Timothy T. Davis

The IDET Procedure for Chronic Discogenic Low Back Pain

Study Design. Retrospective study with independent evaluation of patient outcomes approximately 1 year post-intradiscal electrothermal therapy (IDET). Objective. To assess functional status, symptoms, and subsequent treatments of patients treated with IDET. Summary of Background Data. IDET was introduced as a procedure for discogenic pain. Several studies reported improvement in >70% of patients. Methods. Seventeen physicians referred 60 patients. Each patient had a positive discogram and had been treated with IDET. Patients were contacted approximately 1 year post-IDET, answered a telephone interview, and completed a self-administered questionnaire. Overall patient satisfaction, pain, functional and work status, analgesic usage, and subsequent treatments were noted. Kaplan-Meier survival curve was generated to predict the percentage that would undergo lumbar surgery after IDET. Results. Average age was 40 years (range 25–64 years) with 66% males and 34% females. Of the 44 patients who responded, 6 patients had a lumbar surgery within 1 year. Their outcomes were excluded from descriptive analysis; 97% continued to have back pain, 11 (29%) reported more pain post versus pre-IDET, 15 (39%) had less pain, and 11 (29%) reported no change; 11 (29%) reported using more pain medication post-IDET, 10 (26%) used the same, 12 (32%) used less, and 5 (13%) used none; 19 (50%) were dissatisfied with IDET, 14 (37%) were satisfied, and 5 (13%) were undecided; 20 (53%) would have the procedure again, 12 (31%) would not, and 6 (16%) were unsure. Most patients wore a brace >6 hours/day after surgery (duration 1–15 months). Sixteen (42%) were employed full-time pre-IDET and 11 (29%) were employed full-time post-IDET. Conclusion. At 1-year post-IDET, half of patients were dissatisfied with their outcome. The percentage of patients on disability remained constant. The estimated proportion of patients undergoing fusion was predicted to be 15% at 1 year and 30% at 2 years.

Is the lateral jack-knife position responsible for cases of transient neurapraxia?

OBJECTIVE The lateral jack-knife position is often used during transpsoas surgery to improve access to the spine. Postoperative neurological signs and symptoms are very common after such procedures, and the mechanism is not adequately understood. The objective of this study is to assess if the lateral jack-knife position alone can cause neurapraxia. This study compares neurological status at baseline and after positioning in the 25° right lateral jack-knife (RLJK) and the right lateral decubitus (RLD) position. METHODS Fifty healthy volunteers, ages 21 to 35, were randomly assigned to one of 2 groups: Group A (RLD) and Group B (RLJK). Motor and sensory testing was performed prior to positioning. Subjects were placed in the RLD or RLJK position, according to group assignment, for 60 minutes. Motor testing was performed immediately after this 60-minute period and again 60 minutes thereafter. Sensory testing was performed immediately after the 60-minute period and every 15 minutes thereafter, for a total of 5 times. Motor testing was performed by a physical therapist who was blinded to group assignment. A follow-up call was made 7 days after the positioning sessions. RESULTS Motor deficits were observed in the nondependent lower limb in 100% of the subjects in Group B, and no motor deficits were seen in Group A. Statistically significant differences (p < 0.05) were found between the 2 groups with respect to the performance on the 10-repetition maximum test immediately immediately and 60 minutes after positioning. Subjects in Group B had a 10%-70% (average 34.8%) decrease in knee extension strength and 20%-80% (average 43%) decrease in hip flexion strength in the nondependent limb. Sensory abnormalities were observed in the nondependent lower limb in 98% of the subjects in Group B. Thirty-six percent of the Group B subjects still exhibited sensory deficits after the 60-minute recovery period. No symptoms were reported by any subject during the follow-up calls 7 days after positioning. CONCLUSIONS Twenty-five degrees of right lateral jack-knife positioning for 60 minutes results in neurapraxia of the nondependent lower extremity. Our results support the hypothesis that jack-knife positioning alone can cause postoperative neurological symptoms.

Lumbar intervertebral thermal therapies.

In hopes of improving outcomes for patients with discogenic pain, less invasive techniques that reduce trauma and shorten the recovery period have been developed. This article attempts to present a comprehensive description of minimally invasive techniques, specifically heat treatments, for lumbar disc disease. The goal is to inform and educate the reader on the various thermal therapies available for lumbar disc disease by evaluating the scientific data in an objective manner.

Femoral Neurogram Before Transpsoas Spinal Access at L4-5 Intervertebral Disk Space: A Proposed Screening Tool.

Study Design: Observational study. Objective: To illustrate the variability of the course of the femoral nerve across the L4–5 disk space, and to present a novel application of transforaminal epidural steroid injections (TFESI) in the visualization of femoral nerve roots. Summary of Background Data: A concern regarding the lateral retroperitoneal transpsoas approach is the proximity of the lumbar plexus. Current techniques of assessing the proximity of neural tissue to the L4–5 disk space have limited capabilities. Methods: A total of 100 patients were selected for L4–5 TFESI (L4 selective nerve root blocks) because of lumbar radiculopathy. L4 neurograms were obtained while performing L4–5 TFESI under flouroscopic guidance, using a retroneural technique. The course of the L4 root/femoral nerve was then evaluated under fluoroscopy in the anteroposterior and lateral planes. Images were then reviewed by a radiologist, physiatrist, and 2 orthopedic spine surgeons. Results: Fluoroscopic evaluation revealed that the pattern of location of the femoral nerve was highly variable. In males, it was located 4.7% in zone 2, 32.5% in zone 3, 53.5% in zone 4, and 9.3% in zone P. In female patients, it was located 7.0% in zone 2, 14% in zone 3, 54.4% in zone 4, and 24.6% in zone P. Conclusions: An L4 neurogram will provide an accurate trajectory of L4 root/femoral nerve as it crosses the L4–5 intervertebral disk space. An accurate assessment is essential to help minimize the increasing frequency of thigh pain, paresthesias, and weakness associated with the lateral access to the L4–5 intervertebral disk space. Femoral nerves that fall within zones 2 and 3 will require more manipulation during retraction and may be better suited with a different surgical approach.

Can triggered electromyography be used to evaluate pedicle screw placement in hydroxyapatite-coated screws: an electrical examination.

Objectives: To assess if hydroxyapatite (HA)-coated titanium pedicle screws exhibit the same electroconductive characteristics as non–HA-coated screws. Methods: Resistance measurements were obtained from a random sampling of 10 HA-coated pedicle screws and 10 non–HA-coated screws, and surgical conditions simulated. Surface resistivity measurements were taken for each screw to determine voltage drop over its entire length. Results: The non–HA-coated screws tested showed low resistive properties and proved to be an ideal conductor of electrical current. The resistive properties associated with the HA-coated pedicle screws were found to be similar to those of commonly used insulators removing the effectiveness of triggered electromyographic responses. Conclusions: Based on test results, these data suggest that the resistance value of the HA-coated screw is large enough to prevent modern Intra-Operative Monitoring (IOM) equipment from delivering the necessary current through the shank of the screw to create a diagnostic electromyographic response. Any response that would be produced would be because of shunting of electric current from the non-coated head of the screw into adjacent tissue and not through the shank of the screw. These study results suggest that HA-coated screws cannot be stimulated to assist in determining the accuracy of pedicle screw placement.