Quantitative Discomanometry: Correlation of Intradiscal Pressure Values to Pain Reduction in Patients With Intervertebral Disc Herniation Treated With Percutaneous, Minimally Invasive, Image-Guided Techniques

Abstract

To illustrate quantitative discomanometry's (QD) diagnostic efficacy and predictive value in discogenic-pain evaluation in a prospective study correlating intradiscal pressure values with pain reduction after percutaneous image-guided technique (i.e., percutaneous decompression, PD). During the last 3 years, 36 patients [21 male and 15 female (mean age 36 ± 5.8 years)] with intervertebral disc hernia underwent QD before PD. Under absolute sterilization and fluoroscopy, a mixture of contrast medium and normal saline (3:1 ratio) was injected. A discmonitor performed a constant rate injection and recorded pressure and volume values, thus producing the relative pressure-volume curve. PD was then performed. Pain reduction and improved mobility were recorded at 3, 12, and 24 months after PD using clinical evaluation and a numeric visual scale (NVS; 0 to 10 units). Mean pain values of 7.5 ± 1.9 (range 4 to 8) NVS units were recorded before PD; these decreased to 2.9 ± 2.44 at 3 months, 1.0 ± 1.9 at 12 months, and 1.0 ± 1.9 NVS units at 24 months after PD. Recorded correlations (pressure, volume, significant pain-reduction values) with bilateral statistical significance included a maximum injected volume of 2.4 ml (p = 0.045), P (o) < 14 psi [initial pressure required to inject 0.1 ml of the mixture inside the disc (p = 0.05)], P (max) ≤ 65 psi [greatest pressure value on the curve (p = 0.018)], and P (max) - P (o) ≤ 47 psi (p = 0.038). Patients meeting these pressure or volume cut-off points, either independently or as a total, had significant pain reduction (>4 NVS units) after PD. No complications were noted. QD is an efficient technique that may have predictive value for discogenic pain evaluation. It might serve as a useful tool for patient selection for intervertebral disc therapies.