LAKE FOREST, Ill. — There’s a new option for chronic pain sufferers that ought to spark some growth across external analgesics, including heat and ice packs: Omron’s recently approved ElectroTherapy Pain Relief unit. There are as many as 60 million chronic pain sufferers, according to the American Chronic Pain Association. And of those in search of pain relief solutions, 80% seek more than one type, according to research conducted on behalf of Thermionics. So Omron’s $69.99 transcutaneous electrical nerve stimulation unit should be an adjunctive sale.