Nerve root blocks are injections of local anaesthetic, with or without the addition of steroid (cortisone) around the spinal nerves at the point at which they leave the spine (their roots). It is given to diagnose and to treat pain which tends to travel down the leg. The main causes of nerve root pain are a prolapsed disc (where the disc bulge presses on the nerve root) or spinal stenosis (where the opening for the root is restricted by bony narrowing as in arthritis). The effect of both these conditions is to produce an irritable, possibly inflamed, nerve root which becomes swollen as a consequence. The object of the block is to numb the root with local anaesthetic for immediate relief and counteract the inflammation and swelling with the anti-inflammatory action of the steroid for longer relief. A positive response to a root block means that the pain is arising at this point on the nerve and confirms the diagnosis as well as being therapeutic.

Treatment and Side-Effects

In order to carry out this block, you will need to lie on your side under an X-ray machine (image intensifier) which allows the openings in the side of the spine to be seen, although the nerves themselves are invisible. Injection can then be done accurately into the opening, often after making contact with the nerve root which causes a shooting sensation into the
leg. The X-rays used are a much smaller dose than you would receive if you had a normal back X-ray. Local anaesthetic is used, from the skin puncture to the nerve root so it is not an excessively painful procedure and sedation is rarely used

Afterwards there may be numbness and weakness in the affected leg which may interfere with your ability to walk. This may last for several hours or even until the next day and should not cause concern. You will need to lie down for a short while before going home. You will be given something to drink and eat if you wish. Obviously with a numb, heavy leg you will be unable to drive home but there is no reason to stay in hospital for the anaesthetic to wear off provided there is someone at home to look after you.

You might not feel any benefit for the first day or two and some patients feel temporarily worse for a couple of days. This does not mean that the eventual outcome will be negative.
You will be booked in for a follow up appointment in order to provide us with a progress report.

The pain relief should allow you to gradually increase your activities. It is important that you do not immediately take up unaccustomed exercise until your muscles have time to acclimatise to it. It is suggested that you start exercising in a mild fashion after 3 days taking two walks a day but limiting the distance and time to the level that you know you can manage easily. Do not try new forms of activity within the first 2 weeks or until advised by your specialist.

Please allow for traffic to arrive at the allotted time. You will be asked to sign a consent form.

Frequently Asked Questions

WHAT IS CORTISONE?

Cortisone is a powerful anti-inflammatory medicine which reduces inflammation around the nerve tissue and can break into the cycle of entrapment and swelling. This reduces pain, numbness, weakness.


IS THERE A LIMIT TO THE NUMBER OF INJECTIONS YOU CAN HAVE?

In any particular place in the body there is a natural limit of three injections in a 6 week period. Further injections are allowed in other places and at other times especially if they are effective. Your specialist will guide you.


WHAT COMPLICATIONS MAY OCCUR?

Hot flushes for 2 days.

Allergic reaction to any injection may occur in 1 in 7000 cases. This may just be a rash or a life threatening reaction. These will usually occur immediately and will be treated immediately. Most reactions are treated and cause no permanent harm.

Bleeding - Epidural Haematoma and resulting nerve damage is a very rare (1 in 7000) complication after a bleed around the nerves. This usually requires surgery to remedy.

Infection – Very rarely (1 in 7000). An Epidural Abscess or infection in other tissues can occur rarely. You should watch for signs of fever, redness, swelling and increasing pain. This can be treated with antibiotics or even surgery.