in Therapy- May/June, 1999
The International Journal of Drug Device & Diagnostic Research
Disc Rehabilitation: A New Technology
By C.J. Goodman,
Chief of Staff,
Goodman, Goodman & Goodman, Thousand Oaks, California
Low back pain
and "computer neck" are frequent complaints during visits to a physician(1).
Back and neck pain affects up to 60% of all employees at some time in
their careers and is personally and financially devastating. Repetitive
mechanical stress leads to disc degeneration, loss of disc height, and
other abnormalities. The Vivatek, which is controlled and coordinated
by on-board computer and fiberoptic feedback sensors, is the first biorobotic
system that alleviates intradiscal pressure and myospasm.
After the common cold, low back pain (LBP) is the most common reason for
a visit to a physician. The leading cause of disability in people younger
than 45, LBP is the second most prominent cause of industrial absenteeism,
affecting up to 60% of all employees at some time in their careers (2).
In 1990, costs associated with LBP were more than $50 billion in the United
States alone. That year, workers' compensation costs for LBP exceeded
$11 billion and have been rising steadily each year (3).
LBP can readily be
called the health-care dilemma of the millennium, as our population ages
and the incidence of spinal disc degeneration increases.
LBP is not the only
cause of high health-care costs and vocational disability. Repetitive
microtrauma to the neck ("computer neck" or microlesions of the spine)
has been referred to as the curse of the information age. Eighty-eight
percent of neck injuries do not resolve after 10 years.(4) Back and neck
pain is financially and vocationally devastating, and the long-term prognosis
Disc degeneration, the most common producer of spinal pain, results from
repetitive mechanical stress, altered nutrition to the disc, and ultimate
annulus disruption with protrusions of the nucleus pulposus through the
weakened area (5).
and loss of disc height shift the weight-bearing stress posteriorly onto
the articular facets, leading to unequal weight bearing of the facet joints
and osteoarthritis of the joints.
disc acts as a hydraulic shock absorber that permits flexion, extension,
rotation, and a combination of these motions. Essentially mucopolysaccharide
gelatinous tissue, the disc comprises a central mass, the nucleus, which
is contained within the annulus, an elastic structure. External pressure
compresses the disc and increases intradiscal pressure, which causes deformity
of the annulus and allows vertebral bodies to approximate. Release of
the external pressure allows internal nuclear pressure to restore vertebral
column length (by separating the vertebral endplates) and physiologic
lordotic and kyphotic curvatures.
Migration of nuclear
material and sequestra is influenced by compressive forces, shearing,
and increased intradiscal pressure (6). Abnormal
compressive loads on vertebral joints are responsible for a loss of disc
volume and disruption of the normal triple-joint complex biomechanics
of the spine. Small circumferential tears in an intervertebral disc set
the stage for inflammatory reactions and neurotoxin formation.
Neuroischemia is a
major feature of abnormal compressive loads. The anterior spinal artery,
which supplies 65% to 70% of spinal cord tissues, is vulnerable to compression
and ischemia lead to back pain. The annulus of the disc and the zygapophyseal
joints are richly innervated with nerves responsible for nociceptive and
mechanoreceptive activities. Under normal intradisc pressures, the mechanoreceptive
nerve fibers have a high mechanical threshold. During degenerative conditions,
however, the mechanoreceptive fibers are activated at lower levels of
loading (8). Peripheral nociceptive nerves become sensitized by tissue
damage and degenerative change. This leads to persistent pain and increased
muscular spasm (myospasm).
studies show that many patients with LBP have increased myospasm (9).
Stimulation of low-threshold nerve endings in the disc and zygapophyseal
joint activates the paraspinal musculature and demonstrates the reflex
response of mechanoreceptors and nociceptors in adjacent musculature (10).
The medical practice
of injecting anesthetics and corticosteroids into the zygapophyseal joint
has resulted in varied and inconsistent outcomes. Physiologically, the
injection leads to stretching of the joint capsule, which causes excitation
of inhibitory interneurons that inhibit nociception through activation
of mechanoreceptors. Saline injection effected an identical response,
suggesting that a physiologic mechanism was responsible for reduction
in pain and myospasm (11).
Motor unit action
potentials were recorded with the use of three sets of needle electrodes
placed in the deepest fascicles of the multifidus, bilateral to the L4
and L5 spinous process, and into the center longissimus musculature, bilateral
to the L4 spinous process. Stimulation of nerves within the posterior
annulus elicited reactions in the multifidus and longissimus paraspinal
musculature. Saline injection into the zygapophyseal joint resulted in
immediate and constant reduction in the amplitude of the motor unit action
potential, demonstrating a neuromuscular interaction among the intervertebral
disc, zygapophyseal joint, and paraspinal muscles.
Stretching of the
joint capsule is responsible for reducing muscular spasm. The focus of
any treatment regimen is to restore and normalize reflexogenic neuronal
spasm compounds ischemia, neurotoxin accumulation, and increased intradiscal
pressure gradient. Intradiscal fluid and nutrient exchange is possible
only when the intradiscal pressure gradient is lower than the diastolic
vascular pressure. Intradiscal pressure that is greater than capillary
pressure in the vertebral body impedes oxygen diffusion, which, in turn,
disc normally loses fluids while in a state of pressure gradient increase
greater than diastolic pressure. This occurs during waking, working, and
weight-bearing activities. During sleep and non-weight-bearing activities,
intradiscal pressure drops below diastolic pressure, and intradiscal fluid
reserves are replenished. Any activity, condition, or prolonged muscular
spasm that disturbs intradiscal fluid reserve can produce pain and degenerative
change, with possible catastrophic outcome. Increased and prolonged intradiscal
pressure results in dehydration of the intervertebral disc and loss of
disc height. At normal disc height, the angle of the annular fiber crisscross
intersection is 120 degrees. As disc height decreases, the angle increases,
forming a void conducive to annular tear and migration of nuclear material
(12). Removal of extruded nuclear material by surgery or percutaneous
or laser discectomy has short-term benefit as a result of degraded normalization
of intradiscal fluid exchange, decreased disc height, and increased crisscross
annular fiber intersection, leading to weakening of the annular wall.
by Revel et all (13) showed that percutaneous and laser discectomy procedures
have little value. Normalization of postsurgical intradiscal fluid reserve
promises the best long-term prognosis. In fact, normalizing fluid reserve
before surgery promotes favorable long-term clinical outcome.
Studies of intradiscal
pressures conducted by placing a cannula into the intervertebral disc
have proved conclusively that negative intradiscal pressures (eg,-160
mm Hg) are not only possible but repeatable (14).
pressure gradients of this magnitude can draw nuclear material inward
through the tear site into the nuclear cavity. Prolonged negative intradiscal
pressure normalizes intradiscal fluid exchange and increases disc height,
which, in turn, decreases the annular fiber crisscross angle, closes the
tear site, and restores structural integrity. Therapeutic application
of decreased intradiscal pressure gradient combined with treatment of
the zygapophyseal joint capsule and alignment of the posterior articular
facet results in myospasm reduction, neurotoxin evacuation, and peripheral
The PT machine by
ITM (International Therapeutic Machines, Carson City, Nevada) provides
the first and only fully integrated biorobotic system capable of simultaneous
amelioration of all aspects. This is accomplished by simultaneous integrated
applications of several therapies. Human studies at a local hospital and
at the Division of Neurosurgery, Health Sciences Center, University of
Texas, San Antonio, have revealed that significant negative intradiscal
pressure gradients are possible.
Tests were conducted
by placing a cannula connected to a pressure transducer into the L4-L5
intradiscal space. Intradiscal pressure demonstrated an inverse relationship
to stresses applied to the vertebral segments (14). Pressures of minus
160 mm Hg were consistently shown. Intradiscal pressure at or below normal
diastolic pressure of 70 mm Hg facilitates nutrient and fluid exchange
across the vertebral endplates, replenishing fluid reserves.
As pressure approaches
and exceeds negative values, subligamentous and extruded hernial retraction
can be expected. Intradiscal nutrient infiltration stimulates fibroblast
production, leading to repair of annular tears. Intradiscal pressure that
is greater than capillary pressure in the vertebral body impedes oxygen
diffusion to the disc, which in turn impedes healing (12). Reducing intradiscal
pressure creates a diffusion gradient into the disc, allowing infusion
of oxygen and nutrients.
The PT machine provides intervertebral-segment separation pressures sufficient
to produce significant negative intradiscal pressures. These pressures
are superimposed by an integrated subsonic 10Hz pulse, which maximizes
the efficacy of volumetric nutrient exchange. This pulse also maximizes
vertebral segment separation, which simultaneously decreases the annular
fiber crisscross angle, closing annular tears and stretching the zygapophyseal
joint capsule. The result is excitation of inhibitory interneurons that
inhibit nociception and mechanoreception, thereby reducing myospasms.
This integrated and simultaneous therapeutic application is controlled
and coordinated by on-board computer and fiberoptic feedback sensors.
This combination of simultaneous therapeutic applications is called noninvasive
disc rehabilitation (NDR). NDR combines the effects of intradiscal pressure
reduction to negative values, resulting in hernial retraction, nutrient
and toxin exchange at the intervertebral endplate, replenished intradiscal
fluid reserves, vertebral segment separation (which decreases the annular
fiber crisscross angle and closes annular tears), and fibroblast activation
and stimulation, which promotes annular repair.
capsule stretch results in reflexogenic neuronal activity, with reduced
pain and myospasm and increased range of joint motion. Neurotoxin evacuation
is facilitated, and ischemia in and around the primary and secondary supporting
structures is reduced.
Back pain has a large
psychological component. Issues must be addressed to alleviate stress-related
syndromes and ensure compliance with treatment until symptoms resolve.
A video monitor records stressful events, which the patient can view during
treatment. Explanations of the cause of the condition and visualization
of the healing process are injury-preventive measures.
There is no single cause of neck and back pain. For the first time, however,
the multifaceted and complicated clinical resolution of this ubiquitous
condition may be addressed by means of an integrated therapeutic application.
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