Intradiscal Electrothermal Annuloplasty

Introduction:
Intradiscal Electrothermal Annuloplasty (IEA) is a relatively new procedure to heat the intervertebral disc for the purpose of relieving discogenic pain. In May of 1997 the first author began treating patients utilizing the IEA procedure. Investigation of procedural efficacy at 6 months is ongoing, patients data being included in the data set as they reach 6 months post procedure. This abstract represents the ongoing 6-month follow-up results for the first 33 patients undergoing the IEA procedure.

Methods and Materials:
The IEA procedure utilizes an Oratec Interventions 30cm SPINECath catheter, with a 6cm active tip. Utilizing normal discographic technique, the catheter is inserted anteriorly into the annulus or nucleus via a 17-gauge introducer. The active tip is typically advanced anterior-laterally inside the nuclear tissue, and is directed circuitously to return posteriorally, ideally achieving full 360° penetration. (Figure 1)

Figure 1. Typical catheter placement

Following catheter positioning, electrothermal heat is generated at the active tip, commencing at 65°C and increasing incrementally to (typically) 85°C, for a mean duration of 14 minutes.

From 5/97 to 2/98 we enrolled our first 32consecutive patients undergoing the IEA procedure into a prospective outcome study. Prior to IEA all patients underwent pressure-controlled discography to determine the number of symptomatic discs, the location of annular tears, and to categorize the sensitivity of the disc annulus to pressurization.

Results:
Outcome at 6 months was assessed by examining changes between the baseline questionnaire (administered to each patient just prior to their undergoing the IEA procedure) and a 6 month follow-up questionnaire. Two primary comparative outcome instruments were utilized. A mean 1.8 point decrease on a 10-point visual analogue pain scale was found. An analysis of the 24-point Roland & Morris Disability questionnaire returned a mean 4-point decrease in disability (p<0 .05).

At follow-up, patient satisfaction with the procedure and its outcome was examined on a modified 4-point NASS Patient Satisfaction Index. 78.1% of the sample were satisfied with their outcome, reporting that they would repeat the procedure for the same outcome. 21.9% felt themselves to be the same or worse than before undergoing the IEA procedure.

At follow-up, 5 subjective improvement-in-activity variables were also examined. 53.1% of the sample reported an improvement in general overall activity levels, 40.6% in sitting, 40.6% in standing, 37.5% in walking and 40.6% reported an improvement in their sleeping.

Conclusions:
In the early stages of investigation, intradiscal electrothermal annuloplasty appears promising as a technique to reduce chronic pain of discogenic origin, and as a potential alternative to invasive spine surgery. Further study is warranted, both to compare efficacy against other intradiscal heating procedures and to assess the precise pathology most successfully treated by the procedure. The current study is ongoing, and outcome results at one year are pending.