Morphological distinction of cervical nerve roots associated with motor function in 219 healthy volunteers: a multicenter prospective study

Additional benefit of ultrasonography to evaluate nerve root condition of degenerative cervical spine disease

STUDY DESIGN

A cross-sectional explanatory study.

OBJECTIVES

To clarify the nerve root condition and the association between nerve root cross-sectional area (CA) on ultrasonography (US) and other examinations such as MRI or compound muscle action potentials (CMAPs) in degenerative cervical spine diseases.

SETTING

A university hospital in Japan.

METHODS

Fifty-one patients diagnosed with proximal cervical spondylotic amyotrophy (CSA) (13 patients), cervical radiculopathy of C5 or C6 nerve root (CR) (26 patients), or cervical spondylotic myelopathy (CSM) (12 patients), and twenty-nine healthy volunteers were included in this study. Neurological findings, US findings and CMAPs of deltoid and biceps muscles of all participants were evaluated. In addition, CSA, CR, and CSM patients underwent MRI.

RESULTS

A significant correlation was not observed between CA and CMAP amplitude or foraminal diameter on MRI (P > 0.05). In the US examination, the C6 CA of the affected side of the CR group was significantly larger than that of both the normal side and the other groups (P < 0.001). The C5 CA of the affected side of the CSA group clearly showed a bimodal distribution: enlarged and small CA groups. In the CMAP findings, CSA cases respectively showed the lower amplitude of deltoid and bicep CMAPs on both the normal and the affected side (P ≦ 0.01). CSM and healthy volunteers were nearly identical in CA and CMAPs.

CONCLUSION

Utilizing US in addition to NCS and MRI can contribute towards an evaluation of the nerve root condition of degenerative cervical spine disease.

SPONSORSHIP

no sponsorship.

Shear wave elastography evaluation of brachial plexus in multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) is a chronic neuroinflammatory disease characterized by inflammation involving the peripheral nerves. Shear wave elastography (SWE) is potentially a method of choice for detecting peripheral nerve involvement.

PURPOSE

To compare the degree of thickening and nerve elasticity of brachial plexus (BP) nerve roots and evaluate the usefulness of sonoelastography in patients with clinically diagnosed MS without brachial plexopathy.

MATERIAL AND METHODS

Thirty-two patients with MS and 32 controls were included in the study. Bilateral C5, C6, and C7 mean nerve root diameters, and mean elasticity values in kiloPascal (kPa) were measured in the patient and control groups. The relationship between the age, height, and weight values and nerve diameter-elasticity values of the patient and control groups was compared.

RESULTS

The elasticity values of the C5 and C6 nerve roots were increased, and the nerve root thickness was decreased in the MS group compared to that in the control (P < 0.05). There was no difference between the C7 mean nerve root elasticity (kPa) and diameter measurements in the patient and control groups (P > 0.05).

CONCLUSION

Our study showed an increase in the BP nerve root elasticity values (kPa) in patients with MS compared to that of the control group and a decrease in diameter values thought to be related to the possible chronic atrophic process. The results are consistent with the demyelinating process of the peripheral nervous system (PNS) due to MS.

Nerve root morphological and functional changes after degenerative cervical myelopathy surgery: preliminary study using ultrasound and electrophysiology

STUDY DESIGN

A prospective observational study.

OBJECTIVES

To depict morphological and functional changes in the cervical nerve roots before and after spinal cord decompression surgery for degenerative cervical myelopathy (DCM).

SETTING

A general hospital in Japan.

METHODS

Thirteen DCM patients who underwent posterior spinal cord decompression surgery, laminoplasty or laminectomy, were included in this study. The neural foramen shown on MRI and the cross-sectional area (CSA) of the nerve roots on ultrasound were used to evaluate the C5 and C6 nerve roots. The compound muscle action potentials (CMAPs) of deltoid and biceps muscle were also recorded.

RESULTS

All patients showed sensorimotor functional improvement without the postoperative C5 palsy after surgery. Foraminal stenosis and preoperative CSA of the nerve root: C4/5 foramen and C5 nerve root, C5/6 foramen and C6 nerve root, had no significant correlation (P = 0.53 and 0.08). CSA of the C5 nerve root displayed no significant change before and after surgery (P = 0.2), however, that of the C6 nerve root reduced significantly after surgery (P = 0.038). The amplitude of the deltoid and biceps CMAPs displayed no significant change before and after surgery (P = 0.05 and 0.05).

CONCLUSION

The C6 nerve root CSA change was observed after spinal cord decompression surgery with functional recovery. However, deltoid and biceps CMAPs amplitude showed no significant change. Independent CSA changes on ultrasound might be useful when conducting a functional evaluation of the postoperative nerve root.

SPONSORSHIP

The Grant of Japan Orthopaedics and Traumatology Research Foundation No. 395.

Cross-sectional area reference values for peripheral nerve ultrasound in adults: A systematic review and meta-analysis-Part III: Cervical nerve roots and vagal nerve

BACKGROUND AND PURPOSE

Measurement of the cross-sectional area (CSA) of cervical nerve roots using ultrasound is useful in the evaluation of inflammatory polyneuropathies, and measurement of CSA of the vagal nerve might give information about involvement of the autonomic nervous system. We performed a systematic review and meta-analysis of published CSA reference values for cervical nerve roots and vagal nerve.

METHODS

We included available-to-date nerve ultrasound studies on healthy adults and provide meta-analysis for CSA of the following nerves: cervical nerve roots C5, C6, and C7 as well as vagal nerve in the carotid sheath at the carotid bifurcation level. We report regression and correlation analyses for age, gender, height, weight, and geographic continent.

RESULTS

We included 11 studies with 885 healthy volunteers (mean age = 42.7 years) and 3149 examined nerve sites. Calculated mean pooled CSA of C5 root was 5.6 mm² (95% confidence interval [CI] = 4.6-6.7 mm² , n = 911), of C6 root was 8.8 mm² (95% CI = 7.4-10.3 mm² , n = 909), of C7 root was 9.5 mm² (95% CI = 8.0-10.9 mm² , n = 909), and of vagal nerve was 2.2 mm² (95% CI = 1.5-2.9 mm² , n = 420). No heterogeneity was found across studies for any site. Subgroup analysis revealed no significant effects of age, gender, height, weight, and geographic continent on CSA for any of these nerve sites.

CONCLUSIONS

We provide the first meta-analysis on CSA reference values for the cervical nerve roots and the vagal nerve, with no heterogeneity of reported CSA values at all nerve sites. Our data facilitate the goal of an international standardized evaluation protocol.

Morphometric Study of the Cervical Spinal Canal Content and the Vertebral Artery

BACKGROUND

The morphological features of the cervical spinal nerves (C1-C8), their dimensions, and their anatomical relations with the vertebral artery are important for safe spinal surgery. The aim of the present study is to give detailed morphological data of the region to avoid complications.

METHODS

Five formalin-fixed adult cadavers were studied. The cervical spinal nerves and the vertebral artery were exposed via the posterior approach, and detailed anatomy and morphometric measurements were evaluated. The following measurements were documented: angles between the spinal nerve and the spinal cord of C1 to C8, width of the C1 to C8 spinal nerves at their origin, distance of the spinal cord to the vertebral artery, number of dorsal rootlets, length of the dorsal root entry zone of C1 to C8, and distance between respective spinal nerves. Further, the average length and width of the transverse foramen were measured.

RESULTS

The average angle between the spinal cord and the spinal nerve within the vertebral canal ranged between 54 and 87 degrees and were most acute at C5 (54 degrees) compared to the rest of the cervical spinal nerves. The average width of the spinal nerves (mean ± SD), was thickest at C5 (5.7 ± 1.2 mm) and C6 (5.8 ± 0.7 mm). The average largest distance between the vertebral artery and the spinal cord was at C2 (14.3 ± 1.7 mm) and the smallest at C5 (7.3 ± 0.9 mm) and C6 (7.3 ± 2.2 mm) spinal levels. The number of dorsal rootlets was most numerous at C6 (8.25 ± 0.6) and C7 (7.25 ± 0.9). The dorsal root entry zone length was the largest at C5 (13.0 ± 1.6 mm) and C6 (13.75 ± 0.5 mm). The distance between respective spinal nerves was largest between C2 and C3 (11.8 ± 2.2) and C7 and C8 (11.5 ± 0.6).

CONCLUSION

The knowledge of detailed anatomy of the cervical spine (C1-C8) and its relations with the vertebral artery will reduce the unwanted damage to the vital structures of the region.

Ultrasonography of cervical nerve roots: cross-sectional reference values according to age

INTRODUCTION

The aim of this study is to describe the normal cross-sectional area (CSA) and appearance of cervical nerve roots in ultrasound, correlating it to age and other patient somatic parameters.

METHODS

One hundred healthy volunteers were included. We aimed to achieve uniform representation throughout all age groups. Ultrasound of the cervical nerve roots was performed bilaterally. CSA and margins description were obtained.

RESULTS

C5 nerve, 8.32 ± 2.30; C6 nerve, 11.88 ± 3.36; C7 nerve, 12.79 ± 3.85; C8 nerve, 11.20 ± 3.45. Significant correlation between CSA and age was demonstrated, but not for body mass index. Blurred margins were present in up to 23.71% cervical nerves, more frequently in older individuals and in C7 nerve.

DISCUSSION

If ultrasound morphology of cervical nerve roots is used as a diagnostic parameter, the normal range of CSA values and percentage of blurred margins according to age should be considered.

Correlation of neural foraminal motion after surgical treatment of cervical radiculopathy with long-term patient reported outcomes

Background

Post-surgical changes in adjacent segment motion are considered a factor in further development of degeneration and cervical radiculopathy. The objective was to examine the extent of correlations between physiological motion of cervical foramina and long-term patient reported outcomes (PRO).

Methods

Biplane X-ray imaging and CT-based markerless tracking were used to measure 3D static and dynamic dimensions during neck axial rotation and extension from 18 patients treated for C5-6 radiculopathy with fusion or arthroplasty. Minimum foraminal height (FH.Min) and width (FW.Min), and their range (FH.Range and FW.Range) achieved during a motion task were calculated for adjacent levels (C4-5 and C6-7) at 2.0±0.6 years post-surgery. The modified Japanese Orthopedic Association score (mJOAS), the Neck Disability Index (NDI) including the visual analogue scale (VAS) for neck and arm pain, and the EuroQol EQ-5D score were recorded at 6.5±1.1 years post-surgery. The relationships between 6.5-year outcomes and 2-year foraminal motion were examined using regression.

Results

Worsening patient-reported outcomes were generally associated with lower values of FW.Min (P<0.05 to P<0.008), the associations being stronger for neck extension (r² up to 0.43). Dynamic foraminal measurements from the C6-7 level more significantly and consistently correlated with mJOAS, EQ-5D and NDI Arm Pain VAS (r²=0.27 to 0.43; P<0.03 to P<0.008), whereas those from the C4-5 level correlated with NDI Neck Pain VAS (r²=0.33; P<0.02).

Conclusions

Dynamic 3D foraminal dimensions at 2-year post-surgery, notably FW.Min measured in neck extension at adjacent levels, were associated with PRO at 6.5 years post-surgery. These relationships provide insight into the motion related factors in development of pain and loss of function, and may help develop markers or objective outcome measures.

Ultrasonographic data of cervical nerve roots diameter in 100 healthy adults

Clinically significant evaluation of the diameters of nerve roots by ultrasonography requires the establishment of a normal reference range. Although there are multiple reports of nerve root diameters in normal subjects, none of them describe how to normalize and compare data derived from different facilities that may differ in their methodology, equipment, techniques, and recording sites during data acquisition. The aim of the present investigation was to establish a dataset of normal values using 100 healthy subjects, and to identify the factors that affect the normal ranges of cervical nerve root diameters with regard to age, sex, laterality, and root segments. Compared to previous reports, smaller standard deviations (0.07–0.21) were obtained, and the coefficient of variation ranged from 0.02 to 0.08, which facilitated the precise evaluation of cervical nerve roots. Age had a significant effect on the sixth cervical nerve root (C6) in male participants, and sex had a significant effect at C6 in participants in their 60s. To establish the normal values suitable for use across different facilities, acquired using different equipment, further development of various aspects, including the sophisticated recording techniques and data-sharing capabilities, is essential.

Ultrasonography has a diagnostic value in the assessment of cervical radiculopathy: A prospective pilot study

OBJECTIVE

This study investigated the diagnostic accuracy of the difference in the cross-sectional areas (CSAs) of affected cervical nerve roots (NRs) for diagnosing cervical radiculopathy (CR).

METHODS

In total, 102 CR patients and 219 healthy volunteers were examined with ultrasound. The CSA of the cervical NR at each level was measured on the affected side and the contralateral side in CR patients by blinded ultrasonographic technicians. The difference between the CSAs of CR patients and normal volunteers and the difference in the laterality of CSA at the same affected level (ΔCSA) were calculated for each cervical level.

RESULTS

The CSAs of the affected NRs in CR patients were significantly larger than those of the unaffected NRs in CR patients and those of the control group at the C5, C6 and C7 levels (P<0.005). ΔCSA was also significantly larger in the CR group at all levels (P<0.001). A receiver operating characteristic analysis demonstrated that the threshold values were 9.6 mm² (CSA) for C5NR and 15 mm² for both C6NR and C7NR.

CONCLUSIONS

This study revealed that the CSAs of affected NRs were enlarged and that the laterality of the CSA (ΔCSA) was greater in CR patients than in control patients.

KEY POINTS

• Cervical radiculopathy is diagnosed through ultrasonographic measurement of the CSAs. • The CSAs of affected nerve roots were significantly enlarged. • The ΔCSA in the CR group was significantly higher than in the control group. • Diagnostic CSA and ΔCSA thresholds were identified.

Sonographic evaluation of peripheral nerves in subtypes of Guillain-Barré syndrome

BACKGROUND

Sonography of peripheral nerves can depict alteration of nerve sizes that could reflect inflammation and edema in inflammatory and demyelinating neuropathies. Guillain-Barré syndrome (GBS). Information on sonographic comparison of an axonal subtype (acute motor [and sensory] axonal neuropathy [AMAN and AMSAN]) and a demyelinating subtype (acute inflammatory demyelinating polyneuropathy [AIDP]) has been sparse.

MATERIAL AND METHODS

Sonography of peripheral nerves and cervical nerve roots were prospectively recorded in patients with GBS who were within three weeks of disease onset.

RESULTS

Five patients with AIDP and nine with AMAN (n=6)/AMSAN (n=3) were enrolled. The patients with AIDP showed evidence of greater degrees of demyelination (e.g., slower conduction velocities and increased distal latencies) than those with AMAN/AMSAN. The patients with AIDP tended to show enlarged nerves in the proximal segments and in the cervical roots, whereas the patients with AMAN/AMSAN had greater enlargement in the distal neve segment, especially in the median nerve (P = 0.03; Wrist-axilla cross-sectional ratio).

CONCLUSION

In this small study, two subtypes of GBS showed different patterns of involvement that might reflect different pathomechanisms.

Prevalence of C7 level anomalies at the C7 level: an important landmark for cervical nerve ultrasonography

BACKGROUND

Recently, various examination and intervention techniques using cervical nerve ultrasonography have been developed. The specific shapes of the C7 transverse process and vertebral artery in front of the C7 transverse process have become landmarks.

PURPOSE

To determine the prevalence of anomalies and anomalous vertebral artery entrances at the C7 transverse process.

MATERIAL AND METHODS

The records of patients who underwent plain or contrast-enhanced neck or cervical spine computed tomography (CT) were reviewed. The examinations were scored for the anomalous presence of anterior tubercles or cervical ribs as well as vertebral artery entrances in the C7 transverse process. The prevalence of anomalies was compared based on patient sex and age.

RESULTS

Evaluating the examinations from 2067 patients (1046 men; 1021 women), 1% of patients exhibited an anomalous presence of anterior tubercles, and 0.3% of patients displayed cervical ribs at the C7 transverse process. The prevalence of anomalies process was significantly higher in men aged less than 40 years than in older men (P < 0.001), whereas the prevalence was not higher in women aged less than 40 years than in older women. The prevalence of vertebral artery entry into the C7 transverse foramen was 0.6%.

CONCLUSION

Although an anomalous vertebral artery entry into the C7 transverse foramen was rare, the prevalence of an anomaly at the C7 transverse process was higher in men aged less than 40 years. Therefore, we recommend performing CT in younger men before cervical nerve ultrasonographic intervention to avoid misinterpretations at the cervical level.