Principles of Back Pain

Outpatient Internal Medicine

Cases:

• Mr. A• 43y/o male, works for

a lumber company, strained his back loading his truck 2 wks ago.

• Had to take off work 2/2 pain, muscle spasm. Hurts to move.

• Mrs. B• 68y/o female, retired,

known OA in knees & hands, now feeling low back pain x2months. No h/o trauma.

• Paraspinal muscles tight & sore. Hurts to move.

What could be causing their pain?

• Nerve impingement (roots, nerves)

• Muscle trauma

• Disc pain

• Facet joint pain

• Bony pain

How do you differentiate?

• History: age, red flag signs – Incontinence, bladder retention, saddle anesthesia –

think cord compression or cauda equina syndrome– sudden, excruciating pain with minimal trauma –

think insufficiency fracture 2/2 osteoporosis or tumor– Fever, IV drugs – infection

• Physical exam: – Straight leg raise – think disc herniation– Piriformis tenderness – think sciatic entrapment in the

piriformis muscle– Muscle pain/tightness – raises suspicion for muscle

injury, although pain from any source can cause reactive muscle spasm

– Tenderness over bony prominence – think fracture

A word on sciatica

• Sciatica is a symptom, not a diagnosis

• Inflammation of the sciatic nerve can happen at many places, including:– L4/L5 nerve roots (most common!)– Piriformis or other muscle entrapment of

sciatic nerve– Spinal cord itself (spinal stenosis)

When do you image?– Most low back pain resolves in 6 weeks, so no

imaging is needed– Consider imaging if:

• Young (<20)• Old (>50)• Hx of tumor• Trauma• Night/rest pain• Systemic symptoms• Red flag symptoms

How do you image?

• X-rays:– Good for detecting fracture– Can document presence or absence of

arthritic changes, but won’t assess nerve involvement

• MRI:– Delineates disc disease, nerve impingement– Detects tumors– Use contrast if there is a history of back

surgery or tumors

Examples

L3 endplates should be parallel, like L4. Collapse implies fracture.

L4

L3 White circle shows disc herniation in above sagittal view of MRI

Red arrow shows nerve impingement by disc/osteophyte in axial view of MRI

Treatment

• For most back pain, NSAIDs, heat, early return to normal activity as tolerated x 6 weeks.

• Other options:– Narcotics – patches for constant pain, prn pills for

intermittent pain– Muscle relaxers if significant spasm is causing

problems– Injections (steroid/lidocaine) – epidural, facet joint,

disc, piriformis– Surgery – spinal fusion

Cases:

• Mr. A• Negative straight leg

raise, significant paraspinal tightness and tenderness. Exquisite pain with turning.

• Dx: likely muscle tear. • Tx: NSAIDs, heat, muscle

relaxers, mild activity.

• Mrs. B• Positive straight leg raise,

moderate paraspinal tenderness on palpation. Pain in back and leg on arising from seated position

• Dx: likely herniated disc• Tx: NSAIDs, heat, mild

activity, consider imaging since 2+ months. Consider referral to anesthesia for injections.

References:

• Skyrme, A. Common Spinal Disorders. Remedica, 2003.

• Stone, R. Harrison’s Principles of Internal Medicine. McGraw-Hill, 2001.

• Wheeler, S. et al. “Approach to the diagnosis and evaluation of low back pain in adults”. UpToDate. 2008.