December 2005

Gate Control

By Noel M. Goodstadt, MPT, OCS, CSCS

As an adjunct intervention to improve passive stretching techniques, TENS can enhance manual therapy

In many scenarios, physical therapists are limited in their ability to passively stretch a patient, because of the amount of pain the patient has to endure. Our body can sense pain to protect us from impending damage to muscles, ligaments, bone, and other soft tissue structures; however, pain is also a residual side effect of the injury process. With a patient in the hands of a trained therapist, pain is not necessarily a deterrent to performing the tactics necessary for improvement. For example, if a patient has severe adhesive capsulitis in their shoulder, they will likely have impingement pain during stretches that elevate the arm. Rarely does the pain resolve unless the patient's capsule is stretched. Therefore, treatment of passive stretching and joint mobilizations is indicated even in the presence of pain.

One problem with stretching into pain is the patient's tendency to guard with co-contraction of the surrounding musculature. So how do we prevent it? Medications can be helpful, but often are insufficient to reduce the pain adequately, and therapists turn to other modalities to manage the discomfort. Transcutaneous electrical nerve stimulation (TENS) is a common modality used in physical therapy to manage pain, usually before and/or after the core treatment tactics. However, TENS can also be used in conjunction with other passive tactics during a treatment.

The use of electrical stimulation for pain control, known as the "Gate Control Theory," activates large-diameter myelinated sensory fibers blocking transmission of nocioceptive input carried by small myelinated and nonmyelinated pain fibers.¹ The electrical stimulation input essentially shuts the door on the transmission of pain stimuli.

Conventional TENS is the most studied form of electrical stimulation, with the majority of the research based on the control and management of chronic or induced acute pain. The parameters most commonly discussed include a high frequency range from 100 to 200 pulses per second (pps), a short phase duration from 2 to 50 microseconds, and intensity to perceptible tingling.² Benefits have been seen in patients with peripheral nerve damage, angina pectoris, and musculoskeletal disorders.³ TENS used for postoperative pain also has demonstrated a reasonable benefit.⁴

In a more recent study from 2003, Rakel and Frantz studied patients who had undergone recent abdominal surgery and were having pain greater than 5/10 on a 0 – 10 numeric rating scale. The authors examined active TENS (50 to 100 pulses per second, 150 microsecond pulse duration) versus placebo TENS and their effects on pain, walking, and pulmonary status. The electrodes were placed on both sides of the abdominal incision and turned on for 30 to 60 minutes while the patients completed specific tasks. They concluded that TENS significantly decreased pain intensity during walking and deep breathing maneuvers. More important, it significantly improved the subjects' distance and speed of ambulation when used as a supplement to pharmacologic analgesia.⁵

PAIN BLOCK

The use of TENS as a method of blocking pain with activity and supplementing medication can be applied clinically.

I have used this technique successfully in other cases. Patients with adhesive capsulitis can gain an average of 10° to 20° improvements in rotation or elevation with TENS during joint mobilizations and end-range stretches. Patients with knee joint arthrofibrosis have improved 5° to 10° when TENS was combined with end-range flexion stretches and tibiofemoral joint mobilizations. The additions of TENS to these cases was based on a lack of measurable gains after one or two visits. This combination approach resulted in improvements in both measurable impairments and functional activities, and the patient had less discomfort in the process.

There are many ways to measure effectiveness when TENS is added to impact patient treatment. For example, function can be monitored before, during, and after the intervention; patients can complete functional questionnaires; and impairments can be measured. To determine if the addition of TENS is helpful to outcome measures, data can be recorded and compared with and without TENS. For example, knee ROM before and after the combined technique of TENS with passive stretching can be compared. If the gains are greater with TENS, then the intervention indicated is the combined treatment of TENS with stretching.

TENS during treatment, as noted in the case scenarios, was effective when the patients were unable to progress due to pain. TENS with stretching offers another option or tool in the arsenal of providing quality care. It is a very simple tool, which can easily be overlooked, but has minimal to negligible side effects, and provides an opportunity for significant improvement.

Noel M. Goodstadt, MPT, OCS, CSCS, is associate director of orthopedics and coordinator of the Orthopedic Clinical Residency at the University of Delaware Physical Therapy Clinic, Newark. He is an instructor in the Physical Therapy Department and can be reached at .

REFERENCES

1. Melzack R, Wall PD. Pain mechanism: a new theory. Science. 1965;150:971-976.
2. Robinson AJ, Snyder-Mackler L. Clinical Electrophysiology. 2nd ed. Baltimore: Williams & Wilkins; 1995: 284-291.
3. Meyler WJ, de Jongste MJ, Rolf CA. Clinical evaluation of pain treatment with electrostimulation: a study of TENS in patients with different pain syndromes. Clin J Pain. 1994;10:22-27.
4. Arvidsson I, Eriksson E. Postoperative TENS pain relief after knee surgery: objective evaluation. Orthopedics. 1986;9:1346-1351.
5. Rakel B, Frantz R. Effectiveness of transcutaneous electrical nerve stimulation on postoperative pain with movement. J Pain. 2003;4:455-464.

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