Response to Cervical Medial Branch Blocks In Patients with Cervicogenic Vertigo.

Background: Among the various causes of vertigo, the so-called cervicogenic vertigo (CV) has been the most controversial. However, perturbations of proprioceptive signals and abnormal activity of the cervical afferents can induce vertigo. Medial branch blocks (MBBs) are a diagnostic tool designed to test whether a patient's neck pain is mediated by one or more of the medial branches of the dorsal rami of the spinal nerve. It is unknown whether MBBs are also suitable for testing symptoms other than pain.

Objectives: The purpose of this study was to test whether MBBs of the cervical spine can be used as a diagnostic tool to identify patients with CV.

Study Design: A retrospective practice audit (clinical observation).

Setting: An interventional pain management and spine practice.

Methods: An electronic medical record system was used to identify patients in a single spine center. Included were consecutive patients with neck pain and vertigo, who had received cervical MBBs in a period from July 2001 to April 2016. The patients were tested with a MBB of about 1 mL of bupivacaine (0.25%) and 20 mg triamcinolone. Injections were performed with fluoroscopic visualization using established techniques in 2 or 3 levels on one or both sides. Vertigo was analyzed through the global clinical impression of the patient (i.e., "gone," "better," "the same," or "worse").

Results: One-hundred seventy-eight patients met the inclusion criteria. One-hundred eleven patients (62.4%) experienced a significant improvement of the vertigo. In 47 patients (26.4%), no information about the vertigo was available at follow-up; these patients were assumed to have no improvement (worst-case scenario). Hence, altogether 67 patients (37.6%) had a negative result. The median relief of the vertigo was 2 months. Differences in age, gender, level of treatment, or pain duration between patients with relief of the vertigo and without relief were not found. Nine patients with a whiplash injury in their medical history were also tested. They experienced a lower success rate and had longer duration of pain before the treatment; however, these differences are not statistically significant.

Limitations: It was the primary intention to treat neck pain; the assessment of vertigo was an additional aim. Therefore, the history taken and the clinical examination were not targeted specifically to vertigo. A placebo effect cannot be excluded. Further studies with the primary focus on CV are necessary to prove the significance of MBBs.

Conclusions: This is the first study to demonstrate that MBBs of the cervical spine can be a useful tool for the diagnosis of CV, because they temporarily block cervical afferents. In 63.4% of patients with neck pain and suspected CV, the vertigo was significantly improved. Further placebo-controlled studies with the primary intention on CV are necessary to prove the significance of MBBs.

Key Words: Cervicogenic vertigo, medial branch block, facet joint, zygapophysial joint, neck pain, differential diagnosis.