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Wearable, Sustained Acoustic Medicine for Back Pain

Principal Investigator:
George K. Lewis, Jr., Ph.D.

ZetrOZ, Inc.

Approximately 50-80 million people in the U.S. suffer from some form of chronic pain, and one-third of adults over age 20 show signs of a herniated disc. Among astronauts, space adaptation back pain (SABP) is the most commonly reported issue, with one study finding that 86% of 728 astronauts reported back pain. SABP occurs in 0G conditions when both gravitational and load-bearing mechanical forces are absent, thus removing downward pressure on the spine. Lack of pressure leads to spinal disc distortion and ultimately disc herniation. The microgravity environment, radiation exposure, and exercise limitations are primary sources of space-related back pain. The functional impairment and mission risk caused by SABP require more effective treatment measures be pursued.

ZetrOZ has pioneered an innovative method of delivering therapeutic ultrasound to tissues, without the need for cumbersome equipment or manual operation by clinicians. This technology utilizes long duration low intensity ultrasound, housed in a portable unit no larger than the size of a cell phone. This allows the patient to continue with their normal day while simultaneously receiving therapy. A human clinical trial has been scheduled to quantify the efficacy of two different ultrasound frequencies on herniated disc-related back pain.

Technical Summary

It is known that during space travel, the spine expands due to microgravity and intervertebral discs swell due to the absence of axial loading. After a mission, astronauts suffer herniation of the nucleus pulposus (HNP), due to exposure to gravitational forces on earth at a rate 400% higher than the general population. A herniated disc occurs when a crack in the outer cartilage (annulus fibrosus) of the disc allows some of the inner soft cartilage (nucleus pulposus) to leak out, potentially causing pain, numbness, tingling, and weakness. Several pre-clinical research studies suggest that low intensity ultrasound has beneficial effects on regeneration and growth of nucleus pulposus cells. Therapeutic ultrasound has also been observed to increase extracellular matrix production by fibroblasts thus accelerating recovery, along with increasing fluid circulation and reducing inflammation.

Recently, a wearable therapeutic ultrasound device was developed for application of continuous, low intensity ultrasonic waves to apply mild mechanical stimulation to bodily tissue over multiple hours. This device provides enhanced regenerative benefits to injured tissues to relieve pain and muscle spasms, treat joint contracture, increase local circulation in musculoskeletal tissues and promote healing. Located in Trumbull, Connecticut, ZetrOZ manufactures commercialized devices and develops new products using the core innovative technology. Compared to traditional therapeutic ultrasound, which is manually administered by a practitioner in a physiotherapy clinic for 5-20 minutes once or twice per week, sustained acoustic medicine merges two effective treatment approaches (low-intensity ultrasound + ultrasonic diathermy) of current ultrasound devices, and can be self-applied daily for up to 4 hours, delivering 18,000 Joules of acoustic energy per treatment. Published clinical studies show that ultrasound is most effective when it is delivered daily and provides > 2,500 J of energy per treatment. More frequent treatment and greater energy deposition strongly correlate with positive, statically significant clinical outcomes (e.g. pain reduction, ROM, reduced disability, etc.). Therefore, ZetrOZ technology breaks through the limitations of traditional ultrasound therapy by providing greater patient access to treatment and sustaining therapeutic effects on biological tissues for multiple hours every day.

ZetrOZ proposes that their device has the potential to counteract SABP and herniated discs among astronauts, as well as herniated disc pain on earth through three mechanisms:

1. Mechanical forces from the ultrasound waves (convection and rarefaction) are exerted on the disc to reduce distortion and risk of herniation
2. Increased blood and interstitial fluid circulation to improve diffusion processes
3. Reduced pain through means of reduced inflammation, muscle relaxation and neuromodulation

Specific Aims: This project represents the first measurement of differential responses of back pain to multiple frequencies of ultrasound during multi-hour ultrasound therapy sessions. Mechanical wave penetration is inversely proportional to frequency; therefore lower frequencies ultrasound waves penetrate deeper into tissue. There is scientific evidence for beneficial bioeffects produced by ultrasound at both 3MHz and 1MHz frequencies. Therapeutic ultrasound has previously been shown effective in the clinical setting, and this study seeks to observe the technology in a self-applied outpatient setting. This project will also serve to improve the scientific understanding of the frequency effects, depth of penetration, and ascertain the physiological response of back pain to ultrasound.

Methods: The proposed study will evaluate the use of two different frequencies of a long duration therapeutic ultrasound device to treat back pain on earth and prevent intervertebral disc herniation in space over an 8 week period. The primary objective of this study is to significantly reduce back pain in subjects suffering from herniated discs as measured by the Visual Analog Scale, (VAS). Secondary objectives are to decrease pain measured by objective tests including the Las├Ęgue test, improve range of motion of the lumbar spine, increase mobility and sleep quality as measured by wearable accelerometry, and decrease disability as measured by the Modified Oswestry Disability Questionnaire (MODQ).

Hypotheses: It is expected that significantly decreased lumbar pain will be found in the active intervention cohort, compared to the placebo intervention cohort, during each daily treatment and over the course of the eight-week treatment in the outpatient setting. It is also expected that the active group will experience increased activity as recorded by a wearable accelerometer, compared to no measurable increase in the placebo group. Strength, range of motion, and disability are also expected to significantly improve in the active group compared to the placebo group which is expected to not show significant improvement.

Earth Applications

Back pain is the most common neurological disorder in the United States after headaches. Furthermore, one-third of adults over 20 years of age show signs of a herniated disc. Back pain costs consumers nearly $23 billion annually. Pharmaceuticals currently dominate the treatment options despite a myriad of hurdles including cost of public health, untoward side effects, and addiction to widely available opioid analgesics. Non-pharmaceutical, non-invasive treatment methods, such as the ZetrOZ ultrasound device, provide a safer and potentially lower cost solution to traditional analgesic use. The team expects their technology will improve quality of life for people suffering from lower back pain and disc herniation by bringing to market an easy-to-use, wearable, pain-free device ideal for treating the lower back.