Lumbar interlaminar epidural injection

Lumbar interlaminar epidural injections are one of some possible spinal epidural injections. For an alternative approach for the same region, please refer to the article on lumbar transforaminal epidural injections. 

Indications

Typically, epidural injections are performed in patients with radicular pain who are currently not surgical candidates. 

Contraindications

Allergy to any of the planned medications is a contraindication. Although it is possible to perform the procedure without contrast, provided consent includes the increased risk of intravascular or intradural injection. 

Local or systemic infection is also a contraindication.

Diabetic patients demand caution due to the administration of steroids, but they are not contraindicated. 

Procedure

Positioning/room set-up

The patient is placed prone on the fluoroscopy table, and the lower lumbar region is exposed. Positioning a pillow under the abdomen helps to open the spinous processes and facilitates the procedure; sometimes an extra pillow is necessary. 

Equipment

• alcohol or iodine (or both) containing skin preparation

• fenestrated or chuck-drapes

• 22-gauge (25-gauge is an alternative), 9-10 cm (3.5 inches) spinal needle

• isotonic contrast, e.g. 240 mg/mL iohexol

• local anesthetic, e.g. 1% lignocaine/lidocaine

• steroid, e.g. dexamethasone (non-particulate), betamethasone sodium phosphate, betamethasone acetate suspension

• long-acting local anesthetic, e.g. bupivacaine

• dressing

Technique

• plan the procedure using, when possible, previous CT/MRI exams

• after patient positioning, select the access entry and demarcate it on the skin

  • this technique uses a midline approach between the spinous processes aiming a path through the interspinous ligament, targeting the posterior spinous space

  • on the AP view, select the upper portion of the inferior spinous process as the entrance point 

  • if the spinous processes do not allow the needle insertion in a midline approach, a parasagittal approach is an alternative

• skin preparation and drapes placement

• introduce the needle until it crosses the posterior margin of the facets (under lateral fluoroscopy view)

• proceed with short further advancements (~1 mm) using the "air release technique" to check the resistance until the needle reaches the posterior epidural space (the injection of puffs of air outside the epidural space will cause the plunge to bounce back, this resistance ceases when the needle is inside the epidural space)

• confirm the posterior epidural space with a few mL of contrast injections (optional)

• inject the therapeutic mixture

  • 2 mL of prednisolone acetate (hydrocortancyl 2.5%)

  • note: betamethasone is contraindicated for epidural injections

Postprocedural care

As with other epidural injections, recovery in the department for 20-30 minutes minimum is recommended, as a proportion of patients will experience transient numbness, weakness or loss of proprioception, making ambulation difficult and dangerous. 

Complications

As with all epidural spinal injections, care should be taken to confirm

• extradural location - to avoid intradural injection with resultant adhesive arachnoiditis.

• intravascular location - to avoid spinal cord infarction

A low-pressure headache can also result from dural puncture (subarachnoid tap). 

Post-procedure infection is rare.