Dynamic changes of the ligamentum flavum in the cervical spine assessed with kinetic magnetic resonance imaging

Incidence and Predictors of Inadvertent Dural Puncture After Percutaneous Spinal Cord Stimulation: A Retrospective Database Analysis

OBJECTIVES

Inadvertent dural puncture (IDP) is a known complication associated with traditional neuraxial procedures; however, its characterization after percutaneous spinal cord stimulation (SCS) lead placement has yet to be clearly established in large population studies. This retrospective analysis aims to understand the incidence and associated characteristics of patients with IDP after percutaneous SCS lead placement.

MATERIALS AND METHODS

The PearlDiver Mariner database of national all-payer claims was used to identify patients who received percutaneous SCS leads and had a claim for IDP (intraoperative IDP or postdural puncture headache [PDPH] claim) within 45 days. The primary outcome was to determine the overall incidence of IDP. Secondary outcomes included an evaluation of associated risk factors for IDP and treatments used in symptomatic management.

RESULTS

A total of 90,952 patients who underwent percutaneous lead SCS placement were included. The incidence of IDP was 0.48% (436/90,952 patients). Older age (odds ratio [OR]: 0.96; 95% CI: 0.95-0.97; p < 0.0001) and male sex (OR: 0.66; 95% CI: 0.53-0.81; p < 0.001) had a lower odds of having a claim for IDP, whereas a history of IDP was associated with a higher OR (95% CI) by 13.72 times (10.72-17.58) (p < 0.0001). Of the IDP patients, 64% (277/436 patients) had a claim for a therapeutic blood patch. Discrepancy in type of claim for IDP was observed, with most being for PDPH.

CONCLUSIONS

Our findings suggest that IDP after percutaneous SCS lead placement is an uncommon event; however, certain factors are associated with its development. Overall, early recognition of IDP after percutaneous SCS lead placement is imperative to facilitate the delivery of targeted treatments and prevent further harmful consequences to the patient.

Finite element modeling and analysis of effect of preexisting cervical degenerative disease on the spinal cord during flexion and extension

Recent studies have emphasized the importance of dynamic activity in the development of myelopathy. However, current knowledge of how degenerative factors affect the spinal cord during motion is still limited. This study aimed to investigate the effect of various types of preexisting herniated cervical disc and the ligamentum flavum ossification on the spinal cord during cervical flexion and extension. A detailed dynamic fluid-structure interaction finite element model of the cervical spine with the spinal cord was developed and validated. The changes of von Mises stress and maximum principal strain within the spinal cord in the period of normal, hyperflexion, and hyperextension were investigated, considering various types and grades of disc herniation and ossification of the ligamentum flavum. The flexion and extension of the cervical spine with spinal canal encroachment induced high stress and strain inside the spinal cord, and this effect was also amplified by increased canal encroachments and cervical hypermobility. The spinal cord might evade lateral encroachment, leading to a reduction in the maximum stress and principal strain within the spinal cord in local-type herniation. Although the impact was limited in the case of diffuse type, the maximum stress tended to appear in the white matter near the encroachment site while compression from both ventral and dorsal was essential to make maximum stress appear in the grey matter. The existence of canal encroachment can reduce the safe range for spinal cord activities, and hypermobility activities may induce spinal cord injury. Besides, the ligamentum flavum plays an important role in the development of central canal syndrome.Significance. This model will enable researchers to have a better understanding of the influence of cervical degenerative diseases on the spinal cord during extension and flexion.

Dynamic Flexion-Extension Magnetic Resonance Imaging of the Cervical Spine: An Evolutionary Tool for Diagnosis and Management of Cervical Spondylotic Myelopathy

Dynamic problems need dynamic solutions. High motility of the cervical spine causes a common age-related degenerative condition called cervical spondylotic myelopathy (CSM), manifested by neurological impairments. An accurate and reliable diagnosis of CSM is crucial for determining appropriate management strategies. Traditional static magnetic resonance imaging (MRI) has been the gold standard for imaging CSM; however, it may not fully capture dynamic changes during neck movement. Dynamic flexion-extension (DFE) MRI is an innovative imaging technique that allows for real-time visualization of cervical spine motion. This review article aims to scrutinize the role of DFE MRI in assessing CSM, its added value to clinical implementations, and its limitations. Finally, by addressing the knowledge gaps, this survey sheds light on the road ahead to incorporate DFE MRI into a standard version of the practice.

Effect of Different Types of Ossification of the Posterior Longitudinal Ligament on the Dynamic Biomechanical Response of the Spinal Cord: A Finite Element Analysis

Ossification of the posterior longitudinal ligament (OPLL) has been identified as an important cause of cervical myelopathy. However, the biomechanical mechanism between the OPLL type and the clinical characteristics of myelopathy remains unclear. The aim of this study was to evaluate the effect of different types of OPLL on the dynamic biomechanical response of the spinal cord. A three-dimensional finite element model of the fluid-structure interaction of the cervical spine with spinal cord was established and validated. The spinal cord stress and strain, cervical range of motion (ROM) in different types of OPLL models were predicted during dynamic flexion and extension activity. Different types of OPLL models showed varying degrees of increase in stress and strain under the process of flexion and extension, and there was a surge toward the end of extension. Larger spinal cord stress was observed in segmental OPLL. For continuous and mixed types of OPLL, the adjacent segments of OPLL showed a dramatic increase in ROM, while the ROM of affected segments was limited. As a dynamic factor, flexion and extension of the cervical spine play an amplifying role in OPLL-related myelopathy, while appropriate spine motion is safe and permitted. Segmental OPLL patients are more concerned about the spinal cord injury induced by large stress, and patients with continuous OPLL should be noted to progressive injuries of adjacent level.

The biomechanical effect of different types of ossification of the ligamentum flavum on the spinal cord during cervical dynamic activities

Ossification of the ligamentum flavum (OLF) is thought to be an influential etiology of myelopathy, as thickened ligamentum flavum causes the stenosis of the vertebral canal, which could subsequently compress the spinal cord. Unfortunately, there was little information available on the effects of cervical OLF on spinal cord compression, such as the relationship between the progression of cervical OLF and nervous system symptoms during dynamic cervical spine activities. In this research, a finite element model of C1-C7 including the spinal cord featured by dynamic fluid-structure interaction was reconstructed and utilized to analyze how different types of cervical OLF affect principal strain and stress distribution in spinal cord during spinal activities towards six directions. For patients with cervical OLF, cervical extension induces higher stress within the spinal cord among all directions. From the perspective of biomechanics, extension leads to stress concentration in the lateral corticospinal tracts or the posterior of gray matter. Low energy damage to the spinal cord would be caused by the high and fluctuating stresses during cervical movements to the affected side for patients with unilateral OLF at lower grades.

Prevalence and distribution of ossification of the ligamenta flava in a 16th-18th century skeletal population sample from Poland

OBJECTIVE

This study aimed to determine the prevalence of the ossification of the ligamenta flava (OLF) among skeletal remains from Poland.

MATERIALS AND METHODS

124 skeletons aged 25 years and older were analyzed. The presence and size of OLF were observed macroscopically. OLF was recorded at the cranial and caudal attachment sites of each vertebra. The following factors were analyzed: age at death, sex, and presence of other spondyloarthropathies.

RESULTS

The crude prevalence of OLF in the analyzed series was 68.55 %. OLF was located most frequently in the lower thoracic spine. A statistically significant relationship was observed between the presence of OLF and age at death. OLF coincided with degenerative spondyloarthropathies of the thoracolumbar spine.

CONCLUSIONS

The results of this study indicate that OLF was not a rare condition in past populations of European ancestry. Analysis of OLF prevalence in skeletal materials can contribute to reconstruction of the conditions and lifestyles of past people.

SIGNIFICANCE

This study shed new light on the prevalence of OLF and provides information on the variability of OLF in past European populations. The evaluation of the prevalence of OLF represents an important contribution to the field of paleopathology in understanding disease changes in prehistoric and historic human populations.

LIMITATIONS

The analyzed material came from unknown populations without demographic data. Sex and age at death were assessed using standard anthropological methods.

SUGGESTIONS FOR FURTHER RESEARCH

It is important to understand the influence of sociocultural factors and physical activity patterns on the development of OLF.

Stress Distribution on Spinal Cord According to Type of Laminectomy for Large Focal Cervical Ossification of Posterior Longitudinal Ligament Based on Finite Element Method

Most studies on the ossification of the posterior longitudinal ligament (OPLL) using the finite element method were conducted in the neutral state, and the resulting decompression was judged to be good. As these studies do not reflect the actual behavior of the cervical spine, this study conducted an analysis in the neutral state and a biomechanical analysis during flexion and extension behaviors. After validation via the construction of an intact cervical spine model, the focal OPLL model was inserted into the C4–C5 segment and a simulation was performed. The neutral state was shown by applying a fixed condition to the lower part of the T1 and Y-axis fixed condition of the spinal cord and simulating spinal cord compression with OPLL. For flexion and extension simulation, a ±30-degree displacement was additionally applied to the top of the C2 dens. Accordingly, it was confirmed that spinal cord decompression did not work well during the flexion and extension behaviors, but rather increased. Thus, if patients with focal OPLL inevitably need to undergo posterior decompression, additional surgery using an anterior approach should be considered.

The cervical sagittal curvature change in patients with or without PCSM after laminoplasty

Objective

After laminoplasty, the cervical sagittal curvature of some patients tend to be lordotic, this phenomenon cannot be explained by the theory of laminoplasty, and the reason remains unknown. We explored the possible role played by pinching cervical spondylotic myelopathy (PCSM) in the cervical sagittal curvature change in patients after laminoplasty.

Methods

From April 2017 to May 2019, we studied 122 patients undergoing laminoplasty with cervical spondylotic myelopathy (CSM). All patients were divided into Group A (anterior compression only, without PCSM) and Group B (both anterior and posterior compression, with PCSM). The visual analogue scale (VAS) was used to measure pain, and modified Japanese Orthopedic Association (mJOA) score was derived. The cervical global angle (CGA) and the range of cervical motion (ROM) were compared. The clinical and imaging results were compared between Group A and Group B.

Results

After laminoplasty, both the mean VAS and mJOA scores improved significantly in Group A and Group B, the mJOA recovery rate of Group B was better than that of Group A (P < 0.05). The mean CGA and ROM decreased in Group A, but increased in Group B. MRI revealed that the ligamentum flavum of Group A was significantly thinner than that of Group B (P < 0.05).

Conclusions

Because of the hypertrophic and folded ligamentum flavum compressing the dorsal spinal cord, patients with PCSM may maintain a compulsive kyphotic posture. After laminoplasty, the cervical sagittal curvature of these patients tend to be lordotic due to the release of dorsal spinal cord compression.

Effect of degenerative factors on cervical spinal cord during flexion and extension: a dynamic finite element analysis

Spinal cord injury (SCI) is a global problem that brings a heavy burden to both patients and society. Recent investigations indicated degenerative disease is taking an increasing part in SCI with the growth of the aging population. However, little insight has been gained about the effect of cervical degenerative disease on the spinal cord during dynamic activities. In this work, a dynamic fluid-structure interaction model was developed and validated to investigate the effect of anterior and posterior encroachment caused by degenerative disease on the spinal cord during normal extension and flexion. Maximum von-Mises stress and maximum principal strain were observed at the end of extension and flexion. The abnormal stress distribution caused by degenerative factors was concentrated in the descending tracts of the spinal cord. Our finding indicates that the excessive motion of the cervical spine could potentially exacerbate spinal cord injury and enlarge injury areas. Stress and strain remained low compared to extension during moderate flexion. This suggests that patients with cervical degenerative disease should avoid frequent or excessive flexion and extension which could result in motor function impairment, whereas moderate flexion is safe. Besides, encroachment caused by degenerative factors that are not significant in static imaging could also cause cord compression during normal activities.

Ligamentum Flavum Buckling vs Hypertrophy in Cervical Myelopathy Using Dynamic Imaging: Are Instability and Loss of Disc Height the Culprits?

BACKGROUND

The literature has not distinguished between LF "hypertrophy" and "buckling" when addressing cervical spondylotic myelopathy. The identification of buckling on dynamic magnetic resonance imaging can determine the levels for decompression more accurately and modify the surgical plan accordingly. No studies have been performed in the cervical spine to analyze the factors affecting LF buckling.

PURPOSE

Our objective was to investigate the factors affecting static ligamentum flavum (LF) "hypertrophy" and dynamic LF "buckling."

STUDY DESIGN

Retrospective cohort study.

METHODS

We conducted a retrospective study of hospital records and imaging database from January 2014 to January 2020. The relation of age, disc height, and intervertebral instability to LF hypertrophy and buckling were assessed.

RESULTS

Measurements were performed from C2-3 to C7-T1 in 169 patients who satisfied the eligibility criteria, making a total of 1014 levels. The samples were divided into 2 groups: 798 levels with buckling <1 mm (group A) and 216 levels with buckling >1 mm (group B). Of those, 161 levels satisfied the criteria for radiological instability (sagittal translation/rotation). No correlation was observed between age/disc height and buckling. Intervertebral instability showed significant association (P = 0.046) with buckling. No correlation was found between age/intervertebral instability and hypertrophy.

CONCLUSION

LF buckling but not hypertrophy is related to intervertebral instability in the cervical spine. LF buckling in the cervical spine is not related to age or disc height in the cervical spine.

CLINICAL RELEVANCE

Intervertebral instability on dynamic x-ray imaging of the cervical spine can be a predictor of ligamentum flavum buckling and can be utilized for surgical planning.

LEVEL OF EVIDENCE: 3

Risk factors for the development of degenerative cervical myelopathy: a review of the literature

Degenerative cervical myelopathy (DCM) encompasses various pathological conditions causing spinal cord (SC) impairment, including spondylosis (multiple level degeneration), degenerative disc disease (DDD), ossification of the posterior longitudinal ligament (OPLL), and ossification of the ligamentum flavum (OLF). It is considered the most common cause of SC dysfunction among the adult population. The degenerative phenomena of DDD, spondylosis, OPLL and OLF, is likely due to both inter-related and distinct factors. Age, cervical alignment, and range of motion, as well as congenital factors such as cervical cord-canal mismatch due to congenital stenosis, Klippel-Feil, Ehler-Danlos, and Down syndromes have been previously reported as potential factors of risk for DCM. The correlation between some comorbidities, such as rheumatoid arthritis and movement disorders (Parkinson disease and cervical dystonia) and DCM, has also been reported; however, the literature remains scare. Other patient-specific factors including smoking, participation in contact sports, regular heavy load carrying on the head, and occupation (e.g. astronauts) have also been suggested as potential risk of myelopathy development. Most of the identified DCM risk factors remain poorly studied however. Further researches will be necessary to strengthen the current knowledge on the subject, especially concerning physical labors in order to identify patients at risk and to develop an effective treatment strategy for preventing this increasing prevalent disorder.

Biportal endoscopic unilateral laminotomy with bilateral decompression for the treatment of cervical spondylotic myelopathy

BACKGROUND

The advantages of biportal endoscopic approaches over conventional open surgery include the preservation of the normal structures, less intraoperative bleeding, fast postoperative recovery, and preservation of the motion segments.

METHOD

We attempted the posterior biportal endoscopic approach for cervical stenosis at the C5-C6-C7 levels. Biportal endoscopic right ipsilateral hemilaminectomy with bilateral decompression at the C5-C6-C7 levels and right foraminotomy at the C6-C7 level were performed under general anesthesia.

CONCLUSIONS

We successfully performed neural decompression at the C5-C6-C7 levels using biportal endoscopic surgery. The biportal endoscopic posterior cervical approach may be an alternative surgical method for treating cervical myelopathy.

Wild-Type Transthyretin Amyloidosis Occurring in the Ligamentum Flavum of the Cervicothoracic Spine

BACKGROUND

Wild-type transthyretin amyloid (ATTRwt) has been noted to deposit in the ligamentum flavum of the spine. Prior studies have focused on ATTRwt in the lumbar region, but studies discussing its presence in other levels of the spine are lacking. We report on the presentation of patients with confirmed amyloid in the cervicothoracic regions and discuss the literature to date.

METHODS

We retrospectively identified patients at a single institution who underwent surgery for spinal stenosis and had pathologic specimens sent for amyloidosis testing with Congo red staining. ATTRwt was confirmed by the presence of transthyretin amyloid by typing and the absence of mutations in the TTR gene sequence. A final study group of patients with ATTRwt and spinal involvement was established (n = 27).

RESULTS

Of 27 patients with amyloid in the spine, 24 (89%) had amyloid present in the lumbar region, 2 (7%) had amyloid in the cervical region, and 1 (4%) had amyloid in the thoracic region. The median age at which patients in the study underwent surgery was 71 years (interquartile range: 9). Spinal stenosis was the indication for surgery in 26 of 27 (96%) patients. Surgery involved 1 or 2 spinal levels in 24 of 27 (89%) patients.

CONCLUSIONS

ATTRwt amyloid predominantly deposits in the lumbar region, but it can also be present in the cervical and thoracic regions. While the lumbar regions should remain a focus for evaluation of ATTRwt amyloidosis, the cervicothoracic region should not be ignored.

Difference of Dynamic Morphometric Changes Between in Patients with Ossification of Posterior Longitudinal Ligament and Patients with Cervical Spondylosis: Assessment by Cervical Dynamic Magnetic Resonance Imaging

PURPOSE

To evaluate differences between thicknesses of the ligamentum flavum (LF) and diameter of the spinal canal in different neck positions in patients with ossification of the posterior longitudinal ligament (OPLL) and patients with cervical degenerative spondylosis (CDS) using cervical dynamic magnetic resonance imaging (MRI).

METHODS

Eighty-eight patients (66 CDS and 22 OPLL) who underwent neutral and dynamic MRI at our institute from February 2014 to July 2017 were the subjects of this retrospective study. Canal diameters and LF thicknesses were measured and Muhle's grades were determined in neutral and dynamic MRI from C2-C3 to C7-T1. Patients with CDS and OPLL were compared with respect to changes in morphometric parameters. Statistical analysis was performed using SPSS software and statistical significance was accepted for P values < 0.05.

RESULTS

Mean ages in the CDS and OPLL groups were 68.2 ± 12.27 and 63.1 ± 9.36 years, respectively. Mean canal diameters were smaller in extension than in neutral at all measured levels, especially between C3-C4 and C6-C7 in patients with CDS. LF thickness in extension was significantly greater than in neutral and flexion positions in the CDS group, but not in the OPLL group. In addition, positional changes in Muhle's grades in the CDS group were significantly greater than in the OPLL group (P = 0.042).

CONCLUSIONS

Dynamic morphometric changes were found to be significantly greater in the CDS group than in the OPLL group. The study shows dynamic MRI may provide additional information in CDS patients.

A Dynamic Magnetic Resonance Imaging Study of Changes in Severity of Cervical Spinal Stenosis in Flexion and Extension

Objective

To evaluate changes in the severity of cervical spinal stenosis (CSS) in flexion and extension and determine whether the rate of change with motion varied with severity.

Methods

The study included 92 symptomatic patients with a mean age of 57.80±10.41, who underwent cervical spine dynamic magnetic resonance imaging. The severity of stenosis was evaluated using a semi-quantitative CSS score, ranging from 0 (no spinal stenosis) to 18 (severe stenosis). Radiological evaluation included flexion, neutral, and extension measurements, as determined by the C2–C7 Cobb angle. The severity of stenosis was represented by the total CSS score. The total CSS score in flexion, neutral, and extension positions was compared using repeated measures one-way analysis of variance. The change rate of stenosis per angle motion (CRSPAM) was defined as change in total CSS score divided by change in Cobb angle. The correlation of CRSPAM with severity of stenosis, represented by total CSS score in neutral position, was evaluated using Pearson correlation analysis.

Results

The total CSS score was significantly higher in extension (6.04±2.68) than in neutral position (5.25±2.47) (p<0.001), and significantly higher in neutral than in flexion position (4.40±2.45) (p<0.001). The CRSPAM was significantly and positively correlated with total CSS score in neutral position in the flexion-extension range (r=0.22, p=0.04) and flexion-neutral range (r=0.27, p=0.01).

Conclusion

In symptomatic CSS patients, the radiological severity of stenosis increases with extension and decreases with flexion. In patients with CSS, the rate of variation in spinal stenosis increases with increased severity.

Kinematic analysis of the space available for cord and disc bulging of the thoracic spine using kinematic magnetic resonance imaging (kMRI)

BACKGROUND CONTEXT

The thoracic spine was previously known as a relatively stable region in human spine. Several studies reported that the motion of the thoracic spine and changes in the cross-sectional area of the spinal cord changed with positions in the sagittal plane. The kinematic relationship between the thoracic disc and the space available for cord (SAC) with the positional change is still not well investigated.

PURPOSE

The objective of this study was to evaluate the kinematic change of the intervertebral disc and space available for the spinal cord of the thoracic spine using kinematic magnetic resonance imaging (kMRI).

STUDY DESIGN

This is a retrospective study.

PATIENT SAMPLE

The patient sample included 105 patients who underwent thoracic spine kMRI.

OUTCOME MEASUREMENT

Disc bulging and the SAC were evaluated from T4-T5 to T11-T12 in flexion, neutral, and extension positions.

METHODS

MRAnalyzer3 (TrueMRI Corporation, Bellflower, CA, USA) was used to analyze disc bulging and SAC from T4-T5 to T11-T12. The Friedman test was used to analyze the differences in disc bulging and SAC between neutral, flexion, and extension positions at each segment. The Wilcoxon signed-rank test was used for post hoc analysis for the significant levels from the Friedman test.

RESULTS

The mean value of the thoracic intervertebral disc area from T4-T5 to T11-T12 tended to be larger in flexion than in extension. Initial analysis with the Friedman test revealed a significant difference in disc bulging at T8-T9, T9-T10, and T11-T12 among the three positions (p<.05). Post hoc analysis showed that disc bulging was only significant at T8-T9 between flexion and extension (p<.001), at T9-T10 between neutral and flexion (0.003), and at T9-T10 between flexion and extension (p=.004). The SAC from T4-T5 to T11-T12 tended to be widest in extension and narrowest in flexion. Only T5-T6 exhibited a statistically significant difference in SAC between flexion and extension (p=.002).

CONCLUSIONS

The thoracic discs and the SAC from T4-T5 to T11-T12 showed kinematic changes from flexion to extension. The thoracic spinal canal tended to be narrowest in flexion and widest in the extension. Thus, kyphotic deformities could be one of the etiologies for neurogenic deterioration in patients with thoracic myelopathy.

Thickening Ligamentum Flavum Mimicking Tumor in the Epidural Space of the Cervical Spine

In patients with tumors and spinal cord lesions, inflammation and tissue infection can result in mass effect detection on imaging. As a result, surgical biopsy procedures are often performed on the lesions. We report a rare case in which the thickening ligamentum flavum (LF) appeared to be a tumor in the epidural space of the cervical spine based on imaging findings. A 52-year-old man visited our outpatient clinic with severe shoulder pain and radicular pain in his right arm that had developed gradually after a traffic accident two months earlier. Magnetic resonance imaging of the cervical spine revealed an extradural mass at the cervicothoracic junction level. Suspecting a tumor, spinal decompression surgery was performed and a biopsy of the mass was obtained. At the time of surgery, the LF was thick and compressed the spinal cord. After successful removal of the LF, the spinal cord appeared normal. Histopathological examination confirmed the mass as the LF. The patient was discharged without pain or weakness two weeks postoperatively. This case demonstrated that when the LF of the cervicothoracic junction is thickened, it may be misdiagnosed as a cervical spine tumor compressing the spinal cord.

Diagnosis and treatment of hidden lesions in "mild" cervical spondylotic myelopathy patients with apparent symptoms

Patients with apparent symptoms of cervical spondylotic myelopathy (CSM) may only show a mild compressive lesion in ordinary magnetic resonance imaging (MRI). The aim of this study was to investigate the characteristics of CSM patients with "hidden" lesions on kinetic MRI and to determine an effective treatment.Thirty-one patients with obvious spinal cord compression only on kinetic MRI were included in our study. A variety of parameters were calculated from MRI of the cervical spine at different postures. The anterior cervical decompression and fusion (ACDF) procedure were used for treatment of CSM. To evaluate the effect of surgery, a further 31 age- and gender-matched ordinary CSM patients that received ACDF procedures were enrolled as the control group.The diameter of the cervical cord at the narrowest level in extension was significantly lower than that in the neutral posture (P < .01). The percentage of spinal cord compression was 34.6%. The diameter of the cervical canal at the narrowest level in the extension posture was significantly lower than that in the neutral posture (P < .01). The percentage of cervical canal stenosis was 43.6%. The anteroposterior diameter of the cervical canal in the case group was significantly lower than that in the control group (P < .01). However, the recovery rate of the Japanese Orthopaedic Association score at final follow-up was comparable between the case group and the control group (P = .53).Kinetic MRI is useful for the diagnosis of CSM with hidden lesions. ACDF is an effective procedure for treatment of CSM.

Static and dynamic cervical MRI: two useful exams in cervical myelopathy

BACKGROUND

Cervical magnetic resonance imaging (MRI) is the gold standard exam in the assessment of patients affected by cervical myelopathy and is very useful in planning the operation. Herein we present a series of patients affected by long tract symptoms who underwent dynamic MRI in addition to the static exam.

METHODS

In the period between March 2010 and March 2012, three-hundred-ten patients referred to our department since affected by neck/arm pain or symptoms related to cervical myelopathy. Thirty-eight patients complained "long-tract symptoms" related to cervical myelopathy. This series of patients was enrolled in the study. All patients underwent clinical and neurological exam. In all the cases, a static and dynamic cervical MRI was executed using a 3.0-T superconducting MR unit (Intera, Philips, Eindhoven, Netherlands). The dynamic exam was performed with as much neck flexion and extension the patient could achieve alone. On T2-weigthed MRI each level was assessed independently by two neuroradiologists and Muhle scale was applied.

RESULTS

According to Muhle's classification of spinal cord compressions, static MRI demonstrated 156 findings: 96 (61.54%) anterior and 60 (38.46%) posterior. Dynamic MRI showed 186 spinal cord compressions: 81 (43.5%) anterior and 105 (56.5%) posterior. The anterior compressions were: grade 1 in 23 cases (28.4%), grade 2 in 52 cases (64.2%), grade 3 in 6 cases (7.4%). The posterior compressions were: 32 (30.48%) of grade 1, 60 (57.14%) of grade 2, 13 (12.38%) of grade 3.

CONCLUSIONS

The dynamic MRI demonstrated a major number of findings and spinal cord compressions compared to the static exam. Finally, we consider the dynamic exam able to provide useful information in these patients, but we suggest a careful evaluation of the findings in the extension exam since they are probably over-expressed.

Kinematic relationship between missed ligamentum flavum bulge and degenerative factors in the cervical spine

BACKGROUND CONTEXT

Bulging of ligamentum flavum can happen with the aging process and can lead to compression of the spinal cord and nerves. However, the distribution and the risk factors associated with a missed ligamentum flavum bulge (LFB) are unknown.

PURPOSE

The aim was to evaluate the distribution and risk factors associated with missed LFB in the cervical spine.

STUDY DESIGN

This was a retrospective analysis of kinematic magnetic resonance images (kMRI).

PATIENT SAMPLE

Patients diagnosed with symptomatic neck pain or radiculopathy between March 2011 and October 2012 were included.

OUTCOME MEASURES

The outcome measures were missed LFB and degenerative factors.

METHODS

A total of 200 patients (1,000 cervical segments) underwent upright kMRI in neutral, flexion, and extension postures. The LFB, sagittal cervical angles, disc herniation, disc degeneration, disc height, angular motion, translational motion, age, and gender were recorded. After excluding segments with LFB in neutral and flexion position, Pearson and Spearman correlation coefficients were used to evaluate the relation between the risk factors and missed LFB in the extension position.

RESULTS

The average depth of LFB was 0.24±0.71 mm at C2-C3, 1.02±1.42 mm at C3-C4, 1.65±1.48 mm at C4-C5, 2.13±1.37 mm at C5-C6, and 1.05±1.54 mm at C6-C7. The distribution of LFB was the most frequent at C5-C6 level (76.58%) followed by C4-C5 (63.06%). Disc herniation, disc degeneration, angular variation, and translational motion were significantly correlated with missed LFB at C4-C5 andC5-C6. Disc degeneration was the only factor significantly correlated with missed LFB at all cervical segments.

CONCLUSIONS

Occurrence and depth of missed LFB was the highest at C4-C5 and C5-C6 compared with other cervical levels. Disc degeneration, disc herniation, angular variation, and translational motion could play a role in the development of LFB at C4-C5 andC5-C6.

The Occupancy of the Components in the Cervical Spine and Their Changes with Extension and Flexion

Study Design Retrospective case series. Objectives The kinematics of the cervical spine has been investigated by many researchers. However, the occupancy of the disk bulges, spinal cord, ligamentum flavum, and the rest of the canal as well as the changes of these structures with motion have not yet been investigated. The goal of this study is to investigate these dynamic changes. Methods The kinetic magnetic resonance images of 248 patients (124 men and 124 women) were evaluated, and the occupancy of each structure for each cervical level at neutral, flexion, and extension were calculated. Results Whole canal anteroposterior (AP) diameters showed significant differences between neutral-extension and flexion-extension at the C4-C5 and C5-C6 levels (p < 0.05). The mean disk bulges showed significant differences between neutral-flexion and flexion-extension at the C4-C5, C5-C6, C6-C7, and C7-T1 levels (p < 0.01). The mean spinal canal AP diameter showed significant differences between flexion-extension and neutral-extension at the C3-C4, C4-C5, C5-C6, and C6-C7 levels (p < 0.05). There were significant differences between neutral-flexion at the C4-C5, C5-C6, and C6-C7 levels (p < 0.05). The mean thickness of the ligamentum flavum showed significant differences between flexion-extension at the C3-C4, C4-C5, C5-C6, and C6-C7 levels (p < 0.001). There were significant differences between neutral-extension at the C3-C4 and C5-C6 levels (p < 0.05). There were significant differences between neutral-flexion at the C5-C6 and C6-C7 levels (p < 0.05). The mean thickness of the spinal cord showed significant differences between neutral-flexion at the C2-C3 and C3-C4 levels (p < 0.05). There were significant differences between flexion-extension at the C3-C4 and C4-C5 levels (p < 0.01). The rest of the canal showed significant differences between neutral-extension and flexion-extension at the C3-C4, C4-C5, C5-C6, and C6-C7 levels (p < 0.005). There were significant differences between neutral-flexion at the C5-C6 and C6-C7 levels (p < 0.01). Conclusions The occupancy of each structure in the cervical spine for each level was revealed by this study. In addition, the dynamic changes in the cervical spine with flexion and extension were seen to have different characteristics for each level.

Kinetic magnetic resonance imaging of the cervical spine: a review of the literature

Study Design Literature review. Objective The purpose of this study is to compile and review the body of literature related to kinetic magnetic resonance imaging (kMRI) of the cervical spine. Methods A review of literature related to kMRI was performed using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Results We included 16 prospective and retrospective studies of symptomatic and asymptomatic patients who underwent kMRI of the cervical spine. Conclusions Data suggest that kMRI is able to provide meaningful information regarding changes in the cervical spine in both normal and pathologic segments. A prospective study comparing magnetic resonance imaging and kMRI is needed to confirm clinically utility of this technology.

Risk factors for missed dynamic canal stenosis in the cervical spine

STUDY DESIGN

Retrospective analysis of kinematic magnetic resonance (MR) images.

OBJECTIVE

To elucidate the distribution and risk factors associated with missed dynamic stenosis in cervical spine.

SUMMARY OF BACKGROUND DATA

Motion of the cervical spine is widely accepted to be associated with cervical spondylotic myelopathy; however, the distribution and the risk factors for dynamic spinal stenosis are not well understood.

METHODS

A total of 435 symptomatic patients (2610 cervical segments) obtained upright kinematic MR images in neutral, flexion, and extension postures. Spinal cord compression (SCC), spondylolisthesis, disc bulging, angular motion, translational motion, disc degeneration grade, Modic changes, segmental alignment, and developmental stenosis were all evaluated. Cervical segments C2-C3 to C7-T1 were divided into 2 groups, determined by the presence of SCC. After excluding segments with SCC in the neutral position, a multivariate logistic regression model was used to evaluate for associated risk factors of SCC in flexion and extension that were not present in the neutral position.

RESULTS

SCC in neutral position was observed in 5.3% (139/2610) of segments. After excluding these segments, missed dynamic stenosis was found in 8.3% (204/2471) of segments in extension and 1.6% (40/2471) in flexion. Missed dynamic stenosis in both extension and flexion was most frequent at C5-C6. Multivariate logistic regression analysis for dynamic stenosis in extension revealed that disc bulge greater than 2.4 mm, angular motion greater than 4.8°, moderate and severe disc degeneration, segmental kyphosis, and developmental stenosis were significant risk factors. In flexion, significant risk factors were a disc bulge of 1.9 mm or greater, moderate to severe disc degeneration, and segmental kyphosis.

CONCLUSION

Dynamic cord compression was most common at the C5-C6 segment. Cervical segments with greater disc bulge, more severe disc degeneration, greater angular motion, segmental kyphosis, and developmental stenosis may be at risk for missed dynamic stenosis.