Tests and Diagnosis

1. History and Physical Examination

What Your Doctor Does First — History and Physical Examination

Sorting Into Three Categories

According to clinical practice guidelines from the American College of Physicians and the American Pain Society (Chou 2007), doctors first classify low back pain into three categories:

Most people fall into the "non-specific" category. This means no single cause can be pinpointed, not that there is no cause. (See "Why Does Your Back Hurt?" for more detail.)

Understanding the Questions Your Doctor Asks

Each question has a purpose:

Physical Examination — What Your Doctor Is Checking

The Straight Leg Raise (SLR) Test

While you lie on your back, your doctor lifts your leg straight up. Pain radiating down the back of your thigh or calf suggests a disc herniation compressing a nerve.

But in people over 60, this test is much less reliable:

So if you're over 60 and the SLR test is "negative" (no pain produced), it doesn't rule out a herniated disc (Qazi 2023). Your doctor knows this and will interpret the result alongside other findings.

Neurological Examination

When your doctor taps your knee or Achilles tendon with a reflex hammer, tests sensation in your feet, or checks the strength of your toes and ankles, they are identifying which nerve may be affected:

Other Important Tests

2. Imaging — Do You Really Need an MRI?

The Natural Desire for an MRI

When pain persists, it's natural to want an MRI to "find the cause." But MRI is not a magic answer. Imaging at the wrong time can cause more harm than good.

How an MRI Can Be Harmful

Studies have found (Srinivas 2012, Jenkins 2018):

1. It can create unnecessary anxiety. Many "abnormalities" found on MRI are normal age-related changes (explained in "Why Does Your Back Hurt?")
2. It can lead to unnecessary further tests. Once an "abnormality" is found, more tests tend to follow
3. It can lead to unnecessary surgery. Surgery based on MRI "findings" that aren't causing your pain may not help
4. It can make you feel "broken." Seeing structural changes on a scan can make you believe your spine is damaged, when it may just be aging normally

A Reminder About "Normal" MRI Findings

These numbers are from healthy people with no back pain at all. (Brinjikji 2015)

So being told "your disc is degenerated" or "you have a bulging disc" does not necessarily mean that's what is causing your pain.

When an MRI Is Appropriate

MRI is useful in these situations:

The Problem of Both Over-Testing and Under-Testing

One study found (Jenkins 2018):

• 34.8% of imaging requests were inappropriate: ordered even though there were no red flags
• Meanwhile, 65.6% of patients who did have red flags were not imaged

So tests are often done on the wrong patients: people who don't need them get scanned, while people who do need them are missed.

3. Yellow Flags and Neuropathic Pain Screening

Yellow Flags — Psychological Predictors of Chronic Pain

Potentially More Important Than Red Flags

Red flags (When to Seek Immediate Help) are warning signs of serious underlying disease.

Yellow flags are psychological and social factors that predict whether your back pain will become chronic.

Yellow flags predict the development of chronic pain more accurately than MRI findings (Pincus 2002).

The Main Yellow Flags

The "It Hurts, So I Don't Move" Trap

Fear-avoidance behavior helps explain chronic low back pain (Waddell 1993):

[!note] The fear-avoidance cycle Experience pain → Think "Moving will make it worse" (fear) → Stop moving (avoidance) → Muscles weaken, body stiffens → Even small movements trigger pain → "See, moving does make it worse" (confirmation) → Move even less... (the cycle continues)

An important message: Yellow flags are not a sign of weakness. They are natural human responses that can happen to anyone. Recognizing them is the first step toward breaking the cycle. Appropriate exercise and, when needed, psychological support can interrupt it.

PainDETECT — Screening for Neuropathic Pain

Some chronic low back pain includes a component called neuropathic pain: pain caused by nerve damage or dysfunction rather than tissue injury.

A large survey using the PainDETECT questionnaire (over 300,000 participants) found (Freynhagen 2006):

• 37% of chronic low back pain patients had a neuropathic pain component
• Those with neuropathic pain reported higher pain intensity and were more likely to experience depression and sleep disturbance

Why This Matters

Neuropathic pain often responds poorly to standard painkillers (such as NSAIDs). It typically requires different types of medication or treatment approaches. When conservative treatments have not provided adequate relief, spinal cord stimulation (SCS) may be considered as one option.

If you experience sensations like "tingling," "electric shock–like pain," or "burning pain," describe these to your doctor as specifically as you can.

4. Diagnostic Injections and Questionnaires

Diagnostic Injections — Searching for the Pain Source

When imaging doesn't clearly identify the cause, diagnostic nerve blocks may be used. A local anesthetic is injected near a suspected pain source to see whether the pain temporarily disappears.

Facet Joint Blocks (Medial Branch Blocks)

• Used to determine whether the facet joints (small joints at the back of the spine) are the pain source
• A single block has a false-positive rate of 27–63% (meaning it may incorrectly suggest the joint is the cause)
• For this reason, two separate blocks (using different anesthetics) are recommended (Cohen 2020)
• If both blocks provide relief, radiofrequency ablation (RFA) may be offered as a treatment

Sacroiliac Joint Blocks

• Used to determine whether the sacroiliac joint (in the pelvis) is the pain source
• Physical examination alone is unreliable for this diagnosis, so combining three or more clinical tests is recommended

Limitations of Diagnostic Injections

Diagnostic injections are a useful tool, but they do not provide 100% certainty. Results should always be interpreted alongside your full clinical picture.

Questionnaires — Making Pain Measurable

Doctors use standard questionnaires to measure your pain and how it affects daily life:

There are no "right" or "wrong" answers on these questionnaires. Answer based on how you actually feel. Honest answers give the most accurate assessment.

5. Preparing for Your Appointment

Preparing for Your First Appointment

What to Tell Your Doctor

1. When the pain started, and whether anything triggered it
2. Where it hurts: a specific spot you can point to, or a broader area
3. What makes it better or worse: movement, rest, time of day, nighttime
4. Whether you have leg symptoms: numbness, tingling, weakness, and how far they extend
5. Any changes in bladder or bowel function
6. Current medications: bring a list or your medication packaging
7. Past surgeries or serious illnesses, especially any history of cancer
8. What you can no longer do: be specific about which daily activities are affected

Common Questions

Q: Why didn't my doctor order an MRI?

A: If there are no red flag symptoms and no neurological signs, MRI "findings" are often normal age-related changes that can lead to unnecessary worry and further testing. Your doctor will order imaging when it is clinically indicated and likely to change your treatment plan.

Q: What's the difference between an X-ray and an MRI?

A: X-rays show bone structure, which is useful for detecting fractures and checking spinal alignment. MRI shows soft tissues, including discs, nerves, and ligaments, in detail. They serve different purposes.

Q: Should I get a second opinion?

A: If surgery has been recommended, seeking a second opinion is reasonable, particularly for chronic low back pain, where surgical indications require careful consideration. A good surgeon will support your decision to get another perspective.

Summary

• The foundation of back pain diagnosis is the history and physical examination; imaging is supplementary
• MRI is indicated when red flags are present or surgery is being considered. Imaging "just in case" can be counterproductive
• In people over 60, the SLR test sensitivity drops to approximately 33%, so a negative test does not rule out disc herniation
• Yellow flags (psychological factors) predict the development of chronic pain more accurately than MRI findings
• 37% of chronic low back pain includes a neuropathic component. The PainDETECT questionnaire can help identify this
• Diagnostic injections are useful but have high false-positive rates, so results must be interpreted carefully
• An MRI abnormality does not automatically mean you need surgery. This is perhaps the most important takeaway

References

1. Chou R et al. "Diagnosis and treatment of low back pain: a joint clinical practice guideline." Ann Intern Med. 2007;147(7):478-91.
2. Brinjikji W et al. "Systematic literature review of imaging features of spinal degeneration in asymptomatic populations." AJNR Am J Neuroradiol. 2015;36(4):811-6.
3. Srinivas SV et al. "Application of 'less is more' to low back pain." Arch Intern Med. 2012;172(13):1016-20.
4. Jenkins HJ et al. "Imaging for low back pain: is clinical use consistent with guidelines?" Spine J. 2018;18(12):2266-2277.
5. Qazi SA et al. "The diagnostic accuracy of straight leg raise test in patients more than 60 years." J Neurosci Rural Pract. 2023;14(4):610-614.
6. Pincus T et al. "A systematic review of psychological factors as predictors of chronicity/disability." Spine. 2002;27(5):E109-20.
7. Waddell G et al. "A Fear-Avoidance Beliefs Questionnaire (FABQ)." Pain. 1993;52(2):157-168.
8. Freynhagen R et al. "painDETECT: a new screening questionnaire." Curr Med Res Opin. 2006;22(10):1911-20.
9. Cohen SP et al. "Consensus practice guidelines on interventions for lumbar facet joint pain." Reg Anesth Pain Med. 2020;45(6):424-467.
10. Fairbank JC, Pynsent PB. "The Oswestry Disability Index." Spine. 2000;25(22):2940-52.

Next Steps

• Exercise Therapy — Why Movement Is an Effective Treatment
• Finding the Right Exercise — A Type-Based Flowchart
• Red Flag Symptoms — When to Seek Immediate Help
• Why Does Your Back Hurt? — An Honest Look at Pain