Endoscopic spinal surgery in adjacent segment disease—a viable alternative to transforaminal lumbar interbody fusion: a case report

Introduction

Adjacent segment disease (ASD) is broadly defined as a spectrum of symptomatic conditions resulting from mechanical deterioration of spinal levels adjacent to those that have undergone previous surgical intervention (1). A literature review by Park et al. reported that ASD occurs in 4–6% of patients who have undergone previous lumbar or lumbosacral fusion (2). This not only leads to the recurrence and worsening of their neurological symptoms or lower back pain that originally prompted treatment, but also exposes patients to the risks of additional surgical procedures (3). Even with revision surgeries to mend ASD, further revision rates can be as high as 23% according to a 2018 retrospective review of 118 patients by Drysch et al. (4). Given the substantial costs associated with spinal implants (5), it is important that clinicians aim to minimize the perioperative cost and complications for the betterment of the patient. One emerging alternative to the conventional MIS surgery would be endoscopic spinal surgery (ESS).

ESS is a minimally invasive alternative to conventional microscopic surgery that was successfully introduced by Kambin in the 1970s as a transforaminal approach for lumbar spine procedures (6). Since then, ESS has evolved to encompass translaminar lumbar decompression, anterior and posterior cervical spine decompression, and even spinal fusion with instrumentation in select cases. Compared to conventional open techniques, ESS offers several advantages, including smaller incisions, improved cosmetic outcomes, reduced blood loss, minimized soft tissue injuries, and lower postoperative pain (7). It has even been shown that ESS is better than MIS in improving spinal canal area and neural foramina area in lumbar spinal segments, whilst being non-inferior in terms of neural decompression (8). Despite its benefits, the limitations of ESS, particularly in revision surgeries, are still being explored. The presence of scar tissues from prior operations can obstruct the already narrow, restricted view of the endoscope, giving rise to a higher risk of dural and neuronal damage (9). Herein, we present a case of ASD in an elderly patient that was managed successfully using endoscopic spine surgery in accordance with the CARE reporting checklist (available at https://jss.amegroups.com/article/view/10.21037/jss-24-142/rc).

Case presentation

We report the case of a 69-year-old female who presented with a 1-year history of back pain associated with right thigh numbness spanning the right L2 and L3 dermatomes associated with left-sided leg weakness. She subsequently developed right lower limb radiculopathy extending to her right thigh and knee. Her surgical history included a L4/L5 decompression laminectomy 10 years prior for L4/L5 degenerative spinal canal stenosis with spondylolisthesis. She also has a background of type 2 diabetes mellitus and hypertension.

On neurological examination, based on the American Spinal Injury Association (ASIA) scoring (10), her power was grade 4 out of 5 for both L2 and L3 myotomes on the left side. Sensation was 1 out of 2 for both L2 and L3 dermatomes on the right. Straight leg raise was positive on the right at 30 degrees. The rest of the clinical examination, including that of power, sensation, reflexes, and gait, was normal. In view of the clinical history and examination findings, the clinical concern and main differential diagnosis was that of an ASD. To investigate her symptoms, erect lumbar spine (anterior-posterior/lateral) X-rays and a magnetic resonance imaging (MRI) lumbosacral spine were performed (Figures 1-3). The X-rays and MRI revealed significant adjacent segment degenerative disc disease in L3/L4 and right-sided facet hypertrophy, with foraminal stenosis at the right L2/L3 and L3/L4 levels with significant pseudoarthrosis at the L3/L4 level.

Figure 1 Anterior-posterior (left)/lateral (right) erect lumbar X-rays showing previous L4/L5 decompression laminectomy and fusion with instrumentation. Early evidence of adjacent segment degenerative disc disease in L3/L4 and right-sided facet hypertrophy.

Figure 2 T2-weighted magnetic resonance imaging cuts at the L2/L3 level revealing adjacent segment degeneration. The left and rightmost yellow lines demarcate the scout lines of the image, whilst the middle line represents the corresponding cut seen on the left-sided image.

Figure 3 T2-weighted magnetic resonance imaging cuts at the L3/L4 level revealing adjacent segment degeneration. The top and bottom-most yellow lines demarcate the scout lines of the image, whilst the middle line represents the corresponding cut seen on the right-sided image.

In view of the MRI findings, a shared decision was made with the patient regarding treatment modalities, and a diagnostic nerve block at L3 was subsequently performed. This resulted in significant symptom relief that lasted for less than a month. As such, the decision was made to proceed with the right percutaneous unilateral biportal endoscopic (UbE) foraminal decompression of the L2/L3 and L3/L4 levels.

The operation was carried out in the prone position under general anaesthesia. An alignment rod was used together with intraoperative fluoroscopy to determine the location of the initial incision sites. First, the location of the right pedicle was ascertained (Figure 4). Next, the alignment rod was shifted 2 cm laterally to the pedicle (Figure 4). Subsequently, the relevant levels were identified (Figure 4). Three transverse 1-cm incisions were then made for the endoscopic ports.

Figure 4 Intraoperative fluoroscopy showing (A) location of pedicles and (B) alignment rod being 2 cm lateral to pedicles, and (C) identifying key surgical levels for incision points, as indicated by the horizontal orange lines.

A UbE approach was then used to access the right L2/L3 disc segment. This was followed by careful dissection down to the pedicles whereby osteophytes were removed from the superior articular process using the combination of a straight osteotome, curette and burr (Figure 5). A partial removal of the pars was also performed. The L2 exiting nerve was then found to be mobile following decompression (Figure 6). A large fusion body was encountered whilst attempting to decompress the L3/L4 segment which was hindering surgical exposure (Figure 7). Hence, a combination of curved and straight osteotomes was used to carefully excise it after confirmation with intraoperative imaging. The nerve root was noted to be unhealthy and pale prior to the decompression but showed significantly improved appearance after (Figure 8).

Figure 5 Endoscopic images showing a combination of straight osteotome, curette, and burrs being used for decompression intraoperatively.

Figure 6 Endoscopic view post-decompression of the right L2/L3 showing the nerve root to be completely mobile.

Figure 7 Intraoperative radiograph showing a large fusion body encountered when attempting to decompress L3/4, which was hindering exposure.

Figure 8 Nerve root shown to be initially unhealthy and pale prior to decompression (A) and then pink and healthy post-decompression (B).

Triamcinolone acetonide was given to the L2 and L3 exiting nerve roots prior to skin closure. The arthroscopic portals were closed with a 2-0 Vicryl suture to the subcutaneous layer and a 3-0 Prolene suture to the skin. The wounds were then dressed with Mepilex. Intravenous cefazolin was continued for 24 hours, and regular analgesia was commenced in the form of paracetamol and gabapentin as per institutional guidelines. Neurobion was also prescribed to promote nerve regeneration. Intensive physiotherapy was also incorporated into her recovery regime the following day.

The patient was discharged from the hospital on postoperative day 1 with minimal pain or residual symptoms. Two weeks after surgery, there was marked improvement in both back pain and right radiculopathy. The numbness in her right thigh completely resolved. The Oswestry Disability Index (11) was used to objectively quantify patient outcomes and saw an improvement from 15 to 0. The post-operative period was uneventful, and till date, there have been no notable complications with the patient still being well on recent follow-up 1 year later. No post-operative imaging was attained as per clinical guidelines, as she was symptom-free thereafter.

All procedures performed in this study were in accordance with the ethical standards of Sengkang General Hospital (CIRB Ref No. 2020/2381) and with the Helsinki Declaration and its subsequent amendments. Written informed consent was obtained from the patient for the publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Discussion

ASD is a rare, devastating, and unpredictable complication that follows spinal surgery and manipulation (12). It can lead to pain, neurological symptoms, or in worse cases, even cauda equina syndrome (13,14). The exact cause of ASD has not been unravelled. It has been hypothesized to stem from abnormal biomechanical demands on segments adjacent to the index level where fusion was performed (13,15). Authors also agree that iatrogenic damage to the posterior ligamentous complex and sagittal imbalances during the index surgery can also predispose to degeneration and disease (12). Patient-specific risk factors such as BMI, age, sex, and menopause are also associated with the development of ASD (16). Treatment can be both non-surgical and surgical, with the latter having more predictable and successful outcomes (17-20). Surgery can be both open and minimally invasive.

Traditionally, open techniques treating ASD have the primary aims of decompression and stabilization of adjacent segments. Performing a transforaminal lumbar interbody fusion (TLIF) involves removing the intervertebral disc at the level of the injury, replacing it with a spacer and sequentially fusing the vertebra with screws and rods. Whilst increasing stability, the removal of the diseased disc increases intradiscal pressure (21-23). The increased pressure raises the propensity for attaining secondary ASDs thereafter, perpetrating and creating a vicious cycle for the patient who may require multiple revisions (24) as we continuously play cat and mouse, chasing the adjacent segment. Endoscopic spine surgery has been shown to achieve sufficiently satisfactory clinical outcomes in ASD treatment, with the added advantage of reduced soft tissue trauma and faster recovery (25). Percutaneous endoscopic decompression can hence reap the well-established benefits of endoscopic surgery, negating the need for fusion and preventing excessive load on the adjacent healthy segment, putting a halt to the potential never-ending cat-and-mouse cycle. A disc-sparing approach such as that provided by ESS could thus be more attractive from a mechanical perspective.

ESS is notably technically challenging with a large learning curve (26). It is unsurprising that ESS has a steeper and more complex learning curve when compared to its open counterparts (27). It is reported by Ransom et al. (26) that it takes at least 15 cases of endoscopic lumbar decompression performed by a surgeon whilst being closely mentored by a master spine surgeon before being deemed “free to fly”. Despite the slightly inferior outcomes in the initial stages, experienced surgeons are able to execute ESS to similar and, if not, better outcomes as compared to open spine surgeons with a shortened operation time once the learning curve has been mounted (28,29). In the long run, this could bode well for the cost-effectiveness of the operating suite, as well as increased patient satisfaction. The appeal of an endoscopic surgery over fusion or open surgery could also reduce the number of untreated ASDs in the community (30). In the same vein, it is important to consider the costs to the patient. At Sengkang General Hospital, ESS costs approximately $6,750 while the equivalent offering from vendors for 2 level revisions—which would include 4 more screws, 2 cages, bone graft plus 2 rods costs between $10,000–$11,000. Additionally, TLIF for 2 levels takes an average of 4–5 hours while ESS only takes 2–3 hours, allowing us to minimize the exposure of our patients to general anesthesia and its associated risks. This means that the patient can bear weight and recover rapidly, with most patients being discharged symptom-free and happily on post-operative day 1 and returning to work soon after (31). The benefits of a shorter hospital stay and lower peri-operative complication rate have to be pit against the potentially higher operative cost whilst using the endoscopic approach (32). Shorter hospitalization stays can, in the long run, equate to better efficacious use of limited and scarce hospital beds for other acute patients, and reduce the incidence of hospital-acquired nosocomial infections. Moving forward, a center-based cost analysis should be performed in the future to assess the viability of training an endoscopic spinal surgeon and the potential environmental and institutional impact of using disposable endoscopic systems. Further studies can also be done assessing the societal costs, increased quality of life, and quality-adjusted life years pit against surgical cost.

Endoscopic spine surgery has shown in many instances to have its advantages over open surgery across various procedures and conditions (28,33-35). With sufficient experience, we opine that ESS is a viable non-inferior alternative to TLIF in patients with adequate access and minimally distorted anatomy. Future prospective studies can be performed to compare the surgical, radiographic, and patient reported outcomes for these methods.

Conclusions

This case highlights a successful instance whereby percutaneous unilateral bi-portal endoscopic decompression could adequately treat multilevel ASD of the lumbar spine after an initial decompression laminectomy for lumbar spinal stenosis. ESS is a promising alternative to microscopic/open techniques despite the steep learning curve. A fusion body was successfully overcome with appropriate endoscopic manipulation. ESS may not be as viable in cases where excision of the fusion body destabilizes the spine or where the compression site is severe. ESS boasts benefits of a shorter operative time, minimal blood loss, lower costs, and improved post-operative pain as compared to TLIF. As such, percutaneous endoscopic decompression is a promising minimally invasive alternative that should be considered in a skilled orthopaedic surgeon’s arsenal as an alternative to microscopic/open surgical techniques. Future spine surgeons should start on endoscopic training early to improve patient outcomes in the long run.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the CARE reporting checklist. Available at https://jss.amegroups.com/article/view/10.21037/jss-24-142/rc

Peer Review File: Available at https://jss.amegroups.com/article/view/10.21037/jss-24-142/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jss.amegroups.com/article/view/10.21037/jss-24-142/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of Sengkang General Hospital (CIRB Ref No. 2020/2381) and with the Helsinki Declaration and its subsequent amendments. Written informed consent was obtained from the patient for the publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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