Imaging diagnosis
Case 212
【Progress】
（Case 1）He was given non-steroid anti-inflammatory drugs, although hydro-release treatment is known to be speedily effective.
（Case 2）She was scheduled to wear a lumbar corset.
【Discussion】
As specific lumbago which is recognized well on imaging diagnosis, disc hernia and spinal canal stenosis are listed. It is reported nonspecific lumbago which is not visualized on imaging occurs in 70% of all lumbagos (1, 2). Lumbago is categorized into factors of disk, facet joint, facet foramen, sacroiliac joint, muscular fascia and brain. The real clinical pathogenesis does not arise from single factor but from overlapped complicated pathologic conditions. For example, lumbago from facet joints are strongly related to multifidus muscle injury as muscular fascia factor. Facet joints at L4/5 and L5/S1 must burden not only body weight but also body rotation power, implying susceptible to injury and arthrosis (1). Multifidus muscle also function to burden body weight and body rotation power. Multifidus muscle is one of the most important deep spinal stabilization muscles. The atrophy of multifidus muscle is one of the important risk factors for chronic pain and dysfunction (1, 2). The injury of multifidus muscle is also susceptible to injury L4/5 and L5/S1 levels.
In our Case1, MRI with fat suppression T2WI and T2WI showed high signal intensity corresponded to facet (zygapophyseal) joint and multifidus muscle. Further, it indicates atrophic changes of multifidus muscles, implying origin of lumbago.
When lumbar MRI is conducted to investigate the origin of lumbago, it is imperative to check lumbar disk, facet joint foramen, facet joint itself and muscular fascia. Muscle fascia causing lumbago includes multifidus muscle, supraspinous ligament, interspinous ligament. Sacroiliac joint is not shown on usual lumbar spine images. Then, when suspicious origin of lumbago is sacroiliac joints, the large images different from lumbar images should be scanned.
Supraspinous ligament continues longitudinally from the tip of the seventh vertebrae to the tip of the sacrum (3). Interspinous ligament connects the space between superior spinous process and inferior one (3). Both ligaments function to prevent the backward movement of spinal cord when the spine makes flexion. The injury or tension stretch of supraspinous ligament and/or interspinous ligament cause the chronic lumbago, which sometimes induce severe back pain even if at rest. In Case 2, MRI with T2WI showed high signal intensity in the subcutaneous fat tissue arising from the tip of the spinous process or supraspinous ligament. It implies peri-spinous fat edema caused by injury or inflammation of supraspinous ligament.
【Summary】
We present two cases with lumbago not relevant with disk hernia, vertebral compression fractures, spinal canal stenosis and lumbar osteoarthrosis but relevant with stress burden of muscle facia and ligament. Both cases suffered from lumbago not associated with symptoms of lower extremities. In Case 1, the lumbago arose from stress burden of multifidus muscles. In Case 2. the lumbago arose from stress burden of supraspinous ligament. It is borne in mind that when MRI images are interpreted for lumbago, radiologists check not only spinal disk, spinal canal and lumbar vertebra but also facet joint, facet joint foramen, multifidus muscle fascia, interspinous ligament and supraspinous ligament. Especially, L4/5 and L5/S1 levels are susceptible to stresses of body weight and body stem rotation. The atrophy of multifidus muscle is one of the important risk factors for chronic pain and dysfunction.
【References】
1.Murakami E. How to manage persistent lumbago, how to identify the cause of lumbago appearing from pain of patients. (in Japanese). 2020 Nihonijisinpo, Tokyo, Japan
2.Suzuki H, et al. Diagnosis and Characters of Non-Specific Low Back Pain in Japan: The Yamaguchi Low Back Pain Study. PLoS One . 2016 Aug 22;11(8):e0160454. doi: 10.1371/journal.pone.0160454.
3.Drake, Richard L.; Vogl, Wayne; Tibbitts, Adam W.M. Mitchell; illustrations by Richard; Richardson, Paul (2005). Gray's anatomy for students (Pbk. ed.). Philadelphia: Elsevier/Churchill Livingstone.
2020.11.18