Lumbar Back Pain Diagnosis and Spinal Injections

Part 1 of 3: Accurate diagnosis key to selecting the appropriate spinal injection

Question: There are different types of spinal injections to treat back pain. How do you, a pain medicine physician, determine the type of injection for a patient’s pain?

Answer: In my practice, a history and careful neurological examination usually gives me a good idea of the source of a given patient’s back pain. There are patterns of low back pain into which certain spinal disorders (or diseases) fall.
Man with Low back pain, area highlighted in redFor example, abrupt onset of severe low back pain that is accompanied by abnormal sensations that radiate down one leg (both legs is less common) is called radicular. Abnormal sensations (called paresthesias) are sometimes described as feelings of numbness, tingling, electric-like pain, and may include leg weakness. Radicular pain and paresthesias usually involve a single spinal nerve rootlet. This nerve rootlet may be compressed, impinged or chemically injured by a herniated disc fragment, facet joint cyst, or arthritic bone spur.

Diagnostic Imaging Confirm Pain Source
Plain x-rays and/or MRI scans can help reveal the target source of back pain, such as a disc herniation. The pain management physician should read and interpret the imaging studies himself/herself and not simply rely on the report. Diagnostic spinal images are compared to the patient’s low back and/or leg pain and symptoms to confirm an accurate diagnosis. Thereafter, an appropriate treatment plan for the patient is recommended. The treatment plan may include one or two epidural steroid injections to help reduce inflammation and pain.

About Spinal Epidural Injections
An epidural injection involves injecting a steroid medication (strong anti-inflammatory) from the back (posterior) spine. In Figure 1 you see a Tuohy needle placed through the yellow ligament using a translaminar approach at the level of a disc herniation in a model of a spine.

In this figure (below), the needle is passed through (trans) the yellow ligament, in between the spine’s lamina, below and above. There is nearly always a large enough space between the bony lamina to admit an epidural needle. The lamina are the bones in the back of the vertebra that cover and protect the spinal cord and nerve rootlets.

spinal needle guided into the lumbar (low back) for an epidural steroid injectionFigure 1An alternative technique some physicians favor is reaching the same epidural space through the side of the vertebrae—through the hole through which the spinal nerves emerge called the neuroforamen. Using this transforaminal approach (through the neuroforamen), a spinal needle is carefully inserted into the neuroforamen.  See Figure 2. During a transforaminal epidural injection, the steroid medication is injected around the nerve rootlet exiting the spinal canal.

picture of a transforaminal epidural steroid injectionFigure 2Whether the epidural injection is performed as a translaminar or transforaminal procedure depends the diagnosis and location how the nerve is compressed. Either procedure may be performed to treat other spinal disorders, such as lumbar (low back) spinal stenosis. Often, a patient requires a series of injections (up to 3) during a prescribed time period (eg, one year).

Click below to read the related blogs by Dr. Kamhi:
Part 2: Lumbar Facet Joint Pain and Spinal Injections

Part 3: Sacroiliac Joint Pain and Spinal Injections