Cervical medial branch blocks are local anesthetic injections targeting the articular nerves (the medial branches) that transmit sensory information including nociceptive signals from the cervical facet joints. A cervical medial branch block test is very specific and is intended to determine whether a particular cervical facet joint is a source of pain.
Cervical medial branch blocks can provide important diagnostic information in patients suffering from chronic neck pain. Patients with a positive response to cervical medial branch blocks should be considered for cervical radiofrequency ablation procedure for sustained pain relief. However it is important to note that in some cases injection treatment may not provide the desired results or the pain relief may not be sustained. At Pain Spa Dr Krishna is very experienced in performing interventional pain procedures. Dr Krishna always performs cervical medial branch blocks under fluoroscopy guidance for greater accuracy and improved safety.
The facet joint is richly innervated with nociceptors and mechanoreceptors; these nerves can be adversely affected by facet capsular strain. Inflammation of the facet joint can sensitize nociceptive neurons and lower the firing threshold, causing pain during ‘normal’ motion, or peripheral sensitization. Similarly, disruption of mechanoreceptors can cause subtle proprioceptive disturbances and result in spinal instability or uncoordinated, painful cervical muscle contraction and guarding.
The cervical spine is composed of 7 cervical vertebrae, intervertebral discs, zygapophyseal or facet joints, ligaments, muscles and fascia and neural structures. There are 7 pairs or 14 facet joints in the cervical spine. They are true synovial joints and are composed of a fibrous capsule lined with synovium and hyaline cartilage between the bony structures. The capsule is richly innervated by nociceptors and mechanoreceptors that help with cervical spine proprioception.
The orientation of the facet joint provides resistance to anterior translation and assists in weight-bearing. They are at a 45-degree angle, allowing flexion, extension, rotation, and limited translation. The atlanto- occipital and atlanto-axial joints (C1 and C2) do not have facet joints. The C2/3 joint is innervated by the medial branch of the C2 dorsal rami and the medial branch of the C3 dorsal rami (the third occipital nerve). C3/4 to C7/T1 cervical joints are innervated by the medial branches of the cervical dorsal rami located above and below the joint. Indications for lumbar medial branch blocks
Cervical medial branch blocks are diagnostic injections designed to determine if patient’s neck pain is emanating from the cervical facet joints.
A positive response is considered as one with at least 80% pain relief of at least 2 hours duration when lidocaine is used, and at least 3 hours or longer when bupivacaine was used. Cervical medial branch blocks are not intended to provide therapeutic benefit. Patients with positive response to cervical medial branch blocks are offered radiofrequency denervation treatment for a more sustained response.
Injections are generally avoided in patients with systemic infection or skin infection over puncture site, bleeding disorders or coagulopathy, allergy to local anaesthetics or any of the medications to be administered.
The procedure is usually done on an outpatient basis. The procedure is performed under fluoroscopic guidance to ensure accuracy of needle placement. This involves injection of local anaesthetic around the medial branches innervating the relevant facet joints. Patients who experience good pain relief following diagnostic injections are offered radiofrequency denervation treatment.
Complications are rare, particularly if injections are performed using a precise needle-positioning technique. Severe allergic reactions to local anaesthetics are uncommon. Post-procedural pain flare-up is also uncommon as steroids are not used for these diagnostic injections. Neurological complications including paraesthesias, numbness and paralysis have been described but are rare.
At Pain Spa Dr Krishna is very experienced in performing interventional pain procedures. Dr Krishna always performs cervical medial branch blocks under fluoroscopy guidance for greater accuracy and improved safety.