Abstract
Objective
This descriptive cross-sectional observational study aimed to investigate the prevalence of various types of disc degeneration in the lumbar spine of asymptomatic young adults. The disc degeneration of lumbar spine could be due to age-related physiological changes than to pathological changes in asymptomatic people. Due to the ethnic and racial differences in lifestyle, it is proposed that the prevalence of disc degeneration in the normal population in different region of the world would differ. There are scarce data on the Indian population on the same.
Methods
Fifty individuals between 15 and 30 years of age, with no history of low back pain undergoing MR imaging for spinal pathology other than the lumbar spine, were included in the study. Various abnormalities (herniation HN, annular fissure AF, nuclear degeneration ND) were recorded and their prevalence was calculated by disc counts (DC) and person count (PC). DC is the number of discs with degeneration and PC is the number of patients with disc degeneration.
Results
56% asymptomatic individuals were found to have either HN or AF or ND at one or more levels. The DC of disc degeneration was 20.8% and it was most commonly observed in L4–L5 intervertebral disc (38%) followed by L5–S1 disc (30%). Thirteen individuals had disc degeneration at single level, 12 at two levels and 3 individuals at all the five lumbar intervertebral disc levels.
Conclusion
The current study showed a high prevalence of disc degeneration (either HN, AF or ND) in young asymptomatic individuals. Even if the MRI shows disc degeneration, patients can be asymptomatic and one needs to correlate the symptoms with the MRI. The limitations of the current study are small numbers of patients from a localized geographical area; hence, we recommend a larger multi-centric study as a follow-up.
Keywords: Intervertebral disc degeneration, Magnetic resonance imaging, Asymptomatic, Young adults, Spine
Introduction
Low back pain (LBP) [1] is one of the most common complaints and has the highest prevalence amongst all symptoms both at individual as well at outpatient department level [2–5]. LBP affects major portions of the population ranging from 64 to 80%, at some point of time in their whole life because of a wide range of causative factors and is one of the most frequent reasons both for consulting primary care physician and for taking leaves [2, 3, 6, 7].
Disc degeneration (DD) is common in patients with low back pain, but the impact of DD on LBP disorder is controversial, since DD is a common finding in asymptomatic subjects [8, 9]. According to the Western literature, prevalence of DD in lumbar region is 30–40% in asymptomatic individuals in age group 15–30 years of age [8, 9]. MR imaging is an effective modality for this study because it depicts anatomic, physical, and chemical nature of the intervertebral disc, but MRI shows not only pathological lesions, but also physiological changes at the same time [10, 11].
There are large numbers of adults who undergo advanced imaging to determine the aetiology of their back pain; thus, it is essential to know the prevalence of imaging findings of degenerative disease in asymptomatic populations [12]. The degenerative changes could be considered to be more closely related to age-related physiological changes than to pathological changes in asymptomatic people. Such information will help both clinical providers and patients interpret the importance of degenerative findings noted in radiology reports.
Asymptomatic patients show high degeneration prevalence at lumber disc in previous literature reported for Caucasian and Korean population [12]. Due to the ethnic and racial differences in lifestyle, there has been an opinion that the prevalence of disc degeneration in the normal population in different region of the world differ [8, 9, 12]. There are scarce data on the Indian population on the same. The aim of the current study was to fill this lacunae and to document the prevalence of disc degeneration in lumbar spine of young adults using MRI.
Materials and Methods
The descriptive cross-sectional observational study was conducted at a tertiary care centre after obtaining Institutional Ethical Clearance. Fifty individuals/volunteers between 15 and 30 years of age with history of trauma/tumour/tuberculosis of cervical/dorsal region requiring screening MRI were shortlisted. Only those patients who never had prior history of low back pain (> 3 weeks) were included if the MRI included lumbar spine. Subjects with the criteria depicted in Table 1 were enrolled in the study after obtaining the informed consent.
Table 1.
Subjects inclusion & exclusion criteria
| Inclusion criteria | Exclusion criteria |
|---|---|
| 15–30 years age | < 15 Years, > 30 years |
| Lumbar spine MRI for indications other than back pain (tumour, trauma, tuberculosis) | Pain radiating to lower extremity |
| No previous history of back pain needing rest or consultation | Surgical intervention of spine |
| Not fit for MRI (claustrophobic, morbid obese, steel implants), not giving consent |
MRI scans were obtained with a 1.5-T unit (Sigma, General Electric, Milwaukee, WI) using the imaging protocol for sagittal T1-weighted spin echo and T2-weighted fast spin echo of the entire lumbar spine and the grading was done as per the defined criteria (Table 2) [12]. The grading was done by two independent observers (one orthopedist and one radiologist) and their observations were recorded in a predesigned proforma.
Table 2.
Degree of disc degeneration (Kim et al. [12])
| Grade | Herniation | Annular fissure | Nucleus degeneration |
|---|---|---|---|
| 0 | Normal | Normal | Bright |
| 1 | Diffuse bulging | Annular fissure-p | Bright—band |
| 2 | Protrusion | Annular fissure-A | Bright—narrow |
| 3 | Extrusion | Annular fissure-B | Dim |
| 4 | Sequestration | Dim—slight | |
| 5 | Dim—moderate | ||
| 6 | Dim—collapsed |
P peripheral, A anterior, B both anterior and posterior
Three measurement categories, i.e. herniation (HN), annular fissure (AF) and nucleus degeneration (ND) were used to establish disc abnormalities in all patients. There are many classifications for disc herniation and degeneration, we have used the most prevalent terms for HN and modified Pfirrmann’s classification for ND [13, 14].
Disc herniation is classified as local protrusion in the intervertebral space. The following terms were used to describe disc abnormalities: normal, bulging, protrusion, extrusion, and sequestration (Table 2) [13, 15, 16].
Annular fissure (AF) was defined as a high signal at the fibrous ring of an intervertebral disc on T2-weighted images (T2WI) of MRI. The high signal-intensity zone (HIZ) is a signal (bright white) located in the substance of the annulus fibrosus, clearly dissociated from the signal of the nucleus pulposus [13–16]. AF was graded according to the site of fissure on the mid-sagittal section of the disc on T2WI (Table 2).
The extent of intervertebral disc nucleus degeneration (ND) was graded on mid-sagittal T2WI according to the criteria of modified Pfirrmann classification [14] (Table 3). For the purpose of this investigation, grades 0–2 were grouped together and grades 3–6; the more advanced grades of ND were grouped together.
Table 3.
Degree of nucleus degeneration [12]
| Nucleus degeneration | Nucleus/annulus distinction | Nucleus signal | Disc height |
|---|---|---|---|
| Bright | Clear | Hyper-intense, homogeneous | Normal |
| Bright—band | Clear | Hyper-intense w/horizontal dark band | Normal |
| Bright—narrow | Clear | Hyper-intense w/ or w/o horizontal dark band | Decreased |
| Dim | Unclear | Decreased, slightly or heterogeneous irregularity | Normal |
| Dim—slight | Unclear | Decreased, slightly or heterogeneous irregularity | Slightly decreased (< 1/3) |
| Dim—moderate | Lost | Decreased, moderately | Moderately decreased (1/3–2/3) |
| Dim—collapsed | Lost | Decreased, severely | Collapsed (> 2/3) |
The prevalence of the various abnormalities was calculated by disc counts (DC) and person count (PC). DC is the number of discs with degeneration regardless of patients and PC is the number of patients with disc degeneration at least one or more lumbar level.
Results
Analysis of 250 lumbar disc was done in fifty asymptomatic subjects (45 male, 5 female) for different levels of disc degeneration and assessment was done for—(a) herniation (HN), (b) annular fissure (AF) and (c) nucleus degeneration (ND) as depicted in Table 3. The disc count (DC) and patient count (PC) for each abnormality were calculated and recorded (Table 4).
Table 4.
Radiological findings of different grades of disc degeneration in our patients
| Disc herniation (HN) | Annular fissure (AF) | Nuclear degeneration (ND) | Any evidence of disc degeneration (HN/AF/ND) | |
|---|---|---|---|---|
|
Total discs evaluated (lumbar) n-250 |
36/250 | 15/250 | 20/250 | 52/250 |
| Disc count (DC) (percent) | 14.4 | 6 | 8 | 20.8 |
|
Total subjects evaluated n-50 |
21/50 | 15/50 | 14/50 | 28/50 |
| Patient Count (PC) (percent) | 42 | 30 | 28 | 56 |
The collective data for disc herniation (HN), annular fissure (AF) and nucleus degeneration (ND) were analysed and it was found that 56% (28/50) asymptomatic individuals were found to have either herniation or annular fissure or nucleus degeneration at one or more levels (Figs. 1, 2, 3). Thus, the person count (PC) for disc degeneration was found to be 56%. The disc count (DC) for disc degeneration was 20.8% (52/250) and it was most commonly observed in L4–L5 intervertebral disc (38%) followed by L5–S1 disc (30%).
Fig. 1.
Disc protrusion at L4–L5 level, i.e. grade 2 disc herniation in 25-year-old female
Fig. 2.
Grade 1 annular fissure at L5–S1 level in 21 years old
Fig. 3.
Disc degeneration at multiple levels with L1–L2 disc having grade 4 ND. Grade 1 AF present at L5–S1 level, whereas L2–L3, L3–L4 and L4–L5 levels show grade 1 disc herniation in 45-year-old male
Out of fifty asymptomatic individuals analysed for disc degeneration (either HN, AF or ND) in lumbar spine, 13 individuals had disc degeneration at single level, 12 at two levels and 3 individuals at all the five lumbar intervertebral disc levels (Fig. 4).
Fig. 4.
Depicting number and level of disc degeneration in all subjects
Discussion
The degenerative changes of the disc can be closely related to age-related physiological changes than to pathological changes in asymptomatic people. Such information will help both clinical providers and patients to interpret the importance of degenerative findings noted in radiology reports.
Due to the ethnic and racial differences in lifestyle, there has been an opinion that the prevalence of disc degeneration in the normal population in different region of the world differ [17–21]. There are scarce data on the Indian population on the same [17–21]. The current study was done to evaluate the likelihood of radiological presence of degenerative changes on MRI of lumbosacral spine in young individuals with no clinical symptoms.
In the current study, the prevalence of HN, AF, and ND was 42%, 30%, and 28%, respectively, in asymptomatic individuals of age group 15–30 years. The disc degeneration (either HN, AF or ND) in lumbar spine of asymptomatic individuals in our study was 56% (28/50).
High prevalence of disc degeneration in asymptomatic subjects 15–30 years of age is very interesting. Multiple studies have shown similar findings that asymptomatic patients have a high prevalence of disc abnormalities, especially in advanced age (Table 5).
Table 5.
International literatures comparison of herniation, annular fissure, and nucleus degeneration in asymptomatic subjects (%)
| Study | Year | Case | Nucleus degeneration | Annual fissure | Herniation | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Annual fissure (presence) | High-signal intensity zone | Bulging | Protrusion | Extrusion | ||||||||||
| DC | PC | DC | PC | DC | PC | DC | PC | DC | PC | DC | PC | |||
| Modic et al. [22] (US) | 1994 | 85.0 | 63.0 | |||||||||||
| Jesen et al. [23] (US) | 1994 | 98 | 14.0 | 52.0 | 27.0 | 1.0 | ||||||||
| Boos et al. [24] (SWZ) | 1995 | 46 | 84.8 | 51.0 | 63.1 | 3.0 | ||||||||
| Weishaupt et al. [25] (SWZ) | 1998 | 60 | 20.0 | 72.0 | 8.0 | 32.5 | 14.0 | 62.0 | 16.0 | 67.0 | 3.7 | 18.0 | ||
| Boos et al. [26] (SWZ) | 2000 | 46 | 48.8 | 65.9 | 7.3 | |||||||||
| Borenstein et al. [27] (US) | 2001 | 31 | 74.2 | 65.0 | ||||||||||
| Kim et al. [12] (Korea) | 2013 | 102 | 38.3 | 75.8 | 36.0 | 76.1 | 8.1 | 36.3 | 16.8 | 60.1 | 11.9 | 45.4 | 7.0 | 31.0 |
| Current study (India) | 50 | 8 | 28 | 6 | 30 | 13.6 | 38 | 0.4 | 2 | 0.4 | 2 | |||
Greenberg et al. [28] reported the MRI findings of lumbar spine in 28 asymptomatic subjects (20–39 years of age). They analysed the MRI findings as loss of signal intensity, bulge, protrusion and herniation and concluded that 50% of them had degenerative disc disease, primarily involving the L3–L4, L4–L5 and L5–S1 levels. These findings are similar to our study.
Kim et al. [12] performed MRI sagittal scans from T12 to S1 on 102 asymptomatic subjects (50 men and 52 women) between the ages of 14 and 82 years (mean age 46.3 years) and showed that the prevalence of HN, AF, and ND was 81.4%, 76.1%, and 75.8%, respectively, in asymptomatic individuals. However, they included older subjects also and mean age was 46.3 years; hence, their data show a higher prevalence than our study, which is understandable.
Jesen et al. [23] studied 98 asymptomatic people, from 20 to 80 years old and stated that 64% of these people without back pain had an intervertebral disc abnormality (i.e. bulge, protrusion and extrusion), and 38% had an abnormality at more than one level. However in age group 20–29 years, approximately 60% of these people had intervertebral disc abnormality. In comparison to their results, we found prevalence of disc herniation (i.e. bulge, protrusion and extrusion) to be 42%.
Several studies were conducted in young asymptomatic individuals who were athletically more active (i.e. tennis players, cricketers, gymnasts and weight lifters, etc.), to look for the abnormalities in lumbar intervertebral discs [29–31].
Rajeswaran [30] performed MRI on 98 asymptomatic junior elite tennis players with a mean age of 18 years to evaluate abnormal MRI findings in the lumbar spines of these players and found that prevalence of disc degeneration in lumbar spine of these players was 62.2%. He also stated that disc degeneration occurred in only 20.7% of the discs evaluated (122 out of 588) and the degree of degeneration was mild in 76.2% (93 out of 122) and moderate in 22.1% (27 out of 122). They also observed other abnormalities in these players like facet joint arthropathy (89.7%), synovial cysts (22.4%) and pars interarticularis abnormalities in 29.6%.
Thus, it was observed that athletically active young individuals, who were otherwise asymptomatic, had higher prevalence of disc degeneration and many other abnormalities in lumbar spine compared to normal individuals [29, 32].
The findings of the current study show that the prevalence of having disc degeneration (either HN, AF or ND) in the age group 15–30 in asymptomatic individuals of Indian ethnicity was 56%. Out of 50 asymptomatic individual, 13 individuals had involvement of one level, 12 individuals had two levels involved and 3 even had all five levels involved. 20.8% of the 250 lumbar disc evaluated by MRI in asymptomatic young individuals had disc degeneration. The prevalence of disc degeneration was highest at L4–L5 (19/50; 38%), followed by L5–S1 (15/50; 30%).
The clinical implication of our study is that even if the MRI shows disc degeneration, it may not be leading to any symptoms. One needs to correlate the symptoms with the MRI findings as these may just be part of the normal ageing process. One should not blindly treat the imaging findings as nearly 56% of individuals (i.e. one out of two) who were asymptomatic had disc degeneration present at one or more levels.
The limitations of our study were—small numbers of subjects (more males than females) were enrolled, all subjects were from same geographical area and thus they may not represent the variety of population in different zones of Indian subcontinent. Thus, we propose a multi-centric trial involving large number of subjects from different geographical zone of the Indian subcontinent to extrapolate the outcome for the adult asymptomatic population.
Conclusion
The current study showed a high prevalence of disc degeneration (either HN, AF or ND) in age group 15–30 years in asymptomatic individuals of Indian ethnicity (person count = 56% and disc count = 20.8%). 13 individuals had single level, 12 had two levels and 3 had all the five levels involved. Most common level involved was L4–L5 (n = 19/50; 38%) followed by L5–S1 (n = 15/30; 30%).
The demonstration of a significant number of young individuals having radiological changes without any clinical symptoms suggests that clinical correlation of radiological findings is a must when treating these patients.
The clinical implication of our study is that even if the MRI shows disc degeneration, patients can be asymptomatic. One needs to correlate the symptoms with the MRI findings.
Author Contributions
Dr MC—Substantial contribution in the conception, analysis and interpretation of the study, final approval of the version to be published. Dr AS—rafting of the work and revising it critically for important intellectual content. Dr VK—Contribution in data collection and in the conception of the study. Dr AT—Analysis and interpretation of data and review of publication.
Funding
Nil.
Declarations
Conflict of interest
The authors declare that they have no conflict of interest.
Ethical standard statement
This article does not contain any studies with human or animal subjects performed by the any of the authors.
Informed consent
For this type of study, informed consent is not required.
Footnotes
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Contributor Information
Manish Chadha, Email: mchadha@hotmail.com.
Amit Srivastava, Email: amitsrvstv00@gmail.com.
Vipin Kumar, Email: vipinkumar@gmail.com.
Anupama Tandon, Email: anupamatandon@hotmail.com.
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