Cervical epidural steroid injections for symptomatic disc herniations.

OBJECTIVES: Cervical disc herniations are a common cause of radicular pain from nerve root impingement and may necessitate surgical decompression to alleviate symptoms. The use of cervical epidural injections has not been studied in detail. The objective of this retrospective study was to examine the efficacy of cervical epidural steroid injections for the treatment of symptomatic herniated cervical discs. METHODS: Patients with herniated cervical discs without myelopathy that had failed conservative management and were otherwise surgical candidates were offered a trial of cervical epidural injections. The results and benefits of the injections were examined as well as the incidence of proceeding to surgical intervention. RESULTS: Of the 70 treated patients, 44 (63%) had significant relief of their symptoms and did not wish to proceed with surgical treatment. Of the 26 patients who underwent surgical decompression, 92% had successful resolution of their symptoms. The nonsurgical and surgical groups were similar in terms of gender, preinjection symptoms, or number of injections. However, significant differences between the two groups were found with regard to age (P<0.05) and time from initial consultation to initial injection (P<0.05). With an average of 13-month follow-up, 45 (65.3%) patients reported a good/excellent result per Odom criteria. In addition, 53 (75%) would attempt cervical epidural steroid injections again in the future. No complications were noted in our series. CONCLUSIONS: Cervical epidural injections are a reasonable part of the nonoperative treatment of patients with symptomatic cervical disc herniations. The success rates appear to be very similar to prior studies of lumbar epidural injections for symptomatic lumbar disc herniations. It appears that a large percentage of the patients may obtain relief from radicular symptoms and avoid surgery for the follow-up period up to 1 year. In addition, patients older than 50 years and those who received the injections earlier, less than 100 days from diagnosis, seemed to have a more favorable outcome.

The effect of uniform heating on the biomechanical properties of the intervertebral disc in a porcine model.

BACKGROUND CONTEXT: The use of minimally invasive lumbar intradiscal heating techniques, including intradiscal electro-thermal therapy (IDET), endoscopic radio-frequency annuloplasty, nucleoplasty and laser discectomy, for chronic lumbar discogenic pain and contained disc herniation has recently gained popularity. The purported therapeutic mechanisms of these interventions include subtotal nuclectomy, annular nociceptor ablation, and stabilization of the annular fibers. Basic science data elucidating the biomechanical and histomorphologic alterations of heat treatments on disc remain sparse. PURPOSE: The purpose of this study is to examine the effects of uniform heating on biomechanical properties and histomorphology of intervertebral disc tissues using a porcine model. STUDY DESIGN/SETTING: In a laboratory setting, porcine functional spinal units consisting of vertebra-nucleus pulposus-vertebra core and porcine hamstring tendons were harvested. Studies were performed on these tissue samples by uniformly heating the specimens in a constant temperature water bath. Ten porcine lumbar disc core and twenty-five porcine hamstring tendons were utilized as the subjects for this study. The effects of uniform heat treatments on disc core and hamstring tendon were measured for shrinkage, stiffness, and load to failure strength. Histomorphological study was also carried on the same specimen. METHODS: The porcine vertebra-nucleus pulposus-vertebra segments were cored to a uniform 1-cm diameter. The hamstring tendons were cut to uniform 1.2-inch lengths. The tendon specimens were divided into groups of five each and heated in constant temperature water baths of 60 degrees C, 65 degrees C, 70 degrees C, or 75 degrees C for 10 min. Unheated specimens served as controls. The disc core specimens were divided in two group of five each, and tested at room temperature or after immersion in a 70 degrees C bath. The shrinkage was monitored during immersion in the water bath. Biomechanical testing to failure was carried out using mechanical loading on an MTS servohydraulic testing machine operating under stroke control. Strength and stiffness of the tissue was determined. Histomorphology was studied by staining the specimen with hematoxylin and eosin (H&E), and examined under 200 times magnification. Non-heated controls were used for comparisons. RESULTS: The porcine hamstring tendons had no measurable shrinkage in specimens heated up to 65 degrees C. At temperatures above 65 degrees C, the shrinkage was concluded within 2 min of immersion and 70 degrees C appeared to be the optimal temperature, as temperatures higher than this did not demonstrate incremental effects. The disc core samples were heated to 70 degrees C (optimum temperature), and there appeared to be gross contraction of the disc core circumference to visual inspection, but no measurable lengthwise shrinkage could be appreciated. Histologically, the specimens demonstrated progressive loss of individual collagen fiber outline as the temperature increased. In the tendons, at 75 degrees C all of the fibers appear to be fused together, and the voids between individual collagen fibers were no longer present. Biomechanical testing revealed that the tendons undergo a substantial reduction in stiffness after heating. The mean tendon stiffness for the unheated specimens was 19,356 psi, while the corresponding value for the heated tendons was 1023 psi. These were significantly different using the paired t-test at p=0.0043. For the disc core samples, there was no significant difference in either stiffness (p=0.182) or failure strength (p=0.998) after heating. All failures occurred in mid-substance of the specimen. CONCLUSIONS: The application of uniform heating to nucleus pulposus disc core caused visible contraction of its circumference but not lengthwise shrinkage. The same heating shrinks the hamstring tendon and reduces its stiffness. Ultimate failure strength of the disc core specimen remains unchanged. The failure data was not obtainable for the tendon due to premature slippage from the fixation apparatus before failure. The results of this study fail to support a biomechanical justification for the application of uniform heat treatment to the whole intervertebral disc. Heating annulus fibrosus and nucleus pulposus separately to specific temperatures may have potential clinical benefits.