Intradiscal pressure after repeat intradiscal injection of hypertonic saline: an experimental study

Abstract

IntroductionChemonucleolysis with chymopapain, which was first clinically used by Smith [12], is an effective treatment for intervertebral disc herniation. However, anaphylactic reactions, in particular, have limited the use of this treatment. To prevent anaphylactic reactions, skin testing and the use of H1 and H2 blocking agents have been recommended. Anaphylactic reactions to chymopapain have decreased in frequency over the years [5]. However, the risk of anaphylaxis still remains. Accordingly, an alternative substance for chemonucleolysis has been sought.Proteoglycans are major structural components of the intervertebral disc, and their concentration and organization in the extracellular matrix have a considerable influence on its mechanical properties. Bayliss et al. [2] described a reduction in proteoglycan synthesis rates when disc hydration was decreased.Shioda [11] suggested a mechanism for a decrease in the intradiscal pressure after hypertonic saline injection, by which partial cell necrosis leads to a decrease in matrix production. Released lysosomal enzymes from the cells could then cause partial proteolysis. As a result, the amount of proteoglycan decreases, which means the water-binding capacity decreases. He suggested that the direct effect of hypertonic saline on the matrix was minimal.We have previously reported intradiscal pressure after intradiscal injection of hypertonic saline in rabbits, but the results of the study found that hypertonic saline injected Abstract Chemonucleolysis with chymopapain is an effective alternative to an operation for the treatment of some patients who have a lumbar intervertebral disc herniation. However, chymopapain is associated with rare but serious complications. Accordingly, alternative substances for chemonucleolysis have been sought. The main beneficial effect of chemonucleolysis derives from the decrease in the intradiscal pressure. We have previously reported that hypertonic saline injected into the intervertebral discs decreased the intradiscal pressure, but only temporarily. The present experimental study investigated changes in the intradiscal pressure after a repeat intradiscal injection of hypertonic saline. The lumbar intervertebral discs of 18 living rabbits were examined: 10% hypertonic saline was injected intradiscally just once in 12 rabbits, and the same dosage was injected again, 4 weeks later, in the same animals. The intradiscal pressure was measured at 1, 4, 8, and 12 weeks after the second injection. The remaining six rabbits were used as controls, without puncture and without injection. The intradiscal pressure of the group with repeat hypertonic saline injection at 4 weeks was significantly lower than that of the control group. The decreased pressure showed a tendency to increase at 8 weeks, and it had recovered at 12 weeks. The results of this study suggest that repeat hypertonic saline injections may be clinically useful.

Intradiscal pressure measurements in normal discs, compressed discs and compressed discs treated with axial posterior disc distraction: an experimental study on the rabbit lumbar spine model

“…Although the high range of physiological IVD pressure was not expected, the interindividual range of pressure at corresponding levels of the non-treated rabbit spine was far less extensive. Most reported studies on IVD pressure measurements examined one single disc [2,14,15,[20][21][22]30] or the adjacent discs to fusion [4,5,16,25,29]. We conclude that it is important to compare only corresponding levels of the spine with respect to intradiscal pressure measurements.…”

Endplate Fracture Associated with Intradiscal Dextrose Injection

“…The hyperosmolar nature of high concentrations of dextrose may in effect, cause imbibition (the absorption of a fluid, as the taking up of water by a gel) of the nucleus pulposis, with subsequent increases in intradiscal pressure. Studies of hypertonic saline injections in rats produced decreased intradiscal pressures over 1-12 weeks following injection (44)(45), but the pressures within the first two days were not measured. The potential increase in intradiscal pressures from both the volume of injection, and the potential osmotic effect of swelling may create increased pressure on the endplates.…”

“…Most of the agents have achieved only limited success. There have been animal studies investigating other substances including phenol-glycerin and osmic acid (24), hypertonic saline (24)(25)(26), and chondroitinase (27)(28). Diagnostic intradiscal injections include the use of saline and iohexol for discography, and incorporation of intradiscal antibiotics as prophylaxis against bacterial disciitis.…”

In vivomeasurement of the pressure signal in the intervertebral disc of an anesthetized sheep

“…Since that time, few in vivo studies have been published. [10][11][12][13] Apart from more demanding ethical aspects conducting animal and human research, it has been suggested that the large dimensions of these conventional sensors (usually >1 mm diameter) could interfere with the natural disc behavior and lead to disc degeneration. 14 So minimally invasive sensors could represent a significant advance in this field and fiber optic sensors (FOS) seem to represent an interesting alternative to the large conventional sensors.…”