Department of Physical Therapy, University of Alberta, Edmonton, Alberta, Canada.
Spine (Phila Pa 1976). 2011 Dec 1;36(25):2152-7. doi: 10.1097/BRS.0b013e318204b05a.
A cross-sectional population-based study of paraspinal muscle asymmetry.
To examine level- and side-to-side differences in paraspinal muscle areas on magnetic resonance images in a population-based sample of middle aged men without low back pain (LBP).
Level- and side-specific multifidus muscle atrophy and fat infiltration have been suggested as possible markers for localized spinal pathology and LBP, but prior studies have limited generalizability due to small sample sizes, young age of samples and measurement issues.
From a general population sample of 600 twin men, those reporting no LBP during the prior year, no previous spinal fractures, and no bed rest for at least 1 week in the last 12 months were included in the study. All subjects had T2-weighted axial images available for the three lowest lumbar levels. Both total and fat-free cross-sectional areas (CSAs) of the multifidus and erector spinae muscles at the mid-disc level were measured. Intrarater reliability ranged between 0.90 and 0.98 for area measurements and 0.86 and 0.92 for measurements of side-to-side differences. Data were analyzed using descriptive statistics and paired t tests.
Subjects consisted of 126 men whose mean multifidus total CSA measurements varied between 7.3 and 11.1 cm and between 6.9 and 10.8 cm for right and left sides, respectively, depending on the level. The corresponding mean areas for erector spinae were 9.4 to 19.6 cm2 for right side and 10.4 to 19.7 cm2 for left side. The multifidus was larger on the right side than on the left side in 65% to 68% of subjects, depending on spinal level (P < 0.001). The mean asymmetry at the three lowest lumbar levels was 10% to 13.2% and was smallest at L4-L5. Multifidus side-to-side asymmetry ranged from 0.1% to 44.3%. For erector spinae, the left-side measurements tended to be larger, reaching statistical significance (P < 0.0001) for the two lowest levels. The mean side-to-side asymmetry increased caudally for erector spinae, from 8.2% to 18.8% and was significantly different between adjacent levels (P < 0.01). The amount of intramuscular fat significantly increased caudally for both muscles.
Paraspinal muscle asymmetry greater than 10% was commonly found in men without a history of LBP. This suggests caution in using level- and side-specific paraspinal muscle asymmetry to identify subjects with LBP and spinal pathology.
一项基于人群的脊柱旁肌不对称的横断面研究。
在无下腰痛（LBP）的中年男性人群中，通过磁共振成像（MRI）检查脊柱旁肌的水平和左右差异。
水平和特定的多裂肌萎缩和脂肪浸润被认为是局部脊柱病理和 LBP 的可能标志物，但由于样本量小、样本年龄较小以及测量问题，先前的研究具有一定的局限性。
从一般人群的 600 对双胞胎男性中，选取在过去一年没有报告 LBP、没有既往脊柱骨折且在过去 12 个月内没有卧床休息至少 1 周的男性纳入研究。所有受试者均有可用的 T2 加权轴位图像，用于三个最低的腰椎水平。测量多裂肌和竖脊肌在椎间盘水平的总截面积（CSA）和无脂肪 CSA。内部评估者之间的面积测量可靠性在 0.90 到 0.98 之间，而左右差异的测量可靠性在 0.86 到 0.92 之间。数据分析采用描述性统计和配对 t 检验。
研究对象包括 126 名男性，其多裂肌总 CSA 测量值在 7.3 到 11.1cm 之间，右侧和左侧分别为 6.9 到 10.8cm，具体取决于腰椎水平。右侧竖脊肌的相应平均面积为 9.4 到 19.6cm2，左侧为 10.4 到 19.7cm2。在 65%到 68%的受试者中，右侧的多裂肌比左侧大，具体取决于脊柱水平（P < 0.001）。在三个最低的腰椎水平，多裂肌的平均左右不对称为 10%到 13.2%，在 L4-L5 水平最小。多裂肌的左右不对称范围为 0.1%到 44.3%。对于竖脊肌，左侧测量值较大，在两个最低水平达到统计学意义（P < 0.0001）。竖脊肌的左右不对称从下到上逐渐增加，从 8.2%到 18.8%，相邻水平之间差异显著（P < 0.01）。两种肌肉的肌内脂肪含量均随尾侧增加而显著增加。
无 LBP 病史的男性中，超过 10%的脊柱旁肌不对称是常见的。这表明在使用水平和特定的脊柱旁肌不对称来识别 LBP 和脊柱病理的受试者时应谨慎。
