On physical examination, one pearl can be garnered from simply observing the patient’s posture. Patients with a known history of herniated disc and sciatica usually avoid a flexed posture as this places pressure on the nerve roots. However, if they have cauda equina syndrome or cord compression, they tend to favor a flexed posture in order to allow more room for the spinal cord in the spinal canal. This is similar to the classic posture of spinal stenosis patients, who tend to lean on their shopping carts in the grocery store. Tenderness on percussion of the spinous processes, an underutilized physical examination maneuver, is a red flag for infection and fracture.
Cognitive Forcing Strategies for Low Back Pain Presentations
I find cognitive forcing strategies helpful in picking up serious causes of low back pain. In addition to the classic cognitive forcing strategy, “if you’re thinking renal colic, think leaking AAA,” I use, “if you’re thinking pyelonephritis, think spinal epidural abscess,” and “known cancer + new back pain = spinal metastases until proven otherwise.”
Cauda Equina Syndrome Is a Clinical Diagnosis, Not a Radiographic One
It is vital to understand that cauda equina syndrome is a clinical diagnosis, not a radiographic one, and that it can have an acute as well as chronic onset, with one in 1,000 patients with sciatica developing cauda equina syndrome. The diagnostic criteria are the presence of both: