An interlaminar approach may be used to perform cervical and thoracic epidural injections performed. The patient is placed in a prone position, and the skin is marked in a fashion similar to that used for lumbar injections. The author uses an epidural needle for these injections because of the small caliber of the epidural space and the proximity of the underlying cord, which is only a few millimeters from the intended injection site. Because the needle has a tapered tip, there is lower likelihood of causing inadvertent dural puncture. The needle is placed after initial skin puncture with an 18-gauge introducer needle and advanced in a rostral and medial fashion toward the midline interlaminar gap, under intermittent fluoroscopic observation (Figure 9.6). Again, contact with the lamina subjacent to the interlaminar gap provides depth control, which is extremely important given the underlying anatomy. After contact with the superior aspect of the lamina, the needle is retracted 3 to 4 mm and guided over the lamina toward the midline. Confirmation of needle positioning can be obtained with both oblique views, in addition to the AP view. The contralateral oblique view allows visualization of the needle as it passes over the lamina into the spinal canal (Figure 9.7). After needle placement, 4 to 5 mL of contrast is injected, followed by anterior and lateral (or steep oblique) filming to document dispersal within the epidural space (Figure 9.8). After this, 2 to 3 mL of steroid solution is injected.
We do not inject local anesthetic into the cervical or upper thoracic epidural spaces because it could result in the complication of high cervical anesthesia and potential respiratory suppression. Cervical epidural injections are safest at the C7-T1 level, where the dorsal epidural space is most capacious. The injected materials typically will migrate cephalad into the cervical epidural compartment, as demonstrated by the distribution of contrast media.
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