Chapter 22 Thoracic Interlaminar Epidural Steroid Injection, Paramedian Approach

Thoracic interlaminar epidural steroid injections are indicated more commonly for radiculopathy caused by a disc protrusion or by stenosis of the central canal, the intervertebral foramen, or lateral recess. These injections can also be used less commonly for the treatment of radiculopathy as a result of degenerative disc disease, compression fractures, acute herpes zoster, or postherpetic neuralgia.

Thoracic interlaminar epidural steroid injections are typically performed with the use of a paramedian approach. As a result of the steep and oblique angulation of the overlapping thoracic spinous processes, it is difficult to perform a median (midline) technique, particularly at the mid to upper thoracic levels. The paramedian approach in the thoracic spine allows the physician to “work around” and thus avoid the spinous processes when placing the needle tip in the interlaminar space.

A spinal needle can be used as a marker with the tip making contact with the superior lamina of the targeted interlaminar space in the AP view as long as the laminar bone is visible. The thoracic epidural is performed with the “marker” so that there is no mistaking the level of injection when maneuvering the fluoroscope from the anteroposterior (AP) position to the caudally tilted trajectory view. The epidural needle is placed with the use of a paramedian trajectory view using fluoroscopic imaging and confirming the needle tip’s position and depth via the AP, lateral, and contralateral oblique views.

For thoracic interlaminar epidural injections, advancing the epidural needle in the lateral or contralateral oblique view provides a safe approach into the epidural space not offered by traditional AP only views. The contralateral oblique view allows for an alternative approach to the interlaminar space when it is otherwise not evident with AP imaging (see Chapter 3). This technique identifies the interlaminar space by optimizing the visualization of the laminae that border the space. This is accomplished via the radiologic superimposition of the laminar structures at an oblique angle, which produces an elliptical appearance of the laminae. The interlaminar space is easily identified in between the elliptical-appearing cranial and caudal laminae. The epidural needle is advanced through the space and beyond the spinolaminar line to engage the ligamentum flavum. The epidural space is then identified after the use of a loss-of-resistance technique with air, saline, air and saline, or the hanging drop technique. The use of saline is preferred to an “air only” technique in order to avoid a seizure or cord compression from an inadvertent subarachnoid injection of air.

Note: Please see page ii for a list of anatomical terms/abbreviations used in this book.

Trajectory View (Figure 22–1)

Figure 22–1 A, Fluoroscopic image of a trajectory view with the epidural needle positioned at the thoracic interlaminar space along with the spinal needle marker. Left paramedian approach, T7-T8. Note that the fluoroscopic beam is parallel to the epidural needle. Also note that the angle of the spinal needle used to mark the T7 level. B, Radiopaque structures, trajectory view. C, Radiolucent structures, trajectory view.

Notes on Positioning in the Trajectory View

With this approach, the needle is not “walked off” of the lamina. Rather, the needle is advanced safely and efficiently with the use of multiplanar imaging until it reaches the spinolaminar line.

The needle tip is directed as close as possible to the midline to avoid the epidural veins.

The needle should not be advanced too far ventrally in this view. We recommend observing the safety considerations demonstrated in other views. There are no consistent radiolucent safety considerations in this trajectory view.

The injection level is confirmed with the AP view.

The fluoroscope is then tilted cranial or caudad to maximize the interlaminar space and to allow for needle placement between the overlapping laminae and spinous processes.

The fluoroscope is then obliqued approximately 5 degrees toward the more symptomatic side (or either side for symmetric pain).

The needle is placed parallel to the fluoroscopic beam with the use of this trajectory approach.

Related posts:

Atlantoaxial Joint Intraarticular Injection Lumbar Zygapophysial Joint Nerve (Medial Branch) Radiofrequency Neurotomy, Posterior Approach Thoracic Zygapophysial Joint Intraarticular Injection, Posterior Approach Thoracic Zygapophysial Joint Nerve (Medial Branch) Radiofrequency Neurotomy, Posterior Approach Lumbar Interlaminar Epidural Steroid Injection, Paramedian Approach Cervical Discography/Disc Access

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