Cervical Epidural Depth: Correlation Between Needle Angle, Cervical Anatomy, and Body Surface Area

Abstract

Objectives Prior to performing a cervical interlaminar epidural steroid injection (CIESI), knowledge of the depth from lamina to epidural space may assist in preventing cord injury. Methods This is a prospective analysis of data including gender, age, weight, height, previous surgery, neck circumference, distances from tip of chin to sternal notch, occiput to C7 vertebral prominence, and ear lobe to tip of shoulder, pain score, angle from C7 vertebral prominence to the back, depth at which the Tuohy needle contacted T1 vertebral lamina and depth at which the epidural space was entered was conducted with 92 subjects, average age (± SD) 41.3 ± 13.2 years underwent fluoroscopically-guided C7-T1 intralaminar epidural steroid injections. Results Depth to lamina was the best individual predictor with an r-value of 0.86. Weight, neck circumference, and BMI correlated positively with depth to epidural space with r-values of 0.66, 0.62, and 0.61 respectively. A linear regression model of depth to lamina for predicting depth to epidural space was accurate to within ± 0.5 cm of the actual depth in 69% of subjects. However, when comparing predicted to actual depth to epidural space for individual subjects, the prediction was inaccurate by as much as 1.6 cm deep or 1.7 cm shallow. Conclusions While statistically significant correlations do exist between both quantitative external body characteristics and depth to cervical epidural space and T1vertebral lamina to depth of cervical epidural space for fluoroscopically guided interlaminar epidural steroid injections at C7-T1, even the most optimal regression models do not permit clinical confidence in predicted depth to epidural space.

Method to Reduce the False-Positive Rate of Loss of Resistance in the Cervical Epidural Region

“…In the cervical region, anatomical studies have shown not only high rate of discontinuity, but also anatomic variability in the ligamentum flavum, which plays an inevitable role in the LOR technique. This morphological variability is associated with a higher false-positive rate during CIESI procedures [ 7 , 18 , 19 ].…”

Comparison of contralateral oblique view with the lateral view for fluoroscopic-guided cervical epidural steroid injection: a randomized clinical trial

“…The cervical epidural space is anatomically relatively small compared with the thoracic or lumbar regions and approximates the brain components 4. Incorrect needle advancement and drug injections can lead to catastrophic complications 5 6.…”

Comparative Effectiveness of Parasagittal Interlaminar and Transforaminal Cervical Epidural Steroid Injection in Patients with Cervical Radicular Pain: A Randomized Clinical Trial

“…In general, it has been suggested that TF ESI is more effective than IL ESI because the TF approach has the advantage of being able to place drugs directly to the site of pathology by targeting the posterior side of the intervertebral foramen, whereas in the IL approach, ventral epidural spread was found in only 28% of cases (26). However, in other studies, the cervical region has a narrower epidural space than the lumbar spine (27), and thus the drug spreads well to the ventral epidural space, which is mainly the site of the lesion. Therefore the factor that the drug spreads to the anterior epidural space is strongly related to the dose of the drug (28).…”