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Brown: Atlas of Regional Anesthesia, 3rd ed., Copyright © 2006 Saunders, An Imprint of Elsevier
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Chapter 39 – Facet Blocks

PERSPECTIVE

Facet blocks are used both diagnostically and therapeutically to diagnose and treat subsets of patients with chronic low back and neck pain. Difficulties may arise when interpreting the results of facet blocks in that the innervation of facet joints is diffuse, and radiographic changes in facet joints may or may not be linked to a specific patient’s pain. Despite the caveats, the pain relief attained with facet injection seems convincing to this pain medicine clinician, although in contrast to many other pain management techniques extra care must be taken in balancing the patient, the pain syndrome, and the treatment regimen with the individual clinical setting.

Patient Selection.

Facet-related pain remains a diagnosis of exclusion, supported by reproducing the pain during arthrography and relief of pain after diagnostic facet injection. In patients with lumbar pain syndromes, facet-related pain is often located in the low back and is described as a deep dull ache that is difficult to localize. It may be referred to the buttocks or to the posterior leg, and infrequently it extends more distally into the lower leg. The pain is often made worse by lumbar extension, especially with lateral flexion to the affected side because this maneuver opposes the facet joints more forcefully. In cervical facet pain syndromes the pain remains deep and aching in quality, and the level of the facet involvement dictates the referral pattern of the pain. There are distinct upper, lower, and pancervical neck facet pain syndromes.

Pharmacologic Choice.

Diagnostic blocks are most often performed with 1 to 2 mL of local anesthetic, either 1% to 1.5% lidocaine, 0.25% to 0.5% bupivacaine, or 0.2% to 0.5% ropivacaine. The former is chosen if immediate interpretation is sought, whereas the latter two drugs are used if diagnostic information is sought over a longer interval. If therapeutic injection is performed, the total volume of the solution is kept at 1.5 to 2.0 mL, although 20 mg of methylprednisolone is added to the local anesthetic (most often a longer-acting agent for a therapeutic injection). For either diagnostic or therapeutic injection, confirmation of the needle position is made with 0.25 to 0.5 mL of a radiocontrast agent, Hypaque M-60.

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