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Complications of Lumbar Facet and Medial Branch Blocks and Ablations

Gözde Dağıstan MD and Mert Akbaş MD, FIPP

Akdeniz University School of Medicine, Antalya, Turkey

Introduction

Facet or zygapophyseal joints are considered to be one of the common causes of chronic low back pain [1, 2]. Pain originating from lumbar facet joints may radiate to low back, hip, and proximal lower extremities. Facet joint interventions are often used for therapeutic and diagnostic purposes to manage chronic spinal pain [3]. Facet joint interventions among all other spinal interventions are the second most commonly performed procedures following epidural injections and adhesiolysis [4].

Procedures related to the facet joint can be classified as intra-articular injections, facet joint nerve blocks and facet joint nerve ablation. Although complications related to lumbar facet interventions (LFI) are rare, the most common and concerning complications occur during needle placement, drug administration, and radiofrequency thermocoagulation (RFT) neurotomy.

Anatomy of the Facet Joint

Lumbar facet joints are encapsulated, diarthrodial, and synovial joints that are formed between the inferior articular process of the upper vertebra and the superior articular process of the lower vertebra. Every facet joint is surrounded by a fibrous capsule.

Lumbar facet joints are innervated by the medial branch of the posterior primary ramus. The medial branch innervates the facet joint, multifidus muscle and interspinous ligament. Each medial branch supplies branches to the joint at its level and at the lower level (Figure 34.1). For example, the medial branch of L2 supplies branches to the facet joint of L2–L3 and L3–L4. The medial branch of L5 is an exception and it only branches out to the facet joint of L5–S1.

The medial branches of the dorsal rami of L1–L4 extend through the transverse process of the lower vertebra and settle in the notch where the transverse process and superior articular process join (Figure 34.2).

**Figure 34.2** Anatomic placement of the medial nerve.

This is the area named as the eye of the Scottie dog. The ear of the dog is the superior articular process, its front legs are the inferior articular process, while its tail is the spinous process (Figure 34.3).

Indications

Facet syndrome
Spinal stenosis
Chronic low-back pain with no radicular symptoms
Postlaminectomy syndrome
Compression fracture
Spondylolysis
Spondylolisthesis.

Contraindications

Systemic infection or local infection at the site of injectionBleeding diathesis or anticoagulation useAllergic reaction to contrast, anesthetic or corticosteroidLocal malignancyPatient refusal.

Technique

Lumbar Facet Joint Block

The patient is placed in prone position. A pillow is put under the upper abdomen to decrease physiologic lumbar curve. Lumbar region is prepared and draped in sterile condition (Figure 34.4).

The procedure performed by squaring the lower end plate of the target level vertebra by tilting the fluoroscope cephalad or caudal (Figure 34.5).

Then, the fluoroscope is angled in ipsilateral oblique position. The facet joint is viewed. After infiltration of local anesthetic to the skin, the needle is advanced toward the medial side of the inferior articular process of the target facet joint. The needle is advanced and crosses the joint capsule, then 0.2 cc contrast agent is injected (Figures 34.6 and 34.7).

**Figure 34.6** Oblique view of intra-articular facet joint injection.

**Figure 34.7** Lateral view of intra-articular facet joint injection.

Then, 1–2 cc local anesthetic and steroid mixture is injected.

Lumbar Facet Medial Branch Block and RF Thermocoagulation

The steps mentioned above are repeated. When the fluoroscope is in the oblique position, the junction of the transverse and superior articular processes is viewed. The needle is advanced toward the junction of the transverse process and superior articular process with tunneled vision technique (Figure 34.8).

In order to block the medial branch of L5 that innervates the facet joint of L5–S1, the needle is advanced toward the notch at the junction of the superior articular process and sacral ala (Figure 34.9).

**Figure 34.9** Needle placement for L5 dorsal ramus block.

As the needle contacts the bone, the C-arm is placed in the lateral position. In the lateral view, the needle should be on the lateral facet, in the posterior foramen and below the intervertebral disc level (Figure 34.10).

Sensory stimulation is performed at 50 Hz. Patients should feel sensory stimulation under 0.5 V. Then, 0.5–1 V motor stimulation is performed at 2 Hz. After determining the exact location of the needle, 1–2 cc local anesthetic and steroid mixture is injected for medial branch block. RFT is applied for 60–90 seconds at 80–90 degrees with a 5- or 10-mm active tip electrode.