What is an Epidurogram?

Epidural injections—injections of medication into the epidural space of the spine—are used in several contexts in medicine. For example, epidural glucocorticoid injections have long been utilized for managing pain in patients suffering from radiculopathy, spinal stenosis, and nonspecific low back pain. A needle is inserted between the ligamentum flavum and the dura. An epidural injection can be carried out through various approaches, including the translaminar, transforaminal, or caudal routes, and is typically performed by specialized medical professionals like anesthesiologists, physiatrists, or interventional radiologists. Accurate delivery of the medication to the intended site is critical for efficacy and safety. Physicians may use an epidurogram to visualize the target site and improve injection accuracy.

Traditionally, epidural injections were done using a blind technique without real-time imaging guidance. Though proper training greatly reduces risk, it is still possible to have incorrect needle placement and inadvertent injection into unintended areas such as the subarachnoid space. Studies have shown that even skilled practitioners had inaccurate needle placement rates of 25% to 30% with blind techniques, leading to concerns regarding safety and efficacy. The potential complications of misplacement, including adhesive arachnoiditis, underscore the importance of accurate delivery.

In response to these concerns, there has been an increase in the usage of fluoroscopic guidance and an epidurogram, which involves injecting contrast material under fluoroscopy to visualize the epidural space before administering the medication. This approach significantly reduces the risk of misplacement and associated complications. It allows practitioners to confirm accurate needle placement within the epidural space, minimizing the risk of intrathecal injections and their potential consequences.

The epidurogram has improved the safety and efficacy of epidural injections. By visualizing the dispersion of contrast dye, practitioners can ensure the needle is correctly positioned in the epidural space. Understanding the patterns of contrast spread after obtaining images is essential in determining the placement of an epidural catheter. In the epidural space, the dye should spread circumferentially and along nerve sheaths, creating a ‘wraparound’ pattern, or partially disperse in a ‘honeycomb’ pattern within epidural fat. Malpositioned catheters in the subdural or subarachnoid spaces show different patterns. Subarachnoid injections fill the intrathecal space extensively, while subdural injections only opacify dural margins.

While an epidurogram is generally safe, there are potential side effects, including facial flushing, low-grade fevers, hiccups, insomnia, headaches, water retention, increased appetite, increased heart rate, and abdominal cramping or bloating. However, these side effects are rare and typically resolve within a few days.

Epidural injections are a valuable tool for managing pain in patients in certain situations. The use of fluoroscopic guidance and an epidurogram has significantly improved the safety and efficacy of these injections, ensuring accurate delivery of medications to the intended site and minimizing the risk of complications.

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