MRI Findings for Low Back Pain Can Be Misleading

SEATTLE — MRI findings within 12 weeks of serious low back pain inception are unlikely to represent new structural change, according to a study at Stanford (Calif.) University.

“We had hypothesized that serious low back pain episodes would be commonly associated with new and specific findings on MRI, and we were really thinking about such things as annular tears, fissures, disk herniation, new disk protrusion, and end plate changes. But … the data didn't support that hypothesis,” said Dr. Eugene Carragee, professor of orthopedic surgery, at the annual meeting of the North American Spine Society.

The findings emerged from a 5-year, prospective, observational study with baseline and post-low back pain monitoring of 200 subjects with lifetime histories free of significant low back pain problems but who were at high risk for new low back pain episodes, Dr. Carragee said.

At baseline, patients underwent physical examinations, plain radiographs, and MRIs; they were then followed for 5 years and participated in a detailed telephone interview every 6 months. Those with a new severe low back pain episode were assessed with diagnostic tests. New MRIs, taken within 6–12 weeks of the start of a new low back pain episode, were then compared with baseline (asymptomatic) images.

Within the total cohort, 25% were evaluated with a lumbar MRI for clinically serious low back pain episodes occurring during follow-up, and 6% had a primary radicular complaint. Of those 51 patients, 43 either had an unchanged MRI or showed regression of baseline changes.

“There are relatively few new findings compared to the burden of disease at baseline. That is, when you put the scan up and you see 5 or 10 things—an annular fissure or perhaps some facet arthrosis—the overwhelming amount of those things were there years before,” Dr. Carragee said.

The most common progressive findings were disk signal loss (10%), progressive facet arthrosis (10%), or increased end plate changes (4%). Only two patients, both with primary radicular complaints, had new findings of probable clinical significance.

“Both had primary leg pain and one had a new disk extrusion with root compression but no trauma. The other had some degenerative disease at the L4–5 level and, at follow-up scan, had a grade 1 spondylolisthesis with increased stenosis,” Dr. Carragee said.

Subjects involved in current compensation claims were more likely to have an MRI scan to evaluate a low back pain episode but were unlikely to have significant new findings.

“In usual practice, if a patient has minor trauma from a fender bender or a fall and you get an MRI, it shows a high-intensity zone, an annular fissure, or end plate changes, and the normal thing that we think is that these findings are … attributed to an acute event and are related to the symptoms, but that's not what we found,” he said, adding that fewer than 1 in 12 annular fissures and 1 in 15 disk protrusions found on scans were new.

“In acute low back pain, MRI findings within 12 weeks of events were highly unlikely to represent new structural changes to the spine, and this means [physicians] directing treatment need to be careful before saying, 'Aha! I found the cause'” of a patient's low back pain, Dr. Carragee concluded.

'Physicians directing treatment need to be careful before saying, “Aha! I found the cause.”' DR. CARRAGEE

SEATTLE — MRI findings within 12 weeks of serious low back pain inception are unlikely to represent new structural change, according to a study at Stanford (Calif.) University.

“We had hypothesized that serious low back pain episodes would be commonly associated with new and specific findings on MRI, and we were really thinking about such things as annular tears, fissures, disk herniation, new disk protrusion, and end plate changes. But … the data didn't support that hypothesis,” said Dr. Eugene Carragee, professor of orthopedic surgery, at the annual meeting of the North American Spine Society.

The findings emerged from a 5-year, prospective, observational study with baseline and post-low back pain monitoring of 200 subjects with lifetime histories free of significant low back pain problems but who were at high risk for new low back pain episodes, Dr. Carragee said.

At baseline, patients underwent physical examinations, plain radiographs, and MRIs; they were then followed for 5 years and participated in a detailed telephone interview every 6 months. Those with a new severe low back pain episode were assessed with diagnostic tests. New MRIs, taken within 6–12 weeks of the start of a new low back pain episode, were then compared with baseline (asymptomatic) images.

Within the total cohort, 25% were evaluated with a lumbar MRI for clinically serious low back pain episodes occurring during follow-up, and 6% had a primary radicular complaint. Of those 51 patients, 43 either had an unchanged MRI or showed regression of baseline changes.

“There are relatively few new findings compared to the burden of disease at baseline. That is, when you put the scan up and you see 5 or 10 things—an annular fissure or perhaps some facet arthrosis—the overwhelming amount of those things were there years before,” Dr. Carragee said.

The most common progressive findings were disk signal loss (10%), progressive facet arthrosis (10%), or increased end plate changes (4%). Only two patients, both with primary radicular complaints, had new findings of probable clinical significance.

“Both had primary leg pain and one had a new disk extrusion with root compression but no trauma. The other had some degenerative disease at the L4–5 level and, at follow-up scan, had a grade 1 spondylolisthesis with increased stenosis,” Dr. Carragee said.

Subjects involved in current compensation claims were more likely to have an MRI scan to evaluate a low back pain episode but were unlikely to have significant new findings.

“In usual practice, if a patient has minor trauma from a fender bender or a fall and you get an MRI, it shows a high-intensity zone, an annular fissure, or end plate changes, and the normal thing that we think is that these findings are … attributed to an acute event and are related to the symptoms, but that's not what we found,” he said, adding that fewer than 1 in 12 annular fissures and 1 in 15 disk protrusions found on scans were new.

“In acute low back pain, MRI findings within 12 weeks of events were highly unlikely to represent new structural changes to the spine, and this means [physicians] directing treatment need to be careful before saying, 'Aha! I found the cause'” of a patient's low back pain, Dr. Carragee concluded.

'Physicians directing treatment need to be careful before saying, “Aha! I found the cause.”' DR. CARRAGEE

SEATTLE — MRI findings within 12 weeks of serious low back pain inception are unlikely to represent new structural change, according to a study at Stanford (Calif.) University.

“We had hypothesized that serious low back pain episodes would be commonly associated with new and specific findings on MRI, and we were really thinking about such things as annular tears, fissures, disk herniation, new disk protrusion, and end plate changes. But … the data didn't support that hypothesis,” said Dr. Eugene Carragee, professor of orthopedic surgery, at the annual meeting of the North American Spine Society.

The findings emerged from a 5-year, prospective, observational study with baseline and post-low back pain monitoring of 200 subjects with lifetime histories free of significant low back pain problems but who were at high risk for new low back pain episodes, Dr. Carragee said.

At baseline, patients underwent physical examinations, plain radiographs, and MRIs; they were then followed for 5 years and participated in a detailed telephone interview every 6 months. Those with a new severe low back pain episode were assessed with diagnostic tests. New MRIs, taken within 6–12 weeks of the start of a new low back pain episode, were then compared with baseline (asymptomatic) images.

Within the total cohort, 25% were evaluated with a lumbar MRI for clinically serious low back pain episodes occurring during follow-up, and 6% had a primary radicular complaint. Of those 51 patients, 43 either had an unchanged MRI or showed regression of baseline changes.

“There are relatively few new findings compared to the burden of disease at baseline. That is, when you put the scan up and you see 5 or 10 things—an annular fissure or perhaps some facet arthrosis—the overwhelming amount of those things were there years before,” Dr. Carragee said.

The most common progressive findings were disk signal loss (10%), progressive facet arthrosis (10%), or increased end plate changes (4%). Only two patients, both with primary radicular complaints, had new findings of probable clinical significance.

“Both had primary leg pain and one had a new disk extrusion with root compression but no trauma. The other had some degenerative disease at the L4–5 level and, at follow-up scan, had a grade 1 spondylolisthesis with increased stenosis,” Dr. Carragee said.

Subjects involved in current compensation claims were more likely to have an MRI scan to evaluate a low back pain episode but were unlikely to have significant new findings.

“In usual practice, if a patient has minor trauma from a fender bender or a fall and you get an MRI, it shows a high-intensity zone, an annular fissure, or end plate changes, and the normal thing that we think is that these findings are … attributed to an acute event and are related to the symptoms, but that's not what we found,” he said, adding that fewer than 1 in 12 annular fissures and 1 in 15 disk protrusions found on scans were new.

“In acute low back pain, MRI findings within 12 weeks of events were highly unlikely to represent new structural changes to the spine, and this means [physicians] directing treatment need to be careful before saying, 'Aha! I found the cause'” of a patient's low back pain, Dr. Carragee concluded.

'Physicians directing treatment need to be careful before saying, “Aha! I found the cause.”' DR. CARRAGEE