Lumbar spinal stenosis diagnosis

Lumbar spinal stenosis diagnosis

Diagnosing lumbar spinal stenosis or herniated intervertebral disc is usually helpful only in potential surgical candidates 1).

Boden et al., performed magnetic resonance imaging on sixty-seven individuals who had never had low back pain, sciatica, or neurogenic claudication. The scans were interpreted independently by three neuro-radiologists who had no knowledge about the presence or absence of clinical symptoms in the subjects. About one-third of the subjects were found to have a substantial abnormality. Of those who were less than sixty years old, 20 per cent had a herniated nucleus pulposus and one had spinal stenosis. In the group that was sixty years old or older, the findings were abnormal on about 57 per cent of the scans: 36 per cent of the subjects had a herniated nucleus pulposus and 21 per cent had spinal stenosis. There was degeneration or bulging of a disc at at least one lumbar level in 35 per cent of the subjects between twenty and thirty-nine years old and in all but one of the sixty to eighty-year-old subjects. In view of these findings in asymptomatic subjects, they concluded that abnormalities on magnetic resonance images must be strictly correlated with age and any clinical signs and symptoms before operative treatment is contemplated 2).


Results of a survey suggested that there are no broadly accepted quantitative criteria and only partially accepted qualitative criteria for the diagnosis of lumbar spinal stenosis. The latter include disk protrusion, lack of perineural intraforaminal fat, hypertrophic facet joint degeneration, absent fluid around the cauda equine, and hypertrophy of the ligamentum flavum 3).

There is still no widely accepted diagnostic or classification criteria for the diagnosis of Lumbar spinal canal stenosis LSS and as a consequence studies use widely differing eligibility criteria that limit the generalizability of reported findings 4).

There are no universally accepted radiographic definitions for the diagnosis of central, lateral recess and foraminal stenosis.


Most studies of Lumbar central canal spinal stenosis diagnosis (LCCSS) rely on criteria published by Verbiest et al. 5). He defined relative spinal stenosis as a diameter between 10 and 12 mm whereas absolute stenosis was a diameter less than 10 mm. This method has been criticized for ignoring the trefoil shape of the LSS and the intrusion of ligamentum flavum and disc material in degenerative stenosis 6).

Magnetic resonance imaging

Magnetic resonance imaging (MRI) is most commonly used for the clinical assessment of degenerative LCCSS. LCCSS is a quantitative diagnosis that is made when the measurement of an individual is outside the range of normal. Thus, the criteria for LCCSS should be compared from an analysis of a normative distribution of measurements 7) 8)

In a meta-analysis, CT and MRI were found to have similar accuracy for the assessment of central stenosis 9).

By using a combination of magnetic resonance imaging (MRI) and computed tomography (CT) of the lumbar spine, it is possible to distinguish between spinal stenosis caused by bone compression and specific soft tissue epidural intraspinal lesions that cause localized spinal canal stenosis and neural compression. Examples include facet cysts and yellow ligament hypertrophy 10).

Because imaging findings of lumbar spinal stenosis (LSS) may not be associated with symptoms, clinical classification criteria based on patient symptoms and physical examination findings are needed 11).

Magnetic resonance imaging (MRI) has replaced myelography, now considered an old-fashioned technique. In selected cases with multilevel lumbar spinal stenosis, functional myelography revealed the highest precision in reaching a correct diagnosis. It resulted in a change in the surgical approach in every fifth patient in comparison with the MRI and proved most helpful, especially in elderly patients 12).

Cross sectional area

Narrowing of the lumbar dural sac cross sectional area (DSCSA) and spinal canal cross-sectional area (SCCSA) have been considered major causes of lumbar central canal spinal stenosis (LCCSS). DSCSA and SCCSA were previously correlated with subjective walking distance before claudication occurs, aging, and disc degeneration. DSCSA and SCCSA have been ideal morphological parameters for evaluating LCCSS.

To evaluate lumbar central canal spinal stenosis (LCCSS) patients, pain specialists should more carefully investigate the dural sac cross-sectional area (DSCSA) than spinal canal cross-sectional area (SCCSA) 13).

Schonstrom et al. showed that neurogenic claudication due to LSS was better defined by the cross-sectional area (CSA) of the dural sac, but that the CSA of the lumbar vertebral canal was unrelated to that of the dural sac 14). From in vitro 15) and in situ 16) studies, the authors postulated that constrictions above the critical size 70 to 80 mm2 would be unlikely to cause symptoms and signs of cauda encroachment. Subsequently, conflicting results have been published concerning the relationship between symptom severity and dural CSA. Even after axial loading, no statistically significant correlations were found in some studies 17). However, in another study, the use of the minimal CSA of the dural sac in central stenosis was found to be correlated with neurogenic claudication assessed measuring the maximum tolerated walking distance 18).

Electrodiagnostic studies

Patients with symptoms, physical examination and imaging findings consistent with LSS do not require additional testing. Although there is little evidence in the literature, electrodiagnostic evaluation is used in some patients with symptoms and findings that are equivocal or conflicting with imaging results and in whom procedures are being considered. Electrodiagnostic criteria for stenosis have been proposed:(47) mini-paraspinal mapping with a one side score > 4 (sensitivity 30%, specificity 100%), fibrillation potential in limb muscles (sensibility 33%, specificity 88%), absence of tibial H-wave (sensitivity 36%, specificity 92%). Better sensitivity was found for a composite limb and paraspinal fibrillation score (sensitivity 48%, specificity 88%) 19).

Diagnostic Screening

Jensen et al. developed a self-administered diagnostic screening questionnaire for lumbar spinal stenosis (LSS) consisting of items with high content validity and to investigate the diagnostic value of the questionnaire and the items.

The screening questionnaire was developed based on items from the existing literature describing key symptoms of LSS. The screening questionnaire (index test) was to be tested in a cohort of patients with persistent lumbar and/or leg pain recruited from a Danish publicly funded outpatient secondary care spine clinic with clinicians performing the reference test. However, to avoid unnecessary collection of data if the screening questionnaire proved to be of limited value, a case-control design was incorporated into the cohort design including an interim analysis. Additional cases for the case-control study were recruited at two Danish publicly funded spine surgery departments. Prevalence, sensitivity, specificity and diagnostic odds ratio (OR) were calculated for each individual item, and AUC (area under the curve) was calculated to examine the performance of the full questionnaire.

A 13-item Danish questionnaire was developed and tested in 153 cases and 230 controls. The interim analysis was not in favour of continuing the cohort study, and therefore, only results from the case-control study are reported. There was a positive association for all items except the presence of back pain. However, the association was only moderate with ORs up to 3.3. When testing the performance of the whole questionnaire, an AUC of 0.72 was reached with a specificity of 20% for a fixed sensitivity of 95%.

The items were associated with LSS and therefore have some potential to identify LSS patients. However, the association was not strong enough to provide sufficient accuracy for a diagnostic tool. Additional dimensions of symptoms of LSS need identification to obtain a reliable questionnaire for screening purposes 20).

References

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Deyo RA, Bigos SJ, Maravilla KR. Diagnostic imaging procedures for the lumbar spine. Ann Intern Med. 1989 Dec 1;111(11):865-7. Review. Erratum in: Ann Intern Med 1989 Dec 15;111(12):1050. PubMed PMID: 2530926.
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Boden SD, Davis DO, Dina TS, Patronas NJ, Wiesel SW. Abnormal magnetic-resonance scans of the lumbar spine in asymptomatic subjects. A prospective investigation. J Bone Joint Surg Am. 1990 Mar;72(3):403-8. PubMed PMID: 2312537.
3)

Mamisch N, Brumann M, Hodler J, Held U, Brunner F, Steurer J; Lumbar Spinal Stenosis Outcome Study Working Group Zurich. Radiologic criteria for the diagnosis of spinal stenosis: results of a Delphi survey. Radiology. 2012 Jul;264(1):174-9. doi: 10.1148/radiol.12111930. Epub 2012 May 1. PubMed PMID: 22550311.
4)

Genevay S, Atlas SJ, Katz JN. Variation in eligibility criteria from studies of radiculopathy due to a herniated disc and of neurogenic claudication due to lumbar spinal stenosis: a structured literature review. Spine (Phila Pa 1976). 2010 Apr 1;35(7):803-11. doi: 10.1097/BRS.0b013e3181bc9454. Review. PubMed PMID: 20228710; PubMed Central PMCID: PMC2854829.
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Verbiest H. Pathomorphologic aspects of developmental lumbar stenosis. Orthop Clin North Am. 1975 Jan;6(1):177-96. PubMed PMID: 1113966.
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Eisenstein S. The trefoil configuration of the lumbar vertebral canal. A study of South African skeletal material. J Bone Joint Surg Br. 1980 Feb;62-B(1):73-7. PubMed PMID: 7351439.
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Chatha DS, Schweitzer ME. MRI criteria of developmental lumbar spinal stenosis revisited. Bull NYU Hosp Jt Dis 2011;69:303–7.
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Premchandran D, Saralaya VV, Mahale A. Predicting lumbar central canal stenosis—a magnetic resonance imaging study. J Clin Diagn Res 2014;8:RC01–4.
9)

Kent DL, Haynor DR, Larson EB, Deyo RA. Diagnosis of lumbar spinal stenosis in adults: a metaanalysis of the accuracy of CT, MR, and myelography. AJR Am J Roentgenol. 1992 May;158(5):1135-44. PubMed PMID: 1533084.
10)

Jacobson RE, Granville M, Hatgis DO J. Targeted Intraspinal Radiofrequency Ablation for Lumbar Spinal Stenosis. Cureus. 2017 Mar 10;9(3):e1090. doi: 10.7759/cureus.1090. PubMed PMID: 28413736; PubMed Central PMCID: PMC5388364.
11)

Genevay S, Courvoisier DS, Konstantinou K, Kovacs FM, Marty M, Rainville J, Norberg M, Kaux JF, Cha TD, Katz JN, Atlas SJ. Clinical classification criteria for neurogenic claudication caused by lumbar spinal stenosis. The N-CLASS criteria. Spine J. 2017 Oct 12. pii: S1529-9430(17)31052-5. doi: 10.1016/j.spinee.2017.10.003. [Epub ahead of print] PubMed PMID: 29031994.
12)

Morgalla M, Frantz S, Dezena RA, Pereira CU, Tatagiba M. Diagnosis of Lumbar Spinal Stenosis with Functional Myelography. J Neurol Surg A Cent Eur Neurosurg. 2018 Jan 18. doi: 10.1055/s-0037-1618563. [Epub ahead of print] PubMed PMID: 29346832.
13)

Lim YS, Mun JU, Seo MS, Sang BH, Bang YS, Kang KN, Koh JW, Kim YU. Dural sac area is a more sensitive parameter for evaluating lumbar spinal stenosis than spinal canal area: A retrospective study. Medicine (Baltimore). 2017 Dec;96(49):e9087. doi: 10.1097/MD.0000000000009087. PubMed PMID: 29245329; PubMed Central PMCID: PMC5728944.
14)

Schonstrom NS, Bolender NF, Spengler DM. The pathomorphology of spinal stenosis as seen on CT scans of the lumbar spine. Spine (Phila Pa 1976). 1985 Nov;10(9):806-11. PubMed PMID: 4089655.
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Schönström N, Bolender NF, Spengler DM, Hansson TH. Pressure changes within the cauda equina following constriction of the dural sac. An in vitro experimental study. Spine (Phila Pa 1976). 1984 Sep;9(6):604-7. PubMed PMID: 6495030.
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Schönström N, Hansson T. Pressure changes following constriction of the cauda equina. An experimental study in situ. Spine (Phila Pa 1976). 1988 Apr;13(4):385-8. PubMed PMID: 3406845.
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Lohman CM, Tallroth K, Kettunen JA, Lindgren KA. Comparison of radiologic signs and clinical symptoms of spinal stenosis. Spine (Phila Pa 1976). 2006 Jul 15;31(16):1834-40. PubMed PMID: 16845360.
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Ogikubo O, Forsberg L, Hansson T. The relationship between the cross-sectional area of the cauda equina and the preoperative symptoms in central lumbar spinal stenosis. Spine (Phila Pa 1976). 2007 Jun 1;32(13):1423-8; discussion 1429. PubMed PMID: 17545910.
19)

Genevay S, Atlas SJ. Lumbar spinal stenosis. Best Pract Res Clin Rheumatol. 2010 Apr;24(2):253-65. doi: 10.1016/j.berh.2009.11.001. Review. PubMed PMID: 20227646; PubMed Central PMCID: PMC2841052.
20)

Jensen RK, Lauridsen HH, Andresen ADK, Mieritz RM, Schiøttz-Christensen B, Vach W. Diagnostic Screening for Lumbar Spinal Stenosis. Clin Epidemiol. 2020;12:891-905. Published 2020 Aug 19. doi:10.2147/CLEP.S263646

Intradiscal Platelet-Rich Plasma

Intradiscal Platelet-Rich Plasma

Akeda et al. demonstrated that intradiscal injection of autologous Platelet-Rich Plasma PRP releasate in patients with low back pain was safe, with no adverse events observed during follow-up. Future randomized controlled clinical studies should be performed to systematically evaluate the effects of this therapy 1).

Systemic Reviews

A systematic review was performed using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Level I-IV investigations of intradiscal PRP injections in DDD were sought in multiple databases. The Modified Coleman Methodology Score (MCMS) was used to analyze the methodological quality of the study. Only the outcome measurements used by more than 50% of the studies were included in the data analysis. The study heterogeneity and nature of evidence (mostly retrospective, non-comparative) precluded meta-analysis. Pre and post-injection pain visual analog scales (VAS) were compared using two sample Z-tests. Five articles (90 subjects, mean age 43.6 ± 7.7 years, mean follow-up 8.0 ± 3.6 months) were analyzed. Four articles were level IV evidence and one article was level II. Mean MCMS was 56.0 ± 10.3. There were 43 males and 37 females (10 unidentified). Pain VAS significantly improved following lumbar intradiscal PRP injection (69.7 mm to 43.3 mm; p<0.01). Two patients (2.2%) experienced lower extremity paresthesia after treatment. One patient (1.1%) underwent re-injection. No other complications were reported. In conclusion, intradiscal injection of PRP for degenerative discs resulted in statistically significant improvement in VAS with low re-injection and complication rates in this systematic review. It is unclear whether the improvements were clinically significant given the available evidence. The low level of evidence available (level IV) does not allow for valid conclusions regarding efficacy; however, the positive results suggest that further higher-quality studies might be of value 2).

Critical reviews

In 2019 Although there was only one double-blind randomized controlled trial, all the studies reported that PRP was safe and effective in reducing back pain. While the clinical evidence of tissue repair of IVDs by PRP treatment is currently lacking, there is a great possibility that the application of PRP has the potential to lead to a feasible intradiscal therapy for the treatment of degenerative disc diseases. Further large-scale studies may be required to confirm the clinical evidence of PRP for the treatment of discogenic LBP 3).


In 2018, Mohammed and Yu reviewed the current literature on PRP therapy and its potential use in the treatment of chronic discogenic low back pain, with a focus on evidence from clinical trials 4).

Clinical trials

A trial demonstrates encouraging preliminary 6 month findings, using strict categorical success criteria, for intradiscal PRP as a treatment for presumed discogenic low back pain. Randomized placebo controlled trials are needed to further evaluate the efficacy of this treatment 5).

Case reports

Intradiscal Platelet-Rich Plasma for Discogenic Low Back Pain Owing to a Degenerated and Previously Discectomized L5-S1 Disc 6).

References

1)

Akeda K, Ohishi K, Masuda K, et al. Intradiscal Injection of Autologous Platelet-Rich Plasma Releasate to Treat Discogenic Low Back Pain: A Preliminary Clinical Trial. Asian Spine J. 2017;11(3):380-389. doi:10.4184/asj.2017.11.3.380
2)

Hirase T, Jack Ii RA, Sochacki KR, Harris JD, Weiner BK. Systemic Review: Is an Intradiscal Injection of Platelet-Rich Plasma for Lumbar Disc Degeneration Effective?. Cureus. 2020;12(6):e8831. Published 2020 Jun 25. doi:10.7759/cureus.8831
3)

Akeda K, Yamada J, Linn ET, Sudo A, Masuda K. Platelet-rich plasma in the management of chronic low back pain: a critical review. J Pain Res. 2019;12:753-767. Published 2019 Feb 25. doi:10.2147/JPR.S153085
4)

Mohammed S, Yu J. Platelet-rich plasma injections: an emerging therapy for chronic discogenic low back pain. J Spine Surg. 2018;4(1):115-122. doi:10.21037/jss.2018.03.04
5)

Levi D, Horn S, Tyszko S, Levin J, Hecht-Leavitt C, Walko E. Intradiscal Platelet-Rich Plasma Injection for Chronic Discogenic Low Back Pain: Preliminary Results from a Prospective Trial. Pain Med. 2016;17(6):1010-1022. doi:10.1093/pm/pnv053
6)

Karamanakos PN, Manousakis E, Rozakis D, Kämäräinen OP, Oikonomi E, Panteli ES. Intradiscal Platelet-Rich Plasma for Discogenic Low Back Pain Owing to a Degenerated and Previously Discectomized L5-S1 Disc [published online ahead of print, 2020 Aug 12]. Pain Med. 2020;pnaa241. doi:10.1093/pm/pnaa241

Recurrent laryngeal nerve palsy

Recurrent laryngeal nerve palsy

Vocal cord paresis, also known as recurrent laryngeal nerve paralysis or vocal fold paralysis, is an injury to one or both recurrent laryngeal nerves (RLNs), which control all muscles of the larynx except for the cricothyroid muscle. The RLN is important for speaking, breathing and swallowing.

Recurrent laryngeal nerve palsy (RLNP) is a potential complication of anterior cervical discectomy and fusion (ACDF).


While performing the anterior cervical approach, injury to important anatomic structures in the vicinity of the dissection represents a serious risk. The midportion of the recurrent laryngeal nerve and the external branch of the superior laryngeal nerve are encountered in the anterior approach to the lower cervical spine. The recurrent laryngeal nerve is vulnerable to injury on the right side, especially if ligation of inferior thyroid vessels is performed without paying sufficient attention to the course and position of the nerve, and the external branch of the superior laryngeal nerve is vulnerable to injury during ligature and division of the superior thyroid artery. Avoiding injury to the recurrent laryngeal nerve (especially on the right side) and superior laryngeal nerve is a major consideration in the anterior approach to the lower cervical spine. The sympathetic trunk is situated in close proximity to the medial border of the longus colli muscle at the C6 level (the longus colli diverge laterally, whereas the sympathetic trunk converges medially). The damage leads to the development of Horner’s syndrome with its associated ptosis, meiosis, and anhydrosis. Awareness of the regional anatomy of the sympathetic trunk may help in identifying and preserving this important structure while performing anterior cervical surgery or during exposure of the transverse foramen or uncovertebral joint at the lower cervical levels. Finally, the spinal accessory nerve (embedded in fibroadipose tissue in the posterior triangle of the neck) is prone to injury. Its damage will result in an obvious shoulder droop, loss of shoulder elevation, and pain. Prevention of inadvertant injury to the accessory nerve is critical in the neck dissection 1).


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 2).


The cervical spine is approached from the right side unless the patient has undergone a prior approach from the left side. If so, the original incision line is used. If a patient has subclinical vocal cord palsy on the side of the incision, proceeding with an incision on the opposite side is risky. The potential for recurrent laryngeal nerve palsy is highest on the right side, although the risk has not been documented in recent reports. The thoracic duct, however, can be injured when the approach is from the left side.


For C5–6, the skin incision is made at level of criccoid cartilage, for other levels, appropriate adjustments up or down may be made, sometimes with the assistance of fluoroscopy. The incision is approximately 4–5cm horizontally, centered on the SCM. Many right handed surgeons prefer operating from the right side of the neck, although the risk to the recurrent laryngeal nerve (RLN) is lower with a left sided approach (the RLN lies in a groove between the esophagus and trachea). The skin may be undermined off the platysma to permit a ver- tical incision in the platysma in the same orientation as its muscle fibers. Alternatively, some incise the platysma horizontally with scissors horizontally.


There still is substantial disagreement on the actual prevalence of RLNP after ACDF as well as on risk factors for postoperative RLNP 3).

Case series

The aim of a study of Huschbeck et al. was to describe the prevalence of postoperative RLNP in a cohort of consecutive cases of ACDF and to examine potential risk factors.

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, they examined patient’s age, sex, body mass index, multilevel surgery, and the duration of surgery.

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).

In this 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 4).


A prospective cohort study conducted on 90 patients scheduled for anterior cervical spine surgeries underwent consecutive pre and postoperative vocal cord examination for edema and paralysis by both anterior and lateral approaches laryngeal ultrasonography. Rigid laryngoscopy was the standard confirmatory tool. For postoperative vocal cord edema, the anterior ultrasonography approach diagnostic sensitivity = 88.2%, specificity = 78.9% with PPV = 78.9% and NPV = 88.2% and the novel lateral ultrasonography approach diagnostic sensitivity = 88.2%, specificity = 94.7% with PPV = 93.75% and NPP = 90%. While for paralysis, the anterior ultrasonography approach diagnostic sensitivity = 86.7%, specificity = 85.7% with PPV = 81.25% and NPV = 90% and the novel lateral ultrasonography approach diagnostic (sensitivity, specificity with PPV and NPP) = 100%. The diagnostic accuracy of the novel lateral approach was more correlated to rigid laryngoscopy (91.7% and 100%) compared to anterior approach for vocal cord edema and paralysis (83.3% and 80.6%). Overall incidence of vocal cord paralysis was 16.6%. Risk of vocal cord paralysis was statistically significant more in female, multiple disc herniation, lower and mixed disc levels, Langenbeck retractor, cage and plate and duration of surgery ≥ 1.5 h. Transcutaneous Laryngeal ultrasound is a valid comfortable tool for prediction of vocal cord edema and paralysis after anterior cervical spine surgeries with superiority of the novel lateral over anterior approach 5).


A total of 114 patients undergoing anterior cervical procedures over a 6-year period were included in a retrospective, case-control study. The diagnosis was cervical radiculopathy, and/or myelopathy due to degenerative disc disease, cervical spondylosis, or traumatic cervical spine injury. All our participants underwent surgical treatment, and complications were recorded. The most commonly performed procedure (79%) was anterior cervical discectomy and fusion (ACDF). Fourteen patients (12.3%) underwent anterior cervical corpectomy and interbody fusion, seven (6.1%) ACDF with plating, two (1.7%) odontoid screw fixation, and one anterior removal of osteophytes for severe Forestier’s disease. Mean follow-up time was 42.5 months (range, 6-78 months). The overall complication rate was 13.2%. Specifically, we encountered adjacent intervertebral disc degeneration in 2.7% of our cases, dysphagia in 1.7%, postoperative soft tissue swelling and hematoma in 1.7%, and dural penetration in 1.7%. Additionally, esophageal perforation was observed in 0.9%, aggravation of preexisting myelopathy in 0.9%, symptomatic recurrent laryngeal nerve palsy in 0.9%, mechanical failure in 0.9%, and superficial wound infection in 0.9%. In the vast majority anterior cervical spine surgery-associated complications are minor, requiring no further intervention. Awareness, early recognition, and appropriate management, are of paramount importance for improving the patients’ overall functional outcome 6).


Staartjes et al. analyzed a prospective registry of all consecutive patients undergoing zero-profile ACDF for disc herniation, myelopathy, or stenosis. RLN palsy was defined as persistent patient self-reported dysphagia, hoarseness, or respiratory problems without other identifiable causes. RLN palsy was assessed at scheduled 6-week telephone interviews.

Results: Among 525 included patients, 511 primary and 40 secondary ACDF procedures were performed. Hoarseness was present in 12 (2.2%) cases, whereas dysphagia and respiratory difficulties both occurred in 3 (0.5%) cases. Overall incidence of RLN palsy was 2% after primary procedures and 8% after secondary procedures (P = 0.017). These rates are in line with the peer-reviewed literature, and the difference remained significant after controlling for confounders in a multivariate model (P = 0.033). Other reported risk factors, such as age, sex, surgical time, and multilevel procedures, had no relevant effect (P > 0.05).

Based on our data and other published series in the literature, RLN palsy may occur more frequently after secondary ACDF procedures with a clinically relevant effect size. There is a striking lack of uniformity in methods and reporting in research on RLN injury. 7).

References

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Lu J, Ebraheim NA, Nadim Y, Huntoon M. Anterior approach to the cervical spine: surgical anatomy. Orthopedics. 2000 Aug;23(8):841-5. Review. PubMed PMID: 10952048.
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Erwood MS, Hadley MN, Gordon AS, Carroll WR, Agee BS, Walters BC. Recurrent laryngeal nerve injury following reoperative anterior cervical discectomy and fusion: a meta-analysis. J Neurosurg Spine. 2016 Aug;25(2):198-204. doi: 10.3171/2015.9.SPINE15187. Epub 2016 Mar 25. PubMed PMID: 27015129.
3) , 4)

Huschbeck A, Knoop M, Gahleitner A, et al. Recurrent Laryngeal Nerve Palsy after Anterior Cervical Discectomy and Fusion – Prevalence and Risk Factors [published online ahead of print, 2020 Aug 10]. J Neurol Surg A Cent Eur Neurosurg. 2020;10.1055/s-0040-1710351. doi:10.1055/s-0040-1710351
5)

Kamel AAF, Amin OAI, Hassan MAMM, Elmesallamy WAEA, Hassan EM. Ultrasound prediction for vocal cord dysfunction in patients scheduled for anterior cervical spine surgeries: a prospective cohort study [published online ahead of print, 2020 Jun 15]. J Clin Monit Comput. 2020;10.1007/s10877-020-00546-3. doi:10.1007/s10877-020-00546-3
6)

Tasiou A, Giannis T, Brotis AG, Siasios I, Georgiadis I, Gatos H, Tsianaka E, Vagkopoulos K, Paterakis K, Fountas KN. Anterior cervical spine surgery-associated complications in a retrospective case-control study. J Spine Surg. 2017 Sep;3(3):444-459. doi: 10.21037/jss.2017.08.03. Review. PubMed PMID: 29057356; PubMed Central PMCID: PMC5637201.
7)

Staartjes VE, de Wispelaere MP, Schröder ML. Recurrent Laryngeal Nerve Palsy Is More Frequent After Secondary than After Primary Anterior Cervical Discectomy and Fusion: Insights from a Registry of 525 Patients. World Neurosurg. 2018 Aug;116:e1047-e1053. doi: 10.1016/j.wneu.2018.05.162. Epub 2018 Jun 1. PubMed PMID: 29864565
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