Ultrasound and facet blocks: A review

Facet or zygapophysial joints are considered to be common sources of chronic spinal pain. In addition to causing localized spinal pain, facet joints may refer pain to adjacent structures. Cervical facet-joint pain may radiate to the head, neck, and shoulders. Thoracic facets may produce paraspinous mid-back pain with neuralgic characteristics; and lumbar facet joints may refer pain to the back, buttocks, and proximal lower extremities. Because the facet joint is innervated by the medial branches arising from the posterior rami of the spinal nerve at the same level and a level above the joint, LA blocks of these nerves have been advocated for diagnostic and prognostic purposes. Intra-articular l-z joint injection with LA has also been proposed as a method for diagnosing facet-joint pain, with both procedures appearing to provide comparable diagnostic value. Because several blocks are often needed to identify the symptomatic joint or to rule outzygapophysial joint pain, the procedure may expose patients and personnel to considerable radiation doses. In contrast, ultrasound is not associated with exposure to radiation. Ultrasound guidance was recently proposed as a possible alternative to fluoroscopy for the conduct of lumbar medial-branch block. Ultrasound-guided techniques require training in specific areas: (1) pattern recognition of the ultrasonographic appearances of anatomic structures, (2) probe handling and scanning skills, and (3) manual dexterity in aligning the needle to the ultrasound beam, thereby enabling the needling of the target. Ultrasound could become an attractive alternative to fluoroscopy or CT scanning, helping to increase the practicability of lumbar facet nerve blocks.