The information provided in Table 4.0 is a collaborative summary of the information we have discussed thus far outlining the use of electrical stimulation for the treatment of chronic pain. This table does not in any way provide an exclusive list for each modality of electrical stimulation as other treatment considerations may arise for different conditions and individual patients. The information regarding TENS was most extensive due to the vast amount of research available, whilst other modalities have questionable contraindications and precautions in comparison, with limited amount of evidence. At this point of our blog series, we feel it is important to reiterate that any electrotherapy agents should be avoided when the contraindications in Table 4.0 are listed.
Table 4.0: General parameters, electrode placement, contraindications and precautions of electrical stimulation modalities studied
ESTIM | RECOMMENDED PARAMETERS | ELECTRODE PLACEMENT/SAFETY | CONTRAINDICATIONS | PRECAUTIONS |
GENERAL ESTIM | Acute conditions: Low intensity, short duration Chronic conditions: Moderate-high intensity, long duration | Same size and type of electrodes used bilaterally Consistent amount of gel used over area being treated Size of electrodes: Small = increased density of current Large = decreased density of current Distance between electrodes: Small = superficial structures targeted Large = deeper structures targeted | · Pregnancy · Local malignancy · Pacemakers · Epilepsy (application CI at neck) · Haemorrhage · Active Epiphysis (local) · Negative skin discrimination test · Infections · Unreliable/uncommunicative /unwilling patient | · Local circulatory insufficiency · Devitalised tissue · Superficial metal · Open wounds · Individuals with high pain tolerance · Skin damage or irritation · Do not apply around the eye or testes |
EXTRA CONTRAINDICATIONS | EXTRA PRECAUTIONS | |||
TENS | Duration: Varies depending on type of TENS and area of pain – generally is of longer duration; greater than 30mins for chronic pain Conventional: 40-150Hz, 50-100μs pulse width, low intensity* Acupuncture like: 1-4Hz, 100-400μs pulse width, high intensity* Brief-intense: >80Hz, >150μs pulse width, tolerable intensity* Burst mode: bursts <10Hz, comfortable intensity* Modulation: one or more parameters randomly modulated *intensity is determined by individual patient and their perceptions. | DO NOT PLACE ELECTRODES OVER: · Stomach when pregnant · Carotid sinus · Temples · Local malignancy · Open skin wounds DO NOT PLACE ELECTRODES ACROSS: · Heart · Throat · Cerebrum | See General Estim contraindications | TENS during the first trimester and first stage of labour has been shown to be beneficial, but only when applied over the lower back or wrist for Carpal tunnel syndrome (CTS). Caution must be used to avoid acupuncture points. |
PENS | Frequency: Modulated with a combination of 2Hz, 30Hz and 100Hz. Duration: 30 minutes | See General Estim and TENS Electrode Placement/Safety | See General Estim and TENS contraindications | See General Estim and TENS precautions |
CCEF | Frequency: 60kHz active wave, pulsed with 12.5Hz at a 50% duty cycle Intensity: 7V(peak to peak) AC waveform Current density: 25μA/cm2 Duration: 10 hours per day | See General Estim and TENS Electrode Placement/Safety | Limited research available. Follow contraindications of General Estim | Limited research available. Follow precautions of General Estim |
TCES | Frequency: 77Hz Average pulse width: 3.3msec Duration: 30min | ‘Headset’ with 3 electrodes, adjusted to fit comfortably over the patient’s cranium. Electrode placement: One electrode each side over mastoid process One electrode on forehead | Limited research available. Follow contraindications of General Estim | Limited research available. Follow precautions of General Estim |
rTMS | Frequency: <1Hz (inhibitory effect) Duration: Bursts of up to 10 seconds | Stimulation over motor cortex and/or dorsolateral prefrontal cortex for chronic pain. The patient positions their chin on a stand with their forehead supported. A magnetic field is created by 2 adjoining wire coils approximately 1cm above the patient's head which is positioned so that the area to be treated is aligned with the midline of the two coils. | · Aneurysm clips · Cranial implants · Epilepsy · Recent cardiovascular event · Increased intracranial pressure | · Long durations can induce seizures or fainting |
To conclude, the use of varying modalities of electrotherapy agents to provide analgesia for chronic pain sufferers seems promising but many gaps exist in the research. After discussion and consideration of the available evidence throughout our blog series, we have decided that there are a number of questions which remained unanswered regarding the exact perceived benefits of using electrical stimulation to treat chronic pain, but there is a benefit nonetheless. Whether the patient feels pain relief as a direct result of the electrical stimulation or rather from a placebo effect remains a topic of debate within the literature and the issue merits further investigation into the future of the research surrounding this area. Regardless, pain relief for the patient is always seen as a positive outcome and hence as an indication for the use of electrical stimulation as part of the patient’s treatment regime.
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