Evaluation of Surgical Treatment for the Herniated Cervical Disc: a Retrospective Review

INTRODUCTION

MATERIALS AND METHODS

 Ethics

Patient reports from the electronic hospital database over a 3-year period (2019 - 2021) were analyzed. This study was registered by the Institutional ethics committee, Royal Medical Services (IRB: 15/9/2022) on the 18th of October, 2022. As this study was a retrospective analysis, the requirement for patient consent was waived. Patients’ records and data processing has been accomplished according to the Declaration of Helsinki (2013) and the Health Insurance Portability and Accountability (HIPAA) actions.

Patients

As the protocol of management in our Centre, all patients were initially evaluated clinically, followed by radiological evaluation, after which a trial of conservative treatment is given, in absence of sensorimotor deficits or intractable radiculopathy. In these cases, included in our study, surgical decision based on clinical and radiological evaluations was made. All patient data were documented, including the extensive comprehensive history including demographic features (age, gender, body mass index ［BMI］), co-morbidities and the clinical picture. A meticulous neurological evaluation and examination was then performed. Several confirmatory investigations were performed: magnetic resonance imaging (MRI), computed tomographic scan, dynamic x-ray, to confirm the diagnosis and exclude secondary causes leading to neck and arm pain (Fig. 1).

Figure. I: Shows the pre-operative radiological evaluation for patients presented with signs and symptoms of cervical disc disease. A) X-rays (antero-posterior & dynamic, B) Ct scan (sagittal & axial), C) MRI scan (sagittal and axial).

Study Design

This retrospective chart analysis was conducted by revising all consecutive patients and their medical files for whom intervention for treating cervical disc herniation was conducted.

Inclusion/exclusion criteria

Inclusion criteria:

1. Adult age > 18 years.
2. One or more cervical disc herniation.
3. A minimum follow-up period of 3- months.

 Exclusion criteria:

1. Oncology cases scheme.
2. Age < 18 years
3. Patients with spinal infection.
4. Lack of radiological evaluation, or clinical data.
5. Previous cervical spine surgery.
6. Ossification of posterior longitudinal ligament.
7. Patients with posterior instrumentation.

Surgical technique

The microsurgical procedure of ACDF is a surgery to remove a herniated or degenerative disc in the neck. Procedure was performed in a standardized manner following certain surgical steps. Patient under general endotracheal anesthesia was placed in supine position, and the damaged level was marked with X-ray control. The region was prepped with alcohol, betadine scrub, and betadine paint prior to incision and draped in a sterile fashion in all patients. The skin incision is one to two inches on right hand side of the neck. The incision is made horizontally within a natural skin crease, although occasionally a more vertical incision is used for multilevel cases. The platysma is then split in line with the skin incision, and the plane between the sternocleidomastoid muscle and the strap muscles is then entered. Next, a plane between the trachea/esophagus and the carotid sheath is entered. The pre-vertebral fascia is then dissected away from the disc space. Fluoroscopy was then used to reconfirm the level. After the correct disc space has been identified, the disc is then removed by first cutting the outer annulus fibrosis and removing the nucleus pulposus.

With an anterior cervical discectomy, the entire disc is removed. The cartilage endplates on the vertebral bones are also removed to reveal the hard cortical bone underneath. Dissection is conducted from the front to back of the posterior longitudinal ligament, then the ligament is gently removed to allow access to the spinal canal to remove any disc material that may have extruded through the ligament, which may be contributing to spinal stenosis. The uncinate processes partially removed as well. Cervical fusion is done following the cervical discectomy. The insertion of a cage into the evacuated disc space prevents disc space collapse and promotes a growing together of the two vertebrae into a single unit. Plate is used for all patients with three levels and more ACDF and some of patients with 2- levels, attached with screws into each of the vertebral bones. An operating microscope was used in all the cases.

Statistical analysis

Data were registered into the Microsoft Excel sheet, and analysis was performed using statistical software SPSS Statistics Version 28.0. The categorical data were demonstrated in frequency and percentages, while the scale data were stated employing illustrative statistics such as mean and standard deviation for continuous variables. An Independent sample t-test was used to evaluate mean differences between scale data. Moreover, the chi-square test was used for the association between categorical data, a binomial test was used to assess sample proportion with hypothetical proportion, Alpha level set at 0.05 deemed statistically significant.

RESULTS

This study was conducted at KHMC and included 165 patients who had been diagnosed initially with degenerative disc disease and admitted for ACDF. Patients were included if they met the established diagnostic criteria for CDD. Of those, four patients were disqualified due to additional posterior instrumentation, six patients underwent corpectomy, and three patients were eliminated due to incomplete data. The final study group therefore contained 152 patients to be considered for the final analysis, with 193 cervical levels operated (Fig. II). Of the final cohort, 57.24% of the patients were males (87/152), with a mean age at diagnosis of 45.31 ± 10.89 years (range 25–69 years). The females had a mean age at diagnosis of 48.67 ± 9.93 years (range 23–73 years) as shown in Table 1. Statistical analysis of the data revealed significant differences in terms of the number of levels operated between the two groups and the peak age. On the other hand, our study had several complications; our overall morbidity rate was 16.58% (P = 0194).

 Figure. II: Study flowchart

               Table 1 Demographic and surgery data of the patients.

DISCUSSION

CDD is a universal disabling medical condition in modern society and the estimated prevalence reaches 95% by the age of 65 years (11, 12). Patients with cervical disc degeneration commonly present with neck pain, radiculopathy resulting from nerve root compression, which is mainly attributed to degeneration from natural aging, trauma, or occupational hazards (13). Degenerative CDD is most frequently reported in the age group between 35 and 55 years, and the estimated incidence is around 5.5 patients per 100,000 of the population; it leads to a surgical intervention in 26% of these individuals (14, 15). According to many publications, females are less susceptible to developing this condition (16-23), while a higher incidence of spondylotic changes in the population are correlated with increasing age and with gender (17). In national studies of the Indian population, the main risk factors that precipitate for cervical spondylosis are age and gender (19, 20). In our review, 87 of our patients were male, a slight predominance; the male-to-female ratio was 1.34 : 1. In the male group, predominantly the patients were in the age group of 30–39 years (36.8%) followed by the age group 40–49 years (28.7%), while in the female group in most instances the patients were in the age group 40–49 years (44.6%), followed by the age group 50–59 years (27.7%) (Fig. III). The most reported cervical disc herniation levels are C4/5, followed by C5/6, and lastly C6/7 (24). Nevertheless, our results showed that almost half of the study population (49.74%) presented with degenerative disc disease at the C5–C6 disc level, followed by C6–C7 level (22.79%) (Fig. IV).

Figure. III: Shows the age distribution between the two groups

Figure. IV: Shows the cervical disc distribution between the two groups.

Clinical presentation in patients with CDD is still ambiguous. Although neck pain is the cardinal symptom, its source is still a matter of debate and uncertainty (25, 26). Discogenic pain is also another issue that has no clear definition and evidence to provoke neck pain, although in most cases of cervical disc herniation there is associated neck pain (27-30). In our review, a tingling sensation was the cardinal symptom, followed by neck pain, while sphincteric dysfunction was the least reported complaint reported by our patients (Fig. V).

Figure. V: Shows the clinical presentation among the two groups.

In the diagnosis of degenerative disc disease, there is a correlation between the clinical picture and radiological imaging. In our day-to-day practice it might be challenging to discriminate between the pain resulting from joint and muscle (mechanical pain) and cervical radicular pain, but differentiation between the two entities is of great value. For cases of cervical radiculopathy, established guidelines recommend earlier neurosurgical referral, imaging study, and the use of neuropathic medications (31). Crucial tools are a dedicated musculoskeletal examination and neurological evaluation to distinguish between referred pain, radicular pain, and myelopathy. Supplementary shoulder joint evaluation will help to rule out a principal shoulder problem (32). Patients presenting with radicular symptoms, upper limb myotomes, and dermatomes should be examined (33). In our practice, we apply these guidelines. If the clinical presentation is suggestive of persistent cervical radicular pain for a period of more than 4 to 6 weeks, imaging evaluation should be ordered (31).

Imaging modalities of the cervical segment of the spine have dramatically evolved in the last decades, especially with the development of technologies, and play an essential role in the process of identification and lateralization of cervical radicular pain. The primary examination that is normally done is a plain X-ray. Antero-posterior and lateral exposures are beneficial for gaining an idea about the global alignment of the cervical spine including the existence of any recognizable spondylotic alterations of the facet joints. Lateral dynamic (flexion and extension) exposures are effective to analyze any instability that might not be identifiable on a static radiographic image. A thin slice computed tomography (CT) scan providing high-resolution sagittal and coronal reformats allows for a comprehensive assessment of the vertebral column degenerative process. A CT scan is used to detect bone details in terms of bony lesions, abnormal bone formation, or any osteophyte development in addition to any deceptive process that may cause nerve root impingement (Fig. VI). MRI has become the procedure of choice for evaluation of the spinal cord and surrounding soft tissues when a reliable neurologic examination cannot be performed, or further evaluation is needed (34). MRI has the highest capability to demonstrate the detailed soft tissue configurations besides the nerve root course from cord to its exit from the foramen (35). Electrophysiologic testing is an additional diagnostic tool that can be utilized to assist in diagnosis of radicular pain (36).

Figure. VI: A CT scan evaluation (sagittal and axial cuts) of C5/C6 degenerative cervical disc disease, shows osteophyte formation

Once the diagnosis is established and in the absence of sensorimotor deficit, physiotherapy for 6 weeks is recommended, although the mechanism of pain reduction is still unclear. Non-operative management will improve pain in 75%–90% of patients presented and diagnosed with cervical radicular pain (37, 38). Thus, physiotherapy substantially reduces neck and arm pain, its cardinal aim being to reestablish neck musculature range of motion and strengthening (39, 40). The National Institute for Health and Care Excellence (NICE) has established a series of recommendations: analgesic agents (ibuprofen, paracetamol, or codeine) added to a provisional course of neuropathic drugs (amitriptyline, pregabalin, or gabapentin) for patients developing minor neurological signs or for patients with symptoms lasting more than 4 weeks (31).

It has also been recommended that patients with non-specific neck pain lasting more than 12 weeks are referred to a pain management clinic, with or without a trial of neuropathic agents (31).

For patients with a failed trial of conservative management course or who develop reasons for surgery, such as a major neurological deficit or interactable pain, several valid options are available for the surgical intervention of cervical radicular pain (41).

Some factors, such as spinal alignment, stability, and balance, play a role in a surgeon’s decision to use a preferred technique. Surgical approaches can be allocated into two large categories: anterior and posterior approaches to the spine.

Anterior approach with graft provides the capability to reestablish cervical segmental lordosis, stabilize the vertebral spine, enhance bone fusion, works as weight shearing device, and certainly decompress the nerve roots directly and indirectly (42, 43). This procedure achieves removal of the whole intervertebral disc along with any osteophytes formed at the posterior element of the vertebral body. Historically, the removed intervertebral disc was then replaced by either autologous bone graft material or even left with nothing (44-49). In recent times, restoration of normal intervertebral disc height with bone grafts or cages has gained ground (50-52). The ACDF procedure was one of the most performed spinal techniques in the U.S.A. in the period between 2006 and 2013, with a median of 137,000 cases of ACDF per year (total cases in 7 years 1,059,403) (53).

In our daily practice, we adopted the ACDF technique as the procedure of choice. Following this technique and with the introduction of an allograft, we aim to enhance the rate of fusion and to increase the degree of postoperative lordosis (54-57). Additionally, introduction of a graft permits indirect decompression of neural elements by increasing the cephalocaudal height of the intervertebral space (58).

Although ACDF has a huge success rate in achieving fusion, restoration of disc space height and lordosis, and indirect decompression of nerve roots, still have their complications. We carried out a dedicated analysis of the ACDF cases performed in our center and assessed the complications encountered and registered (Table 2).

Table 2 Overall complications encountered.

Several analyses have documented the morbidity/complication rates of the ACDF procedure; they range from 13.2% to 19.3% (59-61). In our review, the overall morbidity encountered was 16.58%, which was statistically comparable to the literature (P = 0.194). Morbidity rates are demonstrated in Table 2.

We compared each complication we encountered with those reported in the literature to evaluate our efficacy and safeness. Some of these complications might be encountered perioperatively, while others may evolve later.

Esophageal perforation, one of the major and fatal complications that might be faced, has been reported in literature in 0.3%–0.9% of cases (61-63). Luckily, we have not had any.

Unintended dural breach, a rare but still serious complication, occurred in three of our patients (1.55%). In none of our cases did a cerebrospinal fluid (CSF) fistula develop postoperatively. None of our patients needed further actions other than the primary closure or applying a fibrin sealant patch with glue. Patients had no additional consequences. Our results are in line with the literature which shows 0.5%–1.7% incidence of dural breach (59, 61, 64) (P = 0.584).

Dysphagia, one of the most frequent postoperative complications, was reported in seven patients (3.63%) and was resolved spontaneously within 2 weeks. Worldwide reports show a wide range of dysphagia rates (1.7%–9.5%) (65-67). Our study showed a statistically significantly lower rate (P = 0.002).

Another common complication is recurrent laryngeal nerve (RLN) palsy. Previous studies have revealed that RLN palsy incidence is understated (68, 69). Unilateral vocal paralysis results in dysphonia and/or hoarseness, which are the most common clinical manifestations, while respiratory insufficiency might develop due to bilateral RLN palsy (69, 70). In our analysis, symptomatic RLN palsy was reported in 1.55% of our cases. The incidence of spontaneous, asymptomatic, preoperative RLN palsy in the literature is about 1.6% (71, 72). However, around 1.1%–3.1% of patients undergoing anterior cervical spine surgery develop symptomatic RLN palsy (59, 73). Our study a showed significantly lower rate (P = 0.001).

Both superficial and deep surgical site infections exist among the complications of anterior cervical surgery. Reported rates of surgical site infection are around 0.9%–1.6% (64-66, 74). Our review identified four cases of superficial wound infections (2.07%), which were treated with simple dressing and empirical antibiotics, with no significant difference compared with the literature (P = 0.373).

Although postoperative hematoma arises rarely in ACDF, it might be a possibly life-threatening complication. Its immediate detection and surgical evacuation are vital in order to avoid any potential airway compromise. The reported incidence in previously published reviews is around 0.2%–2.4% (59, 61, 75, 76). Postoperative hematoma might develop in an acute or delayed fashion; the majority develop in a delayed fashion, at an average of 6 days postoperatively (76, 77). Meticulous intraoperative hemostasis and drain insertion play a cardinal role in preventing a postoperative hematoma (76). Postoperative wound hematoma that required surgical evacuation occurred in two cases (1.04%) in our series, which was significantly lower than in reports in the literature (P < 0.001).

Degeneration of adjacent intervertebral discs develops due to alteration of the regional biomechanics, increased stress, and instability of loads to the adjacent intervertebral discs (78-82). Although not considered a complication of ACDF, there is still a strong correlation. Recently stated data demonstrate that the incidence of adjacent segment degeneration after ACDF is around 12.2%, and consequently grows to 25% after a second ACDF (83, 84). Other studies concluded that 9% of adjacent level disease develops within 6 years after ACDF, and 7.4% of cases require a reoperation. The annual incidence of degeneration is around 2.9% per year (85, 86). Our review revealed five cases (2.59%) with adjacent level disease within 3 years of the primary surgery, a statistically significant lower rate that in the literature (P < 0.001).

A well-documented but rare complication encountered in anterior approaches to the subaxial cervical spine is Horner’s syndrome (87). Horner’s syndrome is characterized by ipsilateral pupillary miosis, facial anhydrosis, and ptosis, resulting from damage to the cervical sympathetic trunk. Horner’s syndrome rarely manifests with significant clinical impairment, but the cosmetic effect may cause considerable concern (88). Several studies have shown very low incidence, with rates between 0.02% and 4.0%. Our analysis showed two cases (1.04%). Symptoms totally resolved in one patient using steroids and speech therapy, while one female patient suffered from incomplete resolution.

The main aim after decompression of the spine and nerve roots via ACDF is to achieve fusion. Fusion rates stated in the literature for one- to two-level ACDF were higher following one-level vs. two-level ACDF and were also higher when using an autograft (89, 90). The criteria to support bone fusion are the presence of a trabecular bridging bone formation between the cage and vertebral endplate documented by CT scan, and a lack of motion confirmed by dynamic cervical X-ray of the fused levels (91). Studies show fusion rates of 90.1%–100% (92-95). We achieved a fusion rate of 97.93%, while that for pseudoarthrosis was significantly lower at 2.07%, confirmed in four cases (P < 0.001).

The accumulative complication rate encountered in our analysis was 16.58%, with no mortality occurring. The complications developed were more prominent with increased age, smoking, and multilevel cases. However, good diagnosis and preoperative evaluation in addition to good technique would improve outcome.

Although this study shows good results, it still carries substantial limitations. First, the present analysis is a retrospective study, hence holding possible biases of retrospective studies that could compromise the analysis. Moreover, the small sample size of our cohort may weaken the statistical power of the conclusions. Nevertheless, the intention of our analysis was to evaluate treatment of a degenerative cervical disc via the ACDF procedure, in addition to the associated complications, as many of them are correlated with the anterior approach per se. Nonetheless, supplementary studies are still needed to optimize the necessary management approaches and treatment and to avoid or minimize these complications.

.

CONCLUSION

This study to evaluate the ACDF procedure for degenerative disk herniation has revealed good or excellent outcomes in most cases. However, the existence of disruptive complications, although rare, requires consideration. The study failed to distinguish possible changeable and modifiable preoperative risk factors that can minimize or eliminate any complications. The cardinal factors for enhancing the good result for these patients and their quality of life are a high awareness level, early identification, and appropriate direct management, which have vital consequences.

Conflicts of interest: The author certifies that he has no affiliation with or any direct or indirect involvement in any organization or entity with any financial interest, or non-financial interest in the subject matter or materials discussed in this manuscript.

Future work: We need a prospective, study and a larger population.

Availability of data and materials: All data generated or analyzed during this study are included in this published article.

Authors’ contributions: all authors contributed substantially to different article milestones.

AR: acquisition of data, writing manuscript, approving final manuscript, acquisition of data, analysis and interpretation of data. AD: acquisition of data, analysis and interpretation of data. AI: acquisition of data, analysis and interpretation of data, HS: analysis and interpretation of data, writing manuscript, QR: analysis and interpretation of data, drafting manuscript, conception and design, writing manuscript, approving final manuscript, tables, diagrams.

Final approval of manuscript: All authors

Agree to be accountable for all aspects of the work: All authors.

Acknowledgement: We would like to express our special thanks to Mr. Hijazeen Anis for his time and efforts he provided throughout this article. His useful advice and highly professional suggestions were helpful to us during the project's completion.

Ethical Approval

 We declare that the Ethics Committee of Royal Medical Services (No. 9/7/2022) have approved this study

Informed Consent

Patient's informed consent was waived as this is a retrospective study.

Funding

The authors had no relevant funding to disclose.

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