Injections that freeze neck joints can be done using x-rays or ultrasound imaging, which as a newer way of guiding the needle to the right spot. This study will look at how often freezing liquid goes into a blood vessel during neck injections that freeze neck joints when ultrasound guidance is used to place the needle. When this happens, it can go undetected because it does not make the patient feel any different, however it could cause a test block to be falsely negative, leading to the wrong diagnosis. Based on previous studies, we think that this happens rarely, and the purpose of this study is to prove that conclusively

Cervical medial branch blocks (CMBB) are commonly employed for the diagnosis and management of facet-related pain. The latter constitutes the most important cause of axial neck pain and has been implicated in 40% of all cases. In addition, the upper cervical joints can also cause cervicogenic headaches, an often-debilitating condition representing up to 20% of chronic headaches3. Well-defined pain referral patterns for each joint can help operators select the appropriate injection level. While fluoroscopy has long been the imaging standard for spinal procedures, ultrasound guidance (USG) is being increasingly adopted as an alternative and presents several advantages such as the ability to identify and avoid soft tissue structures such as blood vessels during needle insertion. From a clinical perspective, avoiding blood vessels and reducing the incidence of vascular breach can lessen the occurrence of intravascular injections that are associated with false negative diagnostic blocks. Indeed, a recent study examining the safety of USG CMBB reported a lower incidence of vascular breach than previous studies that had used fluoroscopic guidance. While these findings suggested a potential benefit associated with USG, further confirmatory studies employing digital subtraction angiography (DSA), the current imaging standard to detect intravascular spread, are required. We hypothesize that USG will be associated will a lower incidence of intravascular spread during primary needle placement than has been reported with fluoroscopic guidance.

Inclusion Criteria:

Consenting patients over 19 years of age undergoing an ultrasound-guided cervical medial branch blocks as part of their usual care.

Exclusion Criteria:

Subjects with one or more of the following characteristics will be excluded from the study:

Known bleeding disorder or coagulopathy Patients on antiplatelet medication other than aspirin and those on anticoagulants (coumadin, AT III agents) Inability to visualize targeted structures on ultrasound Known allergy to contrast agents

Patients undergoing cervical medial branch blocks as part of their usual care.