Lumbar Interlaminar Epidural Steroid Injection: Paramedian Approach

Abstract

Lumbar interlaminar epidural injections are commonly performed for a variety of spinal pain disorders. They are specifically indicated for radicular symptoms with or without axial pain experienced because of a lumbosacral etiology. Because the injectate disperses over a larger area with interlaminar epidural injection than with transforaminal injection, this type of injection is typically used for bilateral or multilevel symptoms.

Keywords

contralateral oblique, disc herniation, epidural injection, interlaminar, lumbar, radiculopathy, spinal stenosis, spinolaminar line, ventral interlaminar line

Note: Please see pages ii , iii for a list of anatomic terms/abbreviations used throughout this book.

Lumbar interlaminar epidural injections are commonly performed for a variety of spinal pain disorders. They are specifically indicated for radicular symptoms with or without axial pain experienced because of a lumbosacral etiology. Because the injectate disperses over a larger area with interlaminar epidural injection than with transforaminal injection, this type of injection is typically used for bilateral or multilevel symptoms.

With the approach described here, the needle is placed with the use of a trajectory view and advanced with the use of multiplanar imaging, with emphasis on safely using the contralateral oblique (CLO) and/or lateral view to confirm the depth by visualizing the ventral interlaminar line (VILL) or spinolaminar line, respectively.

The CLO view is preferable to the lateral view in advancing the needle to gain access to the interlaminar space. The role of the CLO view is especially preferable to the lateral view, as discussed in Chapter 3 .

Because depth is assessed with one of these “safety views,” it is not necessary to use the “step-off lamina” technique. Once the needle tip location is confirmed with multiplanar imaging, the epidural space is accessed by advancing the needle through the ligamentum flavum using the classic loss-of-resistance technique. The loss-of-resistance technique requires the presence of the ligamentum flavum to identify the epidural space. The postlaminectomy absence of the ligamentum flavum would prevent accurate localization of the epidural space and increase the likelihood of an intrathecal injection. Also, the presence of spondylolisthesis and severe central spinal stenosis will increase the risk of intrathecal injection. In these settings, an alternate route of delivery of the injectate should be considered (transforaminal, caudal with/without catheter, or interlaminar at a nonsurgical level above or below the requested injection level).

For patients with predominantly unilateral or asymmetric pain, the injectate is targeted toward the symptomatic side. In the case of a unilateral dye pattern, in a patient with bilateral symptoms, consider adjusting the needle tip position to the other side as well for bilateral epidural space injectate coverage.

We include a discussion, table, and examples of epidural, subdural, and intrathecal flow to help delineate them. More flow patterns are also available in the Myelography chapter (14) .

Trajectory View

Confirm the level (with the anteroposterior view).

The image intensifier is tilted caudally to open up the target interlaminar space and facilitate easier entry between two adjacent laminae ( Fig. 12.1 ).

The C-arm is then obliqued approximately 5 to 10 degrees toward the more symptomatic side (i.e., the left side, in this case). This angle is used for entry, and the needle should be aimed between the laminae on either side of the space between the superior and inferior spinous processes (i.e., midline).

Because this is the trajectory view, the needle should be placed parallel to the fluoroscopic beam.

Notes on Positioning in the Trajectory View

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With this approach, the needle tip is placed between the laminae instead of “walking off” the lamina.
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The caudal tilt is used to optimally open up the interlaminar space (and not to optimally line up the end plates). Caudal tilt also establishes an ideal trajectory angle to enter between the adjacent lamina.

There are typically no other radiolucent structures that are safety considerations in this trajectory view besides advancing the needle too far ventrally. Please use the other views for needle advancement to best visualize the corresponding landmarks.

Optimal Needle Position in Multiplanar Imaging

Optimal Needle Positioning in the Anteroposterior View ( Fig. 12.2 )

After placing the needle in the trajectory view, oblique the C-arm back to a “true” anteroposterior view.

Notes on Anteroposterior View

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This view should be used to assess only mediolateral and superoinferior needle positions; it should not be used for any substantial ventral needle advancement.
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Ideally, place the needle tip on the more symptomatic side of the patient.

There are typically no other radiolucent structures that are safety considerations in this view, other than advancing the needle too far ventrally. Please use the other views for needle advancement to best visualize the corresponding landmarks.