Lumbosacral Discogenic Pain Syndrome

Background

Spinal abnormalities are more common in athletes than in nonathletes in the general population. Any spinal injury pattern can be observed in athletes who are subjected to trauma. Athletes are susceptible to degenerative disc changes at an early age because of the repetitive loading activities involved in sports.

Back pain is second only to the common cold as a cause of lost time from work and results in more lost productivity than any other medical condition. It has been estimated to result in 175.8 million days of restricted activity annually in the United States, and at any given time, 2.4 million Americans are disabled secondary to low back pain. Of these 2.4 million Americans, one half are chronically disabled. Data from the National Ambulatory Medical Care Survey from 1989-1990 revealed that there were almost 15 million office visits for low back pain, ranking this as the fifth reason for all physician visits.

In most industrialized nations, the lifetime prevalence of back pain exceeds 70%, and in the United States, a 15-20% 1-year prevalence rate has been estimated.[1] In 1990, 400,000 industrial low back injuries resulting in disability occurred in the United States. In 1985, a prospective Swedish study of adults aged 20-65 years conducted over an 18-month period reported over 7,500 work absences related to acute low back pain. Of these episodes, 57% of workers recovered within 1 week, 90% in 6 weeks, and 95% after 12 weeks. In 1987, Deyo reported a slower recovery rate in the United States, with only 33.2% of patients recovering in less than 1 month, 33% recovering in 1-5 months, and 32.7% taking longer than 6 months to recover. Finally, recurrence rates from 60-85% have been reported during the first 2 years following an acute back injury.

Frymoyer reported that 40% of patients experience leg pain in association with back pain; a much lower percentage reported numbness and weakness; and only 1% of adult respondents in the United States reported symptoms indicative of true sciatica. Herniated discs occur primarily in the second through the fifth decades of life and have a slight male preponderance. The L4-5 disc has been shown to be the most commonly herniated disc, resulting an L5 radiculopathy. The L5-S1 disc is a close second in frequency of herniation. Translating the frequency of back pain into economic terms emphasizes the magnitude of the problem. Lower back injuries account for approximately 22% of compensable workplace injuries, but they account for 31% of compensation payments. In the United States, the direct costs of spinal disorders were estimated to be in excess of $23 billion during 1990. This represented an increase of nearly 47% over the estimated costs in1984.

NextEpidemiologyFrequencyUnited States

Thoracolumbar spinal abnormalities are more common in athletes than in nonathletes in the general population. Studies investigating spinal injuries in athletes are largely limited to those injuries that are severe enough to limit participation. Many athletes do not report injuries that allow continued competition, and they participate with chronic low back pain.

Nearly 50% of college football linemen experience low back pain during a typical season, while 10-27% of all college football players experience lumbar spinal symptoms.

The rate of lumbar spinal injury in gymnasts has been directly related to the level of competition. Evidence from magnetic resonance imaging (MRI) scans that support this relationship is found in 9% of pre-elite, 43% of elite, and 63% of Olympic level gymnasts.[2, 3]

Noncontact sports, such as golf and cycling, are also associated with increased low back pain, largely related to repetitive forces or long-term postures.

PreviousNextFunctional Anatomy

The lumbar spine has an average of 5 vertebrae (normal range 4-6), with an intervertebral disc interposed between adjacent vertebral bodies. A cartilaginous endplate exists between the disc and the adjacent vertebral bodies and is considered part of the disc.

The disc itself is comprised of a central nucleus pulposus surrounded peripherally by the annulus fibrosis. In healthy young adults, the nucleus is a semifluid mass of mucoid material. The nucleus is comprised of approximately 70-90% water in a young healthy disc, but this percentage generally decreases with age. The primary nuclear constituents include glycosaminoglycans, proteoglycans, and collagen. Type II collagen predominates in the nucleus. Proteoglycans are the largest molecules in the body and possess an enormous capacity to attract water through oncotic forces. These forces increase their weight by 250% and result in a gellike composition. Biomechanically, the nucleus can display properties of either a solid or a liquid substance, depending on the transmitted loads and its posture.

The annulus fibrosis consists of 10-20 type I concentric collagen fiber layers that surround the nucleus. The layers are arranged in an alternating orientation of parallel fibers lying approximately 65 º from the vertical.

The vertebral endplate is a thin layer of cartilage located between the vertebral body and the intervertebral disc. While normally composed of both hyaline and fibrocartilage in youth, older endplates are virtually entirely fibrocartilage. Because the intervertebral disc is the largest avascular structure in the body, it is dependent on diffusion across the endplate for nutrition and waste removal. The endplate is considered part of the disc because the endplate almost always remains with the disc when the disc is traumatically displaced from the vertebral body.

The principal functions of the disc are to allow movement between vertebral bodies and to transmit loads from one vertebral body to the next. When axial loads are transmitted to the spine, the annulus and nucleus display a complex intertwined role allowing for pressure dispersal. The nucleus has the capacity to sustain and transmit pressure; this function is principally invoked during weight-bearing. In this circumstance, it transmits loads and braces the annulus. The annular lamella is capable of sustaining an axial load on the basis of its bulk. When an axial load is applied to the nucleus, it tends to shorten. The nucleus attempts to radially expand, thereby exerting pressure on the annulus. Annular resistance efficiently opposes this outward pressure, creating a hoop tension effect. The intervertebral disc is so effective at resisting these axial loads that a 40-kg load to a disc causes only 1 mm of vertical compression and only 0.5 mm of radial expansion.

During movement, the annulus acts like a ligament to restrain movements and partially stabilize the interbody joint. The oblique orientation of the annular fibers provides resistance to vertical, horizontal, and sliding movements. The alternation in the direction of the annular fibers in consecutive lamellae causes the annulus to resist twist poorly. When the segment twists one way, the fibers oriented in that direction are placed on stretch while those fibers oriented the opposite direction are placed on slack; therefore, the annulus resists the twisting motion with less than its full complement of fibers.

PreviousNextSport Specific Biomechanics

Any factor that creates excessive demand can lead to injury. Excessive mechanical loading may occur by repetitive fatigue overload, supramaximal overload, or unexpected overload.[4] Improper technique in activities such as in blocking or tackling, poor body mechanics, or improper training can lead to overload. Unexpected overloads result from falls, collisions, or improper technique. Good coaching, proper technique, and safety measures help to minimize fatigue overload and limit dangerous sport situations.

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Cervical Discogenic Pain Syndrome

Background

Cervical intervertebral disc disease accounts for 36% of all spinal intervertebral disc disease, second only to lumbar disc disease, which accounts for 62% of all spinal intervertebral disc disease. Cervical problems tend to be less debilitating than lumbar problems, and they do not cause individuals to miss work as often as lumbar spine problems do.[1, 2]

One of 5 visits to an orthopedic practice is for cervical discogenic pain (CDP), with C5-6 and C6-7 accounting for approximately 75% of visits. C7 is the most common nerve root involved.[3] Cervical discogenic pain syndrome (CDPS) presents with proximal symptoms first, and, later, it can progress to brachialgia.

For excellent patient education resources, visit eMedicineHealth's First Aid and Injuries Center. Also, see eMedicineHealth's patient education articles Shoulder and Neck Pain and Neck Strain.

NextEpidemiologyFrequencyUnited States

Cervical intervertebral disc disease accounts for 36% of all spinal intervertebral disc disease. This condition is somewhat more common in women. Although acute attacks may start at a very young age with episodes of acute torticollis or "wry neck," the incidence peaks when persons are aged 45-50 years (see image below).

Appearance of torticollis as a result of sternomastoid fibrosis in a young child.

Of all sports-related injuries, 2-3% are spinal injuries and the majority of these happened during unsupervised activities such as football, soccer, wrestling, diving, surfing, skiing and sand lot games.[4] The majority of the available literature, however, is found for football and this group is the most likely to sustain cervical trauma.

Statistical estimates of the incidence of cervical injury for football players varies ranging from 1 quadriplegic injury per 7,000 to 1 injury per 58,000.[5] Another review reported that since 1977, there has been an annual incidence of fewer than 10 cases of permanent injury to the cervical spinal cord among football players.[6] In 1976, the National Collegiate Athletic Association football rules committee disallowed the technique of spear tackling or the technique of using the helmet to butt or ram an opponent. This resulted in a remarkable decrease in the incidence of catastrophic neck injuries over the next 9 years.[7]

PreviousNextFunctional Anatomy

The cervical spine permits a wide range of motion (ROM) of the head in relation to the trunk. A degree of stability and flexibility is required to control the motion and dissipate the forces applied to the spine. Great differences in anatomy and function exist between the occiput-C1, the C1-2 (upper complex), and C3-C7 (lower complex) levels. Eight motion segments occur between the occiput and T1. No disc exists between C1 and C2; therefore, the first intervertebral disc is between C2 and C3.

The intervertebral disc consists of an outer annulus fibrosus and an inner nucleus pulposus. The intervertebral disc is thicker anteriorly, contributing to the normal cervical lordosis. The C6-7 disc is the thickest disc of the cervical spine. The nucleus pulposus and the inner one half of the annulus fibrosus are avascular and receive nutrition through diffusion, compression, dehydration, and imbibition of fluids.[8]

The annulus fibrosus, particularly the outer one third, has been found to be innervated by the sinuvertebral nerve and the vertebral nerve. The sinuvertebral nerve arises from the ventral ramus (somatic root), whereas the vertebral nerve (autonomic root) is derived primarily from the sympathetic nervous system. However, the vertebral nerve has connections with the cervical ventral rami, which suggests the possibility of the vertebral nerve also conveying somatic afferents from the disc.[9, 10, 11]

The nociceptors and mechanoreceptors in the annulus fibrosus mediate pain transmission from structural disruption of the intervertebral disc itself or from the chemically mediated inflammatory effect of phospholipase A2.[10, 12] Pacinian corpuscles and Golgi tendon organs present in the posterolateral region of the outer one third of the annulus transmit proprioceptive information from the intervertebral disc.[8, 12, 13, 14, 15]

The adult cervical disc has a crescentic shape anteriorly, with the apex of the crescent at the uncovertebral joints on each side. The posterior annulus has multiple vertical fissures allowing for a very degenerative appearance during discography and on gross examination. In addition, the nucleus of the cervical disc tends to be poorly centralized when compared with the lumbar disc. In the lumbar disc, the nucleus tends to be well localized in the center of the disc, and the posterior annulus tends to remain relatively intact when compared with the cervical disc. Annular fissures in the lumbar disc tend to be circumferential and/or radial in nature.

PreviousNextSport-Specific Biomechanics

Biomechanics is the study of the changes in the anatomic structures occurring during body movements. The movements of the cervical spine include flexion and extension in the sagittal plane, lateral flexion in the coronal plane, and rotation in the horizontal plane. Lateral flexion and rotation occur as coupled movements. Other movements of the cervical spine include protrusion (ie, the head is moved as far forward as possible with the neck outstretched and maintaining forward-facing position) and retraction (ie, the head is moved as far backward as possible and maintaining a forward-facing position).

Fifty percent of rotation of the cervical spine occurs in the upper cervical complex with the atlas rotating ipsilaterally around the odontoid. Protrusion causes upper cervical spine extension and lower cervical spine flexion, whereas retraction causes upper cervical spine flexion and lower cervical spine extension. At the occiput-C1 and C1-2 levels, ROM is greater with the protruded and retracted position than with full-length flexion and full-length extension positions.[16] See the image below.

Three-dimensional computed tomography scan of C1.

The annular fibers are made up of collagenous lamellae with alternating directions of inclination oriented 35° from the horizontal. The annulus is more susceptible to injury with rotation and translation movements due to resistance offered only by the lamella oriented in the direction of movement. In the cervical spine, as in the lumbar spine, the intervertebral disc dissipates the transmission of compressive loads throughout the ROM by slowing the rate at which these forces are transmitted through the spine. By diverting the load via temporarily stretching the annular fibers, the disc protects the vertebra from taking the entire load at once.

In asymmetric loading, the nucleus pulposus migrates toward the area with less load. Thus, in flexion movements of the cervical spine, anterior offset loading of the intervertebral disc occurs, in which the nucleus pulposus moves posteriorly and the posterior annular wall is stretched. In addition, the cervical lordosis reduces, the vertebral canal lengthens, and the intervertebral foramina open.[2]

In extension movements of the cervical spine, posterior offset loading of the intervertebral disc occurs, in which the nucleus moves anteriorly and the anterior annular wall is stretched. Shortening of the vertebral canal and closing of the intervertebral foramen also occur.[2] In lateral flexion and rotation (coupling movement) of the cervical spine, there is offset loading of the intervertebral disc on the side of flexion and rotation, with nuclear material moving to the opposite side (site of the convexity), and the posterolateral annular wall is stretched.[2]

The intervertebral foramina house the exiting cervical nerves. The largest cervical spine foramen is at the C2-3 level, and the smallest foramen is at the C6-7 level.[17] The cervical foramina become very dynamic during cervical spine ROM. The intervertebral foramina enlarge with flexion and decrease with extension. In rotation, the ipsilateral side becomes smaller, and the contralateral side enlarges. The extreme changes of the foramina occur with coupled movements (ie, flexion-rotation and extension-rotation-lateral flexion).[18]

In addition to the above biomechanical concerns, cervical spinal stenosis has been evaluated with regard to catastrophic cervical sports injuries. The Torg/Pavlov ratio (measured by dividing the sagittal diameter of the spinal canal by the sagittal diameter of the vertebral body) when less than 0.8 was thought to subject the football player to high risk of cervical cord injury due to suspected cervical stenosis (see image below). However, subsequent studies found that this ratio may be erroneously low in players that have wide vertebral bodies. A study by Cantu suggested that functional stenosis as documented by myelogram or magnetic resonance imaging (MRI) may be a more appropriate measure of stenosis.[6]

Lateral cervical spine plain radiograph illustrating the Torg/Pavlov ratio. Classification of athletic cervical spine injuries

A review by Bailes and Maroon classified athletes with cervical injuries into 3 types[4] :

Type I injuries were those that caused permanent spinal cord damage, including conditions such as anterior cord syndrome, Brown-Sequard syndrome, central cord syndrome, and mixed incomplete syndrome.Type II injuries were classified as those that occur transiently after athletic trauma with normal neurologic examination and normal radiologic evaluation. Type II injuries included spinal concussion neurapraxia, and "burning hands" syndrome. The burning hands syndrome was described as suspected injury to the spinothalamic and corticospinal tracts, resulting in arm and hand weakness with burning dysesthesias.[19] This is distinct from the burner or stinger injury that is a common cervical injury in football players and is thought to be due to traction on the upper trunk of the brachial plexus. In this condition, athletes typically have a burning, dysesthetic pain that begins in the shoulder region and radiates unilaterally into the arm and hand, with C5-C6 distribution numbness or weakness. Type III injuries were classified in athletes with only radiologic abnormalities but without neurologic deficit. These included congenital spinal stenosis, acquired spinal stenosis, herniated cervical disc, an unstable fracture, fracture/dislocation, ligamentous injury, and spear-tackler’s spine. Spear tackler’s spine was described by Torg et al described athletes that were at high risk for quadriplegic injury. These athletes had developmental cervical canal stenosis, reversal of the cervical lordosis, preexisting posttraumatic cervical radiographic abnormalities, and documentation of using spear-tackling techniques. PreviousProceed to Clinical Presentation , Cervical Discogenic Pain Syndrome

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Thoracic Discogenic Pain Syndrome

Background

Thoracic disc herniation (TDH) is an uncommon and underreported entity that is often challenging to diagnose because of a relative paucity of examination findings and because of its nonspecific presentation. The number of patients with objective neurologic findings due to thoracic disc herniation is low, and most patients can be treated with a conservative approach without surgical intervention.[1, 2]

NextEpidemiologyFrequencyUnited States

Asymptomatic thoracic disc herniations are relatively common in the general population. Autopsy studies have shown that the prevalence rate ranges from 7-15%. The prevalence of asymptomatic disc herniations found radiographically varies with the imaging modality used. Awwad et al showed that 11-13% of asymptomatic subjects were found to have thoracic disc herniation on compute tomography (CT) myelograms,[3] whereas Wood et al showed 37% of such individuals were found to have thoracic disc herniation on magnetic resonance images (MRIs).[4]

Despite the relatively high frequency of asymptomatic disc herniations, symptomatic disc herniations occur in a range from 1 in 1000 to 1 in 1 million persons. The number of patients with objective neurologic findings due to thoracic disc herniation is thought to be closer to 1 in 1 million annually.

Although the frequency of thoracic discectomies is increasing, they are still performed much less frequently than discectomies in the cervical or lumbar regions. These procedures represent approximately 0.13-0.15% of admissions for disc disease and from 0.2% to 4% of all discectomies.

PreviousNextFunctional Anatomy

The thoracic region of the spine is relatively inflexible and functions primarily to provide erect posture and assist in weight bearing of the trunk, head, and upper extremities during daily activities. The vertebral bodies are taller posteriorly than anteriorly, resulting in an anterior concavity and normal thoracic kyphosis.

In the thoracic spine, the addition of the sternum, the ribs, and their associated ligamentous structures provide additional support and rigidity. The 10 most superior ribs articulate anteriorly with the sternum and posteriorly with the transverse processes and vertebral bodies. These ribs are oriented vertically, with slight medial angulation in the coronal plane. This arrangement provides the thoracic spine with relatively good stability in the midsagittal plane. However, it also affords less stability in the lateral and rotational planes. Biomechanical studies have shown that thoracic intervertebral discs are most susceptible to injury when torsional and lateral forces are applied in tandem.

Several features of the thoracic spine increase its susceptibility to spinal cord compression associated with thoracic disc herniation, as follows:

The ratio of the spinal canal to the thoracic spinal cord is smaller than that found in the cervical and lumbar regions. Although the cross-sectional diameter of the thoracic cord is smaller than that of its cervical or lumbar counterparts, the diameter of the spinal canal is proportionally even smaller. Thus, the ratio of the spinal cord to the canal in the thoracic spine is 40%, whereas this ratio in the cervical spine is only 25%. The dentate ligaments situated between the spinal cord and the nerve roots restrict posterior movement of the spinal cord within the canal. This makes the thoracic spine prone to vertical compression from anterior disc and bony prominences. The natural kyphosis of the thoracic spine places the spinal cord in close proximity to the posterior longitudinal ligament and the posterior aspects of both the vertebral bodies and the discs in the thoracic region. This makes the thoracic cord especially susceptible to ventral compression from herniations. Normal discs and disc degeneration

The 3 basic structures of normal vertebral discs are the nucleus pulposus, the annulus fibrosus, and the vertebral endplates. The nucleus pulposus is the gelatinous core of the disc and is composed mostly of water and proteoglycans. The annulus fibrosus surrounds the nucleus pulposus and is composed primarily of water and concentric layers of collagen. The vertebral endplates lie on the superior and inferior aspect of the discs adjacent to the vertebral bodies and aid in the diffusion of nutrients into the discs. As a normal part of aging, the water content of the discs decreases, leading to decreased disc height and impaired capability to absorb the axial loads of the spine. Disc herniations, annular tears, and endplate degeneration all can occur.

Location of thoracic disc herniation

Thoracic disc herniation are generally classified into 4 categories. These are central thoracic disc herniations, centrolateral thoracic disc herniations, lateral thoracic disc herniations, and intradural thoracic disc herniations. Central and centrolateral protrusions are the most common and are found in 70% of cases. Intradural herniations are rare and are found in less than 10% of cases. Clinical presentations vary, but the following generalizations are appropriate:

Central protrusions may cause spinal cord compression, and patients may present with myelopathic symptoms, such as increased muscle tone, hyperreflexia, abnormal gait, and urinary/bowel incontinence. Centrolateral protrusions may result in a presentation resembling Brown-Sequard syndrome, with ipsilateral weakness and contralateral pain or sensory disturbances.Lateral herniations may cause nerve root compression, and patients may present with a radiculopathy.Intraosseous disc herniations

Thoracic intervertebral discs can herniate into the spinal canal as well as through vertebral endplates, directly into the adjacent vertebral bodies. The resulting herniations are called Schmorl nodes or cartilaginous nodes. These can occur in association with osteoporosis, tumors, metabolic diseases, congenital weak points in the endplates, or degenerative endplate changes. Although Schmorl nodes often do not cause symptoms, an inflammatory, foreign body–type reaction can occur, resulting in severe pain.

Scheuermann disease, or juvenile kyphosis, is a disorder of childhood in which these types of changes are particularly pronounced. Children with this disorder generally present at age 8-16 years with rigid thoracic kyphoses. Although the exact etiology is not known, endplate degeneration and avascular necrosis of the ring apophysis result in the development of multilevel Schmorl nodes and vertebral wedging. This may cause the patient to have a severe kyphotic posture and pain in the early teenage years.

Annular tears

Tears in the annulus fibrosis may contribute to thoracic discogenic pain (TDP), even in the absence of an associated disc herniation. The outer third of the annulus fibrosis is innervated by the sinuvertebral nerve, which relays sensory information, including pain, to the dorsal root ganglion. Tears in this region, particularly radial tears, may be clinically significant. A study by Schellhas et al evaluated the results of 100 patients with thoracic discographies.[5] The study found that greater than 50% of painful discs had annular tears with no evidence of significant herniation.

Calcification

Calcification is also a common finding in thoracic disc herniations, particularly in those discs that are herniated as a result of degeneration. The terms “hard” disc herniations and “soft” disc herniations are used throughout the literature to indicate disc herniations with and without calcification, respectively. The presence and extent of calcification is also important in surgical planning.

PreviousNextSport-Specific Biomechanics

In patients with symptomatic thoracic disc herniations for which trauma is implicated as the cause, a twisting or torsional movement is often involved. Participation in any sport that involves axial rotation of the spine can potentially increase the risk of disc herniation. These types of forces may be observed in sports such as golf, in which axial rotation of the spine is required at the top of the backswing, with subsequent uncoiling and hyperextension observed through the downswing and follow-through.

Minimizing forces on the spine through proper mechanics in specific sporting activities is important. Additionally, the dynamic stabilizers of the spine should also be strengthened to counteract the significant forces exerted on the spine during certain athletic activities.

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