Automated pressure-controlled discography with constant injection speed and real-time pressure measurement

Automated Pressure-Controlled Discography in Patients Undergoing Anterior Lumbar Interbody Fusion for Discogenic Back Pain

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To compare the clinical outcomes of patients undergoing anterior lumbar interbody fusion (ALIF) with or without automated pressure-controlled discography (APCD) before the procedure.

METHODS

Patients (n = 36) who underwent ALIF for lumbar discogenic back pain between 2008 and 2013 and were followed for more than 6 months were enrolled in this study. APCD was performed to identify discogenic back pain. Preoperative x-rays, computed tomography images, and magnetic resonance images were obtained. The intervertebral disc height, type of Modic change, grade of disc degeneration, and fusion rate were determined. Additionally, the presence or absence of high-intensity zone and vacuum disc were checked preoperatively. Clinical evaluation was performed by visual analog scale (0 = no pain, 10 = worst pain imaginable), Oswestry Disability Index (ODI), and 36-Item Short Form Health Survey before surgery and every 6 months postoperatively.

RESULTS

The average patient age was 53.3 years (range, 31-73 years). The mean follow-up durations were 19.7 months. Seventeen patients (the APCD-ALIF group) underwent ALIF after APCD, and 19 patients underwent ALIF without APCD. The APCD-ALIF group had significantly improved clinical outcomes compared with the control group (visual analog scale score 1.8 ± 1.6 vs. 3.3 ± 2.4; P = 0.039: ODI score 6.7 ± 6.3 vs. 12.1 ± 6.8; P = 0.019). The surgical improvement rate was significantly associated with ODI score (P = 0.005).

CONCLUSIONS

The results of this study confirm that APCD aids surgical outcomes of ALIF in patients with suspected lumbar discogenic pain. We recommend performing APCD before ALIF to confirm lumbar discogenic pain.

In vivo discography in degenerate porcine spines revealed pressure transfer to adjacent discs

STUDY DESIGN

In vivo experimental porcine study.

OBJECTIVE

To investigate if discography induced pressure increase in adjacent degenerate discs.

SUMMARY OF BACKGROUND DATA

Despite refinements in the past 2 decades, the validity of discography is debated. Discography in healthy pigs has shown that the pressure increase during disc injection transmits to adjacent discs, a potential source for false positive responses.

METHODS

Degeneration in 1 lumbar disc was induced in 10 pigs by drilling a hole through the endplate. Intradiscal pressure was recorded using a 0.36-mm fiber-optic pressure transducer inserted into nucleus pulposus through a 22-gauge needle. The pressure was measured simultaneously in 2 adjacent discs during slow (0.03 mL/s) automated contrast injection into 1 of the discs up to 8 bar (116 psi). Ten adjacent discs were prefilled with contrast from previous discogram. A pressure increase 2 psi or more above baseline was defined as increased pressure in adjacent discs. Pressure was recorded until 15 minutes after injection.

RESULTS

A total of 28 discograms were successfully performed. A pressure increase during injection was detected in 57% (16) of the 28 adjacent discs with mean 3.2 psi (1.7-8.2; standard deviation, 1.8), corresponding to a mean increase above baseline of 11%. Of those 16 adjacent discs, 4 were nondegenerate and 12 degenerate, of which 7 were prefilled. Fifteen minutes after injection, 89% of adjacent discs displayed increase in pressure of mean 14% above baseline.

CONCLUSION

Discography induced pressure increase in adjacent discs in a degenerate disc model, something not reported earlier. If present, also in human spine pressure transmission, may be a potential cause for false positive discography responses.

Effect of intradiscal monopolar pulsed radiofrequency on chronic discogenic back pain diagnosed by pressure-controlled provocative discography: a one year prospective study

Objective

To investigate the efficacy and safety of percutaneous intradiscal monopolar pulsed radiofrequency (PRF) in patients with chronic disabling discogenic back pain.

Method

Twenty-six subjects (7 males; mean age 43.2 years) with chronic back pain refractory to active rehabilitative management were recruited. All subjects underwent MRI for evaluation of Modic changes, and monopolar PRF (20 min at 60 V) at the center of target lumbar intervertebral disc confirmed by pressure-controlled provocative discography. Clinical outcomes were measured by the visual analogue scale (VAS), Oswestry disability index (ODI), and sitting tolerance time (ST) for 12 months after treatment. Successful clinical outcome was described as a minimum of 2 point reduction in VAS compared with the baseline at each follow-up period.

Results

The mean VAS for low back pain reduced significantly from 6.4±1.1 at pre-treatment to 4.4±1.9 at 12 months (p<0.05). The mean ODI score was 47.3±15.4 points at pre-treatment and 36.7±19.5 at 12 months (p<0.001). The ST was 27.8±20.4 minutes at pre-treatment and 71.5±42.2 at 12 months (p<0.001). However, successful clinical outcome was achieved at 58%, 50%, and 42%, measured at 3, 6, and 12 months post-treatment. There were no significant relationship between the clinical outcome and Modic changes; no adverse events were recorded.

Conclusion

The results demonstrated that the application of intradiscal monopolar PRF might be relatively effective but limited; successful intervention for chronic refractory discogenic back pain is needed. To achieve the optimal outcome through intradiscal PRF, we suggested further studies about stimulation duration, mode, and intensity of PRF.