Compared with research on lumbar facet pain, research on cervical facet dysfunction is relatively recent. In 1988, Bogduk and Marsland ⁵ described the positive effect of injection of local anesthetics close to the facet joints in patients with neck pain. Dwyer et al⁶ showed that injection of irritating substances into the facet joints results in a specific radiation pattern (Fig. 14-1). The same radiation pattern is seen with mechanical and electrical stimulation. However, because it was later demonstrated that stimulation of the discus intervertebralis produces the same radiation pattern as stimulation of the facet joints, this is probably a segmental phenomenon.

Fig. 14-1 Radiation pattern of cervical facet pain.

(Illustrated by Rogier Trompert Medical Art. http://www.medical-art.nl.)

Clinical findings of degenerative signs are mainly based on radiological findings. Spondylosis (disorders of the nonsynovial joints) and osteoarthritis (facet osteoarthritis) are frequent in advanced age. Degenerative disorders are usually seen at the low and midcervical levels (C4-C5, C5-C6, C6-C7). A causal relationship with pain symptoms has not been proven.

History

While taking the history, attention should be paid to signs and symptoms potentially indicating a serious underlying pathology (“red flags”). It is important to question the patient about previous trauma and previous or ongoing oncological treatments. Indications for potential spinal metastases are (1) history of malignancy, (2) pain starting after the age of 50 years, (3) continuous pain independent of posture or movement, and (4) pain at night. When symptoms such as weight loss, fever, nausea, vomiting, dysphagia, coughing, or frequent infections are reported, an extensive history and further examination are mandatory.

The most common symptom with pain arising from the cervical facet joints is unilateral pain, not radiating past the shoulder. The pain often has a static component because it does not always occur in relation to movement. Rotation and retroflexion are usually reported as painful or limited.

The radiation pattern is not distinctive for facet problems but can indicate the segmental localization. It is important to determine if the pain symptoms cause functional limitations (e.g., dressing, lifting, car driving, reading, sleeping, and in the work situation).

Physical Examination

Neurological tests (reflexes, sensibility, and motor function) are necessary to exclude radiculopathy. To examine the function of the neck, the following tests are important:

Flexion and extension: passive and active

Lateroflexion: passive and active

Rotation: passive and active

Rotation in maximal flexion: passive and active

Rotation in extension: passive and active

Rotation in a neutral position determines the rotation movement of the entire cervical spinal column. Rotation in flexion assesses the movement in the higher cervical segments. Rotation in extension assesses the movement in the lower cervical segments.

Local pressure pain over the facet joints can indicate problems arising from the facet joints. Recent research showed that local pressure, defined as pain with pressure of at least 4 kg, is a predictor of success of RF treatment (see Radiofrequency Treament sections).⁷ When the neck pain is accompanied by radiation to the shoulder region, shoulder pathology should be excluded.

There is no evidence for the relation between the results of clinical examination and the history with the presence of pain originating from the cervical facet joints.⁸ In daily clinical practice, history and physical examination are useful to exclude serious pathology and to obtain a working diagnosis. An indication of the segmental level (high, mid, or low cervical) involved can be obtained.

Diagnostic Blocks

The working diagnosis of facet pain based on history and clinical examination may be confirmed by performing a diagnostic block. Local anesthetic can be injected intraarticularly or adjacent to the ramus medialis (medial branch) of the ramus dorsalis of the segmental nerve.^2,⁹ Diagnostic medial branch block procedures are performed under fluoroscopy. There is no consensus about the definition of a successful diagnostic block. Some authors claim that 100% pain relief should be achieved.¹⁰ But Cohen et al⁷ showed that there is no difference in outcome of the RF treatment of patients reporting 80% and those reporting more than 50% pain reduction after a diagnostic block. In daily clinical practice, we consider a diagnostic block successful if more than 50% pain reduction is reported.

To minimize the number of false-positive results, a number of researchers have suggested that a second block should be carried out using a local anesthetic with different duration of action (e.g., lidocaine and bupivacaine; comparative double blocks). Only if the patient responds concordantly (longer or shorter pain reduction depending on the duration of action of the local anesthetic) is this indicative of facet joint pain. This is not an etiological but a pharmacological criterion. These researchers suggest that double blocks are the gold standard for the diagnosis of facet pain. A gold standard, however, should be generally accepted and used. The concept of double blocks has theoretical and practical shortcomings. A best evidence synthesis on the assessment of neck pain concluded that diagnostic facet injections have not been validated to identify facet joint pain.¹¹

In summary, on the basis of history and physical examination, a working diagnosis of cervical facet pain is defined. One diagnostic block can be recommended for confirming the clinical working diagnosis of facet pain. A block is considered positive when the patient experiences 50% pain reduction.⁷

Differential Diagnosis

Serious causes of neck pain such as tumors, infections, fractures, and systemic diseases are rare. A clinically relevant prolapsed discus intervertebralis and cervical spondylotic myelopathy cause neurological symptoms. Every patient with motor function loss, reflex changes, or sensibility loss must be thoroughly assessed.

Metastases, cervical herniated nucleus pulposus with radiculopathy, discitis, and fractures should be excluded through history and (additional) tests.

Chronic pain diagnoses such as segmental dysfunction, instability, and muscle strain are not sufficiently documented to be included in the differential diagnosis.² A summary of the differential diagnosis is represented in Table 14-1.

Table 14-1 Differential Diagnosis in Axial Neck Pain without Irradiation

Tumors
Infections	Discitis, septic arthritis, osteomyelitis, meningitis, epidural abscess
Trauma	Fractures, whiplash-associated disorders
Rheumatoid arthritis
Crystal arthropathies	e.g., Gout
Vascular disorders	Aneurysm
Neurological causes*	Neuromas
Degenerative disorders	Spondylosis, osteoarthrosis

* Neurological causes are almost always accompanied with loss of neurological function.

Anatomy

The vertebrae from C2 to S1 articulate with one another at the medial intervertebral joints, or disci intervertebrales between their corpora vertebrae and the lateral intervertebral, zygapophyseal, or facet joints between their processus articulares. The complex of two adjacent vertebrae with their intervertebral joints and ligamentous interconnections is defined as a segment.

The facet joint is located between the processus articularis inferior of a superior vertebra and the processus articularis superior of the adjacent inferior vertebra. It is a synovial joint with joint surfaces, a synovial membrane, and a joint capsule. The bony facets are covered with hyaline cartilage, and the joint capsule is fibrous. The chain of facet joints forms the facet column and permits segmental gliding movements between the vertebrae.

The cervical facet joint capsules are longer and looser than the facet joint capsules in the thoracic and lumbar regions.¹² The more or less flat facet joint surfaces from C2 to C7 form an angle of approximately 45 degrees with the longitudinal axis through the cervical spinal column with a large range of intra- and interindividual variability. Compared with the lumbar facet joints, the cervical facet joints have a high density of mechanoreceptors. McLain took twenty-one cervical facet joint capsules and surrounding tissue from three human subjects by block-excision and processed them in a modified gold chloride technique.¹³ In twenty-five micron serial histological sections he identified, according to the classification of Freeman and Wyke, encapsulated Type I, II, and III mechanoreceptors and non-encapsulated Type IV mechanoreceptors. The Type II receptors were found most frequently, mainly localized in the dens, fibrous joint capsule. Fewer Type I receptors were identified in both the capsule and the areolar, loose connective tissue. Only a handful of Type III receptors were found, at the junction between the capsule and the loose connective, sub-synovial tissue. Unencapsulated, nociceptive Type IV free nerve endings were present throughout the capsule, synovium, and areolar tissue.¹⁴

The facet joints from C3 to C7 are innervated by the ramus medialis (medial branch) of the ramus dorsalis of the segmental nerve (Fig. 14-2). Each facet joint is innervated by nerve branches from the upper and lower segments (Fig. 14-3).¹⁵

Fig. 14-2 Cervical spinal column, lateral view. Forceps opens arthrotic facet joint C4-C5. mmf, musculus multifidus; rl, ramus lateralis of ramus dorsalis; rm, ramus medialis (medial branch) of ramus dorsalis.

Fig. 14-3 Innervation of the cervical vertebral column and the facet joints. DRG, dorsal root ganglion.

(Illustrated by Rogier Trompert Medical Art. http://www.medical-art.nl.)

Imaging

In specific cases, plain radiography of the cervical spinal column (two or three directions) can be indicated to exclude tumor or fracture. Plain radiography does not, however, provide information for establishing the diagnosis of facet problems. This examination can help in estimating the degree of degeneration. The anterior spinal column is inspected for narrowing of the discus intervertebralis and anterior and posterior osteophyte formation. The posterior spinal column is inspected for facet osteoarthritis (facet sclerosis and osteophyte formation). In 1963, Kellgren et al ¹⁶ stated that when degenerative changes are seen on plain radiography, anatomical degeneration has already reached an advanced stage.

With progressing age, degenerative changes are more frequently seen: 25% at the age of 50 years up to 75% at the age of 70 years.¹⁷ An age-related prevalence study concerning facet joint involvement in chronic neck pain indicates a comparable prevalence among all age groups.¹⁸

Degenerative changes of the cervical spinal column are present in asymptomatic patients, indicating that degenerative changes do not always cause pain. However, the conclusion that there is no relation between degeneration and pain cannot be drawn. There are studies indicating a relationship between degenerative changes and pain symptoms.^17,¹⁹

In summary, a relationship between radiologic identification of degenerative changes and pain symptoms is not proven. If neurological etiology of the pain symptoms is suspected, magnetic resonance imaging (MRI) or computed tomography (CT) is indicated.

Guidelines

Recently, the following classification for neck pain and associated symptoms has been proposed:²⁰

Grade I neck pain: No symptoms indicating serious pathology and minimal influence on daily activities

Grade II neck pain: No symptoms indicating serious pathology and influence on daily activities

Grade III neck pain: No symptoms indicating serious pathology, presence of neurological disorders such as decreased reflexes, muscle weakness, or decreased sensory function

Grade IV neck pain: Indications of serious underlying pathology such as fracture, myelopathy, or neoplasm

The following interventions are published options for the treatment of cervical joint pain:

Intraarticular steroid injections

Local infiltration of the ramus medialis (medial branch) of the ramus dorsalis

RF treatment of the ramus medialis (medial branch) of the ramus dorsalis

A practice algorithm for the management of facet pain is illustrated in Fig. 14-4.

Fig. 14-4 Practice algorithm for the treatment of cervical facet pain. RF, radiofrequency.

Indications and Contraindications

Chronic neck pain can be caused by the facet joints. Percentages between 25% and 65% are described, depending on the patient group and selection method. In the group of patients attending a pain clinic for neck pain, it is likely to be more than 50%.^21,²² Conservative treatment options for cervical facet pain such as physiotherapy, manipulation, mobilization, and pharmacological treatment are frequently applied before considering interventional treatments.

Interventional pain management techniques such as medial branch blocks and RF treatment may be considered in any patient with chronic (>3 months) neck pain.

Absolute contraindications for interventional pain management techniques are infection at the injection site and severe coagulation disorders.

Corticosteroid injections are performed after a careful risk-to-benefit analysis in patients with metabolic diseases such as diabetes. Psychological factors such as avoidance behavior and catastrophizing are less commonly related to neck symptoms in contrast to patients with low back problems.²

Technique

Percutaneous Facet Denervation

The (postero-)lateral approach in the supine position is described below (Fig. 14-5). The advantage of this technique is that it is possible to maintain eye contact with the patient. Sedation is rarely required.

Fig. 14-5 Posterolateral approach of the cervical ramus medialis (medial branch) of the ramus dorsalis. DRG, dorsal root ganglion.

(Illustrated by Rogier Trompert Medical Art. http://www.medical-art.nl.)

The patient is placed in the supine position with the head slightly extended on a small cushion. The C-arm is placed in an oblique position (±30 degrees). In this position, the beam runs parallel with the exiting nerve root that runs somewhat caudofrontal. Also in this position, the pedicles from the contralateral side are projected on the anterior half of the vertebral body. In the frontal plane (anteroposterior [AP] direction), the C-arm is positioned in a small angle with respect to the transverse plane. In this position, the discus intervertebralis space and neuroforamen are visible (Fig. 14-6). The ramus medialis (medial branch) of the ramus dorsalis runs over the base of the processus articularis superior. The injection point is marked on the skin, slightly posterior and caudal to the end point of the needle that is dorsal to the posterior boundary of the facet column. The first needle is introduced in a horizontal plane, slightly cranially so the tip of the needle points in the direction of the end point. It is important to understand that this is not a “tunnel-view” technique. The needle is slowly advanced anteriorly and cranially until bony contact with the facet column occurs. The farther the needle is advanced, the more difficult it becomes to change the direction. Therefore, the position of the needle needs to be checked frequently. If the needle points too much in the direction of the neuroforamen without contacting bone, the direction needs to be corrected to be more posterior. If there is no bone contact in the posterior direction, there is a risk that the needle will enter the spinal canal between the laminae. To prevent this, the needle position can be checked in the AP direction. The final position of the needle in the AP direction is in the concave “waist” of the facet column. After placement of the first needle, the other needles are introduced in the same way. The first needle acts as a guide to direction and depth.

Fig. 14-6 Radiofrequency treatment cervical ramus medialis (medial branch) of the rami dorsales/facet C4, C5, C6, left: three quarters projection.

The same technique is used for the facet joints of C3-C4 to C6-C7. For the facet joint of C2-C3, a different end point for the needle is used, just beneath the C2-C3 joint.²³

After an optimal anatomical localization is reached and controlled using fluoroscopy, the position of the needle tip at the ramus medialis (medial branch) of the dorsal ramus is confirmed using electrical stimulation. The stimulation threshold is determined: an electrical stimulation of 50 Hz must give a reaction (tingling) in the neck at less than 0.5 V. Then stimulation is carried out at 2 Hz. Contractions of the paraspinal muscles can occur. Muscle contractions in the arm indicate a position close to the exiting segmental nerve. The needle should then be placed more posterior. After the correct position has been determined, 0.5 to 1 mL local anesthetic (1% or 2% lidocaine) is given. A RF lesion at 80° C for 60 seconds is carried out.

Patient Management and Evaluation

As outlined under the heading Establishing a Diagnosis, a thorough examination is mandatory. A management plan is discussed with the patient, and only after informed consent, an intervention is planned. Evaluation of the effect of the procedure is standard usually after 4 to 6 weeks.

It can be helpful to use at least a Numerical Rating Scale and a Global Perceived Effect Scale. Other evaluation scales are Pain Medication Quantification; Return to Work; General Functioning scales (SF36); and specifically for the neck, The Neck Disability Index. For scientific purposes, it is advised to use scales out of the six core domains: pain, physical functioning, emotional functioning, global improvement, symptoms and adverse events, and participant disposition.

Outcomes Evidence

The recently published Evidence-Based Practice Guidelines based on clinical diagnoses based the recommendations on the “grading strength of recommendations and quality of evidence in clinical guidelines” described by Guyatt et al ²⁴ and adapted by van Kleef et al²⁵ in an editorial in Pain Practice (Table 14-2).

Table 14-2 Summary of Evidence Scores and Implications for Recommendation

Score	Description	Implication
1A+	Effectiveness demonstrated in various RCTs of good quality. The benefits clearly outweigh the risks and burdens.	} Positive recommendation
1B+	One RCT or more RCTs with methodological weaknesses demonstrate effectiveness. The benefits clearly outweigh the risks and burdens.
2B+	One or more RCTs with methodological weaknesses demonstrate effectiveness. The benefits are closely balanced with the risks and burdens.
2B±	Multiple RCTs, with methodological weaknesses, yield contradictory results better or worse than the control treatment. The benefits are closely balanced with the risks and burdens or there is uncertainty in the estimates of benefits, risks, and burdens.	} Considered, preferably study related
2C+	Effectiveness is only demonstrated in observational studies. Given that there is no conclusive evidence of the effect, benefits are closely balanced with the risks and burdens.	} Considered, preferably study related
0	There is no literature or there are case reports available, but these are insufficient to prove effectiveness or safety. These treatments should only be applied in relation to studies.	Only study related
2C−	Observational studies indicate no or too short-lived effectiveness. Given that there is no positive clinical effect, the risks and burdens outweigh the benefits.	} Negative recommendation
2B−	One or more RCTs with methodological weaknesses or large observational studies that do not indicate any superiority to the control treatment. Given that there is no positive clinical effect, the risks and burdens outweigh the benefits.
2A−	RCT of a good quality that does not exhibit any clinical effect. Given that there is no positive clinical effect, the risks and burdens outweigh the benefits.