Facet Syndrome in the Cervical Spine
Wyatt, Lawrence H
Introduction: Neck pain is a common morbid condition seen by chiropractors, affecting approximately one-third of the population. Many different nociceptive structures have been isolated as playing a role in the genesis of neck pain including ligaments, discs, muscles, and bones. The so-called “facet syndrome,” originally described in 1933, has only recently been investigated as a source of neck complaints.
Discussion: Facet syndrome has been determined to be a legitimate and underappreciated cause of neck pain, both acute and chronic. This manuscript addresses the relevant anatomy and biomechanics of the cervical facet joint, the clinical features of disease of the facet joints, and addresses the various therapeutic regimens available to date.
Conclusion: Manual therapy, including spinal manipulation and mobilization, along with therapeutic exercise and paraspinal injections, appear to be the procedures of choice for this condition.
Key Indexing Terms: neck pain, facet syndrome, spinal manipulative therapy, manipulation, chiropractic
Neck pain is second only to low-back pain as the most common musculoskeletal disorder seen in the patients presenting to a chiropractic office. Like low-back pain, it poses an economic burden not only in health care costs, but also in days lost to work and reduced productivity, as it is a frequent source of disability. A Norwegian study estimated the prevalence of neck pain in the general population to be approximately 34%.1 Furthermore, the prevalence of chronic neck pain, defined as lasting six months or longer, is estimated at approximately 10-14%.2
In a classic paper in the Journal of the American Medical Association in 1933, Ghormley coined the term “facet syndrome” to describe a conglomeration of symptoms associated with degenerative arthritic changes in the lumbar spine.3 More recently, the phrase “cervical facet syndrome” has appeared in the literature. It most often implies the existence of axial pain in the neck, often with radiating pain, presumably secondary to involvement of the facet joints of the cervical spine.
It is generally accepted that there are myriad pain generators in the cervical region, including the intervertebral discs, anterior and posterior longitudinal ligaments, facet joints/capsules, muscles, and nerve roots. The facet joints, having innervation from nociceptors, were recently found to be a possible source of neck pain.” The inter-relationship between the facet capsule and other structures, such as the paraspinal muscles and overlying skin, are also postulated as a source of neck pain.5 The authors suggest that “substantial muscle insertions into the cervical facet capsular ligament…provide(s) a possible mechanism for injury to this ligament and the facet joint as a whole.” Hilton’s Law, which states that the nerve trunks that innervate the muscles moving a joint also innervate the skin over the insertion of those muscles, may play a role in the pain referral patterns associated with these syndromes.
The diagnosis of cervical facet syndrome is often one of exclusion, or is often not considered at all by medical physicians. Clinical features that are often, but not always, associated with cervical facet pain include tenderness to palpation over the facet joints or paraspinal muscles, pain with cervical extension or rotation, pain radiating into the shoulders and arms, and absent neurologic abnormalities.6 Imaging studies usually are not helpful, with the exception of ruling out other sources of pain, such as fractures, dislocations, inflammatory arthritides, or tumors.
Estimates of the prevalence of cervical facet joint pain may be as low as 26% or as high as 65%, depending on the aggressiveness of the diagnostician.7 This research suggests that this condition is more common than previously thought and should be considered more often in patients with neck pain.
While the cervical facet joints may be a common source of neck pain, other pain generators in the cervical spine, such as the intervertebral discs, may be involved, as well. To evaluate the contribution of the disc to neck pain, Bogduk, et al. evaluated a sample of 56 patients selected from a previous study population. This group consisted of patients who had undergone both discography and facet joint nerve blocks at the same segment of the cervical spine as part of the diagnostic process.8 Forty-one percent of this group had a painful disc and facet joint at the same segment. An additional 23% of patients had a painful facet joint, but not a painful disc at the same level. Most of the sample, therefore, had a painful facet joint, but there was often a painful disc at the same level. When the intimate anatomy of the facet joints and discs is considered in the mechanics of cervical spine motion, it is not surprising that most of the sample had a painful facet joint but, in many, there was also a painful disc at the same level.
Whiplash injury is commonly seen in the doctor of chiropractic’s office. Recent studies have demonstrated that cervical facet joint pain is a common sequela of this mechanical injury. The incidence of chronic cervical facet joint pain after whiplash injury was studied by Barnsley, et al. using double-blind, controlled, diagnostic blocks of the facet joints.9 This study demonstrated that the prevalence of this sample was 54%. This suggests that cervical facet joint pain was the most common cause of chronic neck pain, after whiplash injury, in this study population. A subsequent study by Lord and Barnsley, et al. investigated the prevalence of chronic cervical facet joint pain after whiplash injury using a double-blind, placebo-controlled protocol.10 The sample consisted of 68 consecutive patients referred for chronic neck pain after a motor vehicle accident. The prevalence of cervical facet joint pain after whiplash injury was found to be 60%. The most common levels were C2-C3 and C5-C6.
The cervical spine is made up of the first seven vertebrae and functions to provide mobility and stability to the head. The C3-C7 vertebrae are similar to each other in that each has a vertebral body that is concave on its superior surface and convex on its inferior surface. On the superior surfaces of the bodies are the uncinate processes, which articulate with depressed areas on the inferior aspect of the superior vertebral bodies. These joints are usually referred to as the Joints of Luschka. Some authors believe that these joints are the result of degenerative changes in the annulus, which lead to fissuring in the annulus and the creation of the joint.11
The cervical spine has six cardinal ranges of motion including flexion, extension, right and left lateral bending, and right and left rotation. The facet joints in the cervical spine are diarthrodial synovial joints with fibrous capsules. These capsules are more lax than in other areas of the spine. This allows for gliding movements of the facet joints, which contribute to the ranges of motion noted above. The joints are generally inclined at 45° from the horizontal plane and angled 85° from the sagittal plane, although there are differences between the upper and lower cervical spine. This alignment helps to prevent excessive anterior translation and is important in weight-bearing of the head on the neck.12 McClain found Type I, II, and III mechanoreceptors and free nerve endings in the sub-synovial loose areolar and dense facet capsular tissues of the cervical spine.4 In fact, there are more mechanoreceptors in the cervical spine than in the lumbar spine.13 It is postulated that neural input from the facet joints may be important for proprioception and pain sensation. In addition, this input may modulate protective muscular reflexes that are important in preventing joint instability and degeneration.
The facet joints in the cervical spine are innervated by both the ventral and dorsal rami of the nerve root. A communicating branch and a medial branch (known as the third occipital nerve) of the dorsal ramus of the third cervical spinal nerve innervate the C2-C3 facet joint. The remaining cervical facets are supplied by the medial branches of the dorsal rami that arise one level above and below the joint.14,15 These medial branches send off articular branches to the facet joints.
Cervical Spine Facet Biomechanics
A single functional spinal unit, consisting of two adjacent vertebrae, has three components of translation and three components of rotation, which create six degrees of freedom of motion altogether. In addition, numerous coupling coefficients, where the motion of one degree of freedom affects other degrees of freedom, have been identified. This evidence confirms that spine motions are coupled, although not in a simple two-dimensional coordinate system. The question then arises, can altered biomechanics of the spine be correlated with pain? Amevo, et al. demonstrated an alteration in the normal biomechanics of the cervical spine in patients with neck pain.16
The contribution of the facet joint to spinal biomechanics has been relatively well researched. Facet joint orientation helps to dictate the patterns of motion from C2-C7. Rotation and lateral flexion in the cervical spine are coupled motions. They are not independent of each other, but occur together with either range of motion. For example, the vertebral bodies rotate to the left as they laterally flex to the left; that is, the spinous processes move to the right. This coupled motion is less in the lower cervical spine, possibly due to the difference in facet orientation in those segments. This change in motion coupling may contribute to the greater prevalence of facet joint injuries in the lower cervical spine.17
The height of the articular processes increases as one moves caudally in the cervical spine. This anatomical detail is important in that it determines the quality of flexion and extension, and allows more gliding motion in the more cephalic segments.18 The orientation of the facet joints alone does not determine the pattern of motion. It is known, however, that there is a great deal of rotation in the cervical spine and it is thought that the discs do not seem to be the primary determinant of motion in the cervical spine.
Clinical Findings (Table 1)
Patients with cervical facet joint syndrome often present with complaints of neck pain, headaches, and limited range of motion. The pain is described as a dull aching discomfort in the posterior neck that sometimes radiates to the shoulder, brachium, or mid-back. The pain may be exacerbated with any neck range of motion but it is more often aggravated by extension. There is typically a history of a previous injury to the neck. As a side note, the insidious onset of neck pain is not typically associated with mechanical neck pain. This historical feature should raise the suspicion of more aggressive diseases such as inflammatory arthropathy, malignancy, and others.
Clinical features that often, but not always, are associated with cervical facet pain include tenderness to palpation over the facet joints or paraspinal muscles. In addition, pain with cervical extension and/or rotation is seen with range-of-motion testing. Orthopedic testing is typically negative for root tension signs, but tests that challenge the facet joints, such as the cervical compression test or compression with rotation and extension, may cause localized and even referred pain into the upper extremity or mid-back. These patients will have sclerotomal pain-referral patterns, rather than the dermatomal patterns associated with radiculopathy. It is important to note the absence of neurologic abnormalities in patients with facet syndrome. The presence of postural changes, degenerative joint disease, and mild spinal anomalies does not increase the propensity for the development of neck pain.
Even in subjects without neck pain, stimulation of the facet joints by injecting contrast material into the joints and distending the capsule produces neck pain in a specific pattern corresponding to the specific joint. In a study of five such subjects, joint pain referral patterns were mapped out.19 The C2-C3 facet joint refers pain to the posterior upper cervical region and head, while the C3-C4 facet joint refers pain to the posterolateral cervical region without extension into the head or shoulder. The C4-C5 joint refers pain to the posterolateral middle and lower cervical region, and to the top of the shoulder. The C5-C6 joint refers pain to the posterolateral middle and primarily lower cervical spine and the top and lateral parts of the shoulder and caudally to the spine of the scapula. The C6-C7 joint refers pain to the top and lateral parts of the shoulder and extends caudally to the inferior border of the scapula. These pain referral maps subsequently have been used to predict the segmental origin of neck pain in 10 symptomatic patients by Aprill.20 The results of this study suggest that these pain referral maps may be a powerful diagnostic tool when evaluating patients with cervical pain.
Facet joint pain referral patterns also have been documented in the atlanto-occipital (AO) joint and the lateral atlanto-axial (AA) joint. One study examined five asymptomatic subjects.21 The resultant pain referral patterns for the AA joints were similar and located posterior and lateral to the C1-2 segments. The patterns for the AO joints were variable and extended from the vertex of the skull to the C5 segment. Perceived pain also was greater with the AO injections, compared to the AA injections. Pain referral patterns also have been documented in symptomatic patients and correspond well to those obtained from asymptomatic subjects.22 Fig. 1 demonstrates some common cervical spine facet joint pain referral patterns.
Radiographs in the neutral, flexed, and extended positions can be obtained when clinically indicated by antecedent trauma or other significant clinical indication. A search for instability should be performed. Horizontal movement of one vertebral body on the next should not exceed 3.5 mm and the angular displacement (flexion) of one vertebral body on the next should be less than 11°. More specifically, the normal translation of the AO joint in the sagittal plane is insignificant. In addition, the atlanto-dental interspace should also be measured. Normal translation at this joint is normally less than 3 mm in an adult and 5 mm in a child. Advanced imaging, including computerized tomography and magnetic resonance imaging, are not generally indicated unless there is suspicion of fracture, dislocation, inflammatory arthropathy, or some other aggressive or destructive skeletal disorder.
Laboratory studies generally are not indicated for the diagnosis of cervical facet joint syndrome unless there is suspicion that the patient may have an inflammatory arthropathy that causes facet joint pain.
Kibler, et al. have defined three phases of soft-tissue injury rehabilitation.23 The goals of the first phase of therapy are to reduce pain and inflammation and increase the pain-free range of motion. Cryotherapy is indicated during the acute phase to decrease blood flow and subsequent hemorrhage into the injured tissues. Ice is also thought to reduce local edema and may help with muscle spasm. The use of other passive physical therapy modalities such as electrical stimulation, including interferential current therapy, may also reduce pain and muscle spasm as well, although a great deal of controversy remains concerning their use.
Manual therapy, including spinal manipulation24-28 and joint mobilization,25,29 are often helpful. Therapeutic exercise through a pain-free range of motion also has therapeutic value.28,30 Finally, muscle strengthening should begin with isometric exercises and progress to isotonic as tolerated. Manual manipulation combined with exercise appears to be more helpful than either alone.31
Intra-articular Facet Joint Injections
Intra-articular facet joint injections have not demonstrated consistent levels of pain relief among different investigators. Some studies of intra-articular joint injections report only minor relief of pain, from a few days to weeks,32,33 while others report substantial relief for weeks to months.34-36 Intra-articular facet joint injections are not without complications, including entering and/or infiltrating the epidural space, intervertebral foramen, and vertebral artery.
Medial Branch Blocks
Medial branch nerve blocks also have been performed with some success.37 Patients with chronic neck pain randomly received two nerve blocks and 45 of the 47 patients involved in the study obtained relief from the first block, and all but one obtained relief from the second block. A related study compared nerve blocks with placebo-controlled blocks in a randomized, double-blind trial. The sensitivity was found to be 54%. This is low and indicates that there were many false-negative results in this study.38
Cervical medial branch blocks are technically easier to perform than intra-articular joint blocks. Transient disequilibrium and presyncope have been noted with this procedure.37
Percutaneous Radiofrequency Neurotomy
In patients with recalcitrant facet joint pain that is unresponsive to conservative therapy, percutaneous radiofrequency neurotomy (PRN) may provide relief, although it may require multiple procedures. PRN denervates the facet joint by coagulating the medial branch of the dorsal ramus,39 which blocks the conduction of pain along the nerve. The nerve, however, is not destroyed since the medial branch cell bodies in the dorsal root ganglion are not affected. In addition, the nerve may grow back. Performing multi-level bilateral PRNs should not be attempted as there is a risk of cervical muscular fatigue with normal activities of daily living.40
McDonald investigated the long-term efficacy of radiofrequency neurotomy for chronic neck pain secondary to motor vehicle accidents.40 Complete relief was reported in 71% of the patients after the initial procedure. The mean duration of pain relief in this group was 422 days after the initial procedure, and 219 days after a repeat procedure. Some patients maintained pain relief for years with multiple repeat procedures.
Surgical intervention for patients with facet syndrome is generally not indicated unless facet joint dislocation or other unstable injury is present. In fact, cervical facet joint pain still can occur after anterior cervical fusion.
Facet syndrome is a common and underappreciated cause of both acute and chronic neck pain and is commonly seen by doctors of chiropractic. The clinical diagnosis of facet syndrome should be part of the differential diagnosis of any physician who deals with neck pain on a regular basis. In addition, a number of procedures are available for both diagnosis and treatment, providing the physician with myriad reasonable management options.
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Lawrence H. Wyatt, DC, DACBR
Dr. Wyatt is a professor in the division of clinical sciences, Texas Chiropractic College, Pasadena, Texas.
Copyright American Chiropractic Association Mar 2004
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