What is the role of spinal synovial joint blocks in pain management?

Updated: Jun 19, 2018
  • Author: Anthony H Wheeler, MD; Chief Editor: Meda Raghavendra (Raghu), MD  more...
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Diagnostic spinal synovial joint blocks are used to assess whether the pain stems entirely from the zygapophyseal joints. No established clinical or radiographic features are recognized uniformly that enable practitioners to assign the posterior articulations as probable pain generators. Furthermore, degenerative features on CT scan have shown poor specificity and sensitivity in implicating these as causative of pain, and joints that appear normal have been demonstrated to be symptomatic. Aprill et al have mapped typical referral patterns that occur with provocative injections into the synovial zygapophyseal joints.

Cervicogenic headache involving the occiput and posterior portion of the head has been demonstrated as a result of injections into the C2-3 facet and lateral atlantoaxial joint. Provocation at C3-4 tends to span the entire cervical area but not to extend into either occiput or shoulder girdle. Provocation at C4-5 sends pain into the angle formed by the neck and top of the shoulder girdle. Provocation at C5-6 tends to produce pain over the supraspinous fossa to the acromion, and provocation at C6-7 provokes pain that radiates into the ipsilateral scapula. Reproducible pain patterns have been harder to establish in similar injection studies of lumbar spine facets, although provocation of these joints at L4-5 or L5-S1 usually results in pain referred into the low back, gluteal, and posterior thigh regions.

Nevertheless, the facet joints of the lumbar spine have been implicated as a source of low back pain since 1911. Injections of intra-articular anesthetic have provoked and alleviated pain. Although some spine specialists and interventionists advocate facet injections as a treatment method, several studies, including a large prospective study and 3 randomized controlled trials, showed no significant long-term benefit. Intra-articular facet injections, which are costly and invasive, should be considered as an adjunctive method for diagnostic identity of pain generator(s), and if convincing pain relief is obtained from intra-articular anesthetic block, the practitioner should remain open-minded in addressing the zygapophyseal joints as a potential pain source. Estimates for the prevalence of lumbar facet syndromes range widely in the published medical literature from as low as 7% to as high as 75%.

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