CHAPTER 62 An Algorithmic Methodology for Cervical Axial Neck Pain
HISTORICAL ASPECTS
Fluoroscopically guided cervical injections have been utilized in the clinical management of cervical axial neck pain for several decades. It is only over the past decade and a half that these techniques have been systematically employed for diagnostic and therapeutic purposes. Smith and Nichols1 first described cervical discography in 1957 as a diagnostic tool for the evaluation of cervical intervertebral disc degeneration. A year later, Cloward2 reported the indications for diagnostic cervical discography. In 1964, Holt3 suggested that discography did not have diagnostic value. In contrast, Simmons and Segil4 reported that cervical discography was a reliable diagnostic tool in the determination of a symptomatic cervical disc level in the setting of degenerative disc disease of the cervical spine. Bogduk and Marsland,5 in 1986, identified the value of local anesthetic blockade of the medial branch nerves to the cervical facet joints, implicating CFJS as a cause of cervicogenic headaches. In 1987, Whitecloud and Seago6 demonstrated the validity of cervical discography as a diagnostic tool. A year later, Bogduk and Marsland7 determined that cervical facet joints could cause neck and/or head pain. This study generated pain referral patterns that were constructed from cervical regions from which patients obtained symptom relief after local anesthetic blockade of the cervical facet joints. In 1990, Dwyer et al.8 described pain referral maps of the cervical facet joints in normal volunteers by distending the joint capsule with contrast injected under fluoroscopy. April et al.9 then assessed the accuracy of the pain referral maps. The location of symptomatic cervical facet joints in patients with cervicogenic neck pain were predicted from the pain referral maps and then assessed with confirmatory local anesthetic blockade of the cervical facet joint. In 1993, Barnsley et al. investigated the diagnostic value of comparative local anesthetic blockade of the cervical facet joints.10 They reported that false positives were present with single diagnostic cervical facet joint injections.11 Barnsley et al., in 1994, reported that intra-articular facet joint steroid injections were efficacious in less than 50% of patients for whiplash-induced cervical facet joint pain syndrome leading to chronic neck pain.12 Also in 1994, Dreyfuss et al.13 determined that the atlanto-occipital and atlantoaxial joints may be nociceptive structures. Subsequently, pain referral maps of the atlanto-occipital and atlantoaxial joints were constructed from this study of asymptomatic volunteers.14 In 1995, Lord et al.15 investigated the value of comparative local anesthetic cervical facet joint blocks in the diagnosis of cervical facet joint pain in relation to placebo-controlled cervical facet joint injections. Fluoroscopically guided placebo-controlled local anesthetic injections were utilized by Barnsley et al.16 and Lord et al.17 to investigate the prevalence of whiplash-induced chronic cervicogenic neck pain and headaches. Slipman et al. reported on the outcomes of intra-articular cervical facet joint steroid injections for traumatically induced C2–3 headache.18 In 1995, Saal19 showed favorable outcomes for nonoperative treatment including the use of cervical epidural space steroid injections for painful cervical disc herniations and radiculopathy. Schellhas et al.20 reported that magnetic resonance imaging (MRI) cannot reliably identify the source(s) of cervical discogenic pain and that significant cervical disc annular tears demonstrated by discography often escape MRI detection. Within that study, they also reported upon the distribution of pain referral patterns for the C3–4 to C6–7 disc levels. That same year, Lord et al.17 demonstrated the efficacy of percutaneous radiofrequency neurotomy for patients with neck pain due to CFJS in a double-blinded, placebo-controlled trial. In 1999, McDonald et al.21 described the long-term effectiveness of cervical radiofrequency neurotomy for chronic neck pain and demonstrated that repeat radiofrequency ablation will reinstate the same degree of pain relief if the pain returned after a successful initial procedure. In 2000, Grubb and Kelly22 reported that cervical discograms frequently identified abnormal concordantly painful fissured discs at multiple disc levels in more than 50% of the 173 patients examined, suggesting that treatment decisions based on fewer discs injected during discography should be reconsidered until more disc levels have been assessed. In 2003, Slipman et al.23 reported upon the various cervical discogenic pain referral maps provoked during cervical discography in the first large multicenter prospective study investigating discogenic pain referral patterns and laterality of pain referral.
ALGORITHMIC METHODOLOGY
A working knowledge of the anatomic interrelationships in the cervical spine is important in understanding the pathomechanism of cervical spinal disorders that cause cervical axial neck pain. Similarly, understanding the epidemiology, etiology, and pathophysiology of these disorders is helpful in organizing a differential diagnosis, initiating a logical systematic treatment plan, and ultimately formulating diagnostic and therapeutic treatment algorithms. This chapter will focus on cervical axial neck pain that has been nonresponsive to a reasonable trial of physical therapy, NSAIDs, acute pain medications, activity modifications, time, and relative rest. Musculoskeletal entities such as muscular strains will not be discussed since these entities typically resolve within 2 months of appropriate nonoperative treatments (Table 62.1).24–26
| Axial pain | Limb pain |
|---|---|
| Cervical sprain/strain | Musculoskeletal |
| Disc herniation | Radiculopathy |
| Fibromyalgia | – Disc herniation |
| Myofascial pain syndrome | – Stenosis |
| Whiplash syndrome |
Clinical assessment
Traumatic versus atraumatic
In formulating an accurate differential diagnosis, obtaining a comprehensive history is the initial step. A detailed history is critical because it will provide the clinical basis of any diagnostic and treatment paradigm and as well as offer prognostic implications. For instance, a history of trauma provides the possibility that more than one structure sustained a traumatic injury. It has been well documented that whiplash injuries can injure a cervical facet joint, intervertebral disc, cervical nerve root, or a combination of these structures.16,27–34 A common cervical intervertebral disc injury that occurs as a result of whiplash is a transverse tear near the anterior vertebral rim.29,30 This ‘rim lesion’ is caused by distraction and shearing at the annular–endplate interface by sudden cervical extension.35–37 Rim lesions have been shown to predispose the disc to premature degeneration.30,31,38–40 Other injuries that can occur may include disc contusion or herniation, facet hemarthroses, cervical nerve root shearing, or fractures of the articular processes.16,27–33,36,41–47 Organizing the history as traumatic versus atraumatic is useful when attempting to formulate a differential diagnosis. It is reasonable to assume that traumatically induced cervical axial neck pain may arise from more than one structure. For nontraumatic cases, the law of parsimony is applied and it is assumed that there is only one structure responsible for the painful symptoms.
Segmentation of pain
The next step in formulating a differential diagnosis within the framework of a diagnostic algorithm is segmenting the distribution of pain into quadrants: head, neck, upper back or periscapular, upper arm, and forearm. The relative distribution of pain in these regions assists in determining whether the pain is axial or radicular. Cervical axial pain includes the neck, head, and/or interscapular regions. Radicular pain refers to upper limb symptoms that are greater or more pronounced than axial complaints. Understanding the various pain referral patterns or dynatomes of the cervical nerve roots will assist in properly interpreting the segmented distribution of painful symptoms. For instance, upper back or periscapular pain that is more intense than neck pain in the patient without arm symptoms can be of radicular etiology despite its relative axial location. A more detailed discussion regarding the historical and examination features of cervical radicular pain and how to differentiate that from cervical axial pain is contained in Chapter 57. It is also generally considered that cervical axial neck pain that is greater in intensity than extremity pain is typically caused by cervical facet joint syndrome or cervical internal disc disruption. However, ipsilateral lower cervical neck pain may be caused by injury to the fourth or fifth cervical nerve root.48 In these more challenging clinical scenarios, physical examination findings can provide additional information to further rank order the differential diagnosis. For example, physical examination findings of increased focal suboccipital pain during 45 degrees of cervical flexion and sequential rotation would suggest pain emanating from the C1–2 joint.13,14
Upper versus lower cervical axial neck pain
Formulating a probability analysis within each grouping, axial or radicular, is the next critical step in successfully implementing treatment algorithms to arrive at an accurate diagnosis. For instance, a history of unilateral occipital headaches more intense than neck pain following a traumatic injury is more suggestive of upper cervical facet joint syndrome than cervical internal disc disruption.16,33 Upper cervical neck pain may be due to cervical internal disc disruption or from an upper cervical facet joint (C2–3, C3–4, C1–2).33 In this scenario, a history of trauma, unilateral symptoms, or the presence of occipital headaches tends to favor the presence of cervical facet joint syndrome involving an upper cervical facet joint. Similarly, an atraumatic history, bilateral symptoms, or the absence of occipital headaches, would more likely suggest cervical internal disc disruption syndrome as the cause of upper cervical axial neck pain. Lower cervical neck pain may be caused by a lower cervical facet joint, intervertebral disc, or an injury to the fourth or fifth cervical nerve root.16,27–33 One may suspect cervical facet joint syndrome more than internal disc disruption if there is focal tenderness following palpation of an isolated cervical facet joint or if the patient is able to point to the painful area corresponding to the distribution of pain reported for a particular facet joint.49 However, one cannot make the diagnosis of CFJS just on the presence of focal tenderness of the cervical paraspinal muscles in the region of a cervical facet joint. In traumatic injuries such as whiplash, cervical facet joint syndrome maybe more common than an injury to an upper cervical nerve root;33,50 however, this may be a consequence of the paucity of epidemiologic data for whiplash-induced cervical radicular pain.
Periscapular and interscapular pain
If symptoms are primarily in the upper back, interscapular, or periscapular region then the differential diagnosis may include CFJS, CIDD, cervical radicular pain and, less likely, thoracic internal disc disruption. If the interscapular or periscapular pain is reproduced by a provocative maneuver such as the Spurling’s test, then nerve root involvement rather than facet joint syndrome or internal disc disruption syndrome is of higher probability. CFJS rarely refers pain below the elbow;8,9 therefore, forearm or hand symptoms would suggest nerve root or disc injury. The differentiating facts would include the relative degree of neck pain versus arm pain and whether ipsilateral neural foramenal closure maneuvers trigger upper extremity complaints. For patients with upper limb greater than cervical axial neck pain, positive provocative maneuvers for radicular pain, such as the Spurling’s test, are suggestive of cervical nerve root involvement.51,52 Information from a positive provocative maneuver is particularly helpful in the absence of a detectable myotomal deficit or reflex change in a patient with an uncharacteristic dermatomal distribution of upper limb pain. In a patient that has a positive nerve root tension maneuver in the setting of a negative Spurling’s maneuver, brachial plexus involvement should be considered. A nerve root tension maneuver is positive when upper limb pain is provoked with contralateral cervical rotation, and/or lateral bending, or forward flexion.53 Provocative maneuvers are an important part of the physical examination armamentarium and can provide useful information to help formulate an accurate differential diagnosis.
Laterality of symptoms
The differential diagnosis is further organized depending upon whether the symptoms are unilateral or bilateral. Unilateral symptoms of occipital headaches, or neck, or upper back pain are more suggestive of cervical facet joint syndrome than internal disc disruption provided there is an exquisitely tender foci overlying a facet joint. In the absence of that complaint and finding on examination, then either the facet joint or the disc could be the culprit. Unilateral cervical axial neck pain (without periscapular symptoms) more intense than headaches could emanate from a cervical facet joint or an intervertebral disc. In our experience, bilateral cervical axial upper neck pain without headaches can be caused by CIDD rather than CFJS. Grubb and Kelly’s study22 supports our clinical observations as they reported bilateral cervical axial neck pain in 34–50% of cervical discs injected at each disc level with provocative diagnostic cervical discography. Additionally, data from a similar, but more detailed study by Slipman23 revealed that 30–62% of discs produced bilateral cervical axial neck pain during cervical discography. In contrast, the study by Dwyer et al.8 investigating the pain referral patterns of cervical facet joints in normal volunteers did not demonstrate any bilateral pain from unilateral facet joint distention. The follow-up study by Aprill et al.9 reported resolution of painful bilateral symptoms in three out of ten patients at C3–4, C6–7, and C7–T1. Slipman and Chow’s study of cervical pain mapping also reported resolution of bilateral symptoms with local anesthetic blockade of the cervical facet joints.55 In general, bilateral symptoms of neck or upper back pain, headaches, or symmetric upper arm pain are no more suggestive of cervical internal disc disruption than unilateral symptoms of cervical facet syndrome (Table 62.2). Although the facet joint can trigger bilateral pain it is rarely considered equally intense on both sides. In contrast, cervical disc pain can elicit pain intensity that is perceived to be equal on each side. If there are complaints that are distributed sometimes on the right and at other instances on the left and the remaining episodes symmetric, this is likely discogenic unless there is a traumatic history. If trauma to the cervical spine led to the aforementioned symptoms then one would have to postulate that at least two structures were injured if the symptoms were not discogenic in origin. For that reason, our algorithm begins with addressing the disc unless, of course, there was a definitive description of focal facet pain corroborated during the examination. One potential morsel of historical data that could be helpful is getting a sense that the symptoms are located in the perfect midline. If the patient can reliably articulate that such occurs, then the probability analyses should weigh heavily toward disc-generated pain. As previously alluded to, a similar description of pain over a facet joint with provoked pain to manual palpation would lend credence to the joint as the painful site. It is unusual for physical therapy to induce increased axial pain; however, this is a common complaint with facet joint-mediated pain. This seems to be particularly relevant when there are associated headaches. Almost invariably, intractable facet joint-mediated neck pain and headaches is dramatically intensified with cervical traction. When this occurrence is described, the authors invariable consider the facet joint as probable locus of pain.
| Axial pain | Limb pain |
|---|---|
| Cervical sprain/strain | Musculoskeletal |
| Annular disc tear | Radiculopathy |
| CIDD | – Disc protrusion |
| CFJS | – Spondylosis |
| Deconditioning/overuse | Radiculitis |
| Traumatic v. atraumatic | Neurogenic |
| Somatic referral | |
| Traumatic v. atraumatic |
Diagnostic testing
Once a differential diagnosis has been formulated, treatment may then be instituted. The treatment plan will initially consist of general measures and in some circumstances specific interventions. However, when a patient fails a reasonable course of nonoperative treatment with medications and physical therapy, diagnostic testing is frequently needed prior to initiating additional treatment. Typically, the initial diagnostic tool is an imaging study. In patients with a history of a traumatic event such as a whiplash injury, cervical flexion and extension radiographs should be obtained. In nontraumatic cases, cervical spine radiographs are rarely required due to its minimal diagnostic yield. Accordingly, MRI is the initial imaging study of choice because of its high sensitivity to detect soft tissue pathology such as a focal disc protrusion or bony pathology such as neuroforaminal stenosis.56–60 While MRI has demonstrated high sensitivity, there are concerns about its clinical specificity. Several studies have reported that a significant percentage of individuals with focal disc protrusions or foraminal stenosis are asymptomatic.61–64 This issue of clinical specificity reinforces the importance of correlating each patient’s history and examination findings with the imaging study to formulate an accurate differential diagnosis and ultimately the correct clinical diagnosis. In patients with a traumatic history, MRI findings of degenerative disease of the CFJS and CIDD is common. Nontraumatic CFJS patients will typically also have MRI results that are not localizing. Patients with traumatic or nontraumatic CIDD may have MRI findings of a focal disc protrusion, annular disc tear, or a broad-based degenerative concentric annular disc bulge with loss of disc height and disc desiccation. These discogenic MRI findings may or may not be clinically symptomatic in patients whom the clinical suspicion of CIDD is high. Nevertheless, these MRI findings should not be ignored as they may be clinically symptomatic in a patient with CIDD and can offer an initial starting point in determining which disc level to treat if the patient is a candidate for a fluoroscopically guided cervical epidural steroid injection.
Cervical facet joint syndrome
Patients with cervical axial neck pain and a high clinical suspicion of CFJS, who have failed a reasonable trial of conservative treatment, are candidates for a fluoroscopically guided diagnostic facet joint injection. When upper cervical facet joint syndrome from trauma or whiplash is suspected, diagnostic facet joint blocks are performed sequentially at C2–3, C3–4, and C1–2, until the offending site is identified. This sequence is based from clinical experience and epidemiologic studies.16,33 In particular, Lord demonstrated that 50% of all patients with chronic whiplash-induced cervicogenic headaches experience symptoms of cervical facet joint arthralgia/synovitis emanating from the C2-3 joint. Whiplash-induced lower neck pain emanating from a facet joint was most common at C5–6.16,33
Diagnostic and therapeutic injections
Fluoroscopically guided diagnostic facet joint blocks are performed in sequential fashion once the diagnostic algorithm has been constructed. If a diagnostic facet joint block is positive, then a fluoroscopically guided therapeutic intra-articular steroid facet joint block is offered. Barnsley et al.12 reported on the ineffectiveness of intra-articular facet joint steroid injections for the treatment of chronic cervical facet joint pain in patients who were involved in a motor vehicle accident. However, this study used a singular outcome measure and only evaluated the efficacy of one intra-articular steroid injection per joint without restricting provocative physical activities or physical therapy. Despite the flaws in the Barnsley et al. study,12 the use of intra-articular facet joint steroid blocks have been discouraged for the treatment of chronic pain due to CFJS. Unfortunately, this is in part due to the paucity of well-designed studies investigating the efficacy of intra-articular steroid injections for chronic pain due to CFJS. In our experience, fluoroscopically guided therapeutic intra-articular steroid injections have been effective in the treatment of CFJS. Slipman et al.18 demonstrated good to excellent results in 61% of patients treated with intra-articular facet joint steroid injections who experienced daily, unremitting headaches emanating from the C2–3 facet joint following a whiplash injury. This study used multiple outcome measures including work status, change in VAS, and reduction in analgesic usage with an average follow-up period of 19 months.
Placebo-controlled blocks
If a patient fails to obtain satisfactory relief from a therapeutic intra-articular facet joint block following an initial positive diagnostic facet joint or medial branch block, the major question that must be addressed is whether the patient failed because of an incorrect diagnosis or if he/she is a true nonresponder. The former issue is raised because single diagnostic facet joint blocks have a 27% false-positive rate.11 Consequently, it is possible that the initial diagnostic block was a false-positive response. In these instances, single-blind, placebo-controlled diagnostic facet joint blocks are recommended. These are performed with 2.0% lidocaine intra-articularly and with saline extra-articularly, though others advocate a different paradigm. Some interventional spine physicians prefer to conduct medial branch blocks. This can be performed as a placebo-controlled trial or using a comparative control paradigm. In the latter instance, two different local anesthetics of varying durations are used. Single-blind, placebo-controlled diagnostic facet joint blocks are considered positive if the lidocaine injection relieved the pain and the saline injection did not. If the single-blind, placebo-controlled diagnostic injections are negative, then the next suspected structure in the diagnostic algorithm should be addressed. If the single-blind, placebo-controlled diagnostic blocks are positive, then the patient is a true nonresponder and is a candidate for radiofrequency ablation of the medial branches of the dorsal rami supplying the involved facet joint.
Radiofrequency ablation
If the patient failed to improve with therapeutic intra-articular steroid facet joint blocks because of a true nonresponse, then radiofrequency ablation or dorsal rhizotomy is considered. Lord et al.17 reported on the efficacy of radiofrequency rhizotomy in patients diagnosed with CFJS confirmed with double-blind, placebo-controlled local anesthetic blockade. McDonald et al.21 then demonstrated that radiofrequency rhizotomy provided statistically and clinically significant long-term pain abatement, and that repeat ablation can reinstate the same degree of pain reduction if the symptoms returned after a successful initial procedure.
SUMMARY
In the past decade and a half, there have been numerous research studies investigating the utility of cervical injection procedures in the treatment of cervical spinal disorders. The majority of these studies have investigated disorders involving one of three primary cervical structures; zygapophyseal joint, intervertebral disc, and nerve root. An algorithmic paradigm is offered that incorporates the use of fluoroscopically guided cervical spinal injections in the treatment of painful cervical spinal disorders that will refine the selection of injection procedures performed. This algorithmic methodology achieves that end by providing the clinician with a mechanism to systematically formulate a differential diagnosis and treatment plan, and minimizing unnecessary interventional procedures. This process necessitates continuous revision as new information is published, thereby implying plasticity to these algorithms.65 Nevertheless, they have been employed successfully at several institutions and clinical practices.
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