Selective Nerve Root Block

Indications

The nerve root block is usually performed in patients who present with radiculopathy, also known as Sciatica. These patients present with pain radiating down from their back of buttocks, into their thigh and calf usually along the outer or the back of the thigh and leg.

The pain may go into the foot also. This pain may be associated with tingling or numbness. Most of these patients have disk herniation or degenerative stenosis with compression of the nerve root leading to symptoms.

The pathology of radiculopathy being inflammation around the nerve root caused due to pressure or pinching of the nerve root due to structures surrounding it, which may be either disk material or hypertrophied ligament of facet in the adjoining area.

The patients usually present with this pain on one side, though occasionally especially patients with lumbar canal stenosis may have bilateral symptoms.

Nerve root block leads to symptomatic pain relief, it may not be very helpful in tingling or numbness. The pain relief due to steroid injection happens due to the decrease in inflammation along the nerve root. The relief in pain gives time to the body to heal itself and take care of the inflammation thus leading to a long-term relief.

Patient may occasionally need repeated injections in the back. Occasionally selective nerve root block can be used as a diagnostic procedure to confirm the level of compression especially in patients with degenerative spine or multilevel stenosis or disk herniation.

Patients whose pain is relieved by the root block, but recurs later can be treated with decompression or diskectomy surgery depending on the presentation and pathology.

Patients with radiculopathy who either have failed conservative means which include medications, short period of rest and physical therapy are good candidate for selective nerve root block.

These patients usually undergo an x-ray and an MRI to confirm the level as well as rule out other causes of radiculopathy.

The Procedure

Selective nerve root blocks are performed in an operative suite. It is performed in a prone (lying on the belly) position and the patient is usually sedated. Local anesthesia is given and image intensifier or intraoperative X rays are used to direct the needle to the exact spot.

The location is checked by injecting a little amount of dye before injecting the mixture of steroid and local anesthetic. Care is taken not to inject into any adjacent vital structures. Patients are usually discharged from the operating area within a couple of hours after the procedure.

They are allowed to walk and continue with activities of daily living. There may be some worsening of pain after 4 to 6 hours due to the weaning off the local anesthetic. Patients are asked to use ice and take anti-inflammatory medications or pain medications if needed.

Patients who undergo multilevel blocks or multiple bilateral blocks may feel weak after the procedure and may not able to ambulate for a few hours. Patients are followed up in the office and are usually put on physical therapy to stretch and strengthen the muscles of the back and the hip.

Selective nerve root block is different from an epidural injection as it blocks only the nerve root which are suspected to be causing the pain as compared to epidural injection which bathes all the nerve roots with the steroid injection and local anesthetic.

This is helpful not only being therapeutic, but also diagnostic to identify the specific level of pathology. At the same time, selective nerve root block has less complication rate as compared to an epidural injection.

Selective nerve root block delivers the steroid injection at the exact site where it needs to act. Systemic absorption of steroid is minimal. This is in comparison to oral steroids which effects all tissues of the body and may have detrimental effect of multiple organs.

Complications

Injection of the medication inadvertently to the adjoining structure like the blood vessel. Occasionally, the injection may become epidural and may cause numbing of multiple nerve roots. Rarely, process of injection will lead to bleeding into the area, which may compress over the nerve roots of the lumbar spine leading to cauda equina syndrome.

If the cauda equina syndrome happens then an emergent surgery may be needed to decompress the nerve roots.
Steroid injection may lead to increasing of blood sugar levels in next 2-3 days and therefore patients with Diabetes are asked to check their sugar levels frequently and consult their primary care if needed.

Summary

Selective Nerve root block are effective way of reducing pain in patients with radiculopathy and may be the only treatment needed. It is safe and avoids the exposure of the body to harmful effects of systemic steroids. It can be repeated if needed. It also helps to confirm the diagnosis and the level of nerve root involvement.