Successful annuloplasty using the cone-beam computed tomography-assisted radiofrequency thermocoagulation system in a patient with severe vertebral deformity: a case report – JA Clinical Reports

This case report provides two important suggestions. First, real-time image guidance of CBCT has led to technical success in needle placement. Second, the steerable radiofrequency thermocoagulation probe of Trigger-Flex Dart (Elliquence, LLC, Baldwin, NY) provided optimal accessibility to the posterior annulus at the L5/S1 degenerative disc with severe vertebral deformity.

There are many different treatment choices for lumbar disc diseases, but the most effective strategy has not been determined yet [4]. The preferred first-line treatments are physical therapy and pharmacological management, after excluding “red flags” suggesting serious pathologies [8, 9]. The less invasive options of local anesthesia and steroids, such as epidural injections and nerve root blocks, can be considered for diagnostic and therapeutic pain relief [9]. Provocative discography is essential for diagnosing lumbar disc disease [9, 10]. With negative discography, other causes need to be ruled out. With positive discography, minimally invasive percutaneous procedures can be considered, such as coagulation of the posterior annulus, decompression of the painful disc, and chemonucleolysis [4]. Among several surgical options, minimally invasive decompression surgeries have recently become popular, providing small openings with microscopic decompression and endoscopic spinal discectomy [9].

Although radiofrequency thermocoagulation is the good therapy for lumbar disc pathologies [3], it is often difficult to advance the needle at the L5/S1 degenerative disc because of degenerative changes in the spine (osteoarthritis, calcified and hypertrophic ligaments, severe scoliosis) and other anatomical structures (high iliac crest and transverse process) [2, 3]. In these cases, to locate the needle at the posterior annular surface is even more difficult [3]. We speculate that a CBCT-assisted radiofrequency coagulation system can improve the success rate of annuloplasty at the L5/S1 degenerative disc with severe spinal deformity and may preserve disc height with resultant spine stability. The L5/S1 disc diminution was within 1 mm during the procedure. Further studies are required to confirm the clinical relevance of these imaging findings.

A potent chemonucleolytic drug with condoliase reduces intradiscal pressure on the nerve root and improves lumbar disc herniation symptoms [11]. However, it may not be reasonable given the patient’s contralateral dysraphism. It may decrease disc height, disrupting coronal balance, and precipitating foraminal stenosis and radiculopathy [12]. Total disc replacement is another motion-preserving surgery, but concerns remain regarding the future of the implant in younger patients [9, 10].

CBCT-guided percutaneous nucleoplasty is highly effective in challenging lumbar disc herniation cases, with adequate procedure time and radiation dose [2]. The high spatial and contrast resolution of multiplanar reconstruction images obtained from CBCT datasets allow precise evaluation of complex anatomical and small structures that cannot be detected with conventional fluoroscopy [1, 2]. CBCT allows effective needle guidance with an accuracy of approximately 3 mm [1]. Although CBCT images are useful for preoperative planning, registration accuracy may be affected by intraoperative patient motion [13]. A second CBCT confirmation should be considered whenever periprocedural assessment of on-table patient motion is required. Acquiring additional CBCT images can revise the correct needle deployment within a range of millimeters, potentially avoiding treatment failure and improving treatment safety [1, 2, 13, 14].

The degenerative disc releases nociceptive and growth factors, causing the ingrowth of nerve fibers and neovascularization in the annulus fibrosus [15, 16]. Degenerative disc neovascularization increases proteolytic enzyme activity, precipitating disc degeneration, and weakening supporting ligaments, leading to instability [17]. The protruding degenerative disc with chemical irritation and mechanical compression contributes to discogenic and radicular pain [18]. Radiofrequency annuloplasty can cauterize the fibrotic tissues containing free nerve endings and neovascularization in the outer annulus, gradually stiffening the collagen in the annulus and diminishing the load on the disc [3, 18,19,20].

SBO is caused by failure of fusion between posterior vertebral elements without affecting the spinal cord or meninges, with a prevalence of 0.6–25% [21, 22]. Although no definitive causal link has been established between congenital SBO and the development of lumbar disc herniation [23, 24], SBO is suspected to be a predisposing factor for degenerative disc disease based on the hypothesis that congenital defects may cause instability of the base of the lumbar spine, therefore leading to degenerative deformities and posterior disc herniation [23]. LSTV is a congenital spinal anomaly defined as either sacralization or lumbarization [24]. LSTV is common in the general population, with a reported prevalence of 4–30% [24]. Several reports indicate that a higher incidence of degenerative disc herniation and nerve root canal stenosis are encountered at a level above the LSTV due to increased mechanical stress and spine instability [22,23,24]. An association between LSTV and SBO was found in 0.02% of the healthy population [23]. Although their existence may be incidental, these developmental malformations aggravate the clinical severity of the condition [21].