Transforaminal Epiduroscopic Basivertebral Nerve Laser Ablation for Chronic Low Back Pain Associated with Modic Changes: A Preliminary Open-Label Study

Background Chronic low back pain (CLBP) arising from degenerative disc disease continues to be a challenging clinical and diagnostic problem whether treated with nonsurgical, pain intervention, or motion-preserving stabilization and arthrodesis. Methods Fourteen patients with CLBP, greater than 6 months, unresponsive to at least 4 months of conservative care were enrolled. All patients were treated successfully following screening using MRI findings of Modic type I or II changes and positive confirmatory provocative discography to determine the affected levels. All patients underwent ablation of the basivertebral nerve (BVN) using 1414 nm Nd:YAG laser-assisted energy guided in a transforaminal epiduroscopic approach. Macnab's criteria and visual analog scale (VAS) score were collected retrospectively at each follow-up interval. Results The mean age was 46 ± 9.95 years. The mean symptoms duration was 21.21 ± 21.87 months. The mean follow-up was 15.3 ± 2.67 months. The preoperative VAS score of 7.79 ± 0.97 changed to 1.92 ± 1.38, postoperatively (P < 0.01). As per Macnab's criteria, seven patients (50%) had excellent, six patients (42.85%) had good, and one patient (7.14%) had fair outcomes. Conclusion The transforaminal epiduroscopic basivertebral nerve laser ablation (TEBLA) appears to be a promising option in carefully selected patients with CLBP associated with the Modic changes.


Introduction
Chronic low back pain (CLBP) is a serious medico-social problem and a cause of disability. According to the United States National Center for Health Statistics reports, 14% of new hospital visits are patients with chronic low back pain. e expense of treating low back pain is over $100 billion per year [1][2][3]. In cases with difficulty in identifying the cause of CLBP, magnetic resonance imaging (MRI) can clearly identify pathologies of CLBP. However, the importance of all these pathologies is still controversial [3]. de Roos and coworkers [4] first introduced evidence of the degenerative vertebral endplate and subchondral bone marrow changes due to an inflammatory process of the endplate on MRI. Modic changes were identified in 19%-59% of patients with lumbar degenerative disk disease (DDD) and prolonged back pain. In most cases, nocturnal pain is characteristic, and it causes most commonly localized constant pain [5][6][7][8].
e Modic change is closely associated with low back pain [9]. A recent study showed that, in nonspecific low back pain (LBP), the prevalence of any type of Modic change was 46%, as opposed to 6% in the general population [10][11][12][13]. Most individuals with Modic changes of more than 90% on MRI will have back pain within one year [8,13,14].
Although a few number of patients need surgical interventions, most of them get better spontaneously with conservative management without much worsening in the middle age. Treatment of CLBP associated with Modic changes has not been established yet. We have treated this condition with the transforaminal epiduroscopic approach (Figure 1) with laser targeting to the basivertebral nerve (BVN) with a good outcome. We want to share its efficacy and safety.

Methods
Patients with isolated CLBP and type 1 or type 2 Modic changes on MRI for more than 6 months' duration that was nonresponsive to at least 3 months of conservative care were analyzed in this single-center retrospective observational study to evaluate the preliminary safety and effectiveness of BVN ablation for the treatment of CLBP with Modic changes.
No specific course of conservative care was mandated before enrollment. Exclusion criteria included were Modic changes without CLBP, spondylolisthesis, scoliosis, history of spinal infection, and prior spinal malignancy. Patients who had radicular symptoms were also excluded. e study was also limited to the L2, L3, L4, L5, and S1 vertebrae. Patients with the identified pathology at more cephalad levels were excluded. Determination of the treatment level(s) was made by clear evidence of Modic type 1 or type 2 changes on MRI and by provocative discography.
Treatment was limited to two or three contiguous vertebral bodies representing one or two motion segments, respectively. A detailed history and physical examination were performed on each patient to exclude origins of pain such as sacroiliac joint, hip, myofascial, genitourinary, gastrointestinal, or gynecologic sources.
We performed 3 steps of provocation tests to check the Modic changes as the source of pain as follows: (1) preoperative provocative discography, (2) intraoperative laser provocation into the basivertebral nerve of the vertebral body with Modic changes, and (3) intraoperative relief of pain assessment by laser reprovocation of the same painful area after completion of the laser ablation procedure.

Surgical Technique.
Fluoroscopic guidance during procedures in the anteroposterior and lateral projection was essential to ensure a precise skin entry point. Anesthesia was limited to 1% local lidocaine 7-10 cc with epinephrine mixed with 1.6% lidocaine 2-3 cc, 3-5 minutes after the 1st injection. In the provocation steps, the main painful point was commonly located in the upper endplate of the lower vertebral body. e needle was inserted into the suprapedicular notch [15] to get access to the vertebral endplate with the Modic change through the epidural space near to the upper endplate of the lower vertebral body. A guide wire was inserted through the needle into the suprapedicular notch. After withdrawing the needle, a tapered cannulated obturator was slid over the guide wire and advanced into the epidural space. A beveled working cannula was introduced over the obturator, and the obturator was removed. Semirigid epiduroscope, NeedleView CH (Lutronic ® , Ilsan, South Korea) (Figure 1), was introduced through the working cannula. For laser ablation, a side-firing Nd : YAG laser cable included in the TELA (transforaminal epiduroscopic laser ablation) system (Lutronic ® , Ilsan, South Korea) with a wavelength of 1414 nm operating in the 0.75-12 watt range was used. However, for our patients, we used a range of 4.5∼6 W. is laser system is capable of thermovibration and can ablate an approximately spherical region of 10 mm diameter (5 mm radius). e laser cable was guided to the predetermined target (BVN terminus) near the Modic change area under fluoroscopic imaging. Each vertebral endplate having a painful Modic change was treated giving a laser locally at the BVN terminus by a 1414 nm Nd : YAG laser system (Figure 1). Self-reported outcome instruments were used to assess the patient's condition preoperatively and at each follow-up. VAS score and Macnab's criteria were      -S1  8  2  2  3  61  24  26  28  Excellent  6  62 M  28  L2-3  8  1  2  2  65  18  20  22  Excellent  7  37 F  6  L3-4  9  1  2  3  68  20  22  25  Good  8  35 F  24  L5-S1  8  1  3  2  58  22  26  24  Excellent  9  55 F  84  L5-S1  8  2  2  3  56  24  23  27  Good  10  31 F  24  L5-S1  8  1  2  2  63  18  21  22  Excellent  11  63 M  48  L2-3  6  6  5  5  54  48  42  42  Fair  12  41 M  5  L5-S1 10  3  2  3  72  28  24  24  Good  13  38 F  14  L4-5  7  3  2  2  55  28  25  25  Good  14 46 M 4 L4-5-S1 7 2 2 2 58 23 23 24 Good Pain Research and Management used in this study. Neurologic examination and adverse event screening and reporting were also performed at each follow-up. e clinical outcomes were evaluated using descriptive statistical analysis. We conducted Student's paired t-test to evaluate the significant difference in the preoperative and postoperative clinical outcome parameter, that is, VAS score. e significance level was considered at 0.05. e statistical software used for the study was SPSS version 20.0 (IBM Corp., Armonk, New York, USA).
ere were no occurrences of infections, discitis, paresis, dural tears, vascular injuries, or systemic complications until the latest follow-up. Furthermore, the patient's VAS scores for back pain and Macnab's criteria were maintained at the final follow-up compared with postoperative scores. All patients maintained their functional neurologic status throughout the entire study follow-up. ere were no device-or procedure-related serious adverse events in this study.

Discussion
e Modic change caused by disc degenerative processes involving damage and microfractures to the vertebral endplates results in the development of edema and inflammation of the adjacent vertebrae [5,11]. Factors associated with endplate damage following degenerative disc disease, ingrowth of new vessels, and collection of inflammatory agents may be important characteristics in the generation of pain [5,6,11,16]. In the normal state, bony endplates have a rich supply of small free nerve endings; degeneration and inflammation will likely trigger the inflammatory pain [13] (Figures 3 and 4).
Modic change is associated with chronic back pain [8]. While previous studies concluded that, among Modic changes, type 1 changes are the strongest and most crucial element in the disc degenerative process in relation to LBP, they also demonstrated that DDD with Modic changes was much more frequently associated with clinical symptoms [6,11,16]. Our patients also had mainly Modic type 1 changes, but some patients with Modic type 2 changes were also symptomatic in provocative discography; so they were also treated with TEBLA.
A study by Becker and coworkers reported that the primary innervation for the vertebral body is by the BVN that enters the bone of the vertebral body via the midline of the posterior cortex. e large, usually paired, neurovascular foramina are located equidistant from each endplate. ese nerves accompany the basivertebral artery and vein [17] ( Figure 3). Previous studies also reported on the innervation within the bone marrow with the presence of immunoreactive neural tissue in rat vertebral bodies and histologically identified intraosseous nerves and neurovascular bundles.
Basivertebral nerve sensitization causes CLBP. Substance P, a peptide neurotransmitter of the tachykinin family, is found within the basivertebral nerve, and there is very strong evidence that this nerve has the potential for transmitting pain signals [16,[18][19][20]. Ablation of this nerve was our target. A recent study also supports ablation of the basivertebral nerve for CLBP associated with Modic changes. ey used radiofrequency through the transpedicular and extrapedicular approach and obtained significant improvement in ODI [17]. Our study differs from this study. We used the transforaminal epiduroscopic approach (Figure 1) with three steps of provocation. We used a laser instead of radiofrequency. Some of the representative cases are illustrated in Figures 5-7. e major limitation of this study is the lack of a comparative control group. Similar to any other retrospective studies, limitations associated with our study include retrospective clinical outcome assessments and small sample size since very few patients actually require surgical intervention. Nevertheless, after TEBLA, we got 93% good-toexcellent results according to Macnab's criteria, and the preoperative VAS score of 7.79 ± 0.97 decreased to 1.92 ± 1.38 at the latest follow-up (P < 0.0001). is result is encouraging and the procedure was safe.

Conclusion
e TEBLA appears to be a promising option in carefully selected patients with chronic low back pain associated with the Modic changes. e treatment improved patients' selfreported outcomes, and the improvement was largely maintained through more than 12 months of the follow-up period.

Conflicts of Interest
e authors declare that they have no conflicts of interest.