Transforaminal epidural steroid injection

Last revised by Henry Knipe on 20 Oct 2023

Transforaminal epidural steroid injections (TFESI), also known as transforaminal nerve root injections or nerve root blocks, are performed for the treatment and diagnosis of radicular pain. They differ from selective nerve root blocks (SNRB), as the aim is to get an "epidural spill" and get the injectate into the epidural space. TFESI are less selective than SNRBs, which are more accurate diagnostically. 

This procedure is commonly performed to diagnose and/or manage 3,6:

Reviewing past imaging should aid the practitioner in technique and equipment selection. Correlating the patient's history and examination with the imaging findings is key to ensuring the correct side, level and procedure type (e.g. epidural vs selective) is performed. 

Nonparticulate steroids (e.g. dexamethasone) are usually preferred over particulate steroids (e.g. triamcinolone, betamethasone) in TFESI (per United States of America's Food and Drug Administration) to reduce the risk of vascular complications such as spinal cord infarction 1, however, complications have been reported with both types of steroid 2,3 and one has not been shown to be safer than the other 6. Blunt-tip needles may also reduce vascular complication rates 3.

See spinal interventional procedures for further details.

Fluoroscopy and CT are the most common imaging guidance methods, and technique will depend on regional preferences, practitioner preference, equipment availability, and type of injection. However, an infraneural approach (below the nerve root) is recommended to reduce the risk of vascular complications 3. Procedural radiation dose is lower for CT than fluoroscopy (0.45 mSv vs 0.85 mSv) although the length of the planning CT scan can substantially increase the overall radiation dose 6.

Under CT guidance, the needle can be advanced to adjacent the lumbar nerve root or into the epidural space. In cervical or thoracic injections, the needle tip can be positioned on the lateral aspect of the facet joint as increased complication rates (e.g. cerebral/spinal cord infarcts) have been reported with intraformainal injections and good clinical outcomes are still reported with indirect injections 6.

Contrast can be injected to exclude an intravascular or intradural needle tip location 6. When contrast is injected, only a small volume (e.g. 0.5-1 mL iodinated contrast media) is needed, the pattern of contrast dispersion (e.g. focal non-linear, linear, tram-track) nor the location (e.g. extraforaminal, foraminal or in the lateral recess) has not been shown to influence clinical outcomes 2,4,6.

Once a satisfactory needle tip position is obtained, a mixture of anesthetic and/or can be injected depending if a diagnostic or diagnostict/herapeutic block is required 6.

Complications generally associated with spinal interventional procedures with TFESI-specific complications including 3:

  • transient, increased pain resolving without further intervention

  • spinal cord infarction, which can occur with particulate and non-particulate steroids; other mechanisms such as vasospasm or dissection proposed

  • numbness or weakness due to local anesthetic including Horner syndrome 5

Such injections are performed in order to give the patient pain relief, so then to enable them to undertake physiotherapy.  

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Cases and figures

  • Case 1: L5 TFESI (CT-guided)
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  • Case 2: lumbar TFESI (CT-guided)
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  • Case 3: C7 TFESI (CT-guided)
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  • Case 4: L5 TFESI (fluoroscopic guided)
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  • Case 5: L5 TFESI (fluoroscopic guided)
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  • Case 6: L5 TFESI (CT guided)
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  • Case 7: S1 TFESI (fluoroscopic guided)
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  • Case 8: intravascular needle tip in a S1 TFESI
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  • Case 9: bilateral L5 TFESI (CT guided)
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