Epidural Steroid Injections

Epidural steroid injections (ESIs) are a common treatment option for the treatment of sciatica, herniated or bulging discs, spinal stenosis, spondylolithesis and pinched nerve in the neck causing arm pain. They have been used for sciatica since the early 1950’s and are still an integral part of the non-surgical management of sciatica or radiculopathy.

Epidurals are performed with the primary goal of relieving buttock and leg pain, but back pain if present might also be reduced or eliminated. Epidurals are generally not done for back pain alone. The injection itself may be sufficient to provide relief, but commonly an ESI is used in conjunction with a comprehensive rehabilitation program to provide additional benefit with respect to discomfort and improvement in function.

The effects of the injection may be temporary or permanent. An epidural can be very beneficial for a patient during an acute episode of sciatica symptoms and also for some specific chronic pain situations. In a comprehensive pain management program an ESI can provide enough pain reduction to allow a person to progress with an exercise program. After the initial injection, the patient is seen back in the office in 10-14 days to determine its effectiveness. Additional injections may be necessary if substantial pain improvement is not provided.

A person may receive up to three epidurals over a 6-8 week time with diabetics them a little bit more spaced out. Up to four ESI’s can be performed in a 12 month period of time. With that said, there is, however, no consensus in the medical community as to the maximum number of injections per year as it has never been studied. The number four in 12 months is a Medicare guideline. As to patients receiving a series of three epidurals there is no science to this and in fact, all major pain societies recommend one at a time and then reevaluate. Some insurance carriers will not approve a second injection unless the patient has received at least a 50% reduction in pain by two weeks. I wrote a blog on this very topic entitled “Why Do I Need a Series of Epidurals.”

ESI’s can also be performed in the neck or cervical region to relieve neck and arm pain or in the mid back or thoracic spine.There are two ways to direct medication to the epidural space, an inter-laminar approach or one that is transforaminal, or into the nerve root hole. The latter used to be known as a selective nerve root block (SNRB) because medication is placed very close to a selected spinal nerve root that may be inflamed and painful. The terminology now is a transforaminal epidural (TFE). As compared to a TFE, larger volumes are used in the interlaminar approach in order to cover many nerve root levels in the spine. TFEs use smaller volumes of more concentrated medication placed on the nerve root sleeve. TFEs can be used for both diagnostic and therapeutic purposes. During the procedure one, two or three spinal nerve roots can be treated.

Selective nerve root blocks or transforaminal epidurals can be performed in both the lower back (lumbar) and neck (cervical).

drawing of interlaminar epidural
Drawing of the epidural space

What is the epidural space?

The membrane that covers the spinal cord and nerve roots in the spine is called the dura membrane. The space surrounding the dura is the epidural space. Nerves travel through the epidural space to the back and into the legs. Inflammation of these nerve roots may cause pain in these regions due to irritation from a damaged disc or from contract in some way with the bony structure of the spine.

What is an epidural and why is it helpful?

An epidural injection places anti-inflammatory medicine (corticosteroids – cortisone) into the epidural space to decrease inflammation of the nerve roots, hopefully reducing the pain in the back and legs. The epidural injection may help with healing by reducing inflammation. It may provide permanent relief or provide a period of pain relief for several months while the injury/cause of pain is healing.

Potential Risks

As with all invasive medical procedures, there are potential risks associated with lumbar epidural steroid injections. In addition to temporary numbness of an extremity, the most common potential risks and complications include:

  • Infection – Severe infections are rare, occurring in 0.1% to 0.01% of injections.
  • Dural puncture (“wet tap”) – A dural puncture occurs in 0.5% of injections. It may cause a post-dural puncture headache (also called a spinal headache) that usually improves within a few days. Although infrequent, a blood patch may be necessary to alleviate the headache. A blood patch is a simple, quick procedure that involves obtaining a small amount of blood from an arm vein and immediately injecting it into the epidural space to allow it to clot around the spinal sac and stop the leak. These are even less common with the transforaminal approach.
  • Bleeding – Bleeding is a rare complication and is more common for patients with underlying bleeding disorder. Those on blood thinners must stop them before the procedure. Please see pre-injection instructions for additional information.
  • Nerve injury – While extremely uncommon, nerve damage can occur from direct trauma from the needle, or from infection or bleeding.
  • There have been reports in the medical literature of very rare complications from epidural steroid injections in the neck that include stroke, paralysis, vision loss and death. These complications have been associated with certain medications injected and the incorrect place of the medication. The choice of cortisone (steroid), the use of fluoroscopy (x-ray) and other precautions are taken to greatly minimize the risk. The FDA recommends only the use of a water soluble steroid (dexamethasone) when performing cervical transforaminal epidurals.

Potential Side Effects of Steroids

All corticosteroids have potential side effects. These tend to range from uncommon to rare but can occur and you need to be aware of them. They are usually much less prevalent than the side effects from taking oral steroids.

  • Facial flushing
  • Headache
  • Anxiety
  • Depression
  • Insomnia
  • Fatigue
  • Fluid retention
  • Elevated blood pressure
  • Fever the night of injection
  • Elevated blood sugar for 2-3 days- diabetics need to monitor their blood sugars closely
  • A transient decrease in immunity because of the suppressive effect of the steroid
  • Heartburn/stomach ulcers
  • Severe arthritis of the hips (avascular necrosis)
  • Post-injection flare – an increase in pain that can occur several hours after the injection and can last for several days