CT-Guided Epidural Injection for Sciatica

An epidural injection should not simply be used to make pain temporarily disappear. The real question is whether the period of relief will help the patient recover – or whether the underlying tissue requires a more regenerative treatment strategy.

What is a CT-guided epidural injection?

A CT-guided epidural injection is a precisely targeted spinal procedure used in selected patients with sciatica, radicular pain and nerve-root inflammation. Using computed tomography, a specialist radiologist guides a fine needle towards the affected epidural space or spinal nerve root. A small amount of medication is then delivered to the anatomical target identified on the patient’s imaging.

The procedure may be described as:

a CT-guided epidural injection;
an epidural steroid or cortisone injection;
a transforaminal epidural injection;
a selective nerve-root injection or nerve-root block;
an interlaminar epidural injection; or
a caudal epidural injection.

These terms do not all describe exactly the same approach. The appropriate technique depends on the location of the problem, the patient’s anatomy, previous surgery and the clinical objective.

At MBR Health, spinal procedures are planned and performed by a specialist, highly experienced radiologist within a diagnosis-led pathway. The objective is not simply to inject the general area where the patient feels pain. It is to identify the structure most likely to be producing the symptoms and then place the treatment accurately at that target.

What conditions can an epidural injection treat?

Epidural and selective nerve-root injections are generally used for radicular pain—pain caused by irritation or inflammation of a spinal nerve root.

In the lumbar spine, this may produce:

sciatica;
pain travelling from the back into the buttock or leg;
burning, tingling or altered sensation;
pins and needles;
numbness; or
selected patterns of nerve-related weakness.

In the cervical spine, nerve-root irritation may cause pain, tingling or numbness extending from the neck into the shoulder, arm or hand.

Common structural causes include:

disc protrusion, extrusion or herniation;
inflammatory irritation around a damaged disc;
narrowing of the neural foramen;
spinal stenosis;
osteophytes or bony narrowing;
recurrent symptoms following spinal surgery; and
scar tissue or altered anatomy after an operation.

An epidural is not a generic treatment for every type of back pain. Pain arising from a facet joint, sacroiliac joint, muscle, ligament, vertebral endplate or the disc itself may require a different diagnostic and treatment pathway.

This is why accurately diagnosing back pain matters before an injection is selected.

Sciatica is a symptom – not the final diagnosis

“Sciatica” describes a pattern of pain, not its precise cause. Two people may both have pain extending down the leg but have very different underlying problems. One may have a disc extrusion irritating the L5 nerve root. Another may have foraminal stenosis, post-surgical scarring, piriformis-related irritation or a non-spinal cause of referred pain.

Even when an MRI shows several abnormalities, not every abnormality is necessarily painful. Disc bulges and degenerative changes are common, including in people without symptoms.

The important questions are:

Which nerve or structure is responsible for the symptoms?
Does the imaging finding match the patient’s pain distribution?
Is the dominant problem mechanical compression, inflammation or both?
Is the affected tissue capable of recovering?
Are we trying to create a temporary window for natural recovery, confirm the diagnosis, or support a regenerative response?

At MBR Health, this correlation between the symptoms, examination, imaging and proposed target is central to the pain and injury pathway.

Why use CT guidance?

The epidural space and spinal nerve roots are small targets surrounded by important structures. Anatomy may also be altered by degeneration, scoliosis, narrowing, previous surgery or spinal hardware.

CT guidance allows the treating radiologist to:

visualise the individual patient’s anatomy;
plan a safe route to the target;
position the needle with anatomical precision;
account for post-surgical or distorted anatomy;
confirm the location of the needle tip;
document the delivery; and
reduce reliance on surface landmarks or estimation.

Different imaging modalities have different strengths. Ultrasound is valuable for many superficial joints, tendons, bursae and peripheral nerves, but it cannot directly visualise all deep spinal targets. CT is particularly useful when detailed visualisation of the vertebrae, neural foramina and post-surgical anatomy is required.

Precision does not guarantee that an injection will work. It does, however, reduce one avoidable source of treatment failure: delivering the medication to the wrong structure.

What is injected?

The two principal pathways discussed in this article are corticosteroid and platelet-rich plasma.

They are not interchangeable. They have different biological objectives.

Cortisone: controlling inflammation and creating a window

Corticosteroid is a powerful anti-inflammatory medication. When delivered around an inflamed nerve root, it may reduce chemical irritation and swelling, allowing pain to settle.

Its potential advantages include:

relatively rapid reduction in inflammation;
short-term improvement in radicular pain;
improved ability to move, sleep and participate in rehabilitation;
creating time for a disc-related episode to settle naturally; and
helping determine whether the targeted nerve root is responsible for the symptoms.

A local anaesthetic may also be included. Immediate temporary improvement following accurate injection can provide useful diagnostic information, although the response must be interpreted in the broader clinical context.

Cortisone does not directly repair a torn disc, regenerate a degenerated structure or reconnect damaged collagen. Its primary role is to suppress inflammation and reduce pain.

That does not make cortisone inherently inappropriate. In the correct patient, reducing pain and inflammation may create a valuable period in which the body can recover, the disc-related inflammation can settle and the patient can progressively return to movement and rehabilitation.

The problem arises when temporary pain suppression is mistaken for tissue healing.

PRP: a biologically directed pathway

Platelet-rich plasma is produced from the patient’s own blood. The blood is processed to concentrate platelets and associated biological signalling molecules before the preparation is delivered to a defined anatomical target.

PRP is not simply another pain-relieving drug. It is intended to influence the biological environment around injured or degenerative tissue and support repair processes where there is a reasonable anatomical and biological rationale.

For spinal pain, the possible target may be:

the epidural space adjacent to an inflamed nerve root;
a damaged ligament or enthesis;
a facet-related structure;
the annular region of a damaged disc; or
the disc itself in carefully selected cases.

These are different procedures. An epidural PRP injection should not be confused with an intradiscal PRP injection. The correct target depends on what is actually producing the pain.

Emerging randomised trials and meta-analyses suggest that epidural PRP may provide pain and functional outcomes comparable with epidural corticosteroid in selected patients with lumbar disc disease and radiculopathy.[2–5] Some studies suggest that cortisone may act faster while PRP may produce a more gradual or sustained response. However, protocols vary, patient numbers remain relatively small, and the evidence does not yet prove that epidural PRP repairs every disc or is superior for every patient.[2–5]

PRP should therefore be described accurately: it is a developing biologic treatment with a regenerative intent, not a guaranteed cure.

Cortisone or PRP: which pathway does MBR Health prefer?

Where the diagnosis, anatomy and available evidence support a biologic treatment, MBR Health generally prefers a regenerative strategy rather than repeated suppression of pain.

This does not mean that cortisone has no place.

A cortisone epidural may be reasonable when:

acute inflammation is preventing movement or sleep;
severe pain is obstructing rehabilitation;
the underlying problem has a reasonable prospect of settling naturally;
rapid short-term symptom control is clinically important;
the injection is being used to test whether a particular nerve root is the pain source;
PRP is not suitable; or
the patient understands that the objective is temporary inflammatory control rather than structural repair.

The period of pain relief should be used intelligently. If cortisone reduces symptoms, the patient may have an opportunity to restore movement, participate in physiotherapy, improve strength, modify load and allow the body’s natural recovery process to progress.

However, if the pain returns after the cortisone effect wears off, that recurrence is important information.

It may mean that:

inflammation was suppressed but the underlying driver remains;
the affected tissue has not adequately recovered;
mechanical compression is still present;
the original target was incomplete or incorrect;
more than one pain generator is involved; or
the condition requires a different treatment strategy.

At MBR Health, recurrent pain would not usually lead automatically to another cortisone injection. The patient and imaging should first be reviewed.

Where the target remains appropriate and the patient is suitable, we would generally recommend considering PRP or another regenerative pathway rather than simply repeating cortisone. The aim is to move from temporarily reducing the pain signal towards supporting the tissue and biological environment responsible for the symptoms.

There are exceptions. Some patients should not receive PRP, some conditions require surgery, and some patterns of pain are not biologically treatable with either injection. Treatment must remain individualised.

Why not simply repeat cortisone?

A second cortisone injection may sometimes be clinically justified, but repetition should not become the default response whenever pain returns.

Repeated injections can create a cycle:

1. inflammation is suppressed;

2. pain temporarily improves;

3. the underlying structural or mechanical problem persists;

4. the effect wears off;

5. symptoms return; and

6. the same treatment is repeated without reconsidering the diagnosis.

That approach risks confusing symptom control with recovery.

A returning symptom should prompt several questions:

Did the first injection reach the correct target?
How much relief occurred?
Was the response immediate, delayed or absent?
How long did it last?
Did function improve as well as pain?
Was the pain-free interval used for rehabilitation?
Has the underlying imaging changed?
Is the structure capable of healing?
Would PRP, another intervention or surgical assessment now be more appropriate?

A useful first injection should provide information as well as relief.

What does the evidence say about epidural cortisone?

Epidural corticosteroid injections are established treatments for selected radicular pain, but their benefits are generally most evident in the short term.

A 2025 systematic review from the American Academy of Neurology evaluated epidural corticosteroid injections for cervical and lumbar radiculopathy and spinal stenosis. It found modest short-term benefits for pain and disability in radiculopathy, with more limited evidence for sustained long-term benefit.[1]

This is consistent with how cortisone should be understood clinically: it can be useful, particularly when inflammation is a major driver, but it should not automatically be interpreted as a definitive repair treatment.

What does the evidence say about epidural PRP?

The evidence for epidural PRP is newer and less mature.

A 2025 meta-analysis of five randomised controlled trials involving 310 patients found that epidural PRP produced pain relief, functional improvement and overall health outcomes comparable with epidural steroid injection in lumbar disc disease with radiculopathy, without an identified increase in adverse events.[2]

Randomised studies have similarly reported improvement with both PRP and corticosteroid. Some have found stronger early improvement with steroid and more sustained later improvement with PRP, while others have found broadly comparable results.[3–5]

Important limitations remain:

PRP preparation methods vary;
platelet doses and cellular compositions are inconsistent;
injection techniques differ;
studies remain relatively small;
follow-up periods vary; and
improvement in pain does not necessarily prove structural disc regeneration.

The evidence is therefore promising rather than definitive. Larger, high-quality studies with standardised PRP characterisation and longer follow-up are still required.

Not all PRP is the same

“PRP” does not describe one standardised product.

The biological effect may be influenced by:

the patient’s baseline platelet count;
the volume of blood collected;
platelet recovery during processing;
the total platelet dose delivered;
leukocyte and red-cell content;
anticoagulant and preparation method;
time between preparation and injection;
sterility and handling;
activation behaviour; and
accurate delivery to the intended tissue.

A small tube of blood producing a low total platelet dose is not equivalent to a high-volume, measured preparation.

This is why MBR Health describes PRP as a combination of diagnosis, dose and delivery. You can read more in:

What happens during a CT-guided epidural injection?

The exact procedure varies according to the target, but a typical pathway includes:

1. Review of the referral and imaging
The radiologist reviews the MRI or CT and determines whether the requested injection corresponds with the likely pain generator.

2. Positioning
The patient is usually positioned face down or occasionally on their side, depending on the procedure.

3. Planning CT images
A limited CT acquisition is used to identify the safest and most accurate needle path.

4. Sterile preparation and local anaesthetic
The skin is cleaned and local anaesthetic is administered.

5. Needle placement
A fine needle is advanced under CT guidance towards the epidural space or selected nerve root.

6. Confirmation
Needle position may be confirmed with imaging and a small amount of contrast where clinically appropriate.

7. Delivery
The selected injectate—such as corticosteroid, local anaesthetic or PRP—is administered according to the planned procedure.

8. Observation and discharge
The patient is monitored for an appropriate period and receives individualised post-procedure instructions.

The technical injection may be relatively brief, but appropriate review, preparation, imaging and observation are essential parts of the procedure.

Is the injection painful?

Most patients experience pressure, brief discomfort or a reproduction of their familiar symptoms as the needle approaches the inflamed nerve. Local anaesthetic is used at the skin and along the needle pathway. The procedure is performed without a general anaesthetic so the patient can communicate what they are feeling.

PRP may produce more of an inflammatory response than corticosteroid. This can cause a temporary increase in discomfort after treatment. Patients should receive procedure-specific instructions because the expected recovery differs between cortisone and PRP.

How quickly does an epidural injection work?

Following cortisone

Local anaesthetic may produce improvement within minutes or hours, although this effect is temporary.

Corticosteroid usually takes longer to act. Improvement may develop over several days, and the duration varies considerably. Some patients experience meaningful relief; others experience partial, brief or no benefit.

Following PRP

PRP is not designed to behave like an immediate anti-inflammatory drug.

Symptoms may initially remain unchanged or temporarily increase. Improvement, where it occurs, is usually more gradual and may develop over weeks or months. The timeline depends on the diagnosis, chronicity, tissue involved, rehabilitation and individual biological response.

What should you do during the pain-relief period?

Pain relief is an opportunity, not proof that the underlying problem has disappeared.

Where clinically appropriate, the relief period may be used to:

restore normal walking and movement;
recommence graded physiotherapy;
improve spinal and lower-limb strength;
correct avoidable load or movement factors;
improve sleep;
reduce fear of movement;
return gradually to work or exercise; and
allow natural inflammatory resolution and tissue recovery.

Suddenly returning to heavy lifting or high-impact exercise because the pain has disappeared may aggravate tissue that has not yet recovered.

Rehabilitation should be tailored to the diagnosis and coordinated with the treating practitioner or physiotherapist.

What if the epidural does not work?

A technically accurate injection can still fail.

Possible explanations include:

the targeted nerve was not the primary pain generator;
pain is arising from another structure;
fixed mechanical compression is too severe;
nerve injury has become chronic;
central sensitisation is contributing;
the medication produced insufficient biological effect;
the diagnosis is incomplete; or
surgery or another intervention is required.

The next step should not automatically be a repeat injection. The clinical response should be reviewed alongside the original imaging and diagnosis.

At MBR Health, this forms part of a broader diagnosis-first approach to spinal pain.

What are the risks?

All epidural and spinal procedures carry risk.

Potential risks include:

temporary worsening of pain;
bleeding or haematoma;
infection;
allergic or medication reaction;
temporary numbness or weakness;
dural puncture and headache;
nerve irritation or injury;
blood-vessel injury;
effects associated with corticosteroid, including temporary elevation of blood glucose; and
rare serious neurological complications.

Individual risk may be affected by anticoagulant or antiplatelet medication, diabetes, infection, immune status, pregnancy, previous surgery and the anatomical level being treated.

Cervical spinal procedures require particular care because of the structures located in the neck. Suitability, technique and injectate should be determined individually by the treating specialist.

When is urgent medical assessment required?

An injection is not an appropriate substitute for urgent assessment where a patient has red-flag symptoms.

Seek urgent medical attention for:

new or progressive limb weakness;
loss of bladder or bowel control;
numbness around the perineum or saddle region;
fever or suspected spinal infection;
significant trauma;
known cancer with new spinal symptoms;
rapidly worsening neurological symptoms; or
severe, unremitting pain associated with systemic illness.

These symptoms may require urgent imaging, specialist review or surgery rather than an elective pain procedure.

Do you need an MRI before an epidural injection?

Current diagnostic imaging is usually important before a targeted spinal injection.

MRI is generally the most useful examination for assessing:

discs;
nerve roots;
spinal canal narrowing;
marrow;
ligaments;
soft tissues; and
many post-surgical complications.

CT may provide additional information about:

bone;
facet joints;
osteophytes;
calcification;
spinal hardware; and
complex post-surgical anatomy.

At MBR Health, advanced 3T MRI and Spectral CT can be used according to the structure and clinical question. The best imaging modality is the one that most accurately identifies the suspected pain generator.

CT-guided epidural and PRP treatment on the Gold Coast

MBR Health provides advanced spinal imaging and precision CT-guided pain and regenerative procedures at Mermaid Beach on the Gold Coast.

Patients attend from across the Gold Coast, Brisbane, Logan, northern New South Wales and South East Queensland for specialist spinal imaging and image-guided treatment.

The pathway may include:

review of existing imaging;
high-resolution 3T MRI;
Spectral CT where additional bony or post-surgical detail is required;
CT-guided diagnostic injection;
CT-guided epidural corticosteroid where appropriate;
epidural or targeted spinal PRP in selected patients;
intradiscal PRP in carefully selected cases;
image-guided rehabilitation planning; and
follow-up imaging where it may alter management.

A referral from a GP or specialist is required. Treatment suitability is determined individually after consideration of the diagnosis, imaging, medical history, treatment alternatives, risks and strength of the available evidence.

The MBR Health position

An epidural injection should have a defined purpose. Cortisone has a legitimate role when short-term reduction of inflammation can create an opportunity for natural recovery, improve participation in rehabilitation or help confirm the pain generator. However, cortisone primarily suppresses inflammation. It should not automatically be confused with healing. If pain returns, repeating the same cortisone injection without reassessing the underlying problem may simply reproduce another temporary period of relief. At that point, the diagnosis, target and treatment objective should be reviewed.

Where the anatomy and biology are suitable, MBR Health generally prefers progression towards PRP or another regenerative strategy rather than routine repeat corticosteroid injection. The objective is not simply to mask the pain again, but to determine whether the affected tissue can be supported towards a more durable recovery.

PRP is not appropriate for every patient and does not guarantee healing. The emerging evidence is encouraging, but the decision must remain diagnosis-led, evidence-aware and individually considered.

Pain relief is useful. But the purpose of treatment should be clearer than making pain temporarily disappear. The real objective is to understand the source, choose the right biological strategy and create the best possible conditions for recovery.

— Dr Zane Sherif, Specialist Radiologist

Frequently asked questions

Below are some epidural specific FAQs, if you have any other questions please visit out FAQs page.

Is a CT-guided epidural the same as a cortisone injection?

Not necessarily. “Epidural” describes where the treatment is delivered. Cortisone is one possible injectate. Selected epidural procedures may instead use local anaesthetic, PRP or another medication, depending on the diagnosis and clinical objective.

Is an epidural injection only for lower-back pain?

Epidural injections are principally used for nerve-root or radicular symptoms rather than nonspecific back pain. Lumbar nerve irritation may cause sciatica, while cervical nerve irritation may cause pain or altered sensation extending into an arm.

Does cortisone heal a disc?

Cortisone reduces inflammation. It does not directly rebuild a damaged disc. The period of symptom relief may nevertheless allow natural recovery and rehabilitation to progress in appropriately selected patients.

Does epidural PRP heal a disc?

Current studies suggest that epidural PRP may improve pain and function in selected patients, but this does not prove that it structurally regenerates every damaged disc. Epidural PRP and intradiscal PRP are also different procedures. Claims of guaranteed disc regeneration are not supported by current evidence.

Should I have another cortisone injection if the first one worked?

Not automatically. The duration and nature of the response should be reviewed. If pain returns, it may indicate that inflammation was temporarily suppressed while the underlying problem persisted. Some patients may benefit from another corticosteroid injection, while suitable patients may be better considered for PRP or another pathway.

Is PRP always better than cortisone?

No. Cortisone may be more useful when rapid inflammatory control is required. PRP may be preferred where there is a reasonable biological target and a regenerative strategy is appropriate. The evidence for epidural PRP is developing, and treatment should be individualised.

How long does an epidural injection last?

The response varies. Local anaesthetic may last hours, while corticosteroid relief may last from days to months. PRP generally has a slower onset and, where effective, may produce improvement over weeks or months.

Can I drive after an epidural injection?

Patients should follow the specific instructions given by the treating clinic. Temporary numbness, weakness or altered sensation may occur, and patients are commonly advised to arrange transport home.

Are epidural injections covered by Medicare?

Medicare eligibility depends on the procedure, referral, item requirements and individual circumstances. PRP itself is not currently covered by Medicare. The clinic should provide clear fee information before treatment.

References

1. Armon C, Narayanaswami P, Potrebic S, Gronseth G, Bačkonja MM, Cai VL, Dorman J, Gilligan C, Heller SA, Silsbee HM, Smith DB. Epidural Steroids for Cervical and Lumbar Radicular Pain and Spinal Stenosis Systematic Review Summary: Report of the AAN Guidelines Subcommittee. Neurology. 2025 Mar 11;104(5):e213361. doi: 10.1212/WNL.0000000000213361. Epub 2025 Feb 12. PMID: 39938000; PMCID: PMC12289388.

2. Muthu S, Viswanathan VK, Gangadaran P. Is platelet-rich plasma better than steroids as epidural drug of choice in lumbar disc disease with radiculopathy? Meta-analysis of randomized controlled trials. Exp Biol Med (Maywood). 2025 Feb 4;250:10390. doi: 10.3389/ebm.2025.10390. PMID: 39968415; PMCID: PMC11832311.

3. Saraf A, Hussain A, Kumar A, et al. Transforaminal injections of platelet-rich plasma compared with steroid in lumbar radiculopathy: a prospective, double-blind, randomized study. Indian Journal of Orthopaedics. 2023. Full text

4. Gupta A, Chhabra HS, Singh V, Nagarjuna D. Lumbar Transforaminal Injection of Steroids versus Platelet-Rich Plasma for Prolapse Lumbar Intervertebral Disc with Radiculopathy: A Randomized Double-Blind Controlled Pilot Study. Asian Spine J. 2024 Feb;18(1):58-65. doi: 10.31616/asj.2023.0115. Epub 2024 Feb 26. PMID: 38433432; PMCID: PMC10910136.

5. Ruiz-Lopez R, Tsai YC. A Randomized Double-Blind Controlled Pilot Study Comparing Leucocyte-Rich Platelet-Rich Plasma and Corticosteroid in Caudal Epidural Injection for Complex Chronic Degenerative Spinal Pain. Pain Pract. 2020 Jul;20(6):639-646. doi: 10.1111/papr.12893. Epub 2020 May 6. PMID: 32255266.

Medical disclaimer: This article provides general educational information and does not constitute personal medical advice. Epidural corticosteroid and PRP procedures are not suitable for every patient. PRP applications in the spine remain an evolving area of medicine, with evidence varying according to the diagnosis and procedure. A referral, clinical assessment and review of appropriate imaging are required before treatment. No specific outcome or structural healing can be guaranteed.