Injectate Volumes Needed to Reach Specific Landmarks in Lumbar TFEs

[ampaphb]

---

Members do not see this ad.

Injectate Volumes Needed to Reach Specific Landmarks in Lumbar Transforaminal Epidural Injections.
Furman MB, Mehta AR, Kim RE, Simon JI, Patel R, Lee TS, Reeves RS.
PM R. 2010 Jul;2(7):625-635.

OBJECTIVES: To identify the volumes of contrast material needed to reach specific landmarks during lumbar transforaminal epidural injections (L-TFEIs).

DESIGN: Prospective, nonrandomized, observational human study.

SETTING: Academic/private pain management practice. PATIENTS: Sixty-nine patients undergoing L-TFEIs were investigated. Sixty patients were included in this study.

INTERVENTIONS: L-TFEIs were performed with the use of contrast-enhanced fluoroscopic visualization.

MAIN OUTCOME MEASUREMENTS: After the appropriate spinal needle position was confirmed, up to 5.0 mL of nonionic contrast material was slowly injected. Under biplanar fluoroscopic guidance, contrast volumes were recorded as flow reached specific anatomic landmarks: ipsilateral neural foramen, ipsilateral disks superior and inferior to the injected level, and across the midline of the spinous process.

RESULTS: After 1.1 mL of contrast was injected, 100% of L-TFEIs spread to the medial aspect of the superior pedicle (PED) of the corresponding level of injection. After 2.8 mL of contrast was injected, 95% of L-TFEIs spread to the superior aspect of the superior intervertebral disk (IVD) of the corresponding level of injection. After 3.6 mL of contrast was injected, 95% of L-TFEIs spread to the inferior aspect of the inferior IVD of the corresponding level of injection. After 3 mL of contrast was injected, 88% of L-TFEIs spread to cover both the superior and inferior IVDs of the corresponding level of injection. After 4 mL of contrast was injected, 93% of L-TFEIs spread to cover both the superior and inferior IVDs of the corresponding injection. After 4 ml of contrast was injected, 55% of L-TFEIs spread beyond the midline of the spinous process, but barely.

CONCLUSION: This study demonstrates injectate volumes needed to reach specific anatomic landmarks in L-TFEIs. A volume of 4.0 mL of injectate reaches both the superior aspect of the superior IVD and the inferior aspect of the inferior IVD 93% of the time.​

While interesting, my question is, do I care? A more useful study (albeit far more time consuming) would have re-imaged the patient 45 minutes post procedure, once they had been upright and active, to see where the dye ultimately spread. Supine imaging has minimal clinical relevance, IMHO

 

[lobelsteve]

Injectate Volumes Needed to Reach Specific Landmarks in Lumbar Transforaminal Epidural Injections.
Furman MB, Mehta AR, Kim RE, Simon JI, Patel R, Lee TS, Reeves RS.
PM R. 2010 Jul;2(7):625-635.

OBJECTIVES: To identify the volumes of contrast material needed to reach specific landmarks during lumbar transforaminal epidural injections (L-TFEIs).

DESIGN: Prospective, nonrandomized, observational human study.

SETTING: Academic/private pain management practice. PATIENTS: Sixty-nine patients undergoing L-TFEIs were investigated. Sixty patients were included in this study.

INTERVENTIONS: L-TFEIs were performed with the use of contrast-enhanced fluoroscopic visualization.

MAIN OUTCOME MEASUREMENTS: After the appropriate spinal needle position was confirmed, up to 5.0 mL of nonionic contrast material was slowly injected. Under biplanar fluoroscopic guidance, contrast volumes were recorded as flow reached specific anatomic landmarks: ipsilateral neural foramen, ipsilateral disks superior and inferior to the injected level, and across the midline of the spinous process.

RESULTS: After 1.1 mL of contrast was injected, 100% of L-TFEIs spread to the medial aspect of the superior pedicle (PED) of the corresponding level of injection. After 2.8 mL of contrast was injected, 95% of L-TFEIs spread to the superior aspect of the superior intervertebral disk (IVD) of the corresponding level of injection. After 3.6 mL of contrast was injected, 95% of L-TFEIs spread to the inferior aspect of the inferior IVD of the corresponding level of injection. After 3 mL of contrast was injected, 88% of L-TFEIs spread to cover both the superior and inferior IVDs of the corresponding level of injection. After 4 mL of contrast was injected, 93% of L-TFEIs spread to cover both the superior and inferior IVDs of the corresponding injection. After 4 ml of contrast was injected, 55% of L-TFEIs spread beyond the midline of the spinous process, but barely.

CONCLUSION: This study demonstrates injectate volumes needed to reach specific anatomic landmarks in L-TFEIs. A volume of 4.0 mL of injectate reaches both the superior aspect of the superior IVD and the inferior aspect of the inferior IVD 93% of the time.​

While interesting, my question is, do I care? A more useful study (albeit far more time consuming) would have re-imaged the patient 45 minutes post procedure, once they had been upright and active, to see where the dye ultimately spread. Supine imaging has minimal clinical relevance, IMHO

So repeat the study with the following protocol:

Consecutive L5 TFESI with your volume of injectate and AP/Lat at time of injection, then AP/Lat plain films at 1 hour. Only cost would be additional Xrays and some patient time.

 

[Mister Mxyzptlk]

I doubt a followup picture would work. The contrast is usually gone by then. There is a radiology group here that proves that all the time. They do postop CT scans after ESIs and then dictate a report that they didn't see any contrast. That's how fast it's gone.

What I would do is use radioisotopes. Figure out how much isotope you'd need to inject to be visible with local injection (my guess is not very much) and use something that won't be absorbed right away (colloidal sulfur?). Then do a nuclear scan postop.

What the cited study shows is the MINIMUM spread, for at least two reasons:

1. The leading edge of the contrast can't be seen. At some point the layer is so thin it blends in with the soft tissues.

2. There might be spread after injection, as already discussed.

Something like I've outlined above with a delayed scan would give you LATE spread.