Relationship between MRI Findings of Posterior Lumbar Elements and Different Stages of Non-specific Low Back Pain

Research Article

Austin Orthop. 2018; 3(2): 1015.

Relationship between MRI Findings of Posterior Lumbar Elements and Different Stages of Non-specific Low Back Pain

Zhang J¹, Hao Y²* and Liu K¹

¹Department of Radiology, North District of Suzhou Municipal Hospital, Suzhou 215008, People’s Republic of China

²Department of Orthopaedics, North District of Suzhou Municipal Hospital, Suzhou 215008, People’s Republic of China

*Corresponding author: Yufeng Hao, Department of Orthopaedics, North District of Suzhou Municipal Hospital, Suzhou 215008, People’s Republic of China

Received: November 19, 2018; Accepted: December 14, 2018; Published: December 21, 2018

Abstract

Background: The purpose of this study was to investigate the relationship between the MRI findings of posterior lumbar elements and different stages of non-specific low back pain.

Methods: A total of 63 patients with low back pain underwent lumbar MRI examinations were divided into acute group (<1 month), sub-acute group (1~3 months) and chronic group (>3 months) according to the time of onset. 14 healthy subjects underwent lumbar MRI examinations served as a control group. The distribution differences of thicknesses, cross-sectional areas (CSA) of bilateral lumbar multifidus muscles (LMM) in L4/5 level, extent of fat infiltration in multifidus muscles, subcutaneous/paraspinal muscles edema and facet joint degeneration symptom in four groups were recorded and compared.

Results: Thicknesses CSAs of LMM, facet joint degeneration symptom had no statistically difference within four groups. Extent of fat infiltration in multifidus muscles between chronic group and control group had statistically difference, and the incidence of subcutaneous/paraspinal muscles edema in chronic group was significantly higher than that in the other three groups.

Conclusions: Extent of fat infiltration in multifidus muscles and subcutaneous/paraspinal muscles edema are probably associated with chronic low back pain. The relationship between the MRI findings of posterior lumbar elements and acute, sub-acute groups are not clear.

Keywords: Low Back Pain; Multifidus Muscles; Magnetic Resonance Imaging

Introduction

Low back pain (LBP) refers to the pain or discomfort in the back or lumbosacral, which may or may not be associated with radiating pain in the lower extremities. It is characterized by self-healing and recurrence. LBP can not only lead to a decline in the individual’s physiological function, increase the risk of suffering from other diseases, cause psychological problems, reduce the quality of life, but also greatly increase the social economic burden and labor loss [1,2]. On the classification of LBP has not been unified. According to the anatomical site can be divided into anterior longitudinal ligament disease, vertebral disease, spinal disorders, etc. According to whether there are clear pathological changes can be divided into specific low back pain and non-specific low back pain. LBP can also be classified by duration as acute (pain lasting less than 1 month), sub-acute (1 to 3 months), or chronic (more than 3 months) [3,4]. The aim of this research was to investigate whether there are differences in the MRI findings of posterior lumbar elements between patients of nonspecific low back pain in different stages.

Methods

General materials

The investigated subjects in this study include 150 patients with low back pain underwent lumbar MRI examinations in our hospital seen between March 2016 and March 2017, 103 of them had pain in one or both of the lower extremities. Patients with a history of surgery and trauma, intraspinal lesions, rheumatic lesions, spondylolisthesis, disc herniation or image quality does not meet the standard, were excluded. A total of 63 patients were included in the study eventually. These patients were divided into acute group (n=20, 8 men and 12 women, age range 22 to 76 years), sub-acute group (n=22, 9 men and 13 women, age range 24 to 73 years) and chronic group (n=21, 8 men and 13 women, age range 23 to 69 years) according to the time of onset. 14 healthy subjects (7 men and 7 women, age range 34 to 71 years) underwent lumbar MRI examinations served as a control group.

Examinations

Examinations were performed on a 1.5T MR machine (Siemens sonata, Germany). Examination protocols included: (1) Sagittal T1- weighted images [repetition time (TR) 613 ms, echo time (TE) 11 ms, section thickness 4mm, intersection spacing 0.4mm, field of view 640 × 640 mm]: (2) Sagittal T2-weighted images [TR 2460 ms, TE 134 ms, section thickness 4mm, intersection spacing 0.4mm, field of view 640 ×640 mm]: (3) Sagittal fast spin echo T2-weighted images [TR 4330 ms, TE 77 ms, section thickness 4mm, intersection spacing 0.4mm, field of view 512 × 521 mm]: (4) Axial T2-weighted images [TR 3200 ms, TE 119 ms, section thickness 4 mm, intersection spacing 0.4mm, field of view 640 × 640 mm].

Image characteristics

Two experienced musculoskeletal radiologists judged MRI characteristics and made diagnoses by consensus.

The MRI signs to be observed included: (1) Thickness of lumbar multifidus muscles. Between the 4th-5th middle introvertebral disc sections on the T2WI transverse segment, the thicknesses of bilateral multifidus muscles were measured from the back edge of the lower arthro-process to the dorsal interface of subcutaneous lipid and muscle. The largest radius vector was chosen as the thickness of the multifidus muscle. (2) The cross-sectional area (CSA) of multifidus muscles [5]. The CSAs of bilateral multifidus muscles were measured at axial T2-weighted image by constructing polygon points around the outer margins of the muscles. (3) Extent of fat infiltration in multifidus muscles. The extent of fat infiltration was defined as grades I, II and III: grade I, intramuscular spaces revealed few fat signals (or none) showing as a single line or dot form; grade II, more fat signals were revealed in the intramuscular spaces, but no signals were shaped like grid or feather patterns; grade III, signals were shaped like grid or feather patterns (Figure 1) (4). Subcutaneous/paraspinal muscles edema. High signal appears in the subcutaneous or paraspinal muscle area on sagittal fat suppression T2WI (5). Facet joint degeneration symptom. Four grades of the facet joint degeneration were defined using criteria similar to published by Weishaupt et al. [6]: grade 0, normal; grade 1, mild degenerative disease; grade 2, moderate degenerative disease; and grade 3, severe degenerative disease (Figure 2). The criteria for grading are given in Table 1.