頚髄症における術中脊髄誘発電位の障害高位診断とMRI画像T2高輝度高位との相関性

The Relationship Between Electrodiagnosis Using Spinal Cord Evoked Potential after Spinal Cord Stimulation and MRI Evaluation for Cervical Myelopathy

　当センターでは，頚髄症に対する頚椎椎弓形成術の脊髄徐圧後に，簡便な方法にて術中脊髄（電気）刺激-脊髄誘発電位〔Sp(E)-SCEP〕による電気生理学的伝導障害部位診断を行っている．200症例を対象に，その結果と術前MRI画像所見とを比較し，それらの相関性および臨床的有用性について検討した．MRI画像上T2高信号域1椎間例では電気的障害高位診断と高い相関性が得られた．また，Sp(E)-SCEPで伝導障害を呈する症例は臨床的に予後不良傾向にあり，今後予後予測などに応用可能と考えられた．

　We studied the correlation between the site of high intensity spinal cord signals on preoperative sagittal T2 MRIs (T2-high signal) and that of intrdaperative electrophysiological abnormalities for 200 cervical myelopathy cases. We recorded the Sp(E)-SCEPs during posterior cervical laminoplasty operations. In the cases with a T2-high signal at single levels, conduction adnormality matched the site of T2-high signal in 50％, and no conduction abnormalities were detected in 44％. In the cases with a T2-high signal at two levels, conduction abnormality matched the site of T2-high signal in only 11％, and no conduction abnormalities were disclosed in 59％. In the cases with a T2-high signal at three or more levels, conduction abnormalities matched the site of T2-high signal in 8％ and no conduction abnormalities were disclosed in 72％. Our study showed a higher correspondence between the MRI finding and conduction abnormalities in the cases with T2-high signal at single levels, although our Sp(E)-SCEP study could not disclose conduction abnormalities in nearly half the cases. False negative findings of Sp(E)-SCEPs may result from the simplified recording technique.