棘突起正中縦割進入腰椎後方除圧術後の傍脊柱筋変性のMRI画像評価

Qualitative Analysis of the Paravertebral Muscle Degeneration after Posterior Spinal Decompression with Midline Spinous Process Splitting Approach by Using Magnetic Resonance Imaging

　顕微鏡視下腰椎後方除圧術において，進入経路や開創器の種類による傍脊柱筋変性をMRI画像で評価し，比較・検討した．変性はMRIのT2強調画像で輝度変化があった範囲と定義した．変性は棘突起正中縦割進入後方除圧(MSp)では1/12椎間，傍脊柱筋進入後方除圧(PV)では9/12椎間に認めた．また，MSp下で，チューブラーレトラクター使用例の変性は1/35椎間，トリムライン使用例では10/10椎間に認めた．以上から，チューブラーレトラクターを使用したMSpが傍脊柱筋に最も低侵襲であることが示唆された．

　We performed qualitative analysis of muscle degeneration of the paravertebral muscle, such as multifidus or longitudinal muscle, after spinal posterior decompression by using magnetic resonance imaging (MRI), and compared the group with the midline spinous process splitting approach (MSp) and paravertebral (PV) muscle approach in the muscle degeneration.　We also compared the subgroups used tubular to trimline retractor in the group of the MSp.　Degeneration muscle in MRI was defined as that newly shown in high signal intensity in MRI T2 weighted image after the decompression surgery.　We found the muscle degeneration in 1/12 levels in the MSp group, while 9/12 levels in the PV.　We also found it in 1/35 levels in the tubular retractor subgroup in the MSp group, while 10/10 levels on the trimline sub group.　Thus, we suggest the spinal posterior decompression in the MSp with tubular retractor as the most minimal invasive surgery.