Transforaminal Epidural Block - Indications, Contraindications, Procedure and Complications

Introduction

When the intervertebral disc in the spine degenerates, it can cause irritation or inflammation of the nearby spinal nerve, resulting in one-sided radicular pain (pain radiating down the leg). There are various treatment options for this type of pain, ranging from conservative methods like medications and physiotherapy to more invasive surgical procedures. An epidural injection is a pain relief treatment that can be used for chronic neck, back, or radiating pain. The 'transforaminal' refers to how the needles are positioned during the procedure. These injections can help reduce pain, improve the ability to move, and may even prevent or delay the need for surgery. One widely accepted and minimally invasive technique is the Transforaminal Epidural Block (TEB), which aims to alleviate radicular pain.

What Is a Transforaminal Epidural Block?

A Transforaminal epidural block (TFEB) is a medical procedure where a particular medicine mixture is injected near the spinal nerves to treat pain. The injected medicine spreads around the nerves and helps reduce inflammation and stabilize overactive pain signals from the spine. This procedure can be helpful for various types of back pain and related issues. The medicine used can be a combination of pain-numbing drugs and sometimes steroids. Overall, it aims to target the area where the pain originates and provide relief.

What Are the Indications of Transforaminal Epidural Block (TFEB)?

TFEB is recommended for the following situations:

• Treating back pain caused by wear and tear or injuries in the spine without the need for surgery.

• Addressing pain that occurs after surgery due to scarring around the nerves.

• Managing pain that originates from the nerves when not treatable surgical problem is found.

• Providing pain relief when urgent surgery is not suitable or recommended due to medical reasons.

• Helping with pain from post-herpetic neuralgia, which occurs after shingles.

• Alleviating discomfort in spinal stenosis, especially when the narrowing affects the openings where nerves exit the spine.

• Sometimes used for pain related to spinal discs.

• Relieving postoperative back pain when other approaches are not feasible for specific anatomical reasons.

What Is the Procedure of Transforaminal Epidural Injection?

Trans-foraminal injections can be performed in three different ways:

• Sub-pedicular (SP).

• Retro-neural (RN).

• Retro-discal (RD).

The most commonly used method is the SP technique, where the needle is inserted just below the pedicle in a safe triangle area. In the RN approach, the target area is more towards the back of the spinal foramen, while in the RD approach, the needle is placed at the bottom of the foramen, closest to the irritated nerve root. The controversy lies in whether the medication should be given before or after reaching the nerve ganglion. Conventionally, the drug is administered around the affected nerve root. However, delivering the medicine to the area above the disc (preganglionic approach) might be necessary in specific cases for better results.

The fluoroscopic SP approach is commonly used, where the patient lies face down on a unique table, and the needle is carefully placed in the safe triangle area. A contrast dye is injected to confirm the needle's position and ensure it is in the right place. The medication, a combination of local anesthetic and steroid, is injected into the foramen. The pattern of dye distribution after the injection, called a radiculogram, helps determine if the medication has reached the desired area. Different patterns indicate different outcomes and potential risks. The spread of the dye depends on the volume of the injection. Overall, trans-foraminal injections are a specific technique to target and alleviate pain in certain spinal conditions, and the choice of approach may vary depending on the individual case.

What Are the Complications of the Transforaminal Epidural Block?

While trans-foraminal epidural injections are generally considered safe, there have been rare severe complications. These complications include nerve or blood vessel injuries, unintended spreading of medication, and infections. The most dangerous complication is spinal cord infarction, which can lead to paralysis in some cases. Various factors can cause these major issues:

• Particles from the injected steroids can block blood vessels, leading to vascular problems.

• The "safe triangle" where the injection is usually placed may contain blood vessels, which, if injured, can cause spinal cord problems.

• The needle placement may cause temporary narrowing of blood vessels (vasospasm).

• Patients taking blood-thinning medications may develop epidural hematomas and nerve-related issues.

• Pain near the area of needle insertion. Pain can be managed and treated by using ice and mild analgesics.

• Infection in the area of the injection site.

• Bleeding in the area of the injection site.

Steroids used in the injections can have side effects, although they are rare. These side effects may affect the adrenal gland, bones, muscles, weight, and blood sugar levels. Additionally, imaging guidance during these procedures exposes patients and medical personnel to radiation. While this can be helpful, it is essential to be aware of the potential risks and consider them before undergoing the procedure.

Other risk factors include:

• Diabetes.

• Pregnancy.

• Allergy to local anesthetic, contrast dyes, or iodine.

• Taking medication for some conditions.

• Severe medical conditions like nerve damage, stroke, paralysis, and death.

What Are the Contraindications of the Transforaminal Epidural Block?

• Patient Refusal: If the patient does not want to undergo the procedure, it will not be done.

• Coagulopathy: When the blood's ability to clot is impaired, it can increase the risk of bleeding during the injection.

• Allergy to injections: If the patient is allergic to the medications used, it should be avoided.

• Therapeutic Anticoagulation: If the patient takes medications to prevent clotting, stopping them before the procedure is essential to reduce bleeding risk.

• Skin Infection at the Injection Site: If there is an infection on the skin where the injection is planned, it must be treated before the procedure.

• Raised Intracranial Pressure: High pressure in the skull can lead to complications during the injection.

• Uncorrected Severe Hypovolemia: The procedure may be unsafe if the patient has significant dehydration or low blood volume.

• Pregnancy: The injection is not recommended for pregnant women.

• Motor Deficit: If there is muscle weakness, it may not be suitable for the procedure.

• Medullar Cone Symptoms: Symptoms related to the spinal cord's lower part might be a concern, and the injection could be avoided.

Conclusion

The effectiveness and duration of pain relief from the injection may vary depending on the level of inflammation in the disc, dura, or nerve root. Other factors can also contribute to the pain. Sometimes, the injection can relieve for several weeks to several months, but further treatment may be necessary afterward. In some cases, a single injection can bring long-lasting pain relief. The technique for a diagnostic injection will be similar, except that corticosteroids will not be used. The anesthetic will numb the area, and if the patient feels alleviated, the needle was correctly put in the problematic area. This aids in determining the precise source of the discomfort.