1. Circulatory impairment :arterial or venousthrombosis, thrombophlebitis.2. Stimulation over the carotid sinus.3. Stimulation across the heart: especially if patient haspacemaker.4. Pregnancy.5. Seizure disorder.6. Fresh fracture.7. Active hemorrhage.8. Malignancy.9. Decreased sensation—direct current can cause burns(electrochemical).10. Atrophic skin.11. Patients inability to report stimulation-induced pain.12. Known allergies to gel or pads.
1. Stimulates nerve fibers for thesymptomatic relief of pain.2. Uses a pocket-size programmable deviceto apply an electrical signal through leadwires and electrodes attached to thepatient’s skin.3. Electrode placement is subjective.Typically placed over peripheral nerve distribution.Locations can be distal or proximal to pain site.
1. Placebo effect is 30–35%.2. Based on the Gate Control Theory by Melzackand Wall (1965):Pain signals can be blocked at the spinal cord beforethey are transmitted to the brain. TENS stimulateslarge Ia myelinated afferent nerve fibers thatstimulate the substantia gelatinosa in the spinalcord, closing the gate on pain transmission to thethalamus.3. Release of endogenous opioids via TENSCheng and Pomerantz (1979)—demonstratedthat pain relief produced at 4 Hz stimulation(low frequency) was blocked by Naloxone;pain relief induced at 200 Hz was not blockedby naloxone .
Attempts to account for mechanisms bywhich other cutaneous stimuli andemotional states alter the level ofpain.
Treatment time with TENS is normally 30minutes to 1 hour per session with amaximum of 2 hours per session, for atotal of 8 hours per day. The treatments are continued for 3 weeksand gradually reduced over 8–12 weeks. Patients may report discomfort or skinirritation if the intensity is too high. Skin irritation can be resolved if theelectrode positions are shifted or if adifferent conducting gel is used. Electrode shifting can increase currentintensities to uncomfortable levels.
Conventional (IF- currents)1. High-frequency, low-intensity stimulation:most effective type of stimulation.2. Amplitude is adjusted to produce minimalsensory discomfort.3. Pain relief begins in 10–15 minutes andstops shortly after removing stimulation.4. Useful for neuropathic pain.5. Duration of treatment is 30 minutes tohours.
Low frequency, high intensity stimulation (DD-currents).1. Amplitude high enough to produce musclecontraction.2. Onset of pain relief can be delayed several hours3. Pain relief persists hours after removingstimulation.4. Useful for acute musculoskeletal conditions.5. Treatment sessions last 30–60 minutes.Hyperstimulation1. High frequency, high intensity stimulation.2. It is considered that this mode stimulates C-fibers causing counter-irritation.3. Rarely tolerated more than 15–30 minutes.
Pulse or burst mode◦ High frequency stimulation bursts atlow frequency intervals◦ Delayed onset of pain relief◦ Treatment can range 30–60 minutes Modulated◦ Impulses vary in intensity andfrequency◦ Attempts to avoid neuro-habituation
Consists of trans-cutaneous electricalstimulation for muscles with or without intactperipheral nerve stimulation, or centralcontrol. When the electrical stimulation is used toprovide functional use of paretic muscles, it iscalled FES (functional electrical stimulation)or FNS (functional neuromuscular stimulation). Multiple muscles can be activated in acoordinated fashion through the use ofelectrical stimulation to attain certainfunctional goals (ambulation, transfers).
1. Maintains muscle mass after immobilization.2. Increases muscle bulk3. Prevents complications from immobility suchas deep vein thrombosis (DVT), osteoporosisand fractures4. Strengthens muscles—effects have beennoted even without voluntary muscle action.5. Changes of type II muscle fibers into type Ifibers are temporarily noted with thetreatments.6. Increases ROM or maintains it.7. Provides feedback to enhance voluntary musclecontrol (muscle reeducation).8. Inhibits spasticity and muscle spasm.9. Can be used for orthotic training andfunctional movement.
Open-loop system:◦ Manual feedback.◦ Most units are open-loop type◦ The user observes the results of the stimulationand based on this adjusts the stimulation intensity.◦ Each cycle of activity starts with the use of manuallyactivating switches that send signals to control theunit. Closed-loop system:◦ Control unit depends on movement sensors thatsend signals from the patient’s body as resultsare obtained.◦ Stimulation is adjusted to improve theprogrammed result.◦ Lack of effective sensors may pose a problem.◦ Advantages include correction of unexpectedproblems such as muscle spasms and fatigue.