Diagnosing Back Pain

Dr. Lali Sekhon, MD

How to Diagnose Back Pain

Back pain and back problems are exceedingly common disorders that affect the general community and up to 40% of the population will suffer this ailment at some time. The essence of the assessment and evaluation of patients with back problems centers around the following key issues. My approach to this problem is shown for residents and professionals, and also for patients so they realize the process undertaken in their evaluation and management.

Process

1. A careful history is taken
2. A thorough physical examination is performed
3. Appropriate investigations are ordered which are correlated to the clinical picture

There are three questions that are being asked:

1. What is the anatomic locus of the pathology on clinical grounds?
2. What pathological process is causing the dysfunction at that anatomic locus on imaging?
3. Is this amenable to surgical intervention?

By and large, the vast majority of back disorders can be managed non-surgically, with a very small subset requiring surgical referral and/or intervention. The conditions that can be helped by surgery comprise the following categories:

1. Compression e.g. disc, tumor, fractured bone fragments
2. Tension e.g. tethered cord
3. Instability e.g. Trauma, degenerative
4. Ischemia e.g. dAVF, compression

Back Pain Diagnosis Procedures

In general, up to 80% of back and spinal disorders can be diagnosed on history alone. In taking a back-related history, the following are important:

• Details of the onset of the illness
• What brought on the Sx
• Was there correlation to any activity?
• The effect of bed rest
• Did the patient awaken with Sx

Specific questioning should be done into the following areas:

• Pain
• Sensory symptoms
• Motor symptoms
• Gait
• Bowel function
• Bladder function

When questioning about pain, it is important to develop a pain history, encompassing the what, where, when and how.

It is important to understand some neuroanatomy in an attempt to correlate radicular symptoms to spinal pathology. In general, if the innervation of C6 and C7 (C6 supplies biceps and wrist extensors and supplies the thumb and index finger sensory regions as well as the biceps jerk; C7 supplies finger flexors, wrist extensors and triceps, as well as sensation to the dorsum of the hand and middle finger and triceps jerk) in the upper limb and L5 and S1 in the lower limb (L5 supplies the ankle dorsiflexors and sensation on the lateral aspect of the calf and dorsum of the foot; S1 supplies plantar flexion in the foot and sensation on the sole of the foot as well as the ankle jerk) are known, 90% of root lesions can be localized.

Important points about taking a pain history are:

Pain quality is important

• Neuropathic pain (burning in quality)
• Mechanical pain (worse on movement; relief with bed rest)

Constipation is a poor symptom of bowel dysfunction

More important questions about sphincters:

• Loss of feeling of fullness
• Loss of feeling of urethral stream
• Numbness on wiping

Physical Examination

The physical examination should not only encompass a general examination, but a thorough neurological examination should also be performed. To be as thorough as possible, the following regions need to be examined:

• Gait
• Back, neck
• Mechanical
• Roots, peripheral nerves
• Long tracts
• Rectal
• Joints
• Vascular
• Other

Sometimes differentiation between neurogenic and vascular claudication is required and an understanding of the differences between these 2 is required. In general the former is associated with back pain and is worse on standing of back extension and is unaffected by cycling, whereas the latter is unaffected by posture, may be associated with diabetes or peripheral stigmata of vascular disease and is typically worsened by either walking or cycling.

Available Investigations

To simplify matters, it is convenient to focus on plain x-rays, bone scanning, CT scanning and MRI scanning

Plain x-rays still play some role in the investigation of back disorders, particularly in the background of possible metastatic spinal disease, or if spinal instability is suspected (e.g. in patients with rheumatoid arthritis). Dynamic x-rays are not, however, usually indicated as a primary screening test. Plain x-rays can also give an assessment of the severity of degenerative disease and exclude fractures/dislocations.

Bone Scanning allows for the exclusion of metastatic disease as well as occult fractures. This is a good screening the aforementioned pathologies in the face of cancer or osteoporotic disease.

CT Scanning is a good baseline investigation for myelopathy or radiculopathy. It is not so good for intradural disease and may miss subtle degenerative changes causing neural compression.

MRI Scanning is our current “gold standard” in the unraveling of spinal disorders. It allows for excellent soft tissue delineation, as well as allowing for the assessment of the craniocervical junction. MRI also allows for postoperative differentiation of scar tissue from disc material. MRI is also unparalleled in the assessment of intradural disease.

Surgical Pathologies

Although most back conditions to not come to surgery, it is important to understand those conditions that do benefit from surgical intervention. They may be subclassified into the following:

Compressive Lesions

• Disc
• Lumbar stenosis
• Disc, facet joint, ligament
• Tumor (intra/extradural)
• Fractures

Ischemic Lesions

• Spinal dural AVF
• Spinal dAVM

Instability

• Rheumatoid arthritis
• Trauma
• Degenerative
• Post-surgical

New Technologies

Over the past few decades, much progress has been made in the assessment and management of spinal conditions. Some of these newer technologies include:

• Ix: flex/ext MRI
• Mx: better techniques for instrumentation
• Minimally invasive approaches

Intraoperative tools to allow more precise surgery e.g. fluoroscopic navigation.

Summary

The differential diagnosis of back pain is just too long. Instead, in the absence of neurological deficit, conservative management should be instituted and, on its failure further investigations or referral should be instituted.

For back pain:

• Need to adopt an initial conservative approach
• Avoid exacerbating factors
• NSAIDs, analgesia, physiotherapy
• Ix by x-rays and CT if neurological signs or unresolved
• Most get better!

For sciatica:

• If there is weakness or persistent Sx (>4 weeks of pain) or pain that is not settling then these should be Ix and referred if needed
• Surgery is best for:
• leg pain >weakness > numbness
• Surgery is not good for back pain
• Most get better also!

The ABCs of unraveling back problems are:

• Careful history
• Thorough physical examination
• Appropriate Ix at appropriate time
• Correlate Ix to clinical picture
• Refer when needed
  • Neurological deficit
  • Sciatica or arm pain that fails conservative Mx
  • Likely instability
• Education/reassurance
• Patience!