The Specificity of Cervical Facet Medial Branch Blocks

Randomized Study Comparing the Accuracy and Specificity of Cervical Facet Medial Branch Blocks With 0.25 ml and 0.5 ml of Local Anesthetic

Cervical facet arthropathy is a common cause of chronic neck pain. The "gold standard" for diagnosis is either blocking the facet joints, or more commonly blocking the medial branch nerves that innervate the joints. However, many studies have found a high false-positive rate when the nerves are blocked using 0.5 ml of local anesthetic. We will randomize patients to receive either cervical facet medial branch blocks with 0.25 ml of local anesthetic and contrast, or 0.5 ml. We will then do a CT scan to determine the accuracy and specificity of each block. Our hypothesis is that using the higher volume (0.5 ml) might be responsible for the high false-positive rate.

Inclusion criteria: Dept. of Defense beneficiaries > 18 years of age; neck pain > 3 months duration; cervical paraspinal tenderness Exclusion criteria: Radicular signs or symptoms; use of anticoagulants or bleeding disorder. Outcome measures: The number of blocks whereby the contrast bathes the target nerve; the number of blocks whereby the contrast spreads to the medial branch nerve at the adjacent spinal level; the number of times the contrast diffuses into the intervertebral foramen or epidural space. We will also compare pain relief over 8 hours following the block between both volumes.

Inclusion Criteria: Age > 18 years Chronic neck pain > 3 months Paraspinal tenderness Exclusion Criteria: Absence of radicular symptoms No bleeding diathesis Contrast allergy

Dreyfuss P, Schwarzer AC, Lau P, Bogduk N. Specificity of lumbar medial branch and L5 dorsal ramus blocks. A computed tomography study. Spine (Phila Pa 1976). 1997 Apr 15;22(8):895-902. doi: 10.1097/00007632-199704150-00013.

Lord SM, Barnsley L, Bogduk N. The utility of comparative local anesthetic blocks versus placebo-controlled blocks for the diagnosis of cervical zygapophysial joint pain. Clin J Pain. 1995 Sep;11(3):208-13. doi: 10.1097/00002508-199509000-00008.

Cohen SP, Strassels SA, Kurihara C, Forsythe A, Buckenmaier CC 3rd, McLean B, Riedy G, Seltzer S. Randomized study assessing the accuracy of cervical facet joint nerve (medial branch) blocks using different injectate volumes. Anesthesiology. 2010 Jan;112(1):144-52. doi: 10.1097/ALN.0b013e3181c38a82.