
==== Front
BMC Musculoskelet Disord
BMC Musculoskelet Disord
BMC Musculoskeletal Disorders
1471-2474
BioMed Central London

7808
10.1186/s12891-024-07808-0
Research
MRI-based assessment paraspinal extensor muscle fatty infiltration in acute cervical spinal cord injury patients - a retrospective study
Liao Yang
Lin Xuping
Su Wanhan
Wu Xiuming
Wang Xiaomen
Yang Wencheng
Lu Haichuan
Huang Chunhui
Wu Yiqi wuyiqi1983@163.com

https://ror.org/030e09f60 grid.412683.a 0000 0004 1758 0400 Department of Spinal Surgery, Longyan First Hospital (Longyan First Affiliated Hospital of Fujian Medical University), Longyan, 364000 China
3 9 2024
3 9 2024
2024
25 7022 7 2024
21 8 2024
© The Author(s) 2024
2024
https://creativecommons.org/licenses/by-nc-nd/4.0/ Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.
Background

The effect of fat infiltration in the paraspinal muscles on cervical degenerative disease has been confirmed by multiple studies. However, little is known about fat infiltration in the paraspinal extensors in patients with acute cervical spinal cord injury (SCI). This study aimed to investigate the difference in paraspinal extensor fatty infiltration between patients with acute cervical SCI and healthy controls, and to further explore the protective role of the paravertebral extensor muscles in patients with cervical SCI.

Methods

A total of 50 patients with acute cervical SCI admitted to the emergency department from January 2019 to November 2023 were retrospectively analyzed, including 26 males and 24 females, with an average age of 59.60 ± 10.81 years. A control group of 50 healthy middle-aged and elderly individuals was also included, comprising 28 males and 22 females, with an average age of 55.00 ± 8.21 years. Cervical spine magnetic resonance imaging (MRI) was used to measure the cross-sectional areas of the superficial and deep cervical extensor muscles, the corresponding vertebral body cross-sectional areas, and the fat area within the superficial and deep extensor muscle groups using Image J software. Differences between the two groups were compared, and the cervical SCI patients were further analyzed based on the severity of the spinal cord injury and gender differences.

Results

The deep fatty infiltration ratio (DFIR) and superficial fatty infiltration ratio (SFIR) at C4-C7 in the cervical SCI group were significantly higher than those in the control group (P < 0.001). The cross-sectional area of the functional deep extensor area (FDEA) relative to the vertebral body area (VBA) and the cross-sectional area of the functional superficial extensor area (FSEA) relative to the VBA at the C5 and C6 levels in the cervical SCI group were significantly lower than those in the control group (P < 0.001, P < 0.001, P = 0.034, P = 0.004 respectively). Among the cervical SCI patients, the cross-sectional areas of the deep extensor area (DEA) and the superficial extensor area (SEA) in males were significantly higher than those in females (P < 0.001). At the C6 and C7 levels, the FDEA/VBA and FSEA/VBA ratios in the male group were higher than those in the female group (P = 0.009, P = 0.022, P = 0.019, P = 0.005, respectively).

Conclusion

Patients with acute cervical SCI exhibit significantly higher fatty infiltration and a greater degree of paravertebral extensor muscle degeneration compared to healthy controls. This finding underscores the importance of the paravertebral extensor muscles in the context of cervical SCI and may guide future therapeutic strategies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-024-07808-0.

Keywords

Cervical
Spine
Magnetic resonance imaging
Spinal cord injuries
Fat infiltration
Cervical extensor
Paraspinal muscle
Cross-sectional
Longyan Science and Technology Project2021LYF17022 2021LYF17022 2021LYF17022 2021LYF17022 2021LYF17022 2021LYF17022 issue-copyright-statement© BioMed Central Ltd., part of Springer Nature 2024
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pmcIntroduction

Spinal cord injury (SCI) is increasingly acknowledged as a critical global health concern, particularly within the context of cervical SCI [1]. These injuries typically result from mechanisms such as flexion, hyperextension, compression, shearing, and rotation, often manifesting clinically through a combination of these mechanisms [2]. It is crucial to monitor SCI trends rigorously and identify high-risk populations to effectively implement targeted preventive policies. Recent literature has extensively documented the correlation between paraspinal muscle and fat infiltration and their influence on cervical spine alignment maintenance [3–5]. These studies have illuminated the stabilizing and protective functions of paraspinal muscles. They provide essential physical support to the spine and are integral to postural biomechanics, proprioception, and fine motor control [6, 7], prompting growing interest among clinicians. Moreover, multiple investigations have underscored the protective significance of neck muscle strength in various accidental injuries, including traffic accidents, falls from height, slips, and high-impact sports collisions [8, 9]. Currently, extensive evidence exists from numerous studies on the atrophic degeneration of paraspinal muscles in chronic SCI patients, yet research focusing on these muscles in acute cervical SCI patients remains limited. With the increasing clinical use of cervical spine magnetic resonance imaging (MRI), our observations reveal heightened levels of paraspinal muscle fat infiltration in acutely admitted cervical SCI patients during their initial comprehensive MRI scans [10, 11]. This study aims to delineate differences between this cohort and the general population and to explore the protective role of paraspinal muscles in cervical SCI patients. Specifically, we hypothesize that individuals with cervical SCI exhibit increased paraspinal muscle fat infiltration compared to healthy counterparts.

Methods

A retrospective review was conducted on medical records and radiological data of patients treated for acute cervical SCI at the Department of Spine Surgery, Longyan First Hospital, from January 2019 to November 2023. The inclusion and exclusion criteria for this study are shown in the table below (Table 1). The study protocol received approval from our hospital’s Health Scie.

Table 1 The inclusion and exclusion criteria

Inclusion	Exclusion	
Patients with cervical SCI caused by trauma, hospitalized within 24 h and completed cervical MRI [12], categorized as ASIA grade D or higher upon admission according to the American Spinal Cord Injury Association (ASIA) impairment scale.	Lack of imaging data

Significant muscle edema observed in the fat-suppressed sequence of cervical spine MRI

Presence of cervical deformity, tumors, or a history of previous cervical spine surgery

	

Assessment of cervical spinal cord injury

In this study, the ASIA classification system was utilized for assessment. ASIA grade A indicates complete injury, characterized by the absence of both motor and sensory functions in the S4-S5 sacral segments. Grade B represents incomplete injury, where there is preservation of some sensory function below the level of injury but complete motor loss. Grade C denotes incomplete injury, with preserved motor function below the injury level, yet more than half of the key muscles have a strength less than grade 3. Grade D signifies incomplete injury, where more than half of the key muscles below the injury level have a strength grade of 3 or higher. Grade E indicates normal motor and sensory functions. Previous studies have suggested a more favorable prognosis for patients classified as ASIA grade D [13]. Therefore, patients classified as grades A, B, or C were grouped as having severe symptomatology, while those classified as grade D were categorized as having mild symptomatology by the authors. In the supplementary material, we have provided three representative images for each ASIA grade (Fig. S1).

Imaging procedures of MRI

In this study, transverse T2-weighted magnetic resonance images were obtained at the level of the vertebral endplates spanning C4-C7 using the Picture Archiving and Communication System (PACS) imaging system for both patient groups. Position with a 3.0TMRI machine (Achieva 3.0 T; Philips Company). There were 12 transaxial slices in each MRI, 3 slices per level, slice thickness 2.5 mm, and spacing 0.25 mm. The sequence of the T2-weighted axial images was 20 × 20 cm field of view, 324 × 252 matrix, 3000 ms repetition time, 110 ms echo time, with 2 excitations.

Cervical muscle measurements

Images were analyzed at the vertebral endplates of C4-C7. Due to the proximity of the C3 vertebra to the attachment points of the deep cervical extensor muscles and suboccipital muscles, measurement errors in muscle cross-sectional area were considered significant and were therefore excluded from the study. The cervical paraspinal muscles were anatomically classified into the deep and superficial layers of the cervical extensor muscle group. The deep layer includes the multifidus, semispinalis cervicis, and levator scapulae muscles, while the superficial layer comprises the splenius capitis, semispinalis capitis, and spinalis cervicis muscles. Measurements in this study were conducted using ImageJ software (National Institutes of Health, Bethesda, MD). These measurements encompassed the cross-sectional area of the deep extensor (DEA), superficial extensor (SEA), and corresponding vertebral body (VBA). The pseudocolor tool in ImageJ was utilized to identify adipose tissue regions, highlighted in red, enabling computation of the fatty area (FA) within the deep and superficial extensor muscle groups. Subtracting the adipose tissue area from the total muscle area yielded the functional deep extensor area (FDEA) and functional superficial extensor area (FSEA), as illustrated in Fig. 1. The ratios of FA to DEA or FA to SEA were calculated to determine the deep fatty infiltration ratio (DFIR) and superficial fatty infiltration ratio (SFIR) of the cervical extensor muscles, respectively. Following previous research [14–17], the ratios of FDEA to VBA and FSEA to VBA were utilized to standardize muscle area measurements [13], thereby mitigating the influence of variations in patient body size on measurement outcomes. The imaging measurements were independently taken by two experienced spine surgeons as observers, blinded to any patient information and each other’s measurements. Intra-observer and inter-observer reliability were assessed using intra-class correlation coefficients (ICC). The inter-observer agreement ICC was 0.829 [95% CI 0.732–0.889], and the intra-observer ICC were 0.826 [95% CI 0.752–0.879] and 0.838 [95% CI 0.764–0.896].

Fig. 1 Schematic representation of measurements conducted using Image J. Notes: This is a schematic representation of MRI cross-sections of the C4-5 level in SCI and normal patients. (A) The T2-weighted axial MRI images of patients with cervical spinal cord injury were processed using Image J software to apply pseudocolor mapping (ASIA grade D). (B) In the MRI images of patients with cervical spinal cord injury, the vertebral body, deep paraspinal extensors, and superficial paraspinal extensors have been outlined with yellow lines for clear identification. (ASIA grade D). (C) The area of adipose tissue within the demarcated paraspinal muscle regions was calculated using Image J software and is identified with yellow coloration (ASIA grade D). (D) The T2-weighted axial MRI images of normal control group were processed using Image J software to apply pseudocolor mapping (ASIA grade E). (E) Original transverse section of the cervical spine in the normal control group (ASIA grade E). (F) Corresponding paraspinal muscle fat area (highlighted in yellow) in the normal control group (ASIA grade E). ASIA American Spinal Cord Injury Association, DEA indicates cross-sectional area of deep extensors; SEA, cross-sectional area of superficial extensors; VBA, cross-sectional area of the vertebral body

Statistical analysis

Statistical analysis of the acquired data was conducted using SPSS 27.0 software. Data distribution was assessed for normality or approximate normality, and results were expressed as mean ± standard deviation (x̅ ± s). Independent sample t-tests were employed to compare the VBA, DEA, SEA, DFIR, SFIR, FDEA/VBA, FSEA/VBA between the two patient groups. Chi-square tests were utilized to compare gender distribution between the two groups of patients. Statistical significance was set at P < 0.05.

Results

Clinical characteristics of participants

A total of 50 patients with cervical SCI, meeting both the inclusion and exclusion criteria, were enrolled in the SCI group. This group included 26 males and 24 females, with an average age of (59.60 ± 10.81) years. Simultaneously, 50 age-matched individuals from the general population, undergoing routine physical examinations and meeting the inclusion criteria for the normal group, were recruited. The normal group consisted of 28 males and 22 females, with an average age of (55.00 ± 8.21) years. The general characteristics of the two groups are summarized in Table 2. There were no statistically significant differences between the groups in terms of gender, age, or C4-7 VBA.

Comparison of paravertebral extensor area and fat infiltration between the two groups

There were no statistically significant differences between the two groups in terms of the DEA and SEA at the C4-C7 levels. However, in the SCI group, both DFIR and SFIR at the C4-C7 levels were significantly higher compared to the normal group, with statistically significant differences (P < 0.001). Additionally, at the C5 and C6 levels, the FDEA/VBA and FSEA/VBA in the SCI group were lower than those in the normal group (FDEA/VBA C5; P < 0.001, FDEA/VBA C6; P < 0.001, FSEA/VBA C5; P = 0.034; SEA/VBA C6; P = 0.004). However, there were no statistically significant differences in FDEA/VBA and FSEA/VBA between the two groups at the C4 and C7 levels (Table 3).

Comparison of paravertebral extensor area and fatty infiltration in patients with mild and severe symptoms of cervical SCI

In patients with cervical SCI, symptom severity was categorized into mild and severe groups, and comparisons were made between paraspinal muscle and fat infiltration levels. The results indicated no statistically significant differences in DEA, SEA, DFIR, SFIR, FDEA/VBA, and FSEA/VBA between the two groups of patients (Table 4).

Comparison of paravertebral extensor area and fatty infiltration between genders in patients with cervical SCI

In SCI group, males exhibited significantly higher levels of DEA and SEA compared to females, with statistically significant differences (P < 0.001). However, there were no statistically significant differences between males and females in terms of DFIR and SFIR. At the C6 and C7 levels, the FDEA/VBA and FSEA/VBA in the male group were higher than those in the female group, with statistically significant differences (FDEA/VBA C6; P = 0.009, FDEA/VBA C7; P = 0.022, FSEA/VBA C6; P = 0.019, FSEA/VBA C7; P = 0.005). Conversely, at the C4 and C5 levels, there were no statistically significant differences between male and female patients (Table 5).

Table 2 Baseline patient characteristics

	SCI group(n = 50)	Normal group (n = 50)	χ2/t	P Value	
Sex, n(Male/Female)	(26/24)	(28/22)	0.641	0.423	
Age, y	59.60 ± 10.81	55.00 ± 8.21	1.453	0.154	
ASIA grade					
A	6				
B	8				
C	6				
D	30				
E		50			
VBA					
C4	3.90 ± 0.86	3.61 ± 0.79	1.098	0.279	
C5	4.14 ± 1.06	3.81 ± 0.88	1.043	0.303	
C6	4.31 ± 0.97	4.09 ± 0.70	0.795	0.431	
C7	4.66 ± 1.32	4.57 ± 0.98	0.241	0.811	
Values are, n (%) or mean ± SD. Abbreviations: SCI, spinal cord injury; ASIA, American Spinal Injury Association; VBA, vertebral body areas

Table 3 Comparison of paravertebral extensor area and fatty infiltration between the two groups

	SCI group(n = 50)	Normal group (n = 50)	χ2/t	P Value	
DEA (cm2)					
C4	5.52 ± 1.38	4.65 ± 1.31	2.013	0.051	
C5	6.74 ± 1.61	6.50 ± 1.23	0.509	0.613	
C6	7.34 ± 1.95	7.70 ± 1.35	-0.635	0.529	
C7	8.05 ± 2.21	7.69 ± 1.80	0.549	0.586	
FDEA/VBA					
C4	1.02 ± 0.34	1.21 ± 0.25	-1.897	0.065	
C5	1.29 ± 0.32	1.67 ± 0.32	-3.776	< 0.001*	
C6	1.31 ± 0.37	1.82 ± 0.36	-4.297	< 0.001*	
C7	1.33 ± 0.52	1.63 ± 0.40	-1.91	0.063	
DFIR (%)					
C4	30.04 ± 13.06	6.25 ± 3.87	7.064	< 0.001*	
C5	23.30 ± 8.31	4.36 ± 3.08	8.704	< 0.001*	
C6	43.06 ± 19.15	9.66 ± 6.75	6.691	< 0.001*	
C7	26.34 ± 12.90	5.47 ± 4.06	6.251	< 0.001*	
SEA (cm2)					
C4	14.56 ± 5.44	13.60 ± 4.18	0.596	0.554	
C5	11.84 ± 3.80	12.64 ± 3.96	-0.651	0.519	
C6	9.58 ± 3.06	11.14 ± 2.71	-1.656	0.106	
C7	8.38 ± 3.02	9.82 ± 3.00	-1.487	0.145	
FSEA/VBA					
C4	3.41 ± 1.05	3.65 ± 1.02	-0.726	0.472	
C5	2.69 ± 0.83	3.29 ± 0.88	-2.201	0.034*	
C6	2.10 ± 0.59	2.68 ± 0.60	-3.067	0.004*	
C7	1.74 ± 0.69	2.11 ± 0.13	-1.819	0.077	
SFIR (%)					
C4	8.90 ± 4.75	2.97 ± 1.70	4.78	< 0.001*	
C5	8.15 ± 3.82	1.59 ± 1.51	6.537	< 0.001*	
C6	6.47 ± 3.76	1.89 ± 1.50	4.622	< 0.001*	
C7	6.15 ± 4.93	1.88 ± 1.48	3.352	0.002*	
Values are, n (%) or mean ± SD.

Abbreviations: SCI, spinal cord injury; DEA, cross-sectional area of deep extensor area; FDEA, cross-sectional area of functional deep extensor area; SEA, cross-sectional area of superficial extensor; SFIR, superficial fatty infiltration ratio; DFIR, deep fatty infiltration ratio; FSEA, cross-sectional area of functional superficial extensor; VBA, cross-sectional area of vertebral body.

Table 4 Comparison of paravertebral extensor area and fatty infiltration in patients with mild and severe symptoms of cervical SCI

	Mild symptoms(n = 30)	Severe symptoms(n = 20)	χ2/t	P Value	
DEA (cm2)					
C4	5.48 ± 1.55	5.58 ± 1.16	0.164	0.622	
C5	6.61 ± 1.64	6.94 ± 1.61	0.498	0.623	
C6	7.38 ± 1.75	7.30 ± 2.32	0.100	0.921	
C7	8.11 ± 2.16	7.96 ± 2.39	0.171	0.866	
FDEA/VBA					
C4	1.01 ± 0.30	1.04 ± 0.40	0.213	0.833	
C5	1.29 ± 0.35	1.28 ± 0.29	0.057	0.955	
C6	1.26 ± 0.32	1.39 ± 0.45	0.861	0.398	
C7	1.23 ± 0.35	1.49 ± 0.70	1.276	0.215	
DFIR (%)					
C4	31.10 ± 11.66	28.45 ± 15.45	0.490	0.629	
C5	24.20 ± 8.37	21.94 ± 8.47	0.659	0.517	
C6	46.41 ± 19.42	38.05 ± 18.56	1.073	0.294	
C7	29.13 ± 13.97	22.15 ± 10.37	1.349	0.190	
SEA (cm2)					
C4	13.94 ± 6.19	15.48 ± 4.22	0.686	0.500	
C5	11.22 ± 4.09	12.77 ± 3.29	0.998	0.329	
C6	9.40 ± 3.50	9.85 ± 2.42	0.356	0.725	
C7	8.44 ± 3.49	8.29 ± 2.32	0.115	0.909	
FSEA/VBA					
C4	3.22 ± 0.92	3.70 ± 1.21	1.117	0.276	
C5	2.56 ± 0.71	2.88 ± 0.98	0.951	0.352	
C6	1.98 ± 0.57	2.27 ± 0.60	1.229	0.232	
C7	1.63 ± 0.51	1.91 ± 0.89	0.975	0.340	
SFIR (%)					
C4	9.95 ± 5.24	7.32 ± 3.57	1.381	0.180	
C5	8.84 ± 3.94	7.12 ± 3.57	1.115	0.276	
C6	7.60 ± 3.69	4.78 ± 3.36	1.940	0.065	
C7	7.27 ± 4.88	4.47 ± 4.73	1.420	0.169	
Values are, n (%) or mean ± SD

Abbreviations: SCI, spinal cord injury; DEA, cross-sectional area of deep extensor area; FDEA, cross-sectional area of functional deep extensor area; SEA, cross-sectional area of superficial extensor; SFIR, superficial fatty infiltration ratio; DFIR, deep fatty infiltration ratio; FSEA, cross-sectional area of functional superficial extensor; VBA, cross-sectional area of vertebral body

Table 5 Comparison of paravertebral extensor area and fatty infiltration between genders in patients with cervical SCI

	Male(n = 26)	Female(n = 24)	t	P	
DEA (cm2)					
C4	6.36 ± 1.17	4.61 ± 0.97	4.052	< 0.001*	
C5	7.70 ± 1.62	5.71 ± 0.72	3.883	< 0.001*	
C6	8.61 ± 1.71	5.97 ± 1.07	4.598	< 0.001*	
C7	9.55 ± 1.93	6.43 ± 1.02	4.969	< 0.001*	
FDEA/VBA					
C4	1.10 ± 0.37	0.94 ± 0.29	1.188	0.247	
C5	1.29 ± 0.30	1.29 ± 0.35	0.016	0.987	
C6	1.49 ± 0.41	1.12 ± 0.20	2.832	0.009*	
C7	1.56 ± 0.57	1.09 ± 0.34	2.452	0.022*	
DFIR (%)					
C4	29.21 ± 15.14	30.94 ± 10.96	-0.324	0.749	
C5	23.51 ± 8.62	23.06 ± 8.34	0.132	0.896	
C6	46.61 ± 18.68	39.22 ± 19.71	0.963	0.345	
C7	24.63 ± 9.02	28.19 ± 16.34	-0.683	0.501	
SEA (cm2)					
C4	18.20 ± 4.88	10.62 ± 2.46	4.843	< 0.001*	
C5	14.48 ± 3.04	8.97 ± 2.05	5.263	< 0.001*	
C6	11.41 ± 2.92	7.60 ± 1.71	3.943	< 0.001*	
C7	10.41 ± 2.72	6.18 ± 1.31	4.899	< 0.001*	
FSEA/VBA					
C4	3.95 ± 0.99	2.83 ± 0.80	0.016	0.987	
C5	2.95 ± 0.84	2.41 ± 0.74	1.715	0.100	
C6	2.36 ± 0.56	1.82 ± 0.50	2.53	0.019*	
C7	2.09 ± 0.75	1.36 ± 0.32	3.103	0.005*	
SFIR (%)					
C4	8.51 ± 4.63	9.33 ± 8.34	0.132	0.896	
C5	7.97 ± 4.61	8.35 ± 2.91	-0.238	0.814	
C6	6.46 ± 3.70	6.48 ± 3.99	-0.013	0.990	
C7	5.73 ± 4.58	6.60 ± 5.45	-0.429	0.672	
Values are, n (%) or mean ± SD

Abbreviations: SCI, spinal cord injury; DEA, cross-sectional area of deep extensor area; FDEA, cross-sectional area of functional deep extensor area; SEA, cross-sectional area of superficial extensor; SFIR, superficial fatty infiltration ratio; DFIR, deep fatty infiltration ratio; FSEA, cross-sectional area of functional superficial extensor; VBA, cross-sectional area of vertebral body

Discussion

This study reveals that patients in the cervical spinal cord injury group exhibit higher levels of fat infiltration compared to individuals without injuries, and the FDEA/VBA and FSEA/VBA at the C5 and C6 levels are lower in the control group. Patients with cervical spinal cord injury demonstrate diminished cervical spine stability and muscle protection relative to healthy individuals, rendering them more vulnerable to spinal cord involvement from external forces. The magnitude and mechanism of direct external forces are primary factors contributing to this susceptibility. Existing research consistently demonstrates the protective role of neck muscles in mitigating traumatic neck injuries [18]. Recent focus has shifted towards the role of cervical paraspinal muscles in maintaining spinal stability and function. The cervical paraspinal muscles are pivotal in supporting both static and dynamic functions of the cervical spine, crucial for postural stability, movement control, and load-bearing capacity [19, 20]. Changes in the composition and quality of these muscles have been linked to an increased risk of degenerative cervical spine conditions such as cervical spondylosis and intervertebral disc degeneration. Despite the expanding literature in this domain, few studies have directly compared cervical paraspinal muscle characteristics between patients with acute cervical SCI and healthy individuals. This study highlights significant degenerative changes observed in the cervical paraspinal muscles of acute cervical SCI patients compared to normal controls, emphasizing potential implications for spinal stability and functional outcomes. Further exploration of the mechanisms underlying these muscle alterations and their correlation with clinical outcomes is essential to guide targeted rehabilitation strategies and improve the management of cervical SCI.

Previous studies have indicated that patients with chronic spinal cord injuries often exhibit an increased fat infiltration ratio (FIR) in paravertebral muscles [21–23]. However, this study focuses on FIR during acute injury. Patients demonstrated higher FIR, extensor muscle degeneration, and decreased muscle mass compared to the normal population prior to injury. Liang et al. [24]. demonstrated that the C4-C6 region is a focal point of stress on the cervical spine. In this study, the FDEA/VBA and FSEA/VBA at the C5 and C6 levels were lower in the cervical spinal cord injury group compared to the control group, indicating weaker muscle protection and higher stress on the muscles at these levels during trauma. This finding aligns with epidemiological data showing high-risk zones for intervertebral disc injury in whiplash cases. Clinically, pathological conditions such as cervical disc protrusion and spinal canal stenosis are observed in some patients with cervical spinal cord injuries, potentially increasing their vulnerability to spinal cord damage. Further investigation is needed to explore the relationship between cervical paraspinal muscle degeneration and these pathological conditions.

Patients with cervical spinal cord injuries were classified into severity groups based on the ASIA classification, with no statistically significant differences observed between the groups. This could be attributed to the grouping method, suggesting the need for validation with larger sample sizes in future studies. Additionally, this study assessed gender differences in paravertebral extensor muscles and FIR among patients with cervical spinal cord injuries. While no significant differences in FIR were found between men and women, notable disparities were observed in DEA and SEA between the genders. Specifically, at the C6 and C7 levels, the FDEA/VBA and FSEA/VBA were higher in males compared to females, indicating greater development of paravertebral muscles in males, consistent with findings by Li et al. [11]. However, Egon et al. [25]. reported in their study on gender differences in FIR in the general population that male FIR was significantly lower than that of females. Therefore, the debate over gender differences in FIR among patients with acute cervical spinal cord injuries remains unresolved.

This study has several limitations. It is a single-center retrospective study with a relatively small sample size, highlighting the need for larger sample sizes and multicenter prospective studies to enhance reliability. Given that many patients with cervical spinal cord injuries also present with conditions like cervical disc herniation and spinal canal stenosis, further analysis to elucidate these correlations is warranted. The cervical spine, being the most intricate segment of the spine concerning movement, possesses a complex structure and composition of surrounding muscle groups. This study specifically focuses on the posterior paravertebral extensor muscles, which introduces certain constraints in its scope.

Conclusions

In summary, this study highlights that patients with acute cervical spinal cord injuries demonstrate elevated levels of fat infiltration and more extensive degeneration of paravertebral extensor muscles compared to the general population. Clinicians should closely monitor patients who exhibit concurrent fat infiltration in these muscles, especially those at risk of spinal cord injury. Proactive measures are essential to manage disease progression effectively. Strengthening exercises targeting neck muscles could be advised based on muscle and fat infiltration assessments, aiming to mitigate paravertebral extensor muscle degeneration and reduce the likelihood of cervical spinal cord injury.

Electronic supplementary material

Below is the link to the electronic supplementary material.

Supplementary Material 1

Acknowledgements

Not applicable.

Author contributions

The authors’ responsibilities were as follows—Research idea and study design: Yang Liao, Xuping Lin; Data acquisition: Yiqi Wu, Yang liao and Wanhan Su; Data analysis/interpretation: Xuping Lin, Wencheng Yang and Xiuming Wu; Statistical analysis: Xiaomen Wang, Haichuan Lu; Supervision and mentorship: Chunhui Huang; Writing guidance: Xiuming Wu, Yang Liao. Each author contributed important intellectual content during manuscript drafting or revision and accepts accountability for the overall work by ensuring that questions on the accuracy or integrity of any portion of the work are appropriately investigated and resolved. The authors declare that there is no competing interest. All authors read and approved the final version.

Funding

Longyan Science and Technology Project (2021LYF17022). The funders had no role in the study design, data collection, and analysis, decision to publish, or preparation of the manuscript; the work was not funded by any industry sponsors.

Data availability

The datasets generated and analyzed during the current study are not publicly available due to the institution policy but are available from the corresponding author upon reasonable request.

Declarations

Ethics approval and consent to participate

This study was approved by the ethics committee of Longyan First Hospital (Longyan First Affiliated Hospital of Fujian Medical University) and followed the Declaration of Helsinki. Informed consent was obtained from all patients.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.

Abbreviations

SCI spinal cord injury

MRI magnetic resonance imaging

ASIA American Spinal Cord Injury Association

PACS Picture Archiving and Communication System

DEA deep extensor area

VBA vertebral body

FA fatty area

FDEA deep extensor area

FSEA superficial extensor area

DFIR deep fatty infiltration ratio

SFIR superficial fatty infiltration ratio

FIR fat infiltration ratio

Publisher’s note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Yang Liao and Xuping Lin have contributed equally to this work and share the first authorship.
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References

1. Badhiwala JH Wilson JR Fehlings MG Global burden of traumatic brain and spinal cord injury Lancet Neurol 2019 18 24 5 10.1016/S1474-4422(18)30444-7 30497967
Badhiwala JH, Wilson JR, Fehlings MG. Global burden of traumatic brain and spinal cord injury. Lancet Neurol. 2019;18:24–5.30497967 10.1016/S1474-4422(18)30444-7
2. Dowdell J Kim J Overley S Hecht A Biomechanics and common mechanisms of injury of the cervical spine Handb Clin Neurol 2018 158 337 44 10.1016/B978-0-444-63954-7.00031-8 30482361
Dowdell J, Kim J, Overley S, Hecht A. Biomechanics and common mechanisms of injury of the cervical spine. Handb Clin Neurol. 2018;158:337–44.30482361 10.1016/B978-0-444-63954-7.00031-8
3. Yang P The Effect of Cervical Paravertebral Extensor Degeneration on Sagittal Alignment and functional status of cervical spine in patients with cervical spondylotic myelopathy Clin Spine Surg 2021 34 E382 9 10.1097/BSD.0000000000001149 34397532
Yang P, et al. The Effect of Cervical Paravertebral Extensor Degeneration on Sagittal Alignment and functional status of cervical spine in patients with cervical spondylotic myelopathy. Clin Spine Surg. 2021;34:E382–9.34397532 10.1097/BSD.0000000000001149
4. Niu Y Predictive effect of cervical sagittal parameters and corresponding segmental paravertebral muscle degeneration on the occurrence of cervical kyphosis following cervical laminoplasty World Neurosurg 2023 175 e723 9 10.1016/j.wneu.2023.04.011 37031734
Niu Y, et al. Predictive effect of cervical sagittal parameters and corresponding segmental paravertebral muscle degeneration on the occurrence of cervical kyphosis following cervical laminoplasty. World Neurosurg. 2023;175:e723–9.37031734 10.1016/j.wneu.2023.04.011
5. Gu Y Association between the cervical Extensor musculature and the Demographic Features, symptoms, and Sagittal Balance in patients with Multilevel Cervical Spondylotic Myelopathy World Neurosurg 2023 169 e40 50 10.1016/j.wneu.2022.10.014 36216245
Gu Y, et al. Association between the cervical Extensor musculature and the Demographic Features, symptoms, and Sagittal Balance in patients with Multilevel Cervical Spondylotic Myelopathy. World Neurosurg. 2023;169:e40–50.36216245 10.1016/j.wneu.2022.10.014
6. Peng B Yang L Li Y Liu T Liu Y Cervical proprioception impairment in Neck Pain-Pathophysiology, clinical evaluation, and management: a narrative review Pain Ther 2021 10 143 64 10.1007/s40122-020-00230-z 33464539
Peng B, Yang L, Li Y, Liu T, Liu Y. Cervical proprioception impairment in Neck Pain-Pathophysiology, clinical evaluation, and management: a narrative review. Pain Ther. 2021;10:143–64.33464539 10.1007/s40122-020-00230-z
7. Fortner MO Woodham TJ Oakley PA Harrison DE Is the cervical lordosis a key biomechanical biomarker in cervicogenic headache? A Chiropractic Biophysics® case report with follow-up J Phys Ther Sci 2022 34 167 71 10.1589/jpts.34.167 35221522
Fortner MO, Woodham TJ, Oakley PA, Harrison DE. Is the cervical lordosis a key biomechanical biomarker in cervicogenic headache? A Chiropractic Biophysics® case report with follow-up. J Phys Ther Sci. 2022;34:167–71.35221522 10.1589/jpts.34.167
8. Gao Z Study of cervical muscle response and injury of driver during a frontal vehicle collision Biomed Mater Eng 2015 26 Suppl 1 S619 27 26406056
Gao Z, et al. Study of cervical muscle response and injury of driver during a frontal vehicle collision. Biomed Mater Eng. 2015;26(Suppl 1):S619–27.26406056
9. Wang D Inconsistent anticipatory postural adjustments (APAs) in rugby players: a source of injuries? BMJ Open Sport Exerc Med 2018 4 e000303 10.1136/bmjsem-2017-000303 29955372
Wang D, et al. Inconsistent anticipatory postural adjustments (APAs) in rugby players: a source of injuries? BMJ Open Sport Exerc Med. 2018;4:e000303.29955372 10.1136/bmjsem-2017-000303
10. Mitsutake T Greater Cervical muscle Fat Infiltration evaluated by Magnetic Resonance Imaging is Associated with Poor Postural Stability in patients with cervical spondylotic Radiculopathy Spine (Phila Pa 1976) 2016 41 E8 14 10.1097/BRS.0000000000001196 26571156
Mitsutake T, et al. Greater Cervical muscle Fat Infiltration evaluated by Magnetic Resonance Imaging is Associated with Poor Postural Stability in patients with cervical spondylotic Radiculopathy. Spine (Phila Pa 1976). 2016;41:E8–14.26571156 10.1097/BRS.0000000000001196
11. Li Z Fatty infiltration of the cervical multifidus musculature and its clinical correlation to cervical spondylosis BMC Musculoskelet Disord 2023 24 613 10.1186/s12891-023-06595-4 37501110
Li Z, et al. Fatty infiltration of the cervical multifidus musculature and its clinical correlation to cervical spondylosis. BMC Musculoskelet Disord. 2023;24:613.37501110 10.1186/s12891-023-06595-4
12. Hachem LD Ahuja CS Fehlings MG Assessment and management of acute spinal cord injury: from point of injury to rehabilitation J Spinal Cord Med 2017 40 665 75 10.1080/10790268.2017.1329076 28571527
Hachem LD, Ahuja CS, Fehlings MG. Assessment and management of acute spinal cord injury: from point of injury to rehabilitation. J Spinal Cord Med. 2017;40:665–75.28571527 10.1080/10790268.2017.1329076
13. Mputu PM Beauséjour M Richard-Denis A Dionne A Mac-Thiong J-M Does improvement in American Spinal Injury Association Impairment Scale Grade Correlate with Functional Recovery in all patients with a traumatic spinal cord Injury? Am J Phys Med Rehabil 2024 103 117 23 37408130
Mputu PM, Beauséjour M, Richard-Denis A, Dionne A, Mac-Thiong J-M. Does improvement in American Spinal Injury Association Impairment Scale Grade Correlate with Functional Recovery in all patients with a traumatic spinal cord Injury? Am J Phys Med Rehabil. 2024;103:117–23.37408130
14. Suo M The association between morphological characteristics of paraspinal muscle and spinal disorders Ann Med 2023 55 2258922 10.1080/07853890.2023.2258922 37722876
Suo M, et al. The association between morphological characteristics of paraspinal muscle and spinal disorders. Ann Med. 2023;55:2258922.37722876 10.1080/07853890.2023.2258922
15. Liu S Inter-software and inter-threshold reliability of quantitative paraspinal muscle segmentation Eur Spine J 2024 33 369 78 10.1007/s00586-023-08050-3 38055039
Liu S, et al. Inter-software and inter-threshold reliability of quantitative paraspinal muscle segmentation. Eur Spine J. 2024;33:369–78.38055039 10.1007/s00586-023-08050-3
16. Wang Z-L Effects of Cervical Paravertebral extensors in patients with cervical ossification of the posterior longitudinal ligament grouped according to mK-Line Orthop Surg 2024 16 346 56 10.1111/os.13964 38097192
Wang Z-L, et al. Effects of Cervical Paravertebral extensors in patients with cervical ossification of the posterior longitudinal ligament grouped according to mK-Line. Orthop Surg. 2024;16:346–56.38097192 10.1111/os.13964
17. Naghdi N Elliott JM Weber MH Fehlings MG Fortin M Cervical muscle morphometry and composition demonstrate prognostic value in degenerative cervical myelopathy outcomes Front Neurol 2023 14 1209475 10.3389/fneur.2023.1209475 37745653
Naghdi N, Elliott JM, Weber MH, Fehlings MG, Fortin M. Cervical muscle morphometry and composition demonstrate prognostic value in degenerative cervical myelopathy outcomes. Front Neurol. 2023;14:1209475.37745653 10.3389/fneur.2023.1209475
18. Kuo C Estimating trunk and Neck stabilization for avoiding Head Impact during Real-World Falls in older adults Annu Int Conf IEEE Eng Med Biol Soc 2020 2020 4823 6 33019070
Kuo C, et al. Estimating trunk and Neck stabilization for avoiding Head Impact during Real-World Falls in older adults. Annu Int Conf IEEE Eng Med Biol Soc. 2020;2020:4823–6.33019070
19. Pinter ZW Paraspinal Sarcopenia is Associated with worse patient-reported outcomes following Laminoplasty for degenerative cervical myelopathy Spine (Phila Pa 1976) 2023 48 772 81 36972148
Pinter ZW, et al. Paraspinal Sarcopenia is Associated with worse patient-reported outcomes following Laminoplasty for degenerative cervical myelopathy. Spine (Phila Pa 1976). 2023;48:772–81.36972148
20. Hou X Lu S Wang B Kong C Hu H Morphologic characteristics of the deep cervical paraspinal muscles in patients with single-level cervical spondylotic myelopathy World Neurosurg 2020 134 e166 71 10.1016/j.wneu.2019.09.162 31605863
Hou X, Lu S, Wang B, Kong C, Hu H. Morphologic characteristics of the deep cervical paraspinal muscles in patients with single-level cervical spondylotic myelopathy. World Neurosurg. 2020;134:e166–71.31605863 10.1016/j.wneu.2019.09.162
21. Abbott R The geography of fatty infiltrates within the cervical multifidus and semispinalis cervicis in individuals with chronic whiplash-associated disorders J Orthop Sports Phys Ther 2015 45 281 8 10.2519/jospt.2015.5719 25739843
Abbott R, et al. The geography of fatty infiltrates within the cervical multifidus and semispinalis cervicis in individuals with chronic whiplash-associated disorders. J Orthop Sports Phys Ther. 2015;45:281–8.25739843 10.2519/jospt.2015.5719
22. Weber KA Deep learning convolutional neural networks for the Automatic quantification of muscle Fat Infiltration following Whiplash Injury Sci Rep 2019 9 7973 10.1038/s41598-019-44416-8 31138878
Weber KA, et al. Deep learning convolutional neural networks for the Automatic quantification of muscle Fat Infiltration following Whiplash Injury. Sci Rep. 2019;9:7973.31138878 10.1038/s41598-019-44416-8
23. Karlsson A An investigation of Fat Infiltration of the Multifidus muscle in patients with severe Neck symptoms Associated with Chronic Whiplash-Associated disorder J Orthop Sports Phys Ther 2016 46 886 93 10.2519/jospt.2016.6553 27590177
Karlsson A, et al. An investigation of Fat Infiltration of the Multifidus muscle in patients with severe Neck symptoms Associated with Chronic Whiplash-Associated disorder. J Orthop Sports Phys Ther. 2016;46:886–93.27590177 10.2519/jospt.2016.6553
24. Liang Z Quantitative cervical spine injury responses in whiplash loading with a numerical method of natural neural reflex consideration Comput Methods Programs Biomed 2022 219 106761 10.1016/j.cmpb.2022.106761 35344767
Liang Z, et al. Quantitative cervical spine injury responses in whiplash loading with a numerical method of natural neural reflex consideration. Comput Methods Programs Biomed. 2022;219:106761.35344767 10.1016/j.cmpb.2022.106761
25. Burian E Age- and gender-related variations of cervical muscle composition using chemical shift encoding-based water-fat MRI Eur J Radiol 2020 125 108904 10.1016/j.ejrad.2020.108904 32088656
Burian E, et al. Age- and gender-related variations of cervical muscle composition using chemical shift encoding-based water-fat MRI. Eur J Radiol. 2020;125:108904.32088656 10.1016/j.ejrad.2020.108904
