Transcutaneous Electrical Nerve Stimulation (TENS) is a small, battery-operated device that delivers low-voltage electrical impulses through electrodes placed on the skin for pain management. Kidney stone pain, medically termed renal colic, is an intense, intermittent pain caused by the stone’s movement or a blockage in the urinary tract. This article explores whether TENS can offer a non-pharmacological option for managing the severe discomfort of renal colic during the passage of a kidney stone.
Understanding TENS Pain Relief
The effectiveness of TENS is explained by two physiological mechanisms that counteract the perception of pain. The first is the Gate Control Theory of Pain, which proposes that non-painful input can close the “gates” to painful input. The high-frequency electrical pulses delivered by the TENS unit stimulate large, non-pain-carrying nerve fibers, which inhibit the transmission of pain signals traveling to the spinal cord and brain. This rapid stimulation “floods” the nervous system with a tingling sensation, reducing painful signal transmission.
The second mechanism involves stimulating the release of natural pain-killing compounds. These compounds are endorphins, which are endogenous opioids that bind to receptors in the brain and spinal cord to produce an analgesic effect. This mechanism is associated with lower-frequency TENS settings, ranging between 2 and 10 cycles per second (Hz). Promoting the release of these internal pain relievers can provide a more sustained period of pain relief, even after the device is turned off.
TENS Application for Kidney Stone Pain
When using a TENS unit for renal colic, precise placement of the electrode pads is important to target the affected nerves. Since kidney stone pain presents as severe flank or lower back pain, electrodes should be placed over the most painful area, generally the lumbar region or flank on the affected side. The pads must be positioned at least one inch apart to allow the current to flow effectively. Local TENS application in this manner can be a rapid method for managing acute renal colic pain.
For acute pain, recommended settings involve high frequency and low intensity. High-frequency pulses, usually between 80 and 120 Hz, maximize the gate-control effect and provide immediate relief. The intensity should produce a strong but comfortable tingling sensation without causing muscle contraction. Using the device for periods such as 60 minutes, multiple times a day, is often recommended.
TENS is a tool for managing the sensation of pain and does not address the underlying cause. While it can reduce the perception of discomfort, it does not dissolve, move, or remove the kidney stone itself. It serves as a non-drug option that complements, but does not replace, standard medical care for stone passage.
Important Safety Considerations
Before using a TENS unit, especially for a severe condition like kidney stone pain, a healthcare provider should be consulted to ensure the device is appropriate for the individual’s specific circumstances. There are several situations where TENS should be avoided due to potential risks. The device should never be used on individuals with a pacemaker or other implanted electrical devices, as the electrical currents could interfere with their function.
TENS use is contraindicated in several areas. Electrodes should never be placed over areas of damaged skin, open wounds, or areas with impaired sensation, which could lead to skin irritation or burns.
Contraindicated Placement Areas
TENS use is also contraindicated over the abdominal or pelvic area during pregnancy. Additionally, the pads should not be placed in the following locations:
- Over the eyes.
- On the front of the neck near the carotid sinus.
- Transcranially (across the head).
Patients must recognize the difference between managing pain and treating the medical condition. A TENS unit should only be used as an adjunct therapy alongside prescribed medical treatment. If the pain worsens, or if symptoms such as a fever, chills, or an inability to urinate develop, immediate medical attention is necessary. These symptoms can signal a serious complication like infection or complete obstruction.