Cranial Electrotherapy to Treat Pain
By Narda Robinson, DO, DVM
Posted: Nov. 3, 2011, 1:05 p.m. EDT
In veterinary patients as well as humans, behavioral problems and chronic pain can be tough to treat. In non-humans, when negotiations, remonstrations, protestations and medications fail, caregivers may consider euthanasia out of frustration.
Chronic pain may underlie and/or contribute to the chaos, sensitizing the central nervous system, augmenting stress and turning touch into pain at the flip of a neuronal switch through a process called “allodynia.”
Attaining a diagnosis from an astute veterinarian equipped with myofascial palpation and neurologic examination skills can help illuminate the underlying issues beyond the psyche. Coupling a precise cause with methods that modulate the nervous system may restore sanity and hope in an otherwise bleak situation.
This is the era of neuromodulation. Several modalities in integrative medicine encourage restorative, analgesic responses in the brain and spinal cord. For example, medical acupuncture, which includes electroacupuncture, affects the central, peripheral and autonomic nervous systems through well-characterized pathways.
Massage participates in several of the same neuromodulatory mechanisms as acupuncture; it excites mechanoreceptor fibers whose signals ascend to the spinal cord and brain, thereby diminishing pain and regulating visceral function. Laser therapy likewise impacts nervous system elements, adjusting their activity and fostering tissue regrowth.
Electrotherapy continues to expand options for pain and behavior treatments, giving researchers and clinicians insights into optimal frequencies and intensities that induce nervous system normalization.
As often occurs, many methods start in human medicine and make their way into the veterinary field. Desperate caregivers of animals battling psychological and physical discomfort are finding websites that promote electrotherapy for the mind, known as “cranial electrotherapy stimulation,” or CES.
Veterinarians need to be able to counsel them on whether and how a simple, non-invasive electrotherapy unit could indeed reduce reliance on pharmaceuticals and restore equanimity in the household.
|Cranial electrotherapy stimulation may help chronic pain. Photo courtesy of Alpha-Stim.|
Certain human populations, such as military veterans suffering from chronic pain, stress and spinal cord injury, actually prefer a modality such as CES that allows self-treatment at home with minimal training.1 The seemingly easy transferability of an easy-to-use, well-researched home treatment to the veterinary field makes CES worth evaluating. Its relative ease of application (perhaps for dogs more than cats) by means of atraumatic ear clips allows it ready inclusion in home as well as clinic circumstances.
The device that has received the most attention, known as “Alpha-Stim,” is now celebrating its 30-year anniversary (www.alpha-stim.com). Its small, handheld microcurrent machines run on 9-volt batteries. Human patients’ testimonials on the product website report deep relaxation followed by a “shift in consciousness.”2
The website also lists a host of veterinary applications, including pain, chronic neuromuscular conditions, cognitive dysfunction, obsessive compulsive disorder, separation anxiety syndrome, depression, urinary incontinence, anorexia in cats, help with healing wounds, non-union fractures, lower motor neuron injuries and reducing chronic infectious states.3 Does research support these claims?
CES research on animals is limited, though some insights have emerged. Preliminary data from an equine study showed reduction in cribbing behavior.4 In dogs, both CES and electroacupuncture reduced the minimum alveolar concentration of isoflurane without inducing adverse effects on hemodynamic status.5
While the analgesic benefits of CES may not be robust enough to supply stand-alone analgesia for operative procedures, its inclusion for situations such as pre-operative anxiety and pain as well as post-operative analgesia should be considered, based on their adjunctive benefits and safety. The ease of application and its amenability to study through a double-blind, placebo-controlled trial make CES a compelling area of research.
In human research, a 2011 Cochrane review found the evidence for CES limited and less than convincing.6 Nevertheless, the individual studies are inspiring to read, given the findings on the value of CES for people suffering from generalized anxiety disorder7, fibromyalgia8, depression9, addiction10 and many other conditions.
CES has received FDA marketing clearance for the treatment of anxiety, insomnia and depression.11 Regulations allow for over-the-counter sale in Europe; U.S. residents interested in purchasing the unit must first obtain an order or prescription from a licensed healthcare professional.12
CES ordinarily involves electrodes applied to clips on the pinna, or the earlobe in humans. Whether the electricity enters the brain directly or whether it mainly causes neuromodulation via extracranial nerve excitation leading to reflex responses in the brain has not been fully elucidated. One author suggested that 70 percent of cranial TENS passes over the face and scalp, affecting sensorimotor fibers in the skin and underlying musculature.13 Thus, modification of brain activity would result from reflex effects as superficial nerves send signals centrally.
As with auricular acupuncture, study of the ear’s neurovascular anatomy reveals an abundance of cranial and upper cervical nerves that crosstalk with the vagus nerve, as well as an auricular branch of the vagus nerve itself. The ear also houses a rich plexus of blood vessels packed with autonomically active nervi vasorum. This fibrous mesh translates into a neuromodulation-ready network capable of infuencing autonomic tone and limbic function, producing parasympathetic dominance through vagal activation and suppression of sympathetic system hyperactivity.14
Analgesia is accentuated as high-frequency stimuli activate large diameter, well-myelinated afferent nerve fibers, invoking a cascade of endogenous analgesic responses.
In humans, CES intensity starts at a low level, increasing to patient tolerance. Excessive current produces stinging pain at the sites where the electrodes make contact with the skin. Patients may also experience dizziness or nausea. Veterinary patients will likely paw at or try to rub off the electrodes if they create discomfort.
Contraindications include the presence of pacemakers and other implanted electronic devices. FDA regulations require that the machine’s label include precautions for use by pregnant women. Epileptic patients appear to be able to utilize the therapy safely.15 After all, vagal neuromodulation has become a point of focus for medically intractable epilepsy.16
Thankfully, the medical and veterinary professions are awakening to the possibilities of safer treatment through non-invasive neuromodulation that unfold as the innate healing capacities of the body are supported and then unleashed, reducing reliance on medication and procedures.
Dr. Robinson, DVM, DO, Dipl. ABMA, FAAMA, oversees complementary veterinary education at Colorado State University.
1. Tan G, Dao TK, Smith DL et al. Incorporating complementary and alternative medicine (CAM) therapies to expand psychological services to veterans suffering from chronic pain. Psychological Services. 2010;7(3):148-161.
2. Alpha-Stim ® SCS. Accessed at http://www.alpha-stim.com/the-alpha-stim-scs/ on 09-21-11.
3. Alpha-Stim ® website. Accessed at http://www.alpha-stim.com/veterinary-medicine/ on 09-18-11.
4. Berger JM, Holcomb K, San Jose N, et al. The effect of cranial electrotherapy stimulation on cribbing behavior in horses. Proceedings, 2010 ACVB/AVSAB Veterinary Behavior Symposium. Atlanta, GA. July, 2010. Pp. 6-8.
5. Culp LB, Skarda RT, and Muir WW. Comparisons of the effects of acupuncture, electroacupuncture, and transcutaneous cranial electrical stimulation on the minimum alveolar concentration of isoflurane in dogs. Am J Vet Res. 2005;66:1364-1370.
6. O’Connell NE, Wand BM, Marston L, et al. Non-invasive brain stimulation techniques for chronic pain (Review). European Journal of Physical and Rehabilitation Medicine. 2011; 47(2):1-124.
7. Bystritsky A, Kerwin L, and Feusner J. A pilot study of cranial electrotherapy stimulation for generalized anxiety disorder. J Clin Psychiatry. 2008;69:412-417.
8. Cork RC, Wood P, Ming N, et al. The effect of cranial electrotherapy stimulation (CES) on pain associated with fibromyalgia. The Internet Journal of Anesthesiology. 2004;8(2).
9. Gunther M and Phillips KD. Cranial electrotherapy stimulation for the treatment of depression. Journal of Psychosocial Nursing. 2010;48(11):37-42.
10. Steiker LKH, Helmly PM, Clements T, et al. New and promising technologies in the field of addiction recovery: highlights of emerging expertise. Journal of Social Work Practice in the Addictions. 2010;10:331-338.
11. Gilula MF and Barach PR. Cranial electrotherapy stimulation: a safe neuromedical treatment for anxiety, depression, or insomnia. Southern Medical Journal. 2004;97(12):1269.
12. Alpha Stim ® online store. Accessed at http://store.alpha-stim.com/SearchResults.asp?Cat=1 on 09-21-11.
13. Taylor DN. The effects of cranial TENS on measures of autonomic somatic and cognitive activity. Acupuncture & Electro-Therapeutics Research. 1989;14(1):29-42.
14. Taylor DN. The effects of cranial TENS on measures of autonomic somatic and cognitive activity. Acupuncture & Electro-Therapeutics Research. 1989;14(1):29-42.
15. Gunther M and Phillips KD. Cranial electrotherapy stimulation for the treatment of depression. Journal of Psychosocial Nursing. 2010;48(11):37-42.
16. Bhargava P and Doshi PK. Neuromodulation for epilepsy. J Pediatr Neurosci. 2008;3:111-116. Accessed at http://neurologicalsurgery.in/en/file/1111100001Neuromodulation_for_epilepsy_-JPediatrNeurosci.pdf on 09-22-11.
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