SPECTRUM OF SPINAL ABNORMALITIES ON MAGNETIC RESONANCE IMAGING OF PATIENTS WITH CLINICAL SUSPICION OF SPINAL LESIONS IN KANO, NIGERIA

Abstract

Background:

Magnetic resonance imaging (MRI) of the spine is a powerful tool for evaluation, assessment of severity, and follow up of diseases of the spine. It is one of the most sensitive diagnostic tests for detecting anatomic abnormalities of the spine and the adjacent structures.

Aim:

To determine the pattern of spinal abnormalities on MRI in Kano, Nigeria.

Materials and Method:

Patients aged between 2 and 95 years who had spinal MRI with AIRIS II TOSHIBA (0.5T) Tesla machine from January to December 2013 were reviewed. Information concerning age, gender, region and findings were recorded.

Results

Two hundred and sixty one patients made up of187 males and 74 females were reviewed. Their ages ranged from 2 to 95 years with the mean of 46.43 ± 15.7 years. Lumbo-sacral MRI was the most commonly performed (46.4 %) followed by cervical (44.1%), thoraco-lumbar spine (4.2%), thoracic spine (3.8%) and cervical and lumbar (1.5%). The most common indication of MRI was low back pain in 211 (80.8% ) patients followed by trauma in 36 (17.8% ) patients. About 19.6% of the MRI examinations were normal while spondylosis and moderate disc prolapse was seen in 31.5% and compressive fracture comprised 7.3% of cases.

Conclusion

Lumbo-sacral MRI was the commonest MRI in this study and the commonest indications for MRI were low back pain and trauma while the commonest findings were spondylosis, disc prolapse, compressive fracture and spinal metastases.

Introduction

The common indication for spinal MRI is low back pain (LBP). Low back pain is defined as pain in the lumbar spinal region with or without sciatica, is a common cause of disability worldwide, with a lifetime prevalence of 60–85%1,2,3. In about 95% of cases LBP is non-specific, yet it can be caused by serious underlying pathology such as disc herniation, spinal stenosis, infection, inflammation, tumour or fractures1. In case of suspicion of serious spinal pathology, diagnostic confirmation is required since delayed treatment has been associated with poorer outcomes.

Magnetic resonance imaging (MRI) of the spine is an invaluable tool for evaluation, assessment of severity, and follow up of diseases of the spine. It is one of the most sensitive diagnostic tests for detecting anatomic abnormalities of the spine and that of the adjacent structures.

MRI is currently the imaging modality of choice in imaging the spinal cord. It has the advantage of not using ionising radiation and has good visualizing capacities especially of the soft tissues. Therefore, it is regarded as the most useful method for the detection of spinal infections, spinal metastases, nerve root disorders and disc abnormalities2.

Many imaging modalities such as basic radiography, ultrasound scan and computed tomography (CT) as well as myelography were riddled with lots of diagnostic limitations, Spinal radiography showed mainly limited bony lesions. CT scan provides further bony details with little soft tissue components while myelography provides indirect information about the contents of the spinal canal. The advent of magnetic resonance imaging (MRI) has proven to be a milestone in the evaluation of spondyloarthritis through its ability to depict objective features of active inflammation, thereby facilitating earlier diagnosis and ongoing management, and permitting quantitative assessment of extent and severity of spinal inflammation. Furthermore, MRI is capable of elucidating the detailed involvement of the spinal cord and theca following trauma or inflammatory process. This can be exemplified by disc protrusion/prolapse and compressive vertebral fracture. In addition, the use of contrast agents allows characterisation of the vascularity of spinal tumours and other vascular lesions; which may not be appreciated with other imaging modalities such as radiography, ultrasound and radio-nuclide scan.

Therefore, studying spinal lesions with MRI will help the health care team and policy maker appreciate the common lesions and extent of radiologically detectable conditions for the purpose of proper treatment/intervention, rehabilitation and prevention. Hence, this study aims to determine the pattern of spinal abnormalities on MRI studies and common findings in Kano Nigeria with particular emphasis on the commonly requested MRI examinations. We also intend to find how sensitive MRI is in detecting spinal abnormality in symptomatic cases.

MATERIALS AND METHOD

This is a retrospective study of spinal MRI of patients with clinical suspicion of spinal lesion using AIRIS II TOSHIBA (0.5T) based at MeCure diagnostics (a private firm in Kano) and the images were reviewed and interpreted by at least a consultant radiologist form Aminu Kano Teaching hospital. The clinical presentation and imaging findings of the patients from January 2013 to December 2013 were included in this study. The request cards, stored MR images and radiologists report were reviewed by the authors. All the examinations considered in this review were done using routine MR protocol which include T1 weighted, T2 weighted and STIR MR images. The STIR images are mainly done for trauma cases. The images are obtained in axial, coronal and sagittal section. No contrast medium is however used in this study. Appropriate protocol was selected depending on the region of interest and clinical information available.All the images were transferred to a "stand alone" diagnostic workstation and were reviewed by at least one consultant radiologist. The information concerning the age, gender, indication for MR examination, type of MR examination, and major findings on each of the patients were documented. The spinal MR examinations for which the above detail could not be obtained were excluded. These variables were thereafter analyzed using Statistical Package for Social Sciences (SPSS) version 16.0 software. Results were expressed numerically, in tabular forms and pictorially. Tests of statistical significance was done at the P-value of 0.05.

Results

The MRI of 261 patients comprising187 (71.6%) males and 74 (28.4%) females were reviewed. Their ages range from 2 to 95 years with the mean of 46.43 ± 15.7 years. Among the male patients, their ages ranged from 6 to 85 years with a mean age of 46.92 + 14.86 years while the age of the females ranged between 2 and 95 years with a mean age of 44.42 + 17.56 years. Table 1 shows the age-sex distribution pattern of the subject. The majority were aged about 30.7±62.1 yrs. The modal age group for males in 69 (%) cases is the 5^th decade while that of the females is 32% in the 4^th decade of life and ranged between 41 - 50 years while the least frequency of patients in males comprised 4(%) and females 1(%) both in the first decade of life.

Table 2 is the Distribution pattern of the regions examined by MRI in the male and female patients. The site most commonly investigated is the lumbosacral region constituting 46.4% of the MRI examinations, followed by cervical spine which in 44.1%. Dorsal spine was the least site investigated constituting 4.2%. However dorso-lumbar in combination is the highest constituting 4.2% while combination of cervical and lumbar at the same is less in percentage constituting 1.5%. Despite the apparent gender variations, there is no statistically significant difference between the two gender populations (p-value = 0.153)

figure 1 is a Chart of the frequency distribution pattern of the Indication for referral of MRI studies in the study population. The most common indication of MRI in these patients is low back pain 211(80%) followed by trauma in 36 (13.7%).

Figure 1 . Indications for spinal MRI .

Table 3 shows the Age & Sex distribution pattern of the spinal abnormalities in the study population, About 19.6% of the examinations were normal while spondylosis and moderate disc prolapse were seen in 31.5% and compressive fracture was seen in 7.3% of cases.

Spondylosis and disc prolapse alone constituted 34% of the finding in combination. However individually, the spondylosis alone was seen in 8.8% of the cases while disc prolapse was seen in 6.9% cases. Traumatic spondilolisthesis comprised 1.91% of the pathologies in the MRI examinations.

Pott’s disease was seen in 5.7% of the cases and spinal neoplasm in 3.8%. Vertebral fracture mostly as a result of trauma is seen in 16.5% of the cases. While others which included congenital kyphosis, post operation check constitute 2.7%. 19.5% of the cases. The table also showed a wide disparity between males and females. For example, there are 30 males with vertebral fracture compared to 13 females. These differences were statistically significant (T-Value = 2.45 P-Value = 0.040). figure 2 is a graphical representation of the common spinal abnormalites observed in the study population with combined spondylosis and disc prolapse showing the tallest or peak value on the graph.

Figure 2 . Common findings from spinal MRI .

Discussion

MRI has provided clinicians with a non-invasive mechanism for viewing lumbar anatomy in great details and thus preferred over CT scan and plain radiography2.

Images may be produced in any plane and exhibit excellent soft tissue contrast. In the lumbar spine, the paraspinal muscles, intervertebral discs and nerve roots can be seen in remarkable details. The size and shape of the spinal canal are readily apparent. MRI allows the assessment of intervertebral disc hydration, enabling early signs of disc degeneration to be detected3.

MRI has been found to clearly demonstrate early abnormalities in “normal” asymptomatic people,in which case, the presence of abnormalities may not correlate well with clinical symptoms. The role of imaging in spinal abnormalities include determination of the possible causes of low back pain, the extent of vertebral/spinal injury, to select patient for surgical procedure, to monitor response to treatment(conservative or surgical) and to monitor patients with complications.

The age range of the study participants is 2 - 95 years. The age group 41-50 years represented the majority (24.14%) of the patients. The reason for this could be the fact that the low back pain constitutes major indication for the study, which is common in this age group.

The study comprises of 261 subjects. Among the study participants 72% of the subjects were males while 28% were females. This is similar to the Estonian study on 595 patients by Sabre et al4 with a male:female ratio of 5.5:1. However, this is at variance with the male:female ratio recorded in the multicentre study on 5,919 patients by Albert et al5

which showed nearly equal gender preponderance with 51.1% females. This difference may be attributable to variations of sample size and other characteristics of the study subjects. The findings in this study shows a male to female ratio of 2.5:1 The higher male ratio may be attributed to the fact either a muscular or ligamentous injury are mostly the cause or because men naturally are more active and so more susceptible. It is well known that musculoskeletal pain is influenced by genetic factors6^-9, socio-economic factors10, lifestyle11 and individual perceptions12. However, high physical work demands are generally considered to be one of the main causes of musculoskeletal pain among workers8. Accordingly, workers with high physical work demands have the highest prevalence of musculoskeletal pain. Examples of these physical work demands are monotonous and repetitive arm movements, awkward body postures, prolonged standing, work with arms above shoulder height, and heavy lifting13,14

Of all the cases reviewed in this study, about 19.6% of them had a normal findings and in most of them, the reason for MRI are that lower back pain. This is less than what was reported by Elders el al3 showed normal MRI findings as a result of non-specific lower back pain to be about 95%. The significant difference may be attributed to easy availability and affordability of MRI in the more advanced economies. Despite the extraordinary ability of MRI to delineate the spine, it is shown that there is no clear relationship between the MRI appearance and low back pain. The causes of low back pain (LBP) are numerous, diverse and poorly understood. LBP is frequently thought to be muscular in origin and may be due to a postural muscle strain or protective muscle spasm. Such an injury are not currently detected by MRI and neither can referred pain from the viscera7. Prevalence estimates vary depending on the definition of low back pain used. Ozguler and colleagues15 recorded prevalence of lower back pain to be 45% when it was defined as pain lasting at least a day. This review has shown that the most frequent age group of patients with low back pain who had spinal MRI was between 31 and 60 years and most of them had lumbo-sacral MRI. The observation was due to the fact the indication for the MRI in majority of cases was lower back pain. Low back pain has become one of the biggest problems for public health systems8. Most people will experience back pain at some point in their life. Individuals who do not seek medical attention do not differ substantially from those who do seek care in terms of the frequency or intensity of low back pain experienced13.

Although the proportion of health-care resources used for low back pain is large, few people with the problem seek health care14.

The lifetime prevalence of low back pain is reported to be as high as 84%, and best estimates suggest that the prevalence of chronic low back pain is about 23%, with 11—12% of the population being disabled by it15.

The findings of lumbo-sacral MRI spondylosis with disc bulge and desiccation of one or more vertebrae in this study is in agreement with study conducted by Jarvick et al16, a longitudinal study with 148 subjects was carried out to assess the prevalence of MRI findings in the lumbar spine. This study was done on subjects either without current low back pain or sciatica, or who had never experienced low back pain. About 83% had moderate to severe desiccation of one or more discs, 64% had one or more bulging discs, 56% had loss of disc height, 32% had at least one disc protrusion while 6% had one or more disc extrusions. They concluded that many MR imaging findings had a high prevalence in subjects without low back pain. These findings are therefore of limited diagnostic use.

The cervical MRI was the second most frequent MRI investigation in this study, and suspected cervical injury from road traffic accident was the most common indication for the investigation. The main cervical abnormality in this study was cervical fracture with compressive myelopathy, which was at variance with the pattern reported by Mustapha et al17 on 170 cases of cervical MRI. They showed that cervical spondylosis occurred more frequently as a single finding in 44.4% of patients and in combination with disc prolapse in 41.9% cases, making it the most frequent overall finding. Among those with detected abnormality on MRI in this study, spondylosis was the most common findings. This finding was similar to what was found in previous studies3,11,15.

Pott’s disease was seen in 5.7% of cases in this study. This illustrates the prevalence of Pott’s disease in developing countries. Pott's spine accounts for 2% of all cases of tuberculosis, 15% of extrapulmonary, and 50% of skeletal TB18. tThese patients may show abnormality with other imaging modalities. Therefore, multi-modality studies with specific correlations with clinical symptoms and degree of neurologic deficit are reguired.

Conclusions

Lumbo-sacral MRI was the commonest MRI in this study and the commonest indications for MRI were low back pain and trauma while the commonest findings were spondylosis, disc prolapse and compressive spinal fractures.