Subclinical respiratory dysfunction in chronic cervical cord compression: a pulmonary function test correlation

Respiratory dysfunction in degenerative cervical myelopathy: A systematic review

INTRODUCTION

Degenerative cervical myelopathy is a condition of symptomatic cervical spinal cord compression secondary to a range of degenerative spinal pathology. Respiratory symptoms such as shortness of breath are not uncommonly reported by people with DCM and respiratory dysfunction has been described in several DCM studies. The objective of this review was therefore to systematically synthesise the current evidence on the relationship between DCM and respiratory function.

METHODS

The review was registered on PROSPERO and adhered to PRISMA guidelines. Ovid MEDLINE and Embase were searched from inception to 14th March 2023. DCM studies reporting on any measure or outcome relating to respiratory function or disease were eligible. Reference lists of included studies and relevant reviews articles were hand searched. Title, abstract and full text screening, risk of bias and GRADE assessments were completed in duplicate. A quantitative synthesis is presented.

RESULTS

Of 1991 studies identified by literature searching, 13 met inclusion criteria: 3 cohort studies, 5 case-control studies, 1 case series and 4 case studies. Forced vital capacity (FVC), peak expiratory flow rate (PEFR) and maximal voluntary ventilation (MVV) were reported to be lower in DCM patients than controls; there was inconsistency in comparisons of forced expiratory volume in 1 s (FEV1). There was conflicting evidence on whether surgical decompression was associated with improvements in respiratory parameters and on the relationship between level of spinal cord compression and respiratory dysfunction.

CONCLUSION

DCM may be associated with respiratory dysfunction. However, consistency and quality of evidence is currently low. Further work should characterise respiratory dysfunction in DCM patients more rigorously and investigate putative mechanisms such as disruption to cervical nerve roots responsible for diaphragmatic innervation and damage to descending spinal projections from brainstem respiratory centres.

Subclinical respiratory dysfunction and impaired ventilatory adaptation in degenerative cervical myelopathy

Degenerative cervical myelopathy (DCM) is a debilitating neurological condition characterized by chronic compression of the cervical spinal cord leading to impaired upper and lower limb function. Despite damage to areas of the cervical spinal cord that house the respiratory network, respiratory dysfunction is not a common symptom of DCM. However, DCM may be associated with respiratory dysfunction, and this can affect the ventilatory response to respiratory challenges during emergence from anesthesia, exercise, or pulmonary disease. Surgical spinal cord decompression, which is the primary treatment for DCM, leads to improved sensorimotor function in DCM; yet its impact on respiratory function is unknown. Here, using a clinically relevant model of DCM, we evaluate respiratory function during disease progression and assess adaptive ventilation to hypercapnic challenge before and after surgical intervention. We show that despite significant and progressive forelimb and locomotor deficits, there was no significant decline in eupneic ventilation from the early to late phases of spinal cord compression. Additionally, for the first time, we demonstrate that despite normal ventilation under resting conditions, DCM impairs acute adaptive ventilatory ability in response to hypercapnia. Remarkably, akin to DCM patients, surgical decompression treatment improved sensorimotor function in a subset of mice. In contrast, none of the mice that underwent surgical decompression recovered their ability to respond to hypercapnic ventilatory challenge. These findings underscore the impact of chronic spinal cord compression on respiratory function, highlighting the challenges associated with ventilatory response to respiratory challenges in individuals with DCM. This research highlights the impact of cervical spinal cord compression on respiratory dysfunction in DCM, as well as the persistence of adaptive ventilatory dysfunction after surgical spinal cord decompression. These results indicate the need for additional interventions to enhance recovery of respiratory function after surgery for DCM.

Comparison of breathing pattern and diaphragmatic motion in patients with unilateral cervical radiculopathy and asymptomatic group

BACKGROUND

The associations between neck pain and respiratory dysfunction were clarified in patients with neck pain. There is dearth of evidence on pulmonary dysfunction and diaphragmatic excursion in patients with unilateral cervical radiculopathy (CR). The purpose of this study was to compare the breathing pattern and diaphragmatic excursion in patients with unilateral CR with those in an asymptomatic group.

METHODS

Twenty-five patients with unilateral CR and 25 asymptomatic individuals aged between 30 and 55 participated in this study. Diaphragmatic motion, breathing pattern, active cervical range of motion and kinesiophobia were investigated in both groups by using fluoroscopy, manual assessment of respiratory motion (MARM), cervical range of motion device, and Tampa scale of kinesiophobia. Statistical significance was set at 0.05.

RESULTS

No statistically significant differences were found between the two groups with regard to sex, age and body mass index. The mean excursion of the hemi diaphragm on the involved side (the side of CR) was significantly lower than that on the uninvolved side in patients with unilateral CR with a large effect size. The excursion of the involved hemi diaphragm in patients was reduced compared to the matched hemi diaphragm in the control group. There was no significant difference between the hemi diaphragms excursion in the control group. The results of the MARM variables showed that the volume of breathing and the percentage rib cage motion in normal and deep breathing were significantly different between the two groups, but there was no significant difference in the balance of breathing between the two groups. Additionally, the active cervical range of motion was reduced in these patients in comparison to the control group, and it was less on the involved side than on the uninvolved side.

CONCLUSION

The results of this study revealed a dysfunctional breathing pattern in normal and deep breathing and a unilateral reduction in diaphragmatic excursion on the side of radiculopathy in patients with unilateral CR compared to the control group.

Targeting patient recovery priorities in degenerative cervical myelopathy: design and rationale for the RECEDE-Myelopathy trial-study protocol

INTRODUCTION

Degenerative cervical myelopathy (DCM) is a common and disabling condition of symptomatic cervical spinal cord compression secondary to degenerative changes in spinal structures leading to a mechanical stress injury of the spinal cord. RECEDE-Myelopathy aims to test the disease-modulating activity of the phosphodiesterase 3/phosphodiesterase 4 inhibitor Ibudilast as an adjuvant to surgical decompression in DCM.

METHODS AND ANALYSIS

RECEDE-Myelopathy is a multicentre, double-blind, randomised, placebo-controlled trial. Participants will be randomised to receive either 60-100 mg Ibudilast or placebo starting within 10 weeks prior to surgery and continuing for 24 weeks after surgery for a maximum of 34 weeks. Adults with DCM, who have a modified Japanese Orthopaedic Association (mJOA) score 8-14 inclusive and are scheduled for their first decompressive surgery are eligible for inclusion. The coprimary endpoints are pain measured on a visual analogue scale and physical function measured by the mJOA score at 6 months after surgery. Clinical assessments will be undertaken preoperatively, postoperatively and 3, 6 and 12 months after surgery. We hypothesise that adjuvant therapy with Ibudilast leads to a meaningful and additional improvement in either pain or function, as compared with standard routine care.

STUDY DESIGN

Clinical trial protocol V.2.2 October 2020.

ETHICS AND DISSEMINATION

Ethical approval has been obtained from HRA-Wales.The results will be presented at an international and national scientific conferences and in a peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ISRCTN Number: ISRCTN16682024.

Life expectancy in patients with degenerative cervical myelopathy is currently reduced but can be restored with timely treatment

PURPOSE

Degenerative cervical myelopathy is a progressive slow-motion spinal cord injury. Surgery is the mainstay of treatment. Baseline disability predicts surgical recovery; therefore, timely treatment is critical to restoring function. However, current challenges mean most patients present with advanced disease and are instead left with life changing disabilities. While short-term mortality is rarely reported, the long-term effects of this on life expectancy are unknown, including whether function could be modifiable with timely treatment. This article investigates the effect of DCM on life expectancy.

METHODS

The survival of patients from an observational study of patients undergoing surgery from 1994 to 2007 was compared to their expected survival using a gender- and aged -matched cohort. Comparisons were made by one sample log-rank test and standardised mortality ratios. Factors associated with survival were explored using a Cox regression analysis, including disease severity.

RESULTS

A total of 357 patients were included in the analysis. After a median follow-up of 15.3 years, 135 of 349 patients had died; 114.7 deaths would have been expected. The DCM cohort had an increased risk of death compared to the non-DCM cohort (standardised mortality ratio 1.18 [95% CI: 1.02-1.34]. Age at operation 1.08 (95% CI: 1.07 to 1.1, p < 0.001) and severe DCM 1.6 (95% CI: 1.06 to 2.3, p = 0.02) were associated with worse survival (N = 287). In those surviving at least 2 years after surgery, only severe DCM was associated with conditional survival (HR 1.6, 95% CI 1.04 2.4, p = 0.03).

CONCLUSION

Life expectancy is reduced in those undergoing surgery for DCM. This is driven by premature mortality among those left with severe disability. As disability can be reduced with timely treatment, these findings reinforce the need for collective and global action to raise awareness of DCM and enable early diagnosis.

Phrenic Nerve Dysfunction Secondary to Cervical Neuroforaminal Stenosis: A Literature Review

BACKGROUND

Phrenic nerve dysfunction has been associated with cervical neuroforaminal stenosis in limited case reports and case-controlled studies. It is unclear if magnetic resonance imaging of the cervical spine should be included in the workup of patients with pulmonary dysfunction. A systematic review of the current literature was conducted on the topic to provide an outline of the body of knowledge and some guidance for neurosurgeons that receive these patient referrals.

METHODS

A systematic literature review was conducted through the PubMed database to identify articles related to phrenic nerve dysfunction secondary to cervical stenosis.

RESULTS

A total of 12 case reports were found. The median subject age was 64 years, 11 were male. Presenting symptoms included shortness of breath (n = 9), radiculopathy (n = 7), myelopathy (n = 5), reduced pulmonary function (n = 6), weakness (n = 4), and neck pain (n = 5). Ten of these patients underwent surgical intervention, all having improvements in their pulmonary and neurological symptoms at follow-up ranging from 10 days to 2 years.

CONCLUSIONS

Cervical stenosis, resulting in neuroforaminal stenosis, may be related to phrenic nerve dysfunction in select patients with idiopathic diaphragmatic paralysis or pulmonary dysfunction. Surgical decompression improves pulmonary and neurological symptoms.

Respiratory Compromise After Anterior Cervical Spine Surgery: Incidence, Subsequent Complications, and Independent Predictors

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

Respiratory compromise (RC) is a rare but catastrophic complication of anterior cervical spine surgery (ACSS) commonly due to compressive fluid collections or generalized soft tissue swelling in the cervical spine. Established risk factors include operative duration, size of surgical exposure, myelopathy, among others. The purpose of this current study is to identify the incidence and clinical course of patients who develop RC, and identify independent predictors of RC in patients undergoing ACSS for cervical spondylosis.

METHODS

A large, prospectively-collected registry was used to identify patients undergoing ACSS for spondylosis. Patients with posterior cervical procedures were excluded. Baseline patient characteristics were compared using bivariate analysis, and multivariate analysis was employed to compare postoperative complications and identify independent predictors of RC.

RESULTS

298 of 52,270 patients developed RC (incidence 0.57%). Patients who developed RC had high rates of 30-day mortality (11.7%) and morbidity (75.8%), with unplanned reoperation and pneumonia the most common. The most common reason for reoperations were hematoma evacuation and tracheostomy. Independent patient-specific factors predictive of RC included increasing patient age, male gender, comorbidities such as chronic cardiac and respiratory disease, preoperative myelopathy, prolonged operative duration, and 2-level ACCFs.

CONCLUSION

This is among the largest cohorts of patients to develop RC after ACSS identified to-date and validates a range of independent predictors, many previously only described in case reports. These results are useful for taking preventive measures, identifying high risk patients for preoperative risk stratification, and for surgical co-management discussions with the anesthesiology team.

Impact of Postoperative ABG Analysis and ICU Weaning Protocol in Surgical Outcome of Atlanto-Axial Dislocation: It's not the Towering Sail, but the Unseen Wind that Moves the Ship

Background

The outcome in patients of atlanto-axial dislocation (AAD) depends on multiple factors like preoperative optimization, intraoperative distractio and cord manipulation. Certain unfocussed factors such as respiratory reserve and compensatory acclimatization to hypoxia warrant consideration.

Aims

The purpose of this study is to find the association of postoperative arterial blood gas (ABG) analysis and respiratory reserve in patients of AAD with clinical outcome.

Study Design

We retrospectively analyzed the available records of patients, operated for AAD, at our institute (n = 66), from January 2014 to November 2018.

Materials and Methods

Preoperative pulmonary function test (PFT) and the postoperative ABG analysis was noted. Timing of extubation, duration of intensive care unit (ICU) stays, and clinical outcomes (Nurick grade) were noted from the inpatient record and the last outpatient follow up. An independent t-test and analysis of variance were used to find significance.

Results

In total, 41% (n = 27) patients had body mass index of less than 18.5, and 50% (n = 33) had breath holding time of less than 20 minutes. There was improvement in mean Nurick grade from 3.17 ± 0.8 to 2.76 ± 0.7 in follow up. A trend suggesting that patients with poor preoperative PFT has more ICU duration and worse outcome. In patients with mild acid-base disorders, extubation was possible within 24 hours. Out of 26 patients with ICU duration less than 2 days, 23 patients had "good" outcome, whereas ten out of 40 patients with ICU duration of more than or equal to 2 days had "bad" outcome (P = 0.00).

Conclusion

Patients having moderate to severe primary or mixed acid-base disorder have a probability of re-intubation or delayed extubation. A strong correlation was seen with the novel grading system (grade >6 had worse outcome).

Outcomes of Degenerative Cervical Myelopathy From The Perspective of Persons Living With the Condition: Findings of a Semistructured Interview Process With Partnered Internet Survey

STUDY DESIGN

Mixed-methods cross-sectional study.

OBJECTIVES

Degenerative cervical myelopathy (DCM) is a common and disabling condition. While classically, assessment and diagnosis has focused on neuromuscular symptoms, many other disabilities have been linked. The aim of this study was to explore the consequences of DCM for those with lived experience, producing a long list to inform the development of a core outcome set for DCM research.

METHODS

A 2-stage process was used: a focus group session of people with DCM (PwCM) and their supporters (n = 8) discussed the impact of DCM. This was used to develop a preliminary list of consequences, which were then placed into a survey of an online community of DCM sufferers (n = 224). Survey participants were asked to tick the consequences that they had experienced and given the opportunity to submit additional. Additional consequences were reviewed by a group of healthcare professionals and PwCM and included if not already represented. Demographic information including disease severity, age, and sex were captured for sampling comparison.

RESULTS

A total of 52 outcomes were identified from the focus group and nominally divided into 2 categories; symptoms (36 outcomes) and handicaps (18 outcomes), and further evaluated using a survey. All outcomes were recognized by at least 5% of respondents. A further 16 outcomes were added following the survey.

CONCLUSIONS

A list of DCM consequences has been defined from the perspective of PwCM. This will now be evaluated as part of AO Spine RECODE-DCM, an international multistakeholder collaboration to establish a core outcome set for research.

Spinal cord injury and degenerative cervical myelopathy

Spinal cord injury (SCI) often results in impaired respiratory function. Paresis or paralysis of inspiratory and expiratory muscles can lead to respiratory dysfunction depending on the level and severity of the injury, which can affect the management and care of SCI patients. Respiratory dysfunction after SCI is more severe in high cervical injuries, with vital capacity (VC) being an essential indicator of overall respiratory health. Respiratory complications include hypoventilation, a reduction in surfactant production, mucus plugging, atelectasis, and pneumonia. Respiratory management includes mechanical ventilation and tracheostomy in high cervical SCI, while noninvasive ventilation is more common in patients with lower cervical and thoracic injuries. Mechanical ventilation can negatively impact the function of the diaphragm and weaning should start as soon as possible. Patients can sometimes be weaned from mechanical ventilation with assistance of electrical stimulation of the phrenic nerve or the diaphragm. Respiratory muscle training regimens may also improve patients' inspiratory function following SCI. Despite the critical advances in preventing, diagnosing, and treating respiratory complications, they continue to significantly affect persons living with SCI. Additional studies of interventions to reduce respiratory complications are likely to further decrease the morbidity and mortality associated with these injuries.

National Trends and Complications in the Surgical Management of Ossification of the Posterior Longitudinal Ligament (OPLL)

STUDY DESIGN

A retrospective database analysis.

OBJECTIVE

The aim of this study was to analyze US trends in surgical approaches for ossification of the posterior longitudinal ligament (OPLL); and to compare US patient and hospital characteristics, length of stay, total charges, and 30-day complications by surgical approach in OPLL management.

SUMMARY OF BACKGROUND DATA

A robust literature on surgical management of OPLL in East Asian countries, where OPLL has a higher prevalence, exists. However, there is a paucity of literature evaluating the surgical management of OPLL in non-Asian countries.

METHODS

Using the Nationwide Inpatient Sample (NIS), we identified surgically treated OPLL patients from 2003 to 2014. Data on patient characteristics, surgical approaches, complications, hospital characteristics, length of stay, and hospital charges were extracted and analyzed. Analysis of variance (ANOVA) and Chi-squared tests were used to assess variation across categorical variables. Linear regression was used to evaluate the trend of surgical management for OPLL over the study timeframe.

RESULTS

Five thousand two hundred twelve patients fit our inclusion criteria. The overall complication rate was 21.5%, but the highest complication rate was for patients undergoing a combined anterior-posterior decompression/fusion (44.7%). Patients undergoing a combined anterior-posterior decompression/fusion had a longer length of stay and higher total charges (P < 0.01). Overall, surgical OPLL cases significantly increased from 2003 to 2014 (336-920; P < 0.01).

CONCLUSION

To our knowledge, this is the largest study examining the surgical treatment of OPLL in a non-Asian country. OPLL surgical cases increased over the study timeframe and the overall surgical complication rate was 21.5%. The percentage of Asians or Pacific Islanders with OPLL undergoing surgical intervention was 10.8%, which is higher than the prevalence in the US population (4.9%). This suggests a potential genetic component to OPLL. Future work is warranted to determine how best to decrease the high complication rate.

LEVEL OF EVIDENCE

4.

The Natural History of Cervical Spondylotic Myelopathy and Ossification of the Posterior Longitudinal Ligament: A Review Article

Cervical spondylotic myelopathy (CSM) is the chronic and slow deterioration of cervical spinal cord function. The pathophysiology of this condition is multifactorial, including compression, repetitive trauma, and vascular compromise of the spinal cord. Clinically, it presents as a progressive decline in patients' appendicular neurological function. The natural history of this disease varies but, it is well-known that the duration and degree of compression correlate negatively with prognosis. A mild degree of CSM tends to stabilize with potential improvement over time while more severe CSM tends to progress. Surgical intervention has shown to positively alter the natural history of the disease by halting the progression with some restoration of function. Ossification of the posterior longitudinal ligament (OPLL) is a chronic disease that results in progressive ossification of the posterior longitudinal ligament of the spine. It commonly affects the cervical spine. The etiology is multifactorial in nature, including genetic and environmental factors. The progressive nature of this condition and the resultant cervical spinal stenosis make it one of the main causes of cervical myelopathy (CM). There is no medical therapy for this disease, and surgery is reserved for patients with CM caused by spinal cord compression. In this article, we review the different aspects of the natural history of both CSM and OPLL.

Restrictive ventilatory impairment improved by laminoplasty for ossification of the posterior longitudinal ligament

We report a woman with severe restrictive ventilatory impairment because of respiratory muscle paralysis caused by ossification of the posterior longitudinal ligament (OPLL). Laminoplasty improved her respiratory function and quality of life. Cervical myelopathy including OPLL should be considered as an important differential diagnosis in patients with respiratory dysfunction.

A Novel Insight Into the Challenges of Diagnosing Degenerative Cervical Myelopathy Using Web-Based Symptom Checkers

Background

Degenerative cervical myelopathy (DCM) is a common debilitating condition resulting from degeneration of the cervical spine. While decompressive surgery can halt disease progression, existing spinal cord damage is often permanent, leaving patients with lifelong disability. Early surgery improves the likelihood of recovery, yet the average time from the onset of symptoms to correct diagnosis is over 2 years. The majority of delays occur initially, before and within primary care, mainly due to a lack of recognition. Symptom checkers are widely used by patients before medical consultation and can be useful for preliminary triage and diagnosis. Lack of recognition of DCM by symptom checkers may contribute to the delay in diagnosis.

Objective

The aims of this study were to investigate whether Web-based symptom checkers were able to recognize relevant symptoms of DCM, to characterize the DCM differential they returned , and to evaluate the diagnostic performance of recognized DCM symptoms.

Methods

We pooled classical DCM symptoms from leading review articles. These symptoms were entered into the algorithms used by the top 20 symptom checker websites (N=4; Google Search). The most widely cited symptom checker, WebMD, was used to characterize the differential diagnosis for DCM symptoms.

Results

A total of 31 classical DCM symptoms were identified, of which 45% (14/31) listed DCM as a differential and 10% (3/31) placed DCM in the top third of the differential. The mean differential rank for motor symptoms was significantly better than that for arthritic symptoms (P=.01) and the average differential rank for all symptoms (P=.048). The symptom checker WebMD performed best at recognizing DCM, placing the condition nearer to the top of the differential list (mean rank of 5.6) than either Healthline (rank of 12.9, P=.02) or Healthtools.AARP (rank of 15.5, P=.001). On WebMD, only one combination of symptoms resulted in DCM as the primary differential: neck, shoulder, and arm pain with hand weakness. Moreover, 151 differential diagnoses for DCM symptoms were recorded on WebMD. Multiple sclerosis and peripheral neuropathy were the most common differentials, shortlisted for 52% (16/31) and 32% (10/31) of the DCM symptoms, respectively.

Conclusions

DCM symptoms are poorly identified by Web-based symptom checkers, which leads to a large differential of many other common conditions. While a diagnosis becomes more likely as the number of symptoms increases, this represents more advanced disease and will not support much-needed earlier diagnosis. Symptom checkers remain an attractive concept with potential. Further research is required to support their optimization.