Cervical Percutaneous Facet (Zygapophyseal Joint = ZA Joint) Denervation

Fig. 19.1

Anatomy of the cervical spine with innervation; entry and target points are marked (VA vertebral artery, TON third occipital nerve)

The facet joints are richly innervated by medial branches of the dorsal ramus from the corresponding level and by the medial branch of the dorsal ramus one level above. For example, the facet joint C3–C4 is innervated by the dorsal rami C3 and C4. Each dorsal ramus innervates two facet joints, and each facet joint is innervated from two levels. The innervation of the C2–C3 facet joint is more complex, since this joint is mainly supplied by the third occipital nerve, which is one of the two medial branches of the C3 dorsal ramus and to some degree also by the C2 dorsal ramus. The C2 medial branch is commonly known as the greater occipital nerve [1]. The practical implication of this observation is that for the treatment of facet joint pain at the level C2–C3, the third occipital nerve and the medial branch of the C2 dorsal ramus are required.

The medial branch innervates skin, ligaments, and muscles. The lateral branch innervates muscles. The medial branches have to be blocked in the concavity between the superior and inferior articular processes, in the “waist” of the vertebra. The medial branches are bound to the periosteum by an investing fascia and are held against the articular pillars by tendons of the semispinalis capitis muscle.

The technique of lumbar facet denervation was first described by Shealy in 1975 [2]. The large thermistor electrodes used at that time made the procedure difficult to perform at the cervical level. The introduction of the SMK system with a much smaller diameter made the application at the cervical level possible without the risk of mechanically induced tissue damage.

As the innervation of the joint is always from two levels, the procedure must always be done at two levels, in case of pain from two adjacent joints at three levels; in our practice we mostly perform RF lesioning at the C2 to C6 level in one session.

The procedure, which is mostly performed in an outpatient setting, can be done uni- or bilaterally, depending on the pain pattern and consequently the causative structures. Preferentially the procedure is performed in conscious patients allowing continuous communication. Therefore, the use of sedatives such as propofol, alfentanil, or remifentanil is rarely necessary, unless the patient is too anxious and the procedure is performed bilaterally in the same session.

Indications

Painful facet joints may cause pain in the neck, head, shoulder, arm, or interscapular region; the upper segments may also cause facial pain or may be a trigger for migraine and cluster headache. The upper zygapophyseal joints may play an important role in the development of cervicogenic headache. The indications listed below have been documented.

Pain from cervical zygapophyseal joint origin, which can give rise to neck pain, irradiation to the head (headache) and shoulder, the interscapular region, and the arm

Post-traumatic neck pain [3]

Cervicogenic headache [4]

Atypical facial pain and some forms of cluster headache and migraine caused by a cervicogenic trigger mechanism from the facet joints.

The possible signs and symptoms of facet pain in the cervical region are listed in Table 19.1

Table 19.1

Possible signs and symptoms of facet pain in the cervical region

Neck pain with or without irradiation to the shoulder, arm, interscapular region, or face

Paravertebral tenderness, a sign of real facet pain in the majority of cases

Pain on rotation and ante-/retroflexion of the neck

Radiculopathy is absent (no neurological deficit)

Morning stiffness

Uni- or bilateral pain lasting longer than 3–6 months not reacting to physical therapy and other conservative management could be an indication for percutaneous facet denervation (PFD). In the absence of a specific facet syndrome, most authors advocate to perform a test block prior to a PFD. This test block is a medial branch block or an intra-articular block with local anesthetics. Some authors add steroids in order to achieve a longer-lasting effect because steroids reduce potential joint inflammation, but in a placebo-controlled study, this strategy has proved to be ineffective on longer term.

Radiological findings per se, such as facet arthritis, are not an indication for a PFD. On the other hand, there may be facet pain without any radiological abnormality.

Contraindications for cervical facet denervation are summarized in Table 19.2.

Table 19.2

Contraindications for cervical facet denervation

Sensory loss

Lack of cooperativeness

Bleeding disorders or use of anticoagulants

Signs of local infection

Signs of local malignancy

Allergy to local anesthetics