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Background
Image-guided lumbar spine injections are increasingly popular interventions for pain management and diagnosis. They can be used to deliver steroids or nerve root blocks therapeutically, and contrast diagnostically. Recognition of improper technique and knowledge of pitfalls and challenges are essential for avoiding complications and developing correct injection technique.

Educational Goals / Teaching Points
This educational exhibit addresses the complications, pitfalls, and challenges surrounding myelography and transforaminal, interlaminar, and facet joint lumbar injections and can serve as a valuable reference for trainees learning these procedures.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Lumbar punctures and interlaminar injections have similar possible complications. Complications include pain, hemorrhage, headache, and infection. Intraprocedural complications include inadvertent dural puncture for interlaminar injections and extrathecal/mixed injections during myelograms. Difficulty accessing the intralaminar space and intravascular injection can occur during both procedures. These complications can be identified with characteristic contrast patterns; intravascular contrast agent follows a curved or linear pattern and dissipates after injection, whereas dural punctures can be identified by more rapidly dispersing contrast agent that accumulates in the ventral portion of the spinal canal rather than the dorsal epidural space. Transforaminal injections predominantly affect single nerves, best treating pain in the lateral recess or foraminal stenosis. Transforaminal injections and selective nerve root blocks can also aid in localization of symptoms during preoperative planning. The most common intraoperative complication is intravascular injection, and dural puncture is less common. The most common complications of facet joint injections are bleeding and intravascular injection. To avoid intravascular injection and more accurately deliver steroids, capsular recesses can be targeted to increase the likelihood of intraarticular needle placement, particularly when osteophytes or listhesis deform the joint. Patients can have allergies to iodinated contrast, and, in these settings, air and gadolinium-based contrast can serve as alternatives. These alternatives were especially important during the recent iodinated contrast shortage and allowed injections to continue while contrast was reserved for emergent studies. The Spine Intervention Society recommends against using gadolinium-based contrast when there is a risk of dural puncture, so we perform interlaminar injections under CT with air in patients with contrast allergy. We use gadolinium-based contrast for transforaminal and facet joint injections in patients with contrast allergy because dural puncture risk is low.

Conclusion
Image-guided lumbar spine injections for pain can provide near-immediate relief for some patients, and, for specific indications, CT myelography is an invaluable diagnostic tool. Technique and knowledge of pitfalls are essential for safe and effective completion of these procedures.