue. The spinal tissue impedance and the spinal tissue temperatures are displayed to the surgeon, enabling the surgeon to determine with certainty the location of the unhealthy spinal tissue, and to exercise control over the ablation apparatus. Nerve stimulation by IMP/STM switch system to detect nerve responses before and after treatment.