A 50 y/o friend of yours called for you. He refers low back pain radiating to his left leg from approximately 2 weeks. “help me doc – he says – I have a sciatica, a dog is biting my buttock, can you favor me with an urgent RMN?”. He is very suffering. During the straight leg raise test (SLR) he develops pain down the left leg to 30-40 degree. The crossed straight leg raise test (CSLR) is negative. There are no changes in bowel or bladder habits.

“Point your big toe to your nose” – you ask putting the hand on the your friend’s feet.

Conclusion

Clinical history, physical examination and pain treatment are the first step for the evaluation and treatment of low back pain. If there aren’t red flags rarely an urgent imaging is necessary.
Recommendation n. 4 of the ACP and APS Guideline (2007) says that RMN is indicated only if patients with symptoms of radiculopathy are potential candidates for surgery.
The SLR and CSLR test have a poor performance to identify this patients.
The presence of a motor deficit like a weak ankle dorsi flexion is stongly associated with a disc herniation that may be potentialy candidated to surgery.

Could the physical examination evidence the neurologic level of disc herniation?

Bibliography

BR Corwell
The emergenct department evaluation, management, and treatment of back pain.
Emerg Med Clin N Am 28 (2010) 811–839

DA van der Windt
Physical exmamination for lumbar radiculopathy due to disc herniation in patients with low back pain.
Cochr Datab Syst Rev 2010 Feb 17 (2) CD 007431

R.Chou
Diagnosis and treatment of low back pain: a joint clinical practice guideline from the American College of Physicians and the American Pain Society.
Ann Intern Med. 2007;147:478-491.