Treating lower back conditions with steroid injections: why, when and how

A variety of back conditions can lead to lower back pain and, in some cases, may need treatment with steroid injections. 

Here, we’ll take a closer look at the most common causes of lower back pain, how these conditions are diagnosed and when epidural steroid injections are an appropriate treatment. First, it helps to understand the anatomy of your back. 

Back anatomy

Your back runs from the base of your neck down to your pelvis and is composed of your spine, which is S-shaped when viewed from the side, as well as muscles, nerves and other soft tissues. 

Your spine contains 33 interlocking bones called vertebrae. These vertebrae are stacked on top of each other and are connected by joints called facet joints. Together they form a channel that runs down your back called the spinal canal, through which a bundle of nerves called your spinal cord runs. 

In between each of the first 24 vertebrae are cushions called intervertebral discs, which act as shock absorbers. They also create space between your vertebrae for your spinal nerves to exit from your spinal cord. 

Muscles surround and attach to the length of your spine — these are called paravertebral muscles.

Lower back pain can occur due to a problem with, an injury to or degeneration of any of the tissues in your back, including your back muscles, spinal nerves, vertebrae or intervertebral discs. 

Common causes of lower back pain

There are many different causes of lower back pain, with the most common including mechanical back pain, sciatica and claudication. These conditions are sometimes associated with other symptoms, such as numbness and/or a ‘pins and needles’ sensation in your foot or feet, as well as weakness in part or all of your leg(s). 

Mechanical back pain 

The most common cause of lower back pain in the UK is mechanical. Around 20–30% of the UK population experience mechanical back pain at any given time, ranging from mild, lasting only a few days, to severe, disabling pain that has a significant impact on your quality of life. 

Lower back pain is a particular problem of modern life as we spend more time sitting with poor posture. This weakens the muscles in your back so they can’t as effectively support your spine, which in turn increases your risk of mechanical back pain. 

Sciatica

A less common cause of lower back pain, which nonetheless affects 13–40% of people in the UK across their lifetime is sciatica (lumbar radiculopathy).  

This refers to pain that often shoots down from the lower back and into the buttock, thigh, calf, ankle and foot. Sometimes this pain can be felt continuously, while at other times, it is felt sporadically along different parts of the leg, running from the lower back to the foot. 

Sciatica causes pain that is typically in the areas that are supplied by the sciatic nerve, which runs from your lower back to your foot. It is often felt in one leg, either on the left or right side, but sometimes can be felt in both legs. 

There are several different reasons for sciatic pain, but it often happens when a nerve is pinched or placed under pressure, such as if you have a slipped disc (disc prolapse) or narrowing of your spinal canal (spinal stenosis). In some cases, conditions that affect your pelvis or hip can also apply pressure to your sciatic nerve causing leg pain. 

Claudication 

Claudication refers to an unpleasant deep pain in the buttocks, the back of the thighs and/or sometimes the calves, which is brought on with standing and walking and relieved on sitting or leaning forward.

This is often caused by the narrowing of your spinal canal, which pinches the nerves that run down into both of your legs. Although claudication is often felt on both sides, sometimes it is felt only in one leg. This can cause pain that is sometimes associated with, tingling, cramping and a heavy feeling.

Claudication mainly occurs in older people as its main cause — spinal stenosis, which affects around one in 10 people in the UK — is most common in those aged over 50.

When to seek urgent care for lower back pain

Although in most cases lower back pain doesn’t need urgent treatment, there are some important ‘red flags’ to be aware of. 

This includes but is not limited to back pain that is unrelenting and not responding to simple lifestyle adjustments or over-the-counter painkillers, and back pain that continues day and night with no respite. 

Other ‘red flag’ symptoms include back pain that is associated with unexplained weight loss, fever, rigors (shivering and feeling very cold while your temperature rises), a loss of bowel or bladder control, an inability to urinate properly or empty your bladder fully, and numbness in your buttocks and groin area that spreads into both of your legs. 

If you notice any of these symptoms, you should visit your local A&E. 

How is lower back pain investigated?

Your doctor will ask you about your symptoms and medical history and may perform a physical examination. It is helpful to keep a record of the pattern of your symptoms and whether they’re associated with any particular circumstances or actions. 

They may then recommend an MRI scan of your back to check the health of your vertebrae, intervertebral discs and nerves, and paravertebral muscles. They will also look for signs of degeneration, pressure on the nerves and, in rare circumstances, infection or tumours. 

In some cases, a CT scan may be needed to investigate bony structures, for example, to check for fractures or the bony structure of your spine. 

An X-ray is not usually helpful when investigating lower back pain but may be recommended if you have a pre-existing deformity such as scoliosis. 

Treating lower back pain

Treatment for lower back pain varies depending on the underlying cause but usually surgery isn’t needed and conservative treatments are effective. In most cases, physiotherapy is helpful alongside lifestyle changes, such as adapting your work and/or living conditions and adjusting your daily habits and leisure activities. 

You may also need to take pain relief medication to help you carry out your daily physiotherapy exercises. This can range from over-the-counter pain relief such as paracetamol and ibuprofen to stronger prescription non-steroidal anti-inflammatory drugs (NSAIDs) — opioids should rarely be used. 

If your back pain is associated with severe muscle spasms in your back, a short course of muscle relaxant can help. 

In certain cases of sciatic pain and or spinal claudication, your doctor may prescribe neuropathic medications, such as amitriptyline, pregabalin or gabapentin to manage your pain so you can undergo physiotherapy. 

If lifestyle changes, physiotherapy and pain relief medication aren’t effective, and if identifiable targets are present on your MRI scans, your doctor may recommend imaging-guided targeted steroid injections.  

Surgery is often reserved for when there is a continuation of symptoms despite the appropriate treatments mentioned earlier, or if there are signs of continued or impending nerve damage which may lead to permanent disability.

How epidural steroid injections can help

These are injections of anti-inflammatory corticosteroid medication directly into the space around your spinal nerves in the epidural space. They can be helpful both as a therapy and as a diagnostic tool. 

If you have a persistent back condition, despite the conservative treatments mentioned earlier, then steroid injections can potentially offer long-lasting relief. This can enable you to continue with physiotherapy and keep your pain levels manageable. 

If the source of your lower back pain isn’t clear, an epidural steroid injection can help your doctor establish the likely source of your pain through what is called selective blocks. This is because the epidural steroid injection can be directed at a specific nerve root — a nerve root is a collection of nerve cell bodies that belong to the nerves exiting your spinal canal at a specific level of your spine. 

This blocks pain coming from the area around that specific nerve root. So, if you experience pain relief when the injection is delivered to a specific nerve root, your doctor can deduce that the source of your pain is in that area. 

How epidural steroid injections are administered

A spinal steroid injection can be carried out by an anaesthetist with a special interest in pain management, a radiologist or a spinal surgeon. 

The injection is performed under the guidance of X-ray imaging or CT scanning to ensure it is delivered at exactly the right location. It is usually performed under a local anaesthetic, so you will be awake. If you’re feeling anxious about the injection, you may be given some sedation to help you relax. Although not painful, you will experience some discomfort during the injection. 

After your injection, the discomfort will settle. The pain-relieving effects of the corticosteroid medication may take effect immediately or may take up to several weeks before you feel any benefit. You will usually have a follow-up appointment after around six weeks.

How effective are epidural steroid injections for lower back pain?

There is little evidence that epidural steroid injections are effective for non-specific back pain, that is, back pain where it isn’t possible to identify the specific underlying cause. 

However, if your back pain is caused by wear and tear of the facet joints of your spine, an injection of local anaesthetic targeting the pain nerve of the facet joint can be effective for establishing that the facets are the source of pain. This can then be followed by a procedure to destroy the pain nerves that supply the facet joint (rhizolysis).

For sciatica caused by a prolapsed disc, in most cases, the pain gets better on its own within six months without any intervention. However, if treatment is needed, a one-off epidural steroid injection, either as a caudal epidural or foraminal injection, can help control your pain while your body naturally recovers. 

For spinal stenosis, the pressure applied to the nerves is caused by narrowing of the spinal canal but can be worsened by local soft tissue inflammation. An epidural steroid injection can, therefore, be effective as it reduces inflammation and swelling of the soft tissues, which eases some of the pressure placed on the spinal nerves. 

When steroid injections around the spine are effective, how long this pain relief lasts varies considerably from one patient to the next, ranging from a few months or years to permanent pain relief. 

How often can you have steroid injections around the spine?

Spinal steroid injections can usually only be given twice a year at most. However, in severe cases, where surgery is definitely not an option and the cause of the pain is known, it may be possible to have up to three injections in a year. 

This is because frequent steroid use comes with many side effects. Furthermore, too many injections around the spine can cause scarring around the nerves, which can cause problems and increase your risk of complications if you later need surgery in this area.

Complications of spinal steroid injections

Spinal steroid injections can temporarily cause a total nerve block, where you lose all feeling and movement from the waist down; however, the overwhelming majority of individuals recover the following day with an overnight stay in hospital.

Other potential complications include a hypersensitivity reaction to the local anaesthetic, steroid or contrast media (which is used to aid imaging during the procedure). 

There is also a low risk of infection and bleeding. If you’re taking blood-thinning medication, the risk of bleeding is higher and your doctor may advise you to temporarily stop taking these medications depending on the type of these medications. 

Please speak to your GP about stopping these blood-thinning medications and if this can be done safely, and speak to the doctor performing your injections about exactly when to stop and restart them.