In a small observational study of 33 people with chronic back pain, 14 (42%) of them experienced a reduction in pain of at least 30% due to TENS. In a study with 40 patients who underwent open heart surgery, the use of the TENS unit at acupuncture points (“ACU-TENS”) helped restore blood pressure and heart rate to normal more quickly and to use fewer medications (compared to patients who did not use TENS). Another study in patients with migraine reported that TENS treatment reduced the total number of days with headaches. The oral health care provider is in a critical position to play an active role in the treatment of patients with a history of hypertension, since many antihypertensive agents interact with pharmacological agents used in dental practice.
Patients who used TENS after surgery improved breathing, felt less pain and needed less pain medication than patients who did not use TENS in a study with 50 patients who underwent thoracic surgery. Vasoconstrictor LA should be avoided or used at low doses in patients who are taking non-selective beta-blockers or in patients with uncontrolled hypertension. A review concluded that the risk of adverse events in people with hypertension (controlled or uncontrolled) was low after the injection of local anesthetics containing epinephrine, although the evidence was limited both in quantity and quality. For example, in a study of 45 patients, using a TENS unit after heart surgery (pulmonary artery bypass) did not reduce the future risk of heart problems. A technique called transcutaneous vagus nerve stimulation or “tVNS” for short, is a method in which TENS is used to stimulate the vagus nerve (which is done by connecting the TENS unit to specific parts of the ear).
In a study conducted with 40 women who had very painful menstrual cramps (dysmenorrhea), TENS was found to be effective in reducing cramp-related pain and improved the quality of life of these patients. They can be approved as “adjuvants” in the treatment of pain, as long as they are sufficiently similar (that is, at least as safe and effective) to TENS devices that are already approved on the market. The evidence suggests that patients with high blood pressure can receive tens treatments, but it is important for oral health care providers to be aware of potential interactions between antihypertensive agents and pharmacological agents used in dental practice. Furthermore, vasoconstrictor LA should be avoided or used at low doses in patients taking non-selective beta-blockers or those with uncontrolled hypertension. Finally, transcutaneous vagus nerve stimulation has been found to be effective for reducing cramp-related pain and improving quality of life for women with dysmenorrhea.