279 lines
15 KiB
XML
279 lines
15 KiB
XML
import Article from "@/components/Article";
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import { Metadata } from "next";
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export const metadata: Metadata = {
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title: "Article - The Basics of Intervertebral Disk Herniation | Dr. Feely",
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authors: [{ name: "Brian Leonard, D.O." }],
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description: `There are a great number of conditions and a variety of states
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of illness that result in the symptom of “back/neck pain.” Back and neck pain
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can be related to conditions ranging from muscle strains, somatic dysfunction
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to nerve compression and anatomic anomalies.`,
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};
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const ArticleIntervertebralDiscHerniation = () => {
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return (
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<Article
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title="The Basics of Intervertebral Disk Herniation"
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author="Brian Leonard, D.O."
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>
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<h2>Introduction</h2>
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<p>
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There are a great number of conditions and a variety of states of
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illness that result in the symptom of “back/neck pain.” Back and neck
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pain can be related to conditions ranging from muscle strains, somatic
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dysfunction to nerve compression and anatomic anomalies.
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</p>
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<p>
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The focus of this article is to discuss herniation of intervertebral
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discs as a cause of pain. We will examine the pathophysiology and
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biomechanics of disc degeneration and herniation as well as aspects of
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the epidemiologic data. Lastly, it is important to mention the role that
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manual/manipulative medicine plays with regard to this issue. While the
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general principles of herniated discs may be applied to any level of the
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spine, we will discuss each spinal level from cervical, thoracic, to
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lumbar.
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</p>
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<h2>Anatomic Review</h2>
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<p>
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An intervertebral disc is formed of two elements: the nucleus pulposis
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and the anulus fibrosis. The anulus fibrosis is composed of sequential
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layers of fibrocartilage that envelope the nucleus pulposis. The nucleus
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pulposis itself is formed of a proteoglycan and a water/gel substance
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that is held loosely in place by a network of collagen and elastin
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fibers. Together they form the intervertebral disc and serve to
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distribute weight and force equally throughout the spine, even during
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motions such as flexion and extension1. Blood vessels course along the
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outer edge of the anulus fibrosis and thereby force the disc to obtain
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its nutrient supply via osmosis. When the discs age, they are subject to
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gradual degeneration as the water content decreases and the ability to
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absorb impact diminishes. Degeneration begins on a microscopic level
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around the age of skeletal maturation, or fifteen years of age. At this
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time, cell densities begin to diminish, resulting in microstructural
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tears and clefts (2).
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</p>
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<h2>Pathophysiology</h2>
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<p>
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The microstructural defects accumulate over time as a person ages and
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the pulposis protrudes deeper into the anulus. These defects can result
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in frank tears of the anulus. There are three main tears that have been
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distinguished, these include:
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</p>
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<ul>
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<li>circumferential tears or delaminations</li>
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<li>peripheral rim tears</li>
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<li>radial fissures</li>
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</ul>
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<p>
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The circumferential tears represent shearing forces acting on the
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interlaminar layers of the anulus fibrosis. The characteristic disc for
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this type of tear is an older disc that has an advanced amount of
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dessication and degeneration, retaining a limited ability to absorb
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these stressors (3). The second type of tear, the peripheral rim tears,
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are most frequently seen in the anterior portion of the disc and are
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associated with bony outgrowths. Histologic data suggest that the actual
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tears are a result of repeated microtrauma (4). Lastly, radial fissures
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represent a grouping of tears that typically occur in a posterior or
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posterolateral direction and are associated with degeneration of the
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nucleus pulposis. These tears have been simulated in cadavers with
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repeated cycles of sidebending and compression (5).
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</p>
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<p>
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These variations of degeneration, dessication, and microstructural
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defects seem to be common among studies reported in the current base of
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literature. These tears, however, have not been shown to have a
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correlation with the actual prolapse, or herniation, of the disc. The
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tears and disc degeneration have been shown to be correlated only with
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repetitive mechanical loading and cigarette smoking6 (as this inhibits
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the body's regulatory healing mechanisms in a vast number of ways). The
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prolapse of the disc has been shown to correlate with heavy lifting.
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That is to say, the degeneration of discs, and not the herniation,
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appears to be a normal process of aging (1).
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</p>
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<h2>Epidemiology</h2>
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<p>
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For the discussion of rates of occurrence and particular mechanisms
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associated with disc herniation, we will begin at the cervical level and
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progress inferiorly to the thoracic and finish at the lumbar vertebrae.
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</p>
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<p>Cervical Disc Herniation</p>
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<p>
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Cervical radiculopathy, or pain in a pattern of the nerve root that is
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compressed, is estimated to occur in 85 per 100,000 people in the
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population. Most commonly affected regions include the seventh cervical
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vertebra, C7, and the sixth cervical vertebra, C6, at rates of 60% and
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25%, respectively (7). These radiculopathies in the cervical region are
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commonly present in specific demographic groups. For instance, sudden
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weight load on the neck while in either flexion or extension can be the
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culprit. Also, in the elderly population, osteophyte formation can play
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a role as previously mentioned. Sport-related injury can be more
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insidious in nature, and can be attributed repetitive extension/rotation
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while actively using postural muscles, as in swimming (7).
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</p>
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<p>Thoracic Disc Herniation</p>
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<p>
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Thoracic disc herniations appear to be less common than lumbar and
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cervical herniations for a number of reasons. While they peak at the
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third to fifth decade of life, similar to other herniations, estimates
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place thoracic disc herniations only between 0.25% to 1% of all disc
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herniations (10,11). One reason for decreased incidence, it is thought,
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is the lesser degree of mobility in the thoracic spine due to the
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presence of the rib cage. The articulation of the rib head with the
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vertebral body naturally limits the amount of flexion, extension, and
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sidebending. The majority of thoracic herniations occur below the level
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of T7. Rib pairs 8-10 maintain a cartilaginous attachment to the
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sternum, thus allowing more motion than vertebrae at higher levels. Rib
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pairs 11 and 12 are known as “floating ribs” and do not maintain any
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attachment to the sternum. This supports the theory that part of the
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pathophysiology of herniated thoracic discs is directly related to the
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ability of the segment to maintain a certain degree of flexability (12).
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</p>
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<p>Lumbar Disc Hernation</p>
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<p>
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Herniation of the nucleus pulposis of the lumbar disc is present more
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commonly than the former two types. It is estimated that 95% of
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herniated lumbar discs occur at the L4-L5 or L5-S1 level (13). Typical
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presentation includes radicular pain that patients often describe as
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shooting or stabbing pain that courses down the leg. There may also be
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paresthesias present in the same distribution pattern. Often, the pain
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is exacerbated by coughing, sneezing, straining, or standing for long
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periods of time (14), as this increases the pressure on the disc and
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therefore on the impinged nerve root. Pain is usually relieved by rest
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and taking weight off of the prolapsed disc.
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</p>
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<p>Manual/Manipulative Medicine and Cervical Disc Herniation</p>
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<p>
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Considering the implications of nerve root impingement (including pain,
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paresthesia, and decreased motor function) secondary to a herniated
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disc, there is a natural concern regarding the safety of manual
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manipulation of such an anomalous disc.
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</p>
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<p>
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With regard to manipulation, a 2006 study was done to evaluate the
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efficacy and safety of cervical manipulation in patients with spinal
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cord compression and radiculopathy. The study incorporated a variety of
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chiropractic techniques, including high-velocity, low-amplitude methods.
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The conclusions drawn by the authors states, “The finding of cervical
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spinal cord encroachment on magnetic resonance imaging, in and of
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itself, should not necessarily be considered an absolute
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contraindication to manipulation.” (8) The authors are specific in
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mentioning exclusion criteria such as acute myelopathy or changes
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indicating myelomalacia and make clear the message that special care and
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astute clinical judgement need be exercised in cases of cervical
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radiculopathy and pathologic segments.
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</p>
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<p>
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A separate study suggests othewise, stating, “Cervical spinal
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manipulation therapy may worsen preexisting cervical disc herniation or
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cause disc herniation resulting in radiculopathy, myelopathy, or
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vertebral artery compression.” (9) This study describes 22 case studies
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and states in its conclusion a list of absolute contraindications
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including patients with rheumatoid arthritis, acute fractures and
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dislocations, os odontoideum, infection of bone, osseous malignancies,
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or cervical myelopathy. These case studies included reports from
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patients previously treated by chiropractors as well as osteopathic
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physicians. The article puts forth the modality of surgical intervention
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as the best treatment for certain cases of disc herniation and
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radiculopathy.
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</p>
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<p>
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With regard to the necessity of surgical intervention, let us consider a
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2007 article from the Massachusetts Medical Society (15). The study
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examines the outcomes of two groups of patients with herniated lumbar
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discs who were randomly assigned to either a surgical intervention or
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observation and symptom management. The study was inconclusive
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statistically due to the high rate of crossover. That is, 40% of
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patients assigned to the surgical intervention declined surgery because
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their symptoms improved before any intervention could take place (with
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observation alone). Conversely, 45% of patients referred to the
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observation therapy, opted for surgical intervention due to worsening of
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symptoms (15). Even though the study is scholastically inconclusive and
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statistically insignificant, it does highlight the need for
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individualized care.
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</p>
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<h2>Conclusion</h2>
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<p>
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As with any topic at the forefront of medicine, especially issues which
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can be treated via different modalities and by different specialists,
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there will be controversy, bias, and ever-emerging new evidence to
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consider. This article demonstrates the basic science behind disc
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degeneration leading to pathologic herniation. It also shows two sides
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of a clinical debate to which there is no defined rule for treatment.
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Patients, therefore, need to be evaluated and treated appropriately on
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clinical grounds of their individual situation by a physician
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well-versed in neuromusculoskeletal medicine to determine which specific
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modality best suits the individual.
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</p>
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<h2>References:</h2>
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<ol>
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<li>
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Michael A. Adams, PhD; Peter J. Roughley, PhD What is Intervertebral
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Disc Degeneration, and What Causes It? Spine. 2006;31(18):2151-2161
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</li>
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<li>
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Boos N, Weissbach S, Rohrbach H, et al. Classification of age-related
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changes in lumbar intervertebral discs: 2002 Volvo Award in basic
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science. Spine 2002;27:2631-44.
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</li>
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<li>
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Goel VK, Monroe BT, Gilbertson LG, et al. Interlaminar shear stresses
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and laminae separation in a disc. Finite element analysis of the L3-L4
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motion segment subjected to axial compressive loads. Spine
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1995;20:689-98.
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</li>
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<li>
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Hilton RC, Ball J. Vertebral rim lesions in the dorsolumbar spine. Ann
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Rheum Dis 1984;43:302-7
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</li>
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<li>
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Adams MA, Bogduk N, Burton K, et al. The Biomechanics of Back Pain.
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Edinburgh, UK: Churchill Livingstone; 2002
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</li>
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<li>
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Battie MC, Videman T, Gill K, et al. 1991 Volvo Award in clinical
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sciences. Smoking and lumbar intervertebral disc degeneration: An MRI
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study of identical twins. Spine 1991;16:1015-21
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</li>
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<li>
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Malanga, Gerard A MD Cervical Radiculopathy. Spine 2006 accessed via
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emedicine
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http://www.emedicine.com/sports/TOPIC21.HTM#section~AuthorsandEditors
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</li>
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<li>
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Murphy, DR; Hurwitz, EL; Gregory AA. Manipulation in the presence of
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cervical spinal cord compression: a case series. J Manipulative
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Physiol Ther. 2006 Mar-Apr;29(3):236-44
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</li>
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<li>
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David G. Malone, M.D., Nevan G. Baldwin, M.D., Frank J. Tomecek, M.D.,
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Christopher M. Boxell, M.D., Steven E. Gaede, M.D., Christopher G.
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Covington, M.D., Kenyon K. Kugler, M.D. Complications of Cervical
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Spine Manipulation Therapy: 5-Year Retrospective Study in a
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Single-Group Practice. Neurosurg Focus 13(6), 2002. © 2002 American
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Association of Neurological Surgeons
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</li>
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<li>
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Fisher, C., Noonan, V., Bishop, P., Boyd, M., Fairholm, D., Wing, P.,
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et al. (2004). Outcome evaluation of the operative management of
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lumbar disc herniation causing sciatica. Journal of Neurosurgery, 100,
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317–324.
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</li>
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<li>
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Strayer, Andrea J Lumbar Spine: Common Pathology and Intervention J
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Neurosci Nurs. 2005;37(4):181-193
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</li>
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<li>
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Thomas L. Schwenk, MD Is Surgery Necessary for Lumbar Disc Herniation?
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Journal Watch. 2007;5(11) ©2007 Massachusetts Medical Society
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</li>
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</ol>
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</Article>
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);
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};
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export default ArticleIntervertebralDiscHerniation;
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