FORAMINAL  INJECTIONS

Injections of steroids into the lumbar epidural space are frequently used for low back and related radicular leg pains.

The traditional epidural injection technique involves the doctor feeling the patient’s spine in order to guide the placement of a needle between the spinal vertebrae. A newer technique involves using x-ray fluoroscopy to guide the needle directly to the neural foramen, the point where the affected spinal nerve root exits the spine. This is likely to increase the success of the procedure. A study in the Archives of Physical Medicine & Rehabilitation did give added support to this idea. 75% of the 69 patients treated with these more precisely placed injections demonstrated good long-term benefit.

We also have had good results with this refined epidural technique. For patients with nerve root pain involving one or two roots, fluoroscopically guided foraminal injections will prove to be superior to the approaches that do not use x-ray guidance. Epidurals in general, but especially foraminal injections, do not appear to be as effective if the pain is caused by widespread degenerative or arthritic problems in the spine.

Do epidural steroid injections work? Yes, if the problem is back and leg pain triggered lumbar disc herniations, and if fluoroscopy is used to guide the injection directly to the affected nerve roots.  The greatest opportunity to prevent nerve damage and symptoms occurs in the early phases of nerve root compression. This creates a clinical dilemma, however, since many patients often don't seek medical care for weeks or months after a disc herniation.

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From a diagrammatic standpoint the epidural space is highlighted with a green dot.  Note that the epidural space is separated from the subarachnoid space by the dura mater as well as the arachnoid membranes.  When a needle is used to deposit substances, such as steroids, in the epidural space the chemicals are separated from the subarachnoid space only by some thin membranes.

If inflammatory changes are produced in the epidural space by re-injection of materials this "space" can become obliterated.  Once the epidural space has been obliterated and further spinal injections at the site will then be directly into the subarachnoid space.