For patients with unilateral and/or radicular symptoms, a transforaminal approach is often used. The patient is placed in a prone position on the fluoroscopy table, and the skin is marked with the C-arm oriented posterolaterally. The lateral angle is greater than that used for the interlaminar technique, generally 30 to 45° from the midline. Additionally, caudal angulation allows visualization of the undersurface of the pedicle above the target foramen. Using a slightly caudal angle to project the undersurface of the pedicle above the foramen will facilitate accurate needle placement. A spinal needle is then advanced to the undersurface of the pedicle, slightly medial to the center of the pedicle (Figure 9.3). Following negative aspiration for CSF, 4 to 5 mL of contrast is injected. This typically results in opacification of the proximal nerve sheath, with reflux of contrast into the adjacent epidural space (Figure 9.4). After fluoroscopic evaluation and filming, 2 to 3 mL of water-soluble steroid mixture, mixed with 3 to 5 mL of local anesthetic, is injected. Mixing the therapeutic agents provides early delivery of the local anesthetic to the (often sensitive) nerve and adjacent structures. Postinjection films are obtained to document dispersal of the injected materials. For a sacral foramen injection (typically S1), a c
dorsal approach is used, with the tube angled slightly cephalad and laterally to profile the sacral foramen (Figure 9.5). Lateral fluoroscopy may be used to assess the depth of the needle and to prevent inadvertent advancement into the presacral space.
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