Thoracic Interlaminar Epidural Steroid Injection: Paramedian Approach




Abstract


Thoracic interlaminar epidural steroid injections are indicated more commonly for radiculopathy caused by a disc protrusion or stenosis of the central canal, 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.




Keywords

epidural steroid injection, fluoroscopy, Hernicated nucleus puplosis, infraneural, interlaminar, radiculopathy, spinal stenosis, Thoracic

 



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


Thoracic interlaminar epidural steroid injections are indicated more commonly for radiculopathy caused by a disc protrusion or stenosis of the central canal, 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 using a paramedian approach. As a result of the significant caudad 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 in contact with the superior lamina of the targeted interlaminar space in the anteroposterior (AP) view as long as the laminar bone is visible. The thoracic interlaminar epidural injection is performed with the “marker” so that there is no mistaking the level of injection when maneuvering the fluoroscope from the AP view 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 position and depth of the needle tip via the AP, lateral, and contralateral oblique (CLO) views.


For thoracic interlaminar epidural injections, advancing the epidural needle in the lateral or CLO view provides a safe approach into the epidural space, which is not offered by traditional AP only views. The CLO view enables visualization of the angle of the interlaminar space that is otherwise not evident with the AP or lateral view (see Chapter 3 ). This technique identifies the interlaminar space by optimizing the visualization of the laminae that border the space. The epidural needle is advanced through the space and beyond the ventral interlaminar line (VILL) to engage the ligamentum flavum. The epidural space is then identified after the use of a loss-of-resistance (a.k.a change 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 to avoid a seizure or cord compression from an inadvertent subarachnoid injection of air.




Trajectory View ( Fig. 20.1 )


The injection level is confirmed with AP view. A 25G spinal needle is advanced down the beam in AP view to contact the superior lamina (shown) or pedicle bordering the targeted interlaminar space. This marker needle is left in place.




Fig. 20.1


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 image intensifier has been caudally tilted and that the epidural needle enters parallel to the fluoroscopic beam. Also note that the C-arm tilt angle makes the spinal needle used to mark the T7 level appear to come from the top of the screen. B, Radiopaque structures, trajectory view. C, Radiolucent structures, trajectory view.


The fluoroscope is then tilted cephalad or caudad to maximize the interlaminar space and 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.



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 using multiplanar imaging until it reaches the VILL in the CLO view or the spinolaminar line in the lateral view.



  • 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.



Jan 27, 2019 | Posted by in RHEUMATOLOGY | Comments Off on Thoracic Interlaminar Epidural Steroid Injection: Paramedian Approach

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