Optimal Angle of Contralateral Oblique View in Cervical Interlaminar Epidural Injection Depending on the Needle Tip Position.

BACKGROUND: Chronic neck and upper extremity pain associated with cervical origin is common, and cervical interlaminar epidural steroid injections (CILESIs) are frequently used to manage the symptoms of cervical spinal disorders. However, CILESIs are associated with risks such as dural puncture and cord injury. OBJECTIVES: We aimed to determine the optimal needle tip visualization, in order to minimize CILESIs-induced complications. STUDY DESIGN: Retrospective observational study. SETTING: The single center study in Seoul, Republic of Korea. METHODS: Participants were 312 adults with neck or upper extremity pain caused by cervical lesion such as cervical herniated nucleus pulposus (HNPs). They underwent magnetic resonance imaging (MRI). Patients with severe cervical spinal stenosis, prior posterior cervical spine surgery, or other anatomical abnormalities of the vertebral laminae were excluded from the study. By using axial T2-weighted spin-echo MRI, we defined the area between the spinous processes as the anterior posterior zone 1 (APZ1), and the area lateral to the spinous processes as the anterior posterior zone 2 (APZ2). Line 1 was drawn along the ventral margin of lamina that confined APZ1, and line 2 was similarly drawn in order to define APZ2. The angles between the midsagittal line and lines 1 and 2 were defined as angle 1 and angle 2, respectively. Angles were measured at the C5-6, C6-7, and C7-T1 levels, on both right and left sides at each level. RESULTS: Angle 1 values (in degrees) at right C5-6, left C5-6, right C6-7, left C6-7, right C7-T1, and left C7-T1 were 62.54 ± 10.52, 64.34 ± 9.86, 62.03 ± 10.27, 62.87 ± 10.64, 61.64 ± 11.0, and 62.58 ± 10.83, respectively. Angle 2 values at right C5-6, left C5-6, right C6-7, left C6-7, right C7-T1, and left C7-T1 were 50.44 ± 6.84, 50.77 ± 7.00, 49.15 ± 6.07, 49.89 ± 6.45, 50.84 ± 6.68, and 50.24 ± 6.60, respectively. There were significant differences between angles 1 and 2 at each level. LIMITATIONS: This study is a retrospective review and did not employ controls, blinding, or randomization. Additionally, the optimal CLO angles for CILESIs and cervicothoracic interlaminar epidural steroid injections (CTILESIs) have not been assessed in clinical studies. Another limitation is that we divided lamina into only APZ1 and APZ2. CONCLUSIONS: During CILESIs, a contralateral oblique (CLO) view at 60 degrees is superior to other angles for visualizing the epidural space when the needle tip is placed in the interlaminar space and within the spinous processes margin. When the needle tip is placed in the interlaminar space and lateral to the spinous processes, a CLO view at 50 degrees is most appropriate.Institutional Review Board (IRB) approval number: S2016-0390-0001Key words: Chronic neck pain, chronic upper extremity pain, cervical epidural injections, cervical interlaminar steroid injections, steroid, needle tip position, needle tip visualization, fluoroscopy, complication, contralateral oblique view.