Incidence and Prognostic Factors of C5 Palsy: A Clinical Study of 1001 Cases and Review of the Literature
Bydon, Mohamad MD*,‡,§; Macki, Mohamed BS*,‡,§; Kaloostian, Paul MD‡; Sciubba, Daniel M. MD‡; Wolinsky, Jean-Paul MD‡; Gokaslan, Ziya L. MD‡,§; Belzberg, Allan J. MD‡; Bydon, Ali MD‡,§; Witham, Timothy F. MD‡
‡Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland;
§Johns Hopkins Spinal Biomechanics and Surgical Outcomes Laboratory, Baltimore, Maryland
Correspondence: Timothy F. Witham, MD, The Johns Hopkins Hospital, Department of Neurosurgery, Meyer 7-109, 600 N. Wolfe Street, Baltimore, MD 21287. E-mail: email@example.com
* These authors contributed equally to this manuscript.
Received October 17, 2013
Accepted February 05, 2014
BACKGROUND: C5 palsy is a known cause of postoperative deltoid weakness. Prognostic variables affecting the incidence of the palsy have been poorly understood.
OBJECTIVE: To determine the incidence and perioperative characteristics/predictors of C5 palsy after anterior vs posterior operations.
METHODS: All patients undergoing C4-5 operations for degenerative conditions were retrospectively reviewed over 21 years. Anterior operations included an anterior cervical discectomy and fusion (ACDF) or a corpectomy, whereas posterior operations included laminectomy and fusion (± foraminotomies).
RESULTS: Of the total 1001 operations, in 49.0% anterior and 51.0% posterior cases, there was an overall C5 palsy incidence of 5.2% (52 cases): 1.6% and 8.6%, respectively (P < .001). Of the 99 corpectomies, the palsy incidence of 4.0% was not only higher than ACDFs (1.0%), but also followed an upward trend with increasing corpectomy levels (P = .009). Of the 69 posterior and 83 anterior C4-5 foraminotomies, the incidence of C5 palsy was statistically higher in the posterior (14.5%) vs anterior (2.4%) cohort (P = .01). Multiple logistical regression identified older age as the strongest predictor of C5 palsy in the anterior (P = .02) and C4-5 foraminotomy in the posterior (P = .06) cohort. This condition improved within 3 to 6 months in 75% of patients in the anterior and 88.6% in the posterior cohort after a mean follow-up of 14.4 and 27.6 months, respectively.
CONCLUSION: In one of the largest cohorts on C5 palsy, we found in anterior operations an increasing number of corpectomy levels had a higher incidence of C5 palsy; however, older age was the strongest predictor of C5 palsy. In posterior operations, C4-5 foraminotomy carried the strongest correlation.
ABBREVIATIONS: ACDF, anterior cervical discectomy and fusion
OPLL, ossification of the posterior longitudinal ligament
Transient segmental motor palsy of the upper limb is a well-recognized complication after cervical spinal decompression. Of the nerve roots contributing to the brachial plexus from C5 to T1, postoperative segmental palsy is most frequently observed in the C5 nerve root.1 Originally thought to be a cystic degeneration of the anterior horn cells within the spinal cord, Keegan,2 in 1965, first attributed a “dissociated motor loss” to compression of the nerve root due to cervical spondylosis rather than an idiopathic cord pathology. In the latter half of the 1980s, physicians began to report iatrogenic causes of the segmental motor loss after cervical spine surgery.3-5 Now a well-documented complication after spine surgery, C5 palsy has reported incidences ranging from 0% to 30%.6,7
Some authors have argued that preoperative diagnosis may predict postoperative C5 palsy. The first publications on C5 palsy were on patients surgically managed for ossification of the posterior longitudinal ligament (OPLL), although the association between the palsy and OPLL was not identified until several years thereafter. C5 palsy has also been widely reported in the context of cervical laminoplasties.8-11 These authors stipulated that the operative technique plays a more important role than the preoperative diagnosis in predicting C5 palsy.7,12-16
In clinical practice, however, several preoperative and intraoperative prognostic factors may influence the postoperative complication. Unfortunately, because C5 palsy is consistently described in the setting of OPLL and laminoplasties, other underlying factors are often overlooked. In this paper, we present one of the largest Western cohorts focusing specifically on C5 palsy in patients with degenerative disease. An analysis of anterior vs posterior operations will provide insight into the perioperative risk factors strongly associated with C5 palsy occurrence. We hypothesize that different prognostic variables are associated with C5 palsy between the anterior and posterior cohorts.
In addition, although the inciting factor has not been thoroughly established in the literature, the molecular pathogenesis of C5 palsy is thought to occur due to an ischemia-reperfusion injury.7,17 As a result, we hypothesize that patients with cardiovascular risk factors may have a higher incidence of C5 palsy.
We retrospectively reviewed the records of all neurosurgical patients undergoing either anterior or posterior spinal decompression and fusion at a single institution over a 21-year period. All patients underwent instrumented fusion. Anterior decompression consisted of discectomy and/or corpectomy (partial or complete) with anterior plating and vertebral body screws. Posterior decompression included laminectomy and/or laminotomy (with or without foraminotomies) and instrumentation with lateral mass screws and rods. All operations, whether anterior or posterior, included the C4-5 spinal segment. Bias was reduced by eliminating patients with incomplete medical records (ie, missing data). Because the primary endpoint of this study was to address an immediate postoperative complication, detailed perioperative documentation was essential. Nevertheless, loss to follow-up is an inherent limitation of retrospective studies. We mitigated a follow-up bias by telephone calls to patients and reporting mean follow-up time in each cohort.
Although various definitions for C5 palsy have been described in the literature,7,12 we adopted the most common definition: C5 palsy is a motor decline of the deltoid muscle function by at least 1 level in a standard manual muscle test within the 6-week postoperative period.1,7,8,18,19 Previous studies, such as that by Sasai et al,8 have held that pain and sensory deficit alone are not included in their definition of C5 palsy. In this study, we do report sensory deficit, radiculopathy, and/or pain, except when superimposed on an underlying deltoid weakness.
We identified 3965 cases of cervical decompression and fusion. Patients with traumatic, neoplastic, infectious, and metabolic indications for surgery were excluded from the study. To limit confounding factors, patients with OPLL were excluded because the diagnosis likely affects the incidence C5 palsy.7,14,20-23 Circumferential operations were similarly excluded. Although laminoplasties have been reported in the literature to affect the incidence of C5 palsy, the procedure is rarely used to treated degenerative spinal pathologies at our institution and was thus excluded.
To further reduce bias, we collected a thorough list of perioperative patient characteristics in Table 1. Because a surgical approach is an effect measure modifier, patient characteristics were stratified by anterior or posterior approach. A subgroup analysis of only C5 palsy cases in the anterior and posterior cohorts was also reported.
Electronic medical records were retrieved from November 1991 to February 2013. In conducting the study, we retrospectively reviewed clinical notes, operative narratives, and radiology reports. STATA (version 12.0; StataCorp, College Station, Texas) and GraphPad (GraphPad Software Inc, La Jolla, California) software were used for statistical interpretations of the raw data. The study cohort was defined with summary statistics. Continuous variables between the anterior and posterior cohorts were compared with the unpaired t test, whereas categorical variables were compared with the Pearson χ2 test. When categorical outcomes were compared between the C5 palsy anterior and posterior cohorts, P values were calculated with the Fisher exact test because of the smaller number of patients used in this subcohort. Two-way measures of association between perioperative prognostic factors and C5 palsy are described following an exact, simple logistical regression reporting unadjusted odds ratios (OR_unadjusted).16 An exact regression model was adopted because of the rarity of the outcome. We established covariates a priori based on hypothesized biological predictors of C5 palsy as well as statistical predictors established in the literature.12,16 In the simple logistical regression, these covariates included sex, age, preoperative Nurick score, number of spinal levels decompressed, C5 foraminotomy, previous anterior surgery at C4-5, and diagnosis (spinal stenosis, cervical spondylotic myelopathy, degenerative disc disease). The number of decompression levels refers to a laminectomy in the posterior cohort and corpectomy or anterior cervical discectomy and fusion (ACDF) in the anterior cohort. After the simple logistical regression, predictors of C5 palsy were calculated with multiple logistical regression with a forward stepwise modeling, reporting adjusted odds ratios (OR_adjusted) and controlling for covariates. Covariates in the multiple logistical regression for the anterior cohort included age, preoperative Nurick score, levels of ACDF, and levels of corpectomy. Covariates in the multiple logistical regression for the posterior cohort included age, number decompression levels, and C5 foraminotomy.
Last, we hypothesized that cardiovascular risk may influence the C5 palsy rate. The association was measured via a logistical regression analysis, such that C5 palsy was the outcome and cardiovascular risk factors were the predictors. Cardiovascular risk factors were defined as coronary artery disease, diabetes mellitus, hypertension, and obesity. Statistical significance was set at P < .05.
We identified 1001 patients who met the inclusion and exclusion criteria. Of the 1001 cervical spine decompression and fusions for degenerative conditions, the spinal column was approached anteriorly in 490 (49.0%) cases and posteriorly in 511 (51.0%) cases (Table 1). On examination of perioperative outcomes, the posterior cohort was statistically associated with older age (P < .001), male sex (P < .001), longer mean length of hospital stay (P < .001), and discharge to rehab (P < .001). Although patients in the posterior cohort were statistically more likely to have undergone a previous anterior surgery including the C4-5 level (P = .04), more patients in the anterior cohort had previous anterior surgeries (P < .001) and anterior surgeries excluding the C4-5 level (P < .001). In comorbidities, obesity did not statistically differ between the 2 cohorts (P = .97). Although ever smoking was higher in the anterior cohort (P = .03), the remaining comorbidities were statistically higher in the posterior cohort. Last, preoperative characteristics of patients approached posteriorly were more likely to include a higher Nurick score (P < .001), a diagnosis of cervical spondylotic myelopathy (P < .001), and spinal stenosis (P < .001), whereas degenerative disc disease was more likely to be surgically managed via an anterior approach (P < .001) (Table 2).
With respect to intraoperative parameters, an average of 2.1 levels were decompressed in the anterior group vs 4.2 levels in the posterior group (Table 1; Figures 1 and 2). Of the 99 patients undergoing corpectomy, almost half (44.44%) underwent decompression at 1 spinal level only (Figure 3). The rate of foraminotomy did not statistically differ between the anterior and posterior cohorts (P = .17). In postoperative parameters, the posteriorly approached patients had a statistically higher incidence of wound infection (P < .001), wound dehiscence (P < .001), and C5 palsy (P < .001).
The cumulative incidence of C5 palsy was 5.2%. The anterior and posterior cohorts were statistically similar in perioperative prognostic factors enumerated in Table 1, although the posterior C5 cohort had more levels decompressed (P < .001) and higher use of autograft (P = .10). In the C5 palsy subcohort, preoperative mean Nurick score (P = .38) and diagnosis of cervical spondylitic myelopathy (P = .29) did not differ, whereas spinal stenosis was statistically more likely to be managed with posterior cervical laminectomy (P = .04). On the other hand, degenerative disc disease was more likely to be managed with anterior cervical discectomy or corpectomy; this approached, but did not reach, statistical significance (P = .06) (Table 2).
The incidence of C5 palsy was statistically higher in the posterior cohort at 8.6% (n = 44) vs the anterior cohort at 1.6% (n = 8) (P < .001). In the posterior cohort, 81.82% experienced postoperative deltoid weakness alone. The remaining patients include 15.91% (n = 7) who experienced radiculopathy or pain in the C5 distribution and 2.27% (n = 1) who experienced a sensory deficit. In the anterior cohort, 87.5% (n = 7) experienced pure motor weakness, whereas 1 patient (12.5%) experienced additional pain in the C5 distribution.
Of the 152 cases including a C5 anterior or posterior foraminotomy, the incidence of C5 palsy increased to 7.89% (n = 12) (Figure 4). Although the rate of C5 foraminotomy did not differ between the anterior and posterior cohorts (P = .13), the incidence of C5 palsy after a posterior C5 foraminotomy [14.49% (n = 10)] was significantly higher than after an anterior C5 foraminotomy [2.41% (n = 2)] (P = .01). In fact, after the multiple regression analysis, posterior C5 foraminotomy demonstrated an increased odds of C5 palsy in the posterior cohort (OR_adjusted = 2.03, P = .06) (Table 3). Thus, of the 3 covariates—age, number of levels decompressed, and C5 foraminotomy—only C5 foraminotomy was a strong predictor in the multiple regression model for the posterior cohort.
In the anterior cohort, the incidence of C5 palsy after a corpectomy was 4.0% (n = 4) (Figure 3) compared with the 1.0% incidence after an ACDF (Figure 1). After a simple regression analysis, increasing corpectomy levels demonstrated a statistically positive correlation with C5 palsy (OR_unadjusted = 2.11, P = .009), whereas ACDF demonstrated a statistically protective effect on C5 palsy (OR_unadjusted = 0.20, P < .001) (Table 3). In the anterior cohort, C5 palsy was also statistically associated with older age (OR_unadjusted = 1.11, P = .002) and preoperative Nurick score (OR_unadjusted = 1.70, P = .04) (Table 3). In fact, the mean age in the anterior C5 palsy group (67.2 ± 8.1 years) is more than 12 years older than the non-C5 palsy group (54.4 ± 11.3 years). After a multiple logistical regression, older age was the strongest predictor of C5 palsy (P = .02). Thus, of the 4 covariates—increasing age, number of corpectomy levels, number of ACDF levels, and preoperative Nurick score—only increasing age was statistically significant in the multiple regression model for the anterior cohort.
In summary, after adjustment with multiple logistical regression, statistical trends persisted, such that older age (P = .02) in the anterior cohort and C5 foraminotomy (P = .06) in the posterior cohort were most strongly correlated with C5 palsy.
Finally, we hypothesized that patients with cardiovascular risk factors would have a higher incidence of C5 palsy. Indeed, in comparing the C5 palsy cohort with the study population, patients in whom C5 palsy developed were more likely to have coronary artery disease (9.62% vs 5.89%), diabetes mellitus (21.15% vs 12.59%), hypertension (46.15% vs 28.87%), and obesity (3.84% vs 3.70%). After a simple logistic regression, hypertension statistically predicted the incidence of C5 palsy (P = .001); however, this was not significant in the multiple logistical regression (P = .06), controlling for hypertension, C5 foraminotomy, and increasing age. Coronary artery disease (P = .37), diabetes mellitus (P = .10), and obesity (P = 1.00) were not significant in the simple logistical regression.
In the 1970s, postoperative C5 palsy was attributed to unwieldy operations and abrasive instruments.16 Despite surgical advances, the incidence of C5 palsy remains high. In an extensive literature review of 48 publications, Sakaura et al7 cited an overall incidence of 4.6% (range, 0%-30%). The incidence after anterior decompression and fusion is, on average, 4.3% (range, 1.6%-12.1%).24 C5 palsy may also follow a positive correlation with an increasing number of corpectomy levels performed, according to a retrospective review of 750 cases of Nassr et al.12,25 In line with these findings, we also report that the incidence of C5 palsy increased with increasing corpectomy levels (P = .009) in a logistical regression model.
The surgical approach may also affect the incidence of C5 palsy. Hasegawa et al16 compared anterior vs posterior decompressions. The laminectomy cohort had the highest incidence of C5 palsy at 6.8%. Commensurate with these findings, we report a statistically higher rate of C5 palsy in the posterior laminectomy and fusion cohort (8.6%) vs the anterior cohort (1.6%) (P < .001). Heller et al26 accredited the increased risk of C5 palsy to the concurrent instrumented fusions performed with laminectomies. After the posterior decompression, the extensive reduction of the vertebrae may induce iatrogenic foraminal stenosis of the C5 nerve root.
Authors have also argued that the preoperative diagnosis may play a critical role in predicting C5 palsy.27-29 In a report citing an overall incidence of 4.6%, Sakaura et al7 found the average incidence of C5 palsy in myelopathic patients to be 5.6%. Hasegawa et al16 quoted 4.8% in their myelopathic group. Of the 690 patients with cervical spondylotic myelopathy in this study, we report an incidence of 6.5%. In cervical degenerative disc disease, these percentages decrease substantially to 0.85% according to Hasegawa et al16 and 0.91% in this current study. In this cohort of patients, the most common symptom was radiculopathy.
This paper provides a summary of the literature on C5 palsy in degenerative spinal disease (Table 4). The average incidence in the published anterior series was 4.6%,3-5,7,12,16,19,24,30-37 whereas our study population under the same criteria had an incidence of 1.6%. This discrepancy is attributed to differences in preoperative diagnoses. Radiculopathy caused by degenerative disc disease, which reflects a low incidence of C5 palsy, was the primary operative indication for an anterior decompression and fusion in our clinical study, whereas cervical spondylotic myelopathy was the primary reported indication in the literature. On the other hand, our review of the literature in the posterior series demonstrated an incidence of 8.6%,12,16,23,33,38,39 which exactly matched our posterior cohort incidence of 8.6%. Here, spinal stenosis was the primary indication for surgery in both the literature and our clinical study.
With anterior surgeries, Hasegawa et al16 found that older age and number of levels decompressed statistically predicts C5 palsy. In corroboration with these findings, we also identified older age as the strongest predictor of postoperative C5 palsy in the anterior cohort. On the other hand, anterior foraminotomy did not statistically affect the incidence of C5 palsy. With anterior operations, C5 palsy increased minimally from 4.6% without foraminotomy to 5.0%40-45 with foraminotomy in the literature and from 1.6% to 2.4% in our study (Table 4).
The cause of C5 palsy after posterior operations has been debated in the literature. In an analysis of posterior fusion, Nakashima et al23 recognized 2 risk factors: posterior shift of the spinal cord and postoperative width of the C5 intervertebral foramen. In the latter regard, some have argued in favor of prophylactic foraminotomy as a preventive measure against the development of C5 palsy.8,9,23 However, our study revealed that C4-5 foraminotomy correlated with increased risk of C5 palsy in the posterior cohort (P = .06). In a review of the literature, the incidence of C5 palsy after a C4-5 posterior foraminotomy was 11.6%,15,46-50 whereas we reported an incidence of 14.5% (Table 4). In an anatomic consideration of motor palsy after posterior cervical foraminotomy, Choi et al15 argued that posterior removal of hypertrophied ligaments, herniated discs, and bony outgrowths places excessive retraction on the inherently thin C5 nerve root. Therefore, tension on the nerve root often goes unrecognized intraoperatively and may lead to an incidental C5 palsy postoperatively. Interestingly, after anterior operations, C5 palsy increases minimally with foraminotomy from 4.3% to 5.0%40-45 in the literature and from 1.6% to 2.4% in our study. We did not find that a direct intraoperative insult led to this injury because all 52 cases of C5 palsy had intraoperative neuromonitoring without changes noted. Alternatively, some authors suggest posterior migration of the spinal cord within the decompressed spinal canal places tension on the C5 nerve roots and may lead to subsequent postoperative injury.51,52 We hypothesized that lordotic correction of the cervical spine may affect posterior spinal cord migration in patients with posterior cervical decompression and fusion plus foraminotomy. From this subgroup of cases, we identified 41 patients with both preoperative and postoperative imaging. In a simple linear regression, we found that lordotic correction did not predict the incidence of C5 palsy (P = 0.99).
Although the inciting factor has not been thoroughly established in the literature, the molecular pathogenesis of C5 palsy is thought to occur due to a rapid and transient ischemia-reperfusion injury.7,17 Although patients in the C5 palsy cohort had a higher mean prevalence of coronary artery disease, diabetes mellitus, hypertension, and obesity, these covariates failed to predict C5 palsy in the regression analysis. Based on the current findings, a correlation between cardiovascular disease and increased incidence of C5 palsy could not be confirmed.
Taken collectively, methods for preventing C5 palsy should take into account surgical approach. In the anterior cohort, older patients have an increased risk of C5 palsy. In the posterior cohort, extensive decompression via wider foraminotomy may increase the risk of C5 palsy. The time at which the nerve damage occurs is often unknown, and postoperative fatigue and pain may lead to a delay in clinical diagnosis. Thus, motor deficits may not become apparent until 2 to 7 days postoperatively7,17,39,53 as we show in Table 5. The median time to C5 palsy after an anterior operation was postoperative day 1, whereas the median time to C5 palsy after a posterior operation was longer—postoperative days 4 to 7. These discrepancies in time to C5 palsy may reflect different pathogeneses of the complication in the anterior vs posterior operations. Time to recovery is similarly difficult to predict and may depend on the severity of the deficit. In a published review of 48 cases, 47.8% of mild palsy cases resolved in less than 3 months, whereas 52.0% of severe palsy cases persisted for up to 6 months. The severe cases required a significantly longer time to recovery (P < .05).7 In this study, we report improvement in 75% of patients in the anterior cohort and 88.6% in the posterior cohort.
Although our results are statistically significant, retrospective, nonrandomized studies have inherent limitations. Additionally, single-institution studies such as ours have limited sample size. Prospective studies may help to establish definitive risk factors and causal relationships. Because of the relatively rare incidence of C5 palsy (<10%), a case-control study nested in a prospective cohort provides the best study design. Future studies may ensure that cohorts are matched on potential confounders: sex, operative diagnosis, type of operation (eg, corpectomy vs discectomy), comorbidities, surgeon, and instrumentation. In addition, patients may be stratified on potential effect measure modifiers identified in this study: age, surgical approach (anterior vs posterior), and foraminotomy.
One common cause of C5 palsy is a postoperative complication of cervical spine surgery. In this study, we evaluated 1001 degenerative cervical spine operations (both anteriorly and posteriorly approached and spanning the C4-5 segment) and found an overall C5 palsy incidence of 5.2%. In patients approached posteriorly, the incidence of 8.6% was statistically higher than the 1.6% in the anterior cohort. In the posterior cohort, the incidence of C5 palsy with a posterior C4-5 foraminotomy was increased from 8.6% to 14.5%. After multiple regression modeling, older age as an independent variable statistically predicted C5 palsy in the anterior cohort, whereas C5 foraminotomy correlated with C5 palsy in the posterior cohort. Last, improvement was seen in 75% of patients in the anterior cohort and 88.6% of patients in the posterior cohort.
Dr Bydon is the recipient of a research grant from Depuy Spine and serves on the clinical advisory board of MedImmune, LLC. Dr Gokaslan is the recipient of research grants from Depuy Spine, AO Spine North America, Medtronic, NREF, Integra Life Sciences, and K2M; receives fellowship support from AO Spine North America; and holds stock in Spinal Kinetics and US Spine. Dr Witham is the recipient of a research grant from Eli Lilly and Company and The Gordon & Marilyn Macklin Foundation. Dr Sciubba is the recipient of a research grant from Depuy Spine and has consulting relationships with Medtronic, Nuvasiv, Globus, and Depuy. The other authors have no personal financial or institutional interest in any of the drugs, materials, or devices described in this article.
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The authors present one of the largest series of C5 palsies after both anterior and posterior cervical decompression procedures. They find that the incidence of C5 palsy is higher in anterior corpectomies vs ACDFs and that C5 palsies are more common in posterior decompression and fusion procedures compared with anterior operations. The authors should be commended for their contribution to the literature.
The authors reviewed 1001 cervical spine patients who had either anterior or posterior cervical decompression to treat degenerative diseases of the cervical spine; there was a nearly equal amount of patients in each group. There was an overall incidence of C5 palsy of 5.2% (52 of patients). The patients who had posterior cervical decompression had an incidence of C5 palsy of 8.6%, and the anterior group had an incidence of C5 palsy of 1.6%. The patient that had cervical corpectomy had a higher incidence of C5 palsy compared with the patients who had anterior cervical discectomy and fusion. Posterior C5 foraminotomy carried a strong correlation with C5 palsy. However, older age was the strongest predictor of C5 palsy. The authors provided an excellent review of the literature, which is outlined in Table 4. In the Discussion, the authors reviewed the possible causes, as mentioned by other authors, but they themselves do not offer a plausible cause of C5 palsy. This paper may help surgeons caution older patients of having a higher risk of C5 palsy, especially after anterior cervical corpectomy or posterior C5 foraminotomy.
Volker K. H. Sonntag
C5 palsy after cervical surgery remains a morbid complication. Avoiding this complication is of paramount importance; however, patient selection, surgical approach, and intraoperative factors that cause this problem remain poorly understood. The authors provide a retrospective cohort study of 1001 cases of anterior or posterior decompression and fusion procedures for the treatment of cervical spondylosis with radiculopathy or myelopathy. The study evaluates multiple risk factors for the development C5 palsy after surgery. This paper adds to the literature by providing hypothesis-generating data to allow for further prospective study of this important problem.
This large series has value in identifying the frequency of C5 palsies after cervical spine surgery for degenerative lesions. Additionally, the authors identify prognostic factors for the development of the complication and offer some additional insight into the pathophysiology of the complication of C5 palsy. The contents of this article are very pertinent to decision making and risk assessment in general neurosurgical practice.
Montreal, Quebec, Canada
The authors present one of the largest series of patients who were surgically treated for degenerative cervical spine disease involving the level C4-5, either anteriorly or posteriorly. The limitations of retrospective studies such as this one including selection bias are adequately addressed. A minor shortcoming is the interpretation of the contribution of C5 foraminotomy in Table 3. Statistical significance was assumed when P < .05. After multiple regression, P = .06 for C5 foraminotomy. That is not statistically significant, and, therefore, any suggestion that it would be a predictor for C5 palsy is not justified. Older age is identified as a predictor for C5 palsy in the anterior group. I cannot explain it biologically except for the greater presence of osteophytic formation compressing nerve roots. Age could be a confounder for the presence of foraminal stenosis. Despite these considerations, the authors have to be commended for their immense but thorough work. It is an important contribution to literature.
Ronald H.M.A. Bartels
Nijmegen, the Netherlands
1. A 62 year old male is brought to the OR for a C4/5 anterior cervical discectomy and fusion. What factor increases the likelihood of developing a post-op C5 palsy?
B. Number of ACDF levels
C. Preoperative Nurick Score
D. History of cardiovascular disease
2. Which cervical spine surgical procedure is least likely to result in a post-operative C5 palsy?
A. Posterior cervical foraminotomy
B. Laminectomy and fusion
C. Anterior corpectomy and fusion
D. Anterior cervical foraminotomy
3. In cervical spine surgical procedures, what perioperative technique has been shown to decrease the incidence of postoperative C5 palsy?
A. Intraoperative Gardner-Wells tongs with weights.
B. Post-op rigid external fixation.
C. Post-op bedrest.
D. Intraoperative EMG monitoring.
ACDF; Age; C5 palsy; Corpectomy; Foraminotomy; Fusion; Laminectomy
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