Methylene blue injections effectively treated discogenic low back pain in study

Improvements in scores for pain and function were similar at 3- and 12-months follow-up, suggesting the injection's effects are long lasting.

Methylene blue injections may be an effective treatment alternative to interbody fusion for patients with discogenic low back pain, a prospective study suggests. Most patients with discography-confirmed discogenic pain treated with the injections maintained significant improvements in pain and disability at 1-year follow-up, the study authors noted.

Baogan Peng, MD, and colleagues at the 304th Hospital in Beijing, China, conducted the study, which initially included 52 consecutive patients suffering from chronic low back pain that had not responded to 6 months or more of conservative treatment, including physical therapy and NSAIDs. Of these 52 patients, 47 agreed to undergo methylene blue injections should their diagnosis of discogenic pain be confirmed via discography, according to the study.

Using discography, surgeons confirmed discogenic pain in 24 patients — 15 men and nine women averaging 43.4 years of age. These patients had experienced low back pain for an average of 64 months, with 18 patients experiencing pain at a single level and six experiencing pain at two levels, according to the study, published in the European Spine Journal.

Surgeons injected 1 ml of 1% methylene blue (10 mg, Sujichuan Pharmaceutical Ltd.) into patients' diseased discs using the discographic needle during discography. The injection was followed by an injection of 1 mL of 2% lidocaine to relieve postop pain, the authors reported.

All patients were confined to their bed for the first postoperative day and were instructed to avoid strenuous exercise for 3 weeks, the authors noted.

Postoperatively, 21 of the 24 patients (87%) had clinically important improvements in Visual Analog Scale (VAS) pain scores, with five patients having complete pain relief and six noting a dramatic improvement. Only two patients showed no improvement, and one had a modest improvement initially, but pain relapsed at 3 months follow-up, according to the study.

Overall, mean VAS pain scores decreased a significant 5.34 points, from 7.52 preoperatively to 2.18.

Investigators also found significant improvements in function in 21 of the 24 patients (87%), with an average 68% improvement in Oswestry Disability Index (ODI) scores.

"When the VAS and the ODI at 3 months were compared with those at 12 months (or more), no significant difference was found," the authors reported. "The results indicated that the effectiveness of intradiscal [methylene blue] injection for the treatment of discogenic low back pain was long lasting."

Of the 24 patients, surgeons achieved successful results in 17 of 18 patients (94%) who were treated at a single level and in four of six patients (67%) treated at two levels, the authors noted.

VAS scores decreased an average of 5.65 points among patients treated at a single level and decreased an average of 4.4 points for those treated at two levels (P=.007).

ODI scores improved an average of 35.72 points among those treated at a single level and improved an average of 24.5 points among those treated at two levels (P=.029), according to the study.

No patients experienced side effects or complications, the authors noted.

For more information:
Peng B, Zhang Y, Hou S, et al. Intradiscal methylene blue injection for the treatment of chronic discogenic low back pain. Eur Spine J. 2007;16:33-38.