Recurrent laryngeal nerve injury with anterior cervical spine surgery risk with laterality of surgical approach

Anatomical variations of recurrent laryngeal nerve: a systematic review and meta-analyses

PURPOSE

The aim of this systematic review and meta-analysis was to systematically review and perform a meta-analysis on the anatomical variations of the RLN.

METHODS

We performed online research for studies that addressed anatomical variations of the RLN and laterality, published between 2015 and 2021. We found 230 articles, and nine were included.

RESULTS

Eight variations were found, with Type I prevailing (41.17%; 95% CI 19.44-64.88), extra laryngeal divergence of the RLN. The other types were: II-fan shape; III-distance greater than 5 mm to the cricothyroid joint; IV-thickening and adipopexy in the elderly; V-non-recurrent laryngeal nerve; VI-intracranial branch; VII-tortuous ascending RLN; and VIII-combination between the inferior branch of the NV and the ascending trunk of the RLN. Types I (p = 0) and III (p < 0.01) prevailed on the left and types II (p < 0.01) and V (p < 0.01) on the right.

CONCLUSIONS

It was observed that variations occurred due to the path of the RLN to the entrance to the larynx, its shape, and the age of the evaluated individual. The most frequent variation and side were, respectively, Type I, extra laryngeal divergence and left.

Changes in vocal fold gene expression and histology after injection augmentation in a recurrent laryngeal nerve injury model

OBJECTIVE

To investigate changes in neuroregenerative pathways with vocal fold denervation in response to vocal fold augmentation.

METHODS

Eighteen Yorkshire crossbreed swine underwent left recurrent laryngeal nerve transection, followed by observation or augmentation with carboxymethylcellulose or calcium hydroxyapatite at two weeks. Polymerase chain reaction expression of genes regulating muscle growth (MyoD1, MyoG and FoxO1) and atrophy (FBXO32) were analysed at 4 and 12 weeks post-injection. Thyroarytenoid neuromuscular junction density was quantified using immunohistochemistry.

RESULTS

Denervated vocal folds demonstrated reduced expression of MyoD1, MyoG, FoxO1 and FBXO32, but overexpression after augmentation. Healthy vocal folds showed increased early and late MyoD1, MyoG, FoxO1 and FBXO32 expression in all animals. Neuromuscular junction density had a slower decline in augmented compared to untreated denervated vocal folds, and was significantly reduced in healthy vocal folds contralateral to augmentation.

CONCLUSION

Injection augmentation may slow neuromuscular degeneration pathways in denervated vocal folds and reduce compensatory remodelling in contralateral healthy vocal folds.

Effect of Fusion and Arthroplasty for Cervical Degenerative Disc Disease in Active Duty Service Members Performed at an Overseas Military Treatment Facility: A 2-Year Retrospective Analysis

INTRODUCTION

Among U.S. military active duty service members, cervicalgia, cervical radiculopathy, and myelopathy are common causes of disability, effecting job performance and readiness, often leading to medical separation from the military. Among surgical therapies, anterior cervical discectomy and fusion (ACDF) and cervical disc arthroplasty (CDA) are options in select cases; however, elective surgeries performed while serving overseas (OCONUS) have not been studied.

MATERIALS AND METHODS

A retrospective analysis of a prospectively collected surgical database from an OCONUS military treatment facility over a 2-year period (2019-2021) was queried. Patient and procedural data were collected to include ACDF or CDA surgery, military rank, age, tobacco use, pre- and post-operative visual analogue scales for pain, and presence of radiographic fusion after surgery for ACDF patients or heterotopic ossification for CDA patients. Chi-square and Student t-test analyses were performed to identify variables associated with return to full duty.

RESULTS

A total of 47 patients (25 ACDF and 22 CDA) underwent surgery with an average follow-up of 192.1 days (range 7-819 days). Forty-one (87.2%) patients were able to return to duty without restrictions; 10.6% of patients remained on partial or limited duty at latest follow-up and one patient was medically separated from the surgical cohort. There was one complication and one patient required tour curtailment from overseas duty for ongoing symptoms.

CONCLUSIONS

Both ACDF and CDA are effective and safe surgical procedures for active duty patients with cervicalgia, cervical radiculopathy, and cervical myelopathy. They can be performed OCONUS with minimal interruption to the patient, their family, and the military unit, while helping to maintain surgical readiness for the surgeon and the military treatment facility.

Atrophy of the Posterior Cricoarytenoid Muscle as an Indicator of a Recurrent Laryngeal Nerve Injury History Before Revision Anterior Cervical Spine Surgery

STUDY DESIGN

Retrospective study.

OBJECTIVES

In our recent study, we observed some cases of symptomatic normal vocal cord motility instead of asymptomatic vocal cord palsy (VCP) in preoperative laryngoscopy of a revision anterior cervical spine surgery (ACSS) cohort. We assumed the intrinsic muscle atrophy caused by recurrent laryngeal nerve injury could cause vocal cord-related symptoms. Thus, radiological examinations were reviewed in relation to the posterior cricoarytenoid (PCA) muscle, one of the intrinsic muscles.

METHODS

We retrospectively analyzed 64 patients who underwent a revision ACSS. Patients with vocal cord-related symptoms were classified as symptomatic group (group S, n = 11), and those without symptoms as asymptomatic group (group AS, n = 53). The bilateral size and signal intensity of the PCA muscles in these patients were measured in the axial view with preoperative computed tomography (CT) and magnetic resonance imaging (MRI) evaluations. Since the size and signal intensity values were different on each image, the ratios of the contralateral and ipsilateral muscle values were analyzed for each modality.

RESULTS

There was no VCP on laryngoscopy study. However, the mean ratio of the PCA muscle size on CT was 1.40 ± .37 in group S and 1.02 ± .12 in group AS (P = .007). These values on the MRI were 1.49 ± .45 in group S and 1.02 ± .14 in group AS, which was also a significant difference (P = .008).

CONCLUSIONS

Evaluating the size of the PCA muscle before revision ACSS may predict a previous recurrent laryngeal nerve injury. Careful planning for the appropriate approach should be undertaken if vocal cord-related symptoms and atrophy of PCA muscle are evident.

Pseudoarthrosis after anterior cervical discectomy and fusion: rate of occult infections and outcome of anterior revision surgery

BACKGROUND

Pseudoarthrosis after anterior cervical discectomy and fusion (ACDF) is relatively common and can result in revision surgery. The aim of the study was to analyze the outcome of patients who underwent anterior revision surgery for pseudoarthrosis after ACDF.

METHODS

From 99 patients with cervical revision surgery, ten patients (median age: 48, range 37-74; female: 5, male: 5) who underwent anterior revision surgery for pseudoarthrosis after ACDF with a minimal follow up of one year were included in the study. Microbiological investigations were performed in all patients. Computed tomography (CT) scans were used to evaluate the radiological success of revision surgery one year postoperatively. Clinical outcome was quantified with the Neck Disability Index (NDI), the Visual Analog Scale (VAS) for neck and arm pain, and the North American Spine Society Patient Satisfaction Scale (NASS) 12 months (12-60) after index ACDF surgery. The achievement of the minimum clinically important difference (MCID) one year postoperatively was documented.

RESULTS

Occult infection was present in 40% of patients. Fusion was achieved in 80%. The median NDI was the same one year postoperatively as preoperatively (median 23.5 (range 5-41) versus 23.5 (7-40)), respectively. The MCID for the NDI was achieved 30%. VAS-neck pain was reduced by a median of 1.5 points one year postoperatively from 8 (3-8) to 6.5 (1-8); the MCID for VAS-neck pain was achieved in only 10%. Median VAS-arm pain increased slightly to 3.5 (0-8) one year postoperatively compared with the preoperative value of 1 (0-6); the MCID for VAS-arm pain was achieved in 14%. The NASS patient satisfaction scale could identify 20% of responders, all other patients failed to reach the expected benefit from anterior ACDF revision surgery. 60% of patients would undergo the revision surgery again in retrospect.

CONCLUSION

Occult infections occur in 40% of patients who undergo anterior revision surgery for ACDF pseudoarthrosis. Albeit in a small cohort of patients, this study shows that anterior revision surgery may not result in relevant clinical improvements for patients, despite achieving fusion in 80% of cases.

LEVEL OF EVIDENCE

Retrospective study, level III.

Intraoperative Measurement of Endotracheal Tube Cuff Pressure and Its Change During Surgery in Correlation With Recurrent Laryngeal Nerve Palsies, Hoarseness, and Dysphagia After Anterior Cervical Discectomy and Fusion: A Prospective Randomized Controlled Trial

STUDY DESIGN

Prospective randomized controlled trial.

OBJECTIVES

Adjustment of endotracheal tube cuff pressure (ETCP) in anterior cervical discectomy and fusion (ACDF) may influence the incidence of complications such as recurrent laryngeal nerve palsy (RLNP), hoarseness, and dysphagia.

METHODS

The prospective randomized controlled trial was designed to investigate the influence of ETCP on the incidence of postoperative complications. All eligible patients underwent vocal cord examination before and after ACDF and were randomized into a control group (CG) and intervention group (IG). Endotracheal tube cuff pressure was passively monitored in CG, and in IG, it was maintained at 20 mmHg. Outcomes were evaluated during hospitalization and during follow-up.

RESULTS

A total of 98 patients were randomized, each group consisted of 49 patients. Statistical analysis showed that gender and age did not influence the incidence of complications. In CG, duration of retractor placement and extent of approach significantly impacted the occurrence of complications. The incidence of postoperative RLNP was 8.2% in IG and 12.2% in CG, hoarseness and dysphonia were present in 18.4% in IG and in 37.5% in CG, and dysphagia in 20.8% in IG and in 22.5% in CG. Hoarseness was significantly present more in CG (P = .018). Only one patient from CG presented with RLNP after 1 year, the remaining nine patients spontaneously recovered.

CONCLUSIONS

Unregulated ETCP can lead to a significantly higher incidence of hoarseness; however, its improvement rate is 100%. The early postoperative complication rate was higher in CG, and after one year, 1 patient had RLNP and 1 patient had dysphagia.

Outcome and Health-Related Quality of Life After Combined Anteroposterior Surgery Versus Anterior Surgery Alone in Subaxial Cervical Spine Fractures : Analysis of a National Multicenter Data Set

STUDY DESIGN

Observational study on prospectively collected data.

OBJECTIVES

To compare patient-reported outcomes and complications after anteroposterior surgery or anterior surgery in subaxial cervical spine fractures.

SUMMARY OF BACKGROUND DATA

There is no consensus regarding the optimal surgical approach for subaxial cervical spine fractures. Although anterior surgery is often sufficient to restore stability, anteroposterior surgery is sometimes preferred in severe instability. The effects of a more extensive procedure on patient-reported outcomes have not been investigated. We hypothesized that patient-reported outcomes and complication rates were similar between these surgical approaches.

MATERIALS AND METHODS

Individuals treated with either a combined anteroposterior or anterior surgery alone between 2006 and 2016 and with at least 1-year follow-up were identified in the Swedish Spine Registry. Cases were matched 1:2 for age (±5 y). Outcomes were Neck Disability Index (NDI), EQ-5D-3L index, satisfaction, reoperations, and surgeon-reported and patient-reported complications within 90 days. Mann-Whitney U -tests and χ 2 tests were used in statistical comparisons.

RESULTS

The median [interquartile range] number of instrumented vertebrae was 3 [2-5.5] in the anteroposterior group and 2 [2-3] in the anterior group ( P <0.001). The mean±SD follow-up time was 3.5±2.3 years in the anteroposterior and 3.8±2.0 years in the anterior group ( P =0.39), respectively. At follow-up, Neck Disability Index was 20 [6-37] in the anteroposterior group and 18 [3.5-40] in the anterior group ( P =0.69), and the median EQ-5D-3L index was 0.73 [0.12-0.80] in the anteroposterior group and 0.75 [0.62-0.89] in the anterior group ( P =0.27). Satisfaction with the treatment was reported by 90% in the anteroposterior group and by 87% in the anterior group ( P =0.98). None of the individuals in the anteroposterior and 6 of the individuals in the anterior group were reoperated ( P =0.18).

CONCLUSION

Patients operated on with anteroposterior or anterior surgery for subaxial cervical spine fractures are equally satisfied and report similar health-related quality of life measures.

Anterior Cervical Corpectomy and Fusion for Degenerative Cervical Spondylotic Myelopathy: Case Presentation With Surgical Technique Demonstration and Review of Literature

Anterior cervical corpectomy and fusion (ACCF) provides an extensive decompression and provides a large surface area for fusion in patients presenting with cervical spondylotic myelopathy. Unfortunately, this procedure is a more difficult spinal surgery to perform (compared with a traditional anterior cervical discectomy and fusion) and has a higher incidence of overall complications. In literature, ACCF has functional outcomes that seem clinically equivalent to those for multilevel anterior cervical discectomy and fusion, especially when contained to 1 vertebral body level, and in cases, for which both posterior and anterior procedures would be appropriate surgical options, may provide greater long-term clinical benefit than posterior fusion or laminoplasty. In this manuscript, we summarize the indications and outcomes following ACCF for degenerative cervical spondylotic myelopathy. We then describe a case presentation and associated surgical technique with a discussion of complication avoidance with this procedure.

Augmentation and vocal fold biomechanics in a recurrent laryngeal nerve injury model

Objectives/hypothesis

Composite vocal fold (VF) biomechanical data are lacking for augmentation after recurrent laryngeal nerve (RLN) injury. We hypothesize resulting atrophy decreases VF stiffness and augmentation restores native VF biomechanics.

Methods

Sixteen Yorkshire Crossbreed swine underwent left RLN transection and were observed or underwent carboxymethylcellulose (CMC) or calcium hydroxyapatite (CaHa) augmentation at 2 weeks. Biomechanical measurements (structural stiffness, displacement, and maximum load) were measured at 4 or 12 weeks. Thyroarytenoid (TA) muscle cross‐sectional area was quantified and compared with two‐way ANOVA with Tukey's post hoc test.

Results

After 4 weeks, right greater than left structural stiffness (mean ± SE) was observed (49.6 ± 0.003 vs. 28.4 ± 0.002 mN/mm), left greater than right displacement at 6.3 mN (0.54 ± 0.01 vs. 0.46 ± 0.01 mm, p < .01) was identified, and right greater than left maximum load (72.3 ± 0.005 vs. 40.8 ± 0.003 mN) was recorded. TA muscle atrophy in the injured group without augmentations was significant compared to the noninjured side, and muscle atrophy was seen at overall muscle area and individual muscle bundles. CMC augmentation appears to maintain TA muscle structure in the first 4 weeks with atrophy present at 12 weeks.

Conclusions

VF biomechanical properties match TA muscle atrophy in this model, and both CMC and CaHa injection demonstrated improved biomechanical properties and slower TA atrophy compared to the uninjured side. Taken together, these data provide a quantifiable biomechanical basis for early injection laryngoplasty to improve dysphonia and potentially improve healing in reversible unilateral vocal fold atrophy.

Level of evidence

N/A

Laryngoscopic Screening Before Revision Anterior Cervical Spine Surgery: Is Vocal Cord Palsy a Relevant Factor in Deciding the Approach Direction?

STUDY DESIGN

Retrospective study.

OBJECTIVES

The aim was to evaluate the exact incidence of vocal cord palsy (VCP) caused by previous anterior cervical spine surgery (ACSS) and aid surgeons in deciding the approach direction in revision ACSS.

SUMMARY OF BACKGROUND DATA

The incidence of VCP detected by preoperative laryngoscopic screening before revision ACSS appeared to be much higher in previous reports than in our experience.

MATERIALS AND METHODS

We reviewed the data of 64 patients who underwent revision ACSS. Preoperative laryngoscopy was performed in all patients to detect VCP and/or structural abnormalities of the vocal cords. The patients' characteristics, laryngoscopy results, and symptoms before revision surgery that were potentially caused by previous recurrent laryngeal nerve injuries (voice change, foreign body sensation, and chronic aspiration) were recorded.

RESULTS

Laryngoscopy demonstrated no complete VCP or decreased vocal cord motility. Eleven patients (17.2%) showed vocal cord-related symptoms and 13 patients (20.3%) showed abnormal laryngoscopic findings without VCP. Four patients (6.2%) showed vocal cord-related symptoms and abnormal laryngoscopic findings simultaneously. At the initial operative level, no significant differences in vocal cord-related symptoms were observed between the upper and lower levels (C3-4-5 vs. C5-6-7). However, the frequency of vocal cord-related symptoms was significantly high at the larger number of levels (≥3 segments) (P=0.010).

CONCLUSIONS

In contrast to previous reports, this study demonstrated that VCP is rarely detected before revision ACSS. Therefore, deciding the approach direction with only vocal cord motility can be dangerous, and more attention is required in setting the approach direction in patients who show both vocal cord-related symptoms and abnormal laryngoscopic finding. In other cases, a contralateral approach which has a low risk of bilateral VCP could be utilized if necessary.

Characterization of dysphagia following anterior cervical spine surgery

BACKGROUND

Post-operative dysphagia is one of the most common complications of anterior cervical spine surgery (ACSS).

OBJECTIVE

Examine post-operative structural and physiologic swallowing changes in patients with dysphagia following ACSS as compared with healthy age and gender matched controls.

METHODS

Videofluoroscopic swallow studies of adults with dysphagia after ACSS were retrospectively reviewed. Seventy-five patients were divided into early (≤2 months) and late (> 2 months) post-surgical groups. Modified Barium Swallow Impairment Profile (MBSImP), Penetration-Aspiration Scale (PAS) scores, and pharyngeal wall thickness (PWT) metrics were compared.

RESULTS

Significant differences were identified for all parameters between the control and early post-operative group. MBSImP Pharyngeal Total (PT) scores were greater in the early group (Interquartile Range (IQR) = 9-14, median = 12) versus controls (4-7, 5, P < 0.001) and late group (0.75-7.25, 2, P < 0.001). The early group had significantly higher maximum PAS scores (IQR = 3-8, median = 7) than both the control group (1-2, 1, P < 0.001) and late post-operative group (1-1.25, 1, P < 0.001). PWT was significantly greater in the early (IQR = 11.12-17.33 mm, median = 14.32 mm) and late groups (5.31-13.01, 9.15 mm) than controls (3.81-5.41, 4.68 mm, P < 0.001).

CONCLUSION

Dysphagic complaints can persist more than two months following ACSS, but often do not correlate with validated physiologic swallowing dysfunction on VFSS. Future studies should focus on applications of newer technology to elucidate relevant deficits.

Anterior Approach to the Subaxial Cervical Spine: Pearls and Pitfalls

Since its introduction by Smith and Robinson, the anterior approach to the subaxial cervical spine has become one of the standard procedures for numerous cervical spine pathologies, including, but not limited to degenerative disease, trauma, tumor, deformity, and instability. Along with its increasing popularity and improvements in anterior instrumentation techniques, a comprehensive knowledge of the surgical anatomy during the anterior exposure is critical for trainees and experienced spine surgeons alike to minimize the infrequent but potentially devastating risks associated with this approach. Understanding the anatomy and techniques to minimize damage to relevant structures can reduce the risks of developing notable postoperative complications and morbidity.

Correlation of Voice Hoarseness and Vocal Cord Palsy: A Prospective Assessment of Recurrent Laryngeal Nerve Injury Following Anterior Cervical Discectomy and Fusion

BACKGROUND

Injury to the recurrent laryngeal nerve (RLN) has been implicated as a common complication following anterior cervical discectomy and fusion (ACDF) surgery. The purpose of this study is to determine the true incidence of voice hoarseness and RLN palsy following ACDF surgery, to determine the reliability of symptoms in the diagnosis of RLN injury, and to evaluate factors related to the development of these symptoms.

METHODS

All patients undergoing elective (primary or secondary) ACDF surgery at a single institution consented to and enrolled in the present study. All approaches were through the left side. Enrolled patients received both preoperative and postoperative (within 1 month following surgery) laryngoscopy by a fellowship-trained ENT physician for evaluation of RLN function. Patients also responded as to whether they were experiencing postoperative symptoms of dysphagia, aspiration, and voice changes.

RESULTS

In total, 108 patients were included in this study. Mean age of the population was 59.2 ± 10.7 years and mean body mass index was 31.2 ± 7.1 kg/m². Three patients had previously undergone a thyroidectomy, whereas 20 patients had undergone a previous ACDF. Average intubation time for ACDF surgery was 121.6 ± 38.5 minutes. After surgery and excluding patients who were experiencing preoperative symptoms, 19 patients (20.4%) complained of dysphagia, 2 patients (1.9%) complained of aspiration symptoms, and 5 patients (4.6%) complained of voice hoarseness. There was no incidence of vocal cord palsy from postoperative laryngoscopy. From multivariate analysis, endotracheal cuff pressure after retractor placement was correlated to postoperative voice hoarseness, dysphagia, and aspiration symptoms.

CONCLUSIONS

From the results of this prospective study, the RLN remained functional even a month after surgery despite several cases of postoperative dysphagia, aspiration, and voice changes. Endotracheal cuff pressure, number of vertebral levels, body mass index, and intubation time were important variables related to postoperative symptoms.

CLINICAL RELEVANCE

Voice hoarseness does not necessarily indicate recurrent laryngeal nerve injury after ACDF but may be caused by compressive forces on laryngeal tissue during retraction or intubation. Laryngoscopy should be performed in cases with high clinical suspicion.

LEVEL OF EVIDENCE

2.

Comparison of Patient-Reported Postoperative Dysphagia in Patients Undergoing One-Level Versus Two-Level Anterior Cervical Discectomy and Fusion with the Zero-P Implant System

To investigate whether dysphagia differs between one-level and two-level anterior cervical discectomy and fusion (ACDF) with the Zero Profile (Zero-P) Implant System. A retrospective analysis of 208 patients who underwent ACDF with the Zero-P Implant System and had at least one year of follow-up was performed from January 2013 to December 2018. The patients were divided into two groups based on the number of operated levels (one-level group, N = 86; two-level group, N = 122). Dysphagia was assessed based on the Bazaz grading system. The incidence of dysphagia and the severity of dysphagia at each follow-up were compared between the two groups. The patients were divided into two groups (nondysphagia group, N = 160; dysphagia group, N = 48), and covariates were obtained for multivariate analysis, including demographic parameters, surgical parameters, and radiographic parameters. The results showed that the incidence and severity of postoperative dysphagia in the two-level group were significantly greater at 1 week, 1 month and 3 months postoperatively than those in the one-level group. The results of ordinal logistic regression showed that older age, two-level surgery, greater prevertebral soft tissue swelling (PSTS) and the difference between the postoperative and preoperative C_2-7 angle (dC_2-7A) were significantly associated with a higher incidence of dysphagia after ACDF with the Zero-P. Two-level ACDF with the Zero-P can result in a significantly greater incidence and severity of transient postoperative dysphagia. Older age, greater PSTS and the dC_2-7A were also associated with postoperative dysphagia after ACDF with the Zero-P.

Recurrent laryngeal nerve injury following single- and multiple-level anterior cervical discectomy and fusion: a meta-analysis

Background

Recurrent laryngeal nerve (RLN) palsy is a common and potentially debilitating complication of anterior cervical discectomy and fusion (ACDF). The relationship between the risk of RLN palsy and the number of operated levels remains unclear, and no previous studies address potential differences between short- and long-term RLN injury following ACDF.

Methods

Electronic searches of PubMed, Cochrane, ScienceDirect and Google Scholar were performed from database inception to June 2019. Relevant studies reporting the rate of RLN palsy for patients undergoing ACDF for cervical spine pathology were identified according to predetermined inclusion and exclusion criteria. Statistical analysis was performed using fixed effects and random effects modelling. I2 and Q statistics were used to explore heterogeneity.

Results

Five studies with a total of 3,514 patients were included in the meta-analysis. The incidence of RLN palsy was found to be 1.2%. There were no statistically significant differences in the rate of RLN palsy between multiple- and single-level ACDF [odds ratio (OR) 1.04; 95% CI: 0.56-1.95; P=0.891, I2=0%]. There were similarly no statistically significant differences in RLN palsy rates for multiple- and single-level ACDF when patients were stratified based on length of follow-up of less than or greater than 12 months.

Conclusions

This analysis suggests that there is no statistically significant association between the number of ACDF operative levels and the risk of short- or long-term RLN palsy.

Recurrent Laryngeal Nerve Palsy after Anterior Cervical Discectomy and Fusion - Prevalence and Risk Factors

BACKGROUND AND STUDY AIMS

 Recurrent laryngeal nerve palsy (RLNP) is a potential complication of anterior discectomy and fusion (ACDF). There still is substantial disagreement on the actual prevalence of RLNP after ACDF as well as on risk factors for postoperative RLNP. The aim of this study was to describe the prevalence of postoperative RLNP in a cohort of consecutive cases of ACDF and to examine potential risk factors.

MATERIALS AND METHODS

 This retrospective study included patients who underwent ACDF between 2005 and 2019 at a single neurosurgical center. As part of clinical routine, RLNP was examined prior to and after surgery by independent otorhinolaryngologists using endoscopic laryngoscopy. As potential risk factors for postoperative RLNP, we examined patient's age, sex, body mass index, multilevel surgery, and the duration of surgery.

RESULTS

 214 consecutive cases were included. The prevalence of preoperative RLNP was 1.4% (3/214) and the prevalence of postoperative RLNP was 9% (19/211). The number of operated levels was 1 in 73.5% (155/211), 2 in 24.2% (51/211), and 3 or more in 2.4% (5/211) of cases. Of all cases, 4.7% (10/211) were repeat surgeries. There was no difference in the prevalence of RLNP between the primary surgery group (9.0%, 18/183) versus the repeat surgery group (10.0%, 1/10; p = 0.91). Also, there was no difference in any characteristics between subjects with postoperative RLNP compared with those without postoperative RLNP. We found no association between postoperative RLNP and patient's age, sex, body mass index, duration of surgery, or number of levels (odds ratios between 0.24 and 1.05; p values between 0.20 and 0.97).

CONCLUSIONS

 In our cohort, the prevalence of postoperative RLNP after ACDF was 9.0%. The fact that none of the examined variables was associated with the occurrence of RLNP supports the view that postoperative RLNP may depend more on direct mechanical manipulation during surgery than on specific patient or surgical characteristics.

Choice and management of negative pressure drainage in anterior cervical surgery

BACKGROUND

Postoperative unobstructed drainage is an important measure for avoiding hematoma formation and preventing complications from anterior cervical surgery.

AIM

To discuss the characteristics and key points of clinical management of two types of commonly used negative pressure drainage systems in clinical settings.

METHODS

Two types of commonly used silica gel negative pressure drainage balls and a type of gastrointestinal decompression apparatus were fully emptied and then injected with different amounts of water and air. Following this, the negative pressure values of the three devices were measured. Meanwhile, we undertook a retrospective analysis of the clinical data of 1328 patients who had been treated with different negative pressure drainage apparatuses during their anterior cervical surgery in our department between January 2007 and January 2018.

RESULTS

As the amount of injected air or water increased, the negative pressure of the silica gel negative pressure drainage ball decreased rapidly, dropping to zero when 150 mL of water or air was injected. In contrast, the negative pressure of gastrointestinal decompression apparatus decreased slowly, maintaining an ideal value even when 300 mL of water or air was injected. And statistical analysis demonstrated that patients who had been treated with the gastrointestinal decompression apparatus were less likely to develop severe complications than those who had been treated with the silica gel negative pressure drainage ball (P < 0.05).

CONCLUSION

This study showed that the gastrointestinal decompression apparatus has the advantages of large suction capacity, long duration of continuous negative pressure, and good drainage effect, all of which are the favorable factors for the use of this apparatus for negative pressure drainage in anterior cervical surgery.

Immediate Voice and Swallowing Complaints Following Revision Anterior Cervical Spine Surgery

OBJECTIVE

To report on the incidence of dysphagia, dysphonia, and acute vocal fold motion impairment (VFMI) following revision anterior cervical spine surgery, as well as to identify risk factors associated with acute VFMI in the immediate postoperative period.

STUDY DESIGN

Retrospective cohort study.

SETTING

Tertiary care center.

SUBJECTS AND METHODS

All patients who underwent 2-team reoperative anterior cervical discectomy and fusion (ACDF) were retrospectively reviewed. Incidence of dysphonia, dysphagia, and acute VFMI was noted. Patient and operative factors were evaluated for association with risk of acute VFMI.

RESULTS

The incidence of postoperative dysphonia and dysphagia was 25% (18/72) and 52% (37/72), respectively. The incidence of immediate VFMI was 21% (15/72). Subjective postoperative dysphonia (odds ratio, [OR] 8; 95% CI, 2.2-28; P = .001) and dysphagia (OR, 22; 95% CI, 2.5-168; P = .005) were significantly associated with increased risk of VFMI. Three patients with VFMI required temporary injection medialization for voice complaints and/or aspiration. Infection (OR, 14; 95% CI, 1.4-147, P = .025) and level C7/T1 (OR, 5.5; 95% CI, 1.3-23, P = .02) were significantly associated with an increased risk of acute VFMI on multivariate logistic regression analysis. Number of prior surgeries, laterality of approach, side of approach relative to prior operations, and number of levels exposed were not significant.

CONCLUSION

Early involvement of an otolaryngologist in the care of a patient undergoing revision ACDF can be helpful to the patient in anticipation of voice and swallowing changes in the postoperative period. This may be particularly important in those being treated at C7/T1 or those with spinal infections.

Total subaxial reconstruction

Cervical deformity, particularly kyphosis, is frequently encountered in surgical practice. While many cases are asymptomatic, some patients may have significant pain and disability. We provide a brief review of the pathophysiology of cervical deformity and the technical aspects of deformity correction in the cervical spine. Anterior techniques reviewed here include anterior cervical discectomy and fusion (ACDF), anterior corpectomy and fusion (ACCF) and anterior osteotomy (ATO). Posterior techniques include laminectomy and fusion, posterior column osteotomy (PCO) and pedicle subtraction osteotomy (PSO). This is a fast-evolving field as our understanding of cervical deformity matures and longer-term surgical outcomes are available.

Right Versus Left Approach to Anterior Cervical Discectomy and Fusion: An Anatomic Versus Historic Debate

The debate over the influence approach sidedness has on the risk of recurrent laryngeal nerve palsy (RLNP) following anterior cervical discectomy and fusion (ACDF) has its origins with the introduction of the procedure for radicular pain in the 1950s. The recurrent laryngeal nerves follow disparate courses in the lower neck secondary to differences in embryogenesis. Because of these differences, some authors believe a right-sided approach increases the risk of RLNP. However, modern surgical series have not shown a clear risk of RLNP with a right- versus left-sided approach. By looking at the historical context surrounding the introduction of ACDF, we propose the dogmatic view of an increased risk of RLNP with a right-sided approach likely arose from a combination of theoretical anatomic risk and the early surgical experience of a pioneer of the procedure.

Posterior longitudinal ligament resection during microscopic anterior cervical discectomy: technique and safety consideration

Background

Herniation of the cervical disk material results in interruption of the posterior longitudinal ligament (PLL) in the majority of patients. Routine opening of the PLL during ACDF is a necessary step for complete removal of all disk fragments.

Objectives

Safety measures during PLL opening during microscopic anterior cervical discectomy and risk-free surgery

Study design

A retrospective clinical case series

Patients and methods

The study was conducted on 145 patients. The main symptom was radicular pain. Pre-operative identification of PLL was assessed by MRI. All patients were operated upon by ACDF. We started dissection off the midline in patients with intact ligament while we used the site of disruption to start and complete dissection in patients with interrupted ligament. Follow-up was done monthly.

Results

Ninety-seven percent of patients underwent single level surgery. The most commonly operated level was C5-6. PLL was interrupted in 60.7% of patients. There was a statistically significant difference between median VAS in immediate, early, and late post-operative period. Bleeding was encountered in 46% of patients. Saline irrigation was a suitable method for hemostasis.

Conclusion

Conventional MRI is the modality of choice for pre-operative identification of PLL. It is better to use the site of ligament interruption to start sharp dissection and to start lateral to the midline in intact ligament. Sharp dissection is better with curved knife. Thin foot plate Kerrison is suitable for excision of the remaining parts. Hemostasis using saline irrigation is better and non-risky than using bipolar coagulation.

Dysarthria Consequent to Cervical Spinal Cord Injury and Recurrent Laryngeal Nerve Damage: A Case Report

Objective

To assess and describe the involvement of all speech subsystems, including respiration, phonation, articulation, resonance, and prosody, in an individual with cervical spinal cord injury.

Methods

Detailed speech and voice assessment was performed that included Frenchay Dysarthria Assessment, cranial nerve examination, voice (per-ceptual and instrumental) and nasometric evalua-tion, and intelligibility and communicative effecti-veness.

Results

Impaired respiratory and phonatory con-trol correlated with the physical impairment of C4 and C5 prolapsed intervertebral disc. Cranial nerve examination indicated nerve IX and XI pathology. Phonatory deficits such as imprecise consonants and mild sibilant distortions were apparent. Voice analysis revealed a hoarse, breathy voice with re-duced loudness and no problems with resonance. Reading and speaking rate was reduced, and over-all a mild reduction in communicative effectiveness was perceived.

Conclusion

Assessment of the speech subsystems produced a comprehensive picture of the patient’s condition and impairments in one or more areas was identified. Treatment options to improve speech outcomes were provided.

Platysma sparing approach to anterior cervical spine surgery: A less exposure surgery technique

Introduction

Authors aim to demonstrate the surgical technique and outcomes of using a platysma sparing approach to anterior cervical spine surgery.

Methods

Medical records of 496 prospective patients, group 1 (259 patients) with an outpatient platysma muscle-sparing approach. Group 2 (237 patients) with inpatient standard muscle-splitting approach.

Results

Intergroup comparison showed statistical significant improvement in VAS neck and NDI scores p = 0.009 and p = 0.012 and surgical operative time and estimated blood loss, p = 0.003 and p = 0.006 respectively.

Conclusion

This anatomy sparing technique demonstrates a safe, effective and reproducible approach to cervical spine surgery which is a goal of less exposure surgery philosophy.

Recurrent laryngeal nerve transection in mice results in translational upper airway dysfunction

The recurrent laryngeal nerve (RLN) is responsible for normal vocal-fold (VF) movement, and is at risk for iatrogenic injury during anterior neck surgical procedures in human patients. Injury, resulting in VF paralysis, may contribute to subsequent swallowing, voice, and respiratory dysfunction. Unfortunately, treatment for RLN injury does little to restore physiologic function of the VFs. Thus, we sought to create a mouse model with translational functional outcomes to further investigate RLN regeneration and potential therapeutic interventions. To do so, we performed ventral neck surgery in 21 C57BL/6J male mice, divided into two groups: Unilateral RLN Transection (n = 11) and Sham Injury (n = 10). Mice underwent behavioral assays to determine upper airway function at multiple time points prior to and following surgery. Transoral endoscopy, videofluoroscopy, ultrasonic vocalizations, and whole-body plethysmography were used to assess VF motion, swallow function, vocal function, and respiratory function, respectively. Affected outcome metrics, such as VF motion correlation, intervocalization interval, and peak inspiratory flow were identified to increase the translational potential of this model. Additionally, immunohistochemistry was used to investigate neuronal cell death in the nucleus ambiguus. Results revealed that RLN transection created ipsilateral VF paralysis that did not recover by 13 weeks postsurgery. Furthermore, there was evidence of significant vocal and respiratory dysfunction in the RLN transection group, but not the sham injury group. No significant differences in swallow function or neuronal cell death were found between the two groups. In conclusion, our mouse model of RLN injury provides several novel functional outcome measures to increase the translational potential of findings in preclinical animal studies. We will use this model and behavioral assays to assess various treatment options in future studies.

Horner Syndrome After Anterior Cervical Discectomy and Fusion: Case Series and Systematic Review

BACKGROUND

Horner syndrome is an infrequently seen complication of anterior cervical discectomy and fusion (ACDF). Multicenter studies have reported a very low incidence, less than 0.1%.

OBJECTIVE

To identify the incidence in, characteristics of, and postoperative course in patients in whom postoperative Horner syndrome developed after ACDF.

METHODS

We performed a retrospective review of all patients who experienced Horner syndrome after ACDF for cervical degenerative disease at a single tertiary care institution between 2017 and 2018. A systematic review was then performed to identify studies investigating prevalence, diagnosis, and treatment of postoperative Horner syndrome after ACDF.

RESULTS

Of 1116 patients at our institution who underwent ACDF, the incidence of Horner syndrome was 0.45%. C4/5 and C5/6 were the 2 most common surgical levels. The complication was noted to occur immediately after surgery, and at least partial improvement was identified in all patients an average 3.5 months after surgery (range, 10 days to 6 months). These findings were consistent with our systematic review of 21 studies that showed an incidence of 0.6% (range, 0.02% to 4.0%), the most common surgical level C5/6 (64%), and 82% of patients experiencing at least partial resolution of symptoms within 1 year (60.7% complete, 21.4% partial resolution).

CONCLUSION

Horner syndrome occurs in 0.6% of patients undergoing ACDF. Careful postoperative examination should reveal this complication, which may be underdiagnosed or underreported in larger multicenter case series. The majority of patients experience complete resolution of symptoms within 6 months to 1 year and can be treated conservatively and expectantly.

Assessment of the Reliability of the Fiberoptic Endoscopic Evaluation of Swallowing as an Outcome Measure in Patients Undergoing Revision Anterior Cervical Discectomy and Fusion

BACKGROUND

Dysphagia is one of the most common complications of anterior cervical spine surgery, and there is a need to establish that the means of testing for it are reliable and valid. The objective of this study was to measure observer variability of the fiberoptic endoscopic evaluation of swallowing (FEES) test, specifically when used for evaluation of dysphagia in patients undergoing revisionary anterior cervical decompression and fusion (ACDF).

METHODS

Images from patients undergoing revision ACDF at a single institution were collected from May 1, 2010, through July 1, 2014. Two senior certified speech pathologists independently evaluated the swallowing function of patients preoperatively and at 2 weeks postoperatively. Their numeric evaluations of the Rosenbeck Penetration-Aspiration Scale and the Swallowing Performance Scale during the FEES were then compared for interrater reliability.

RESULTS

Positive agreement between raters was 94% for the preoperative Penetration-Aspiration Scale (prevalence-adjusted bias-adjusted κ, 0.77). The postoperative Penetration-Aspiration Scale showed reliability coefficients for κ, Kendall's W, and intraclass correlation coefficient (ICC) of 0.34 (fair agreement), 0.70 (extremely strong agreement), and 0.35 (poor agreement), respectively. The preoperative Swallowing Performance Scale showed strong agreement, with a Kendall's W coefficient of 0.68, and fair reliability, with an ICC of 0.40. The postoperative Swallowing Performance Scale indicated extremely strong agreement between raters, with a Kendall's W of 0.82, and good agreement, with an ICC of 0.53.

CONCLUSIONS

The FEES test appears to be a reliable assessor of dysphagia in patients undergoing ACDF and may be a useful measure for exploring outcomes in this population.

Alcoholism as a predictor for pseudarthrosis in primary spine fusion: An analysis of risk factors and 30-day outcomes for 52,402 patients from 2005 to 2013

Introduction

This study assessed the incidence and risk factors for pseudarthrosis among primary spine fusion patients.

Methods

Retrospective review of ACS-NSQIP (2005-2013). Differences in comorbidities between spine fusion patients with and without pseudarthrosis (Pseud, N-Pseud) were assessed using chi-squared tests and Independent Samples t-tests. Binary logistic regression assessed patient-related and procedure-related predictors for pseudarthrosis.

Results

52,402 patients (57yrs, 53%F, 0.4% w/pseudarthrosis). Alcohol consumption (OR:2.6[1.2-5.7]) and prior history of surgical revision (OR:1.6[1.4-1.8]) were risk factors for pseudarthrosis operation. Pseud patients at higher risk for deep incisional SSI (at 30-days:OR:6.6[2.0-21.8]). Pseud patients had more perioperative complications (avg:0.24 ± 0.43v0.18 ± 0.39,p=0.026).

Conclusions

Alcoholism and surgical revision are major risk factors for pseudarthrosis in patients undergoing spine fusion.

Morbidity and mortality in cervical spine injuries in the elderly

BACKGROUND

The aim of our study was to identify the demographics and complications in elderly cervical spine injuries and predictive factors for surgery, complications and mortality. We hypothesized younger healthier patients were more likely to undergo surgical intervention.

METHODS

A retrospective review of 225 consecutive patients aged 65 years and over with cervical spine injuries was carried out over a 3-year period.

RESULTS

There were 113 males and 112 females with an average of 79.7 years (range 65-98). The most common fracture was C2 peg type (21.8%). Five patients had complete spinal cord injury (2.2%), 25 had incomplete spinal cord injury (11.1%) and 84% were neurologically intact. Fifty-four patients were managed operatively (24%), while 171 patients were managed non-operatively (76%). The operative group had higher rates of pneumonia (odds ratio (OR) 5.3, 95% confidence interval (CI) 2.6-10.7, P < 0.01), cardiac arrhythmia (OR 4.1, 95% CI 1.5-11.2, P < 0.01) and respiratory failure (OR 2.6, 95% CI 1.2-5.5, P < 0.05). There was no difference in mortality between the operative and non-operative group (18.5% and 12.9%, P = 0.3). Patients with complete spinal cord injury had 100% mortality. Significant predictive factors for complications and death were neurological deficits, comorbidities and the presence of other injuries (P < 0.05). Surgery was not predictive for death and the operative group was younger than the non-operative group (P < 0.05).

CONCLUSIONS

In the setting of a high complication rate, consideration should be given to palliation in elderly patients with complete spinal cord injury and there must be good rational for surgery.

Cervical spondylotic myelopathy: A two decade experience

Context Cervical myelopathy occurs as a result of compression of the cervical spinal cord. Symptomatology includes, but is not limited to, pain, weakness, paresthesias, or gait/balance difficulties. Objective To present a two-decade experience with the management of cervical myelopathy. Methods Literature was reviewed to provide current guidelines for management as well as accompanying clinical presentations. Results Surgical decompression, if necessary, may be achieved from either an anterior, a posterior, or a combined anterior-posterior (AP) approach. The indications for each approach, as well as the surgical techniques, are described. Conclusion Several etiologies may lead to cord compression and cervical myelopathy. The best vector of approach with regard to anterior versus posterior surgical intervention is still under investigation. Regardless, management via surgical decompression has been demonstrated repeatedly to improve the CSM patients' quality of life.

Bilateral vocal cord palsy after a posterior cervical laminoplasty

PURPOSE

To report a patient with bilateral vocal cord palsy following cervical laminoplasty, who survived following a tracheotomy and intensive respiratory care.

METHODS

Acute respiratory distress is a fatal complication of cervical spinal surgery. The incidence of bilateral vocal cord palsy after posterior cervical decompression surgery is extremely rare. The authors report a 71-year-old woman who suffered from cervical myelopathy due to ossification of the posterior longitudinal ligament. Open-door laminoplasty from C2 to C6 and laminectomy of C1 were performed. Following surgery, extubation was successfully conducted. Acute-onset dysphagia and stridor had occurred 2 h following extubation. A postoperative fiber optic laryngoscope revealed bilateral vocal cord palsy. After a tracheotomy and intensive respiratory care, she had completely recovered 2 months after surgery.

DISCUSSION

One potential cause of this pathology was an intraoperative hyper-flexed neck position, which likely induced mechanical impingement of the larynx, resulting in swelling and edema of the vocal cords and recurrent laryngeal nerve paresis. Direct trauma of the vocal cords during intubation and extubation could have also induced vocal cord paralysis.

CONCLUSIONS

We reported a case of bilateral vocal cord palsy associated with posterior cervical laminoplasty. Airway complications following posterior spinal surgery are rare, but they do occur; therefore, spine surgeons should be aware of them and take necessary precautions against intraoperative neck position, intubation technique, even positioning of the intratracheal tube.

Option for transverse midline incision and other factors that determine patient's decision to have cervical spine surgery

BACKGROUND

Authors aim to determine patients' preference for surgical incision and factors affecting the decision for surgery to the anterior neck.

METHODS

A questionnaire was presented prior to evaluation and if preceded to surgery followup given.

RESULTS

243 patients completed questionnaire, with 60% female population and younger than 50 years. 151 patients preferred a transverse midline incision with a statistically significant increase in outcomes and cosmesis importance and a decrease in the importance of board certification.

CONCLUSION

Findings of questionnaire demonstrate that patients' prefer a transverse midline anterior neck incision, with surgical outcomes being the overall factor affecting decision making.

Cervical fusion for degenerative disease: A comprehensive cost analysis of hospital complications in the United States from 2002 to 2014

Purpose

Recent data suggest great variability in costs for surgical hospitalization for spinal surgery. However, the magnitude of expenditures attributable to complications is unknown. The purpose of this study is to describe cost of care associated with surgical and medical complications after cervical spine surgery.

Materials and Methods

A retrospective cohort study utilizing the National Inpatient Sample years 2002-2014 was conducted. A weighted sample of 901,508 adults undergoing elective cervical fusion for degenerative indications was extracted using diagnostic and procedure codes. Twelve categories of major complications were identified, and patient/hospital variables were evaluated as predictors of the overall reimbursed cost using multivariate regression. Mean differences (B) and 95% confidence intervals were reported.

Results

The mean age was 52.2 ± 11.4 years, with 5.2% of patients experiencing a complication. Mean overall increase in inflation-adjusted cost associated with complication was $16,435 ± 10,358, varying significantly by type of complication, surgical approach, and number of levels fused. The most common complications and their attributed costs were dysphagia (1.6%, B = $2624 [2476-2771], P < 0.001), pulmonary complications (1.0%, B = $9334 [9110-9558], P < 0.001), and device-related complications (0.9%, B = $3125 [2927-3324], P < 0.001). The costliest complications were infection (0.1%, B = $25359 [24723-25994], P < 0.001), thromboembolism (0.1%, B = $17480 [16808-18153], P < 0.001), and neurological complications (0.2%, B = $10098 [9629-10567], P < 0.001).

Conclusions

Although complications are rare after elective cervical fusion, they are associated with dramatically increase costs of care as high as $25,359 in the setting of postoperative infection. Improved understanding of the economic magnitude of complications may help guide efforts in reducing health care spending and improving perioperative care.

Voice and swallowing outcomes following reoperative anterior cervical discectomy and fusion with a 2-team surgical approach

OBJECTIVE Dysphagia and vocal cord palsy (VCP) are common complications after anterior cervical discectomy and fusion (ACDF). The reported incidence rates for dysphagia and VCP are variable. When videolaryngostroboscopy (VLS) is performed to assess vocal cord function after ACDF procedures, the incidence of VCP is reported to be as high as 22%. The incidence of dysphagia ranges widely, with estimates up to 71%. However, to the authors' knowledge, there are no prospective studies that demonstrate the rates of VCP and dysphagia for reoperative ACDF. This study aimed to investigate the incidence of voice and swallowing disturbances before and after reoperative ACDF using a 2-team operative approach with comprehensive pre- and postoperative assessment of swallowing, direct vocal cord visualization, and clinical neurosurgical outcomes. METHODS A convenience sample of sequential patients who were identified as requiring reoperative ACDF by the senior spinal neurosurgeon at the University of Alabama at Birmingham were enrolled in a prospective, nonrandomized study during the period from May 2010 until July 2014. Sixty-seven patients undergoing revision ACDF were enrolled using a 2-team approach with neurosurgery and otolaryngology. Dysphagia was assessed both preoperatively and postoperatively using the MD Anderson Dysphagia Inventory (MDADI) and fiberoptic endoscopic evaluation of swallowing (FEES), whereas VCP was assessed using direct visualization with VLS. RESULTS Five patients (7.5%) developed a new postoperative temporary VCP after reoperative ACDF. All of these cases resolved by 2 months postoperatively. There were no new instances of permanent VCP. Twenty-five patients had a new swallowing disturbance detected on FEES compared with their baseline assessment, with most being mild and requiring no intervention. Nearly 60% of patients showed a decrease in their postoperative MDADI scores, particularly within the physical subset. CONCLUSIONS A 2-team approach to reoperative ACDF was safe and effective, with no new cases of VCP on postoperative VLS. Dysphagia rates as assessed through the MDADI scale and FEES were consistent with other published reports.

The Role of C2-C7 Angle in the Development of Dysphagia After Anterior and Posterior Cervical Spine Surgery

STUDY DESIGN

This is a retrospective clinical study.

OBJECTIVE

To analyze the relationship between cervical alignment and the development of dysphagia after anterior and posterior cervical (PC) spine surgery [anterior cervical discectomy and fusion (ACDF), cervical disk replacement (CDR), and PC].

SUMMARY OF BACKGROUND DATA

Dysphagia is a known complication of cervical surgery and may be prolonged or occasionally serious. A previous study showed dysphagia after occipitocervical fusion was caused by oropharyneal stenosis resulting from O-C2 (upper cervical lordosis) fixation in a flexed position. However, there have been few reports analyzing the association between the C2-C7 angle (middle-lower cervical lordosis) and postoperative dysphagia.

MATERIALS AND METHODS

In total, 452 patients were reviewed in this study, including 172 patients who underwent the ACDF procedure, 98 patients who had the CDR procedure, and 182 patients who had the PC procedure between June 2007 and May 2010. The presence and duration of postoperative dysphagia were recorded via face-to-face questioning or telephone interview performed at least 1 year after the procedure. Plain cervical radiographs before and after surgery were collected. The O-C2 angle and C2-C7 angle were measured. The change of O-C2 angle and C2-C7 angle were defined as dO-C2 angle=postoperative O-C2 angle-preoperative O-C2 angle and dC2-C7 angle=postoperative C2-C7 angle-preoperative C2-C7 angle. The association between postoperative dysphagia with dO-C2 angle and dC2-C7 angle was studied.

RESULTS

A total of 12.8% ACDF, 5.1% CDR, and 9.4% PC patients reported dysphagia after cervical surgery. The dC2-C7 angle has considerable impact on postoperative dysphagia. When dC2-C7 angle is >5 degrees, the chance of developing postoperative dysphagia of this patient is significantly greater. The dO-C2 angle, age, sex, body mass index, operative time, blood loss, procedure type, revision surgery, most cephalic operative level, and number of operative levels did not significantly influence the incidence of postoperative dysphagia. No relationship was found between the dC2-C7 angle and the degree of dysphagia.

CONCLUSIONS

Postoperative dysphagia is common after cervical surgery. The dC2-C7 angle may play an important role in the development of dysphagia in both anterior and PC spine surgery. Overenlargement of cervical lordosis should be avoided to reduce the development of postoperative dysphagia.

Adjacent Segment Disease in the Cervical and Lumbar Spine

Adjacent segment disease (ASD) is disappointing long-term outcome for both the patient and clinician. In contrast to adjacent segment degeneration, which is a common radiographic finding, ASD is less common. The incidence of ASD in both the cervical and lumbar spine is between 2% and 4% per year, and ASD is a significant contributor to reoperation rates after spinal arthrodesis. The etiology of ASD is multifactorial, stemming from existing spondylosis at adjacent levels, predisposed risk to degenerative changes, and altered biomechanical forces near a previous fusion site. Numerous studies have sought to identify both patient and surgical risk factors for ASD, but a consistent, sole predictor has yet to be found. Spinal arthroplasty techniques seek to preserve physiological biomechanics, thereby minimizing the risk of ASD, and long-term clinical outcome studies will help quantify its efficacy. Treatment strategies for ASD are initially nonoperative, provided a progressive neurological deficit is not present. The spine surgeon is afforded many surgical strategies once operative treatment is elected. The goal of this manuscript is to consider the etiologies of ASD, review its manifestations, and offer an approach to treatment.

Effect of perioperative steroids on dysphagia after anterior cervical spine surgery: A systematic review

BACKGROUND

Dysphagia following anterior cervical spine surgery is common. Steroids potentially reduce post-operative inflammation that leads to dysphagia; however, the efficacy, optimal dose and route of steroid administration have not been fully elucidated.

OBJECTIVE

The purpose of this systematic review is to evaluate the effect of peri-operative steroids on the incidence and severity of dysphagia following anterior cervical spine surgery.

METHODS

A PubMed search adherent to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was performed to include clinical studies reporting use of steroids in adult patients following anterior cervical spine surgery. Data regarding steroid dose, route and timing of administration were abstracted. Incidence and severity of post-operative dysphagia were pooled across studies.

RESULTS

Seven of 72 screened articles met inclusion criteria for a total of 246,298 patients that received steroids. Patients that received systemic and local steroids had significant reductions in rate and severity of dysphagia postoperatively. Reduction of dysphagia severity was more pronounced in patients undergoing multilevel procedures in both groups. There was no difference in infectious complications among patients that received steroids compared with controls. There was no difference in fusion rates at long-term follow-up.

CONCLUSIONS AND CLINICAL RELEVANCE

Steroids may reduce dysphagia after anterior cervical spinal procedures in the early post-operative period without increasing complications. This may be especially beneficial in patients undergoing multilevel procedures. Future studies should further define the optimal dose and route of steroid administration, and the specific contraindications for use.

Differences in Short-Term Outcomes Between Primary and Revision Anterior Cervical Discectomy and Fusion

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To compare short-term morbidity for primary and revision anterior cervical discectomy and fusion (ACDF).

SUMMARY OF BACKGROUND DATA

Revision ACDF procedures are relatively common, yet their risks are poorly characterized in the literature. There is a need to assess the relative risk of revision ACDF procedures compared with primary surgery.

METHODS

The prospectively collected American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was used to identify patients who underwent primary and revision ACDF from 2005 to 2014. The occurrence of 30-day postoperative complications, readmission, operative time, and postoperative length of stay were compared between primary and revision procedures using multivariate regression to control for patient and operative characteristics.

RESULTS

A total of 20,383 ACDF procedures were identified, 1219 (6.0%) of which were revision cases. On multivariate analysis, revision procedures were associated with significantly increased risk of any adverse event (relative risk [RR] 2.3, P < 0.001), any severe adverse event (RR 2.2, P < 0.001), thromboembolic events (RR 3.3, P = 0.001), surgical site infections (RR 3.2, P < 0.001), return to the operating room (RR 1.9, P = 0.001), any minor adverse event (RR 2.5, P < 0.001), and blood transfusion (RR 8.3, P < 0.001). Revision procedures had significantly increased risk of readmission within 30 days (RR = 1.6, P = 0.001). Minor, but statistically significant increases in average operative time and postoperative length of stay were identified for revisions procedures (7 min and half a day, respectively [P < 0.001 for both]).

CONCLUSION

Revision procedures were associated with significantly increased risk of multiple adverse outcomes, including thromboembolic events, surgical site infections, return to the operating room, blood transfusion, and readmission within 30 days. These results are important for patient counseling and risk stratification.

LEVEL OF EVIDENCE

3.

An In Vitro Biomechanical Study Evaluating Cervical Extension Plates for Stabilizing Degenerated Adjacent Levels

STUDY DESIGN

To evaluate the biomechanical stability of 2 extender plates in a human cervical cadaveric model.

OBJECTIVES

To evaluate 2 extender plates, placed adjacent to initially implanted plates and to compare their biomechanical stability with traditional techniques.

SUMMARY OF BACKGROUND DATA

Traditionally, adjacent level degeneration is surgically treated by removing the previously implanted plate and extending the instrumentation to the new degenerated level. The exposure needed to remove the previously implanted plate may be extensive. To overcome these complications, cervical extension plates, which add-on to the initially implanted plate, were developed.

MATERIALS AND METHODS

Fourteen fresh-frozen human cadaver cervical spines (C2-C7) were divided into 2 groups of 7 for a series of constructs to be tested. In group 1, an extender plate, which attaches to its own primary plate, was tested. In group 2, a universal extender plate, which can be placed adjacent to any previously implanted plate, was tested. The specimens prepared were mounted on a 6-degree-of-freedom spine simulator and were sequentially tested in the following order: (1) intact; (2) single-level plate; (3) single-level plate with extender plates; and (4) 2-level plate. An unconstrained pure moment of ±1.5 N m was used in flexion-extension, lateral bending, and axial rotation.

RESULTS

All instrumented constructs significantly reduced the range of motion compared with the intact condition. In both the groups, single-level plates with adjacent extender plates demonstrated stability comparable to their respective 2-level plates in all loading modes.

CONCLUSIONS

Extender plates give surgeons the opportunity to treat adjacent levels without removing the primary implants, which may reduce the overall risk of damage to vital neurovascular structures. From this cadaveric biomechanical model, both types of extender plates prove to be viable options for treating adjacent level degeneration.

Indications for Direct Laryngoscopic Examination of Vocal Cord Function Prior to Anterior Cervical Surgery

Recurrent laryngeal nerve palsy (RLNP) is among the most common complications in both thyroid surgeries and anterior approaches to the cervical spine, having both a diverse etiology and presentation. Most bilateral paresis, with subsequent devastating impact on patients, are due to failure to recognize unilateral recurrent laryngeal nerve paralysis and, although rare, are entirely preventable with appropriate history and screening. Recurrent laryngeal nerve palsy has been shown to present asymptomatically in as high as 32% of cases, which yields limitations on exclusively screening with physical examination. Based on the available literature, diagnosis of unilateral RLNP is the critical factor in preventing the occurrence of bilateral RLNP as the surgeon may elect to operate on the injured side to prevent bilateral paresis. Analysis of incidence rates shows postoperative development of unilateral RLNP is 13.1 (95% confidence interval [CI]: 6.1-28.1) and 13.90 (95% CI: 6.6-29.3) times more likely in anterior spine and thyroid surgery, respectively, in comparison with intubation. Currently, there is no consensus on when to order a preoperative laryngoscopic examination prior to anterior cervical spine surgery. The importance of patient history should be emphasized, as it is the basis for indications of preoperative laryngoscopy. Efforts to minimize postoperative complications must be made, especially when considering the rising rate of cervical fusion. This study presents a systematic review of the literature defining key causes of RLNP, with a probability-based protocol to indicate direct laryngoscopy prior to anterior cervical surgery as a screening tool in the prevention of bilateral RLNP.

Intraoperative Neurophysiological Monitoring of the Laryngeal Nerves During Anterior Neck Surgery: A Review

Contributions to the literature on intraoperative neuro monitoring (IONM) during endocrine and head and neck surgery have increased over recent years. Organizational support for neural monitoring during surgery is becoming evident and is increasingly recognized as an adjunct to visual nerve identification. A comprehensive understanding of the role of IONM for prevention of nerve injuries is critical to maximize safety during surgery of the anterior compartment of the neck. This review will explore the potential advantages of IONM to improve the outcomes among patients undergoing anterior neck surgery.

Complications and long-term outcomes after open surgery for traumatic subaxial cervical spine fractures: a consecutive series of 303 patients

Background

Patient selection for surgical treatment of subaxial cervical spine fractures (S-CS-fx) may be challenging and is dependent on fracture morphology, the integrity of the discoligamentous complex, neurological status, comorbidity, risks of surgery and the expected long-term outcomes. The purpose of this study is to evaluate complications and long-term outcomes in a consecutive series of 303 patients with S-CS-fx treated with open surgical fixation.

Methods

Medical charts were retrospectively reviewed. The surviving patients participated in a prospective long-term follow-up, including clinical history, physical examination and updated cervical CT. Patients with ankylosing spondylitis were excluded from this study.

Results

The median patient age was 48 years (range 14.7–93.9), and 74 % were males. Preoperatively, 43 % had spinal cord injury (SCI), and 27 % exhibited isolated radiculopathy. The median time from injury to surgery was 2 days (range 0–136). The risks of SCI deterioration and new-onset radiculopathy after surgery were 2.0 % and 1.3 %, respectively. Surgical mortality (death within 30 days after surgery) was 2.3 %. The reoperation rate was 7.3 %. At the long-term follow-up conducted a median of 2.6 years after trauma (range 0.5–9.1), 256 (99.2 %) of the patients who had survived and were living in Norway participated. Of the patients with American Injury Severity Scale (AIS) A–D at presentation, 51 % had improved one or more AIS grades. At the time of follow-up, 89 % of the patients with preoperative radiculopathy were without symptoms. Furthermore, 11 % of the patients reported severe neck stiffness, 5 % reported severe neck pain (Visual Analog Scale (VAS) ≥7), 6 % reported hoarseness, and 9 % reported dysphagia at the follow-up. The stable fusion rate, as evaluated using cervical-CT, was 98 %.

Conclusions

In this large consecutive series of patients with S-CS-fx treated with open surgical fixation, the surgical mortality was 2.3 %, the risk of neurological deterioration was 3.3 % and the reoperation rate (any cause) was 7.3 %. The neurological long-term results were good, with 51 % improvement in AIS grade and resolution of radiculopathy in 89 % of the patients. Stable fusion was excellent and was achieved in 98 % of the follow-up group.

Cervical Disc Arthroplasty with Prestige LP Disc Versus Anterior Cervical Discectomy and Fusion: Seven-Year Outcomes

BACKGROUND

Cervical disc arthroplasty (CDA) has emerged as an alternative to anterior cervical discectomy and fusion (ACDF) for the treatment of cervical pathologies. Studies are on-going to assess the long term outcomes of CDA. This study assessed the safety and efficacy of the Prestige(®) LP Disc at 84-months follow up.

METHODS

Prospective data from 280 CDA patients with single-level cervical disc disease with radiculopathy or myelopathy were compared with 265 historical control ACDF patients. Clinical and radiographic follow up was completed pre-operatively, intraoperatively, and at intervals up to 84 months.

RESULTS

Follow-up rate was 75.9% for CDA and 70.0% for ACDF patients. Statistical improvements (p < 0.001) in Neck Disability Index (NDI), neck/arm pain, and SF-36 were achieved by 1.5 months in both groups and maintained through 84 months. At 84 months, 86.1% of CDA versus 80.1% of ACDF patients achieved NDI success, (≥15-point improvement over baseline). Mean NDI score improvements exceeded 30 points in both groups. SF-36 PCS/MCS mean improvements were 13.1±11.9/8.2±12.3 points for CDA and 10.7±11.8/8.3±13.6 points for ACDF. Neurological success was 92.8% for CDA and 79.7% for ACDF patients. The rate of Overall Success was 74.9% for CDA and 63.2% for ACDF. At 84 months, 17.5% of CDA and 16.6% of ACDF patients had a possibly implant- or implant-surgical procedure-related adverse event. Eighteen (6.4%) CDA and 29 (10.9%) ACDF patients had a second surgery at the index level. In CDA patients, mean angular motion at the target level was maintained at 24 (7.5°) and 84 (6.9°) months. Bridging bone was reported in 5.9%/9.5%/10.2%/13.0% of CDA patients at 24/36/60/84 months. Change in mean preoperative angulation of the adjacent segment above/below the index level was1.06±4.39/1.25±4.06 for CDA and (-0.23)±5.37/1.25±5.07 for ACDF patients. At 84 months, 90.9% of CDA and 85.6% of ACDF patients were satisfied with the results of their treatment.

CONCLUSIONS

Prestige LP maintained significantly improved clinical outcomes and segmental motion; statistical superiority of CDA was concluded for overall success. This investigational device exemption study was sponsored by Medtronic Spinal and Biologics, Memphis, TN. Study approved by the Hughston Sports Medicine Center Institutional Review Board on January 7, 2005. Clinical trial registered at clinicaltrials.gov: NCT00667459. All participants signed an informed consent.

Anterior cervical discectomy and fusion with a compressive staple of C-JAWS

OBJECTIVE

To evaluate the clinical value of C-JAWS in anterior cervical discectomy and fusion (ACDF) surgery.

METHODS

Between January 2012 and December 2013, nine consecutive patients with cervical spondylopathy underwent ACDF process using a polyetheretherketone cervical spacer prefilled with bone substitute and secured by a cervical compressive staple in our department. The Neck Disability Index (NDI) score and visual analogy scale (VAS) of neck or arm pain as well as radiographic examination were adopted to assess the postoperative outcome and fusion.

RESULTS

Bony fusion was observed in all of the nine patients, and no serious surgery-related or implant-related complications were observed during the operation or postoperative period. The average operative time was 60.3 ± 11.6 min. The average hospital stay was 3.2 ± 0.8 days. The average skin incision length was about 3.0 ± 0.3 cm. The average of the follow-up days was 18.4 ± 4.3 months. At the last follow-up, the NDI changed from the baseline of 23.4 ± 10.3 to 7.1 ± 4.8, the VAS of neck or arm pain from 6.1 ± 1.0 and 4.6 ± 1.6 to 2.3 ± 1.7 and 2.4 ± 1.1, respectively. The patients' subjective satisfaction was excellent in 6 and good in 3.

CONCLUSIONS

Without screws, this low-profile designed compressive staple C-JAWS performed well in the ACDF surgeries.

Complications of Anterior and Posterior Cervical Spine Surgery

Cervical spine surgery performed for the correct indications yields good results. However, surgeons need to be mindful of the many possible pitfalls. Complications may occur starting from the anaesthestic procedure and patient positioning to dura exposure and instrumentation. This review examines specific complications related to anterior and posterior cervical spine surgery, discusses their causes and considers methods to prevent or treat them. In general, avoiding complications is best achieved with meticulous preoperative analysis of the pathology, good patient selection for a specific procedure and careful execution of the surgery. Cervical spine surgery is usually effective in treating most pathologies and only a reasonable complication rate exists.

Recurrent laryngeal nerve injury following reoperative anterior cervical discectomy and fusion: a meta-analysis

OBJECTIVE Recurrent laryngeal nerve (RLN) injury is one of the most frequent complications of anterior cervical discectomy and fusion (ACDF) procedures. The frequency of RLN is reported as 1%-11% in the literature. (4 , 15) The rate of palsy after reoperative ACDF surgery is not well defined. This meta-analysis was performed to review the current medical evidence on RLN injury after ACDF surgery and to determine a relative rate of RLN injury after reoperative ACDF. METHODS MEDLINE, PubMed, and Google Scholar searches were performed using several key words and phrases related to ACDF surgery. Included studies were written in English, addressed revisionary ACDF surgery, and studied outcomes of RLN injury. Statistical analysis was then performed using a random-effects model to calculate a pooled rate of RLN injury. The heterogeneity of the studies was assessed using Cochran's Q statistic and I(2) statistic, and a funnel plot was constructed to evaluate publication bias. RESULTS The search initially identified 345 articles on this topic. Eight clinical articles that met all inclusion criteria were included in the meta-analysis. A total of 238 patients were found to have undergone reoperative ACDF. Thirty-three of those patients experienced an RLN injury. This analysis identified a rate of RLN injury in the literature after reoperative ACDF of 14.1% (95% confidence interval [CI] 9.8%-19.1%). CONCLUSIONS The rate of RLN palsy of 14.1% was greater than any published rate of RLN injury after primary ACDF operations, suggesting that there is a greater risk of hoarseness and dysphagia with reoperative ACDF surgeries than with primary procedures as reported in these studies.

A Tunneled Subcricoid Approach for Anterior Cervical Spine Reoperation: Technical and Safety Results

OBJECTIVE

Anterior cervical spine decompression and fusion are common neurosurgical operations. Reoperation of the anterior cervical spine is associated with increased morbidity. The authors describe a novel subcricoid approach to protect the recurrent laryngeal nerve in a cuff of tissue while facilitating surgical access to the anterior cervical spine.

METHODS

Single institution, consecutive case review of 48 patients undergoing reoperation in the anterior cervical region including the level of C5 and below. Univariable and multivariable regression analysis was used to determine predictors of postoperative morbidity.

RESULTS

No intraoperative complications were reported. Estimated blood loss for the approach was 13.6 ± 3.1 mL. Nine of 48 patients developed immediate postoperative complications, including vocal cord paresis (10.4%), moderate-to-severe dysphagia (10.4%), and neck edema requiring intubation (2.1%). No postoperative hematomas or death occurred. All complications occurred with 4 or more levels of exposure (1-3 disc levels, 0%, vs. ≥ 4 disc levels, 31%). Extension of the exposure to the upper thoracic spine was associated with odds for postoperative complications (adjusted odds ratio, 6.50; 95% confidence interval, 1.14-37.03) and prolonged hospital stay (adjusted increase 4.23 days, P < 0.01).

CONCLUSION

The tunneled subcricoid approach is a relatively safe corridor to reapproach the anterior cervical spine at the level of C5 and below. However, caution must be exercised when using this approach to expose 4 or more disc levels and with extension of the exposure to the upper thoracic spine. Future comparative studies are needed to establish patient selection criteria in determining the use of this technique compared with classic approaches.