Spinal cord stimulation to treat pain has long been associated with mixed efficacy and substantial side effects such as paresthesia, which is an unpleasant tingly or prickly sensation. Redwood City, Calif.-based Nevro Corp. famously has built a multi-billion-dollar business on next-gen, pain neurostimulation technology that improves efficacy and reduces side effects. Sommerville, Mass.-based Micro-leads Medical Inc. hopes that it could be next in successfully further refining spinal cord stimulation.