1. 2019;22;E127-E132Incidence of Cervicogenic Headache Following Lower Cervical Radiofrequency Neurotomy
   Observational Study
   Joseph LaGrew, MD, Pavel Balduyeu, MD, Terrie Vasilopoulos, PhD, and Sanjeev Kumar, MD.

BACKGROUND: The facet joints contribute to chronic cervical spine pain in an estimated 55% of chronic neck pain cases and can be treated with percutaneous radiofrequency neurotomy (PRN). Damage to surrounding structures during treatment or successful treatment of the primary pain source leading to unmasking could lead to new onset of pain, including cervicogenic headache (CGH). In this study, we aimed to define the incidence of headache in patients who have been previously treated with PRN for lower cervical facet pain.

SETTING: All patients treated at a single academic institution’s pain management clinic from 2014 to 2016 with cervical PRN were reviewed.

METHODS: All patients treated at a single institution’s pain management clinic from 2014 to 2016 were reviewed. Those treated with lower cervical PRN were identified, and incidence of CGH was described as a percentage of the study population. Patient age and pain scores between those with and without headaches following treatment were compared by unpaired T-tests. Gender, presence of comorbid disease and levels involved, quality of pain, exacerbating and alleviating factors, location of referred pain, and previous treatments between those with and without headaches following treatment were compared using chi-square tests.

RESULTS: Among the 88 patients in the study group, 12 were found to have only moderate relief of their pretreatment pain as well as a new onset headache meeting the diagnostic criteria for cervicogenic headache. Compared to those without a headache after treatment, those diagnosed with cervicogenic headache were more likely to be female (P = 0.041), report a higher maximum pain level on presentation (P = 0.015), have a diagnosis of diabetes prior to presentation (P = 0.011), and have had the procedure performed at levels which included C3 (P = 0.013) (Table 1).

LIMITATIONS: The limitations of this study include its single-center design, as this cohort may not be truly representative of the population of patients receiving cervical PRN as a whole, and as a result, these results may not be generalizable. Due to the small size of the cohort, more subtle differences in presenting signs and symptoms between those with and without headaches may not be detectable. Finally, as previously mentioned, the lack of data on some of the patients who presented with headache may have led to underdiagnosis of the true incidence of cervicogenic headache. Future work should look to re-examine the incidence of CGH in a larger cohort to validate the findings here and further define risk factors for post-procedural CGH.

CONCLUSIONS: This retrospective review of all patients seen over 2 years in an academic pain clinic found a 13.6% incidence of cervicogenic headache following cervical radiofrequency neurotomy at levels C3-C7. This supports the possibility of the unmasking phenomenon following the procedure, though contributing mechanisms underlying this phenomenon may be multifactorial and require further study.

IRB: This study was approved by the institution’s Institutional Review Board (IRB2010601795).

KEY WORDS: Cervical spine, facetogenic pain, percutaneous radiofrequency neurotomy, cervicogenic headache, chronic pain, zygapophysial joints, innervation convergence, retrospective chart review