C3-4頚椎症性脊髄症モデルにおける索路障害の進展様式について

Progression of Spinal Tract Lesion in the Cervical Spondylotic Myelopathy at the C3-4 Intervertebral Level

　圧迫性頚髄症における索路症状の進展様式，臨床所見との対比を詳細に知るために，術中脊髄誘発電位でC3-4単椎間障害と診断された頚椎症性脊髄症（CSM）20例を対象として検討した．脊髄誘発電位の異常所見の有無と索路障害の広がりを対比させ，横断型（すべての脊髄誘発電位で異常を呈するもの），後外側型（正中神経刺激と経頭蓋電気刺激で異常を呈するもの），上肢知覚型（正中神経刺激でのみ異常を呈するもの）に分類した．CSMの索路障害は急激な悪化例を除けば，上肢の後索，皮質脊髄路，体幹・下肢の後索の順に索路障害が生じるものと結論した．

　A total of 20 patients with cervical spondylotic myelopathy (CSM) were included in this study. In all the patients, only the C3-4 intervertebral level was symptomatic, as shown by examinations of the spinal cord evoked potentials (SCEPs). SCEPs following median nerve stimulation (MN-SCEPs), transcranial electric stimulation (TES-SCEPs), and spinal cord stimulation (Spinal-SCEPs) were recorded. MN-SCEPs were most sensitive (100％ sensitivity), followed by TES-SCEPs (83.3％ sensitivity). The patients were grouped into three types as follows：transverse type, all SCEPs were abnormal；posterolateral type, abnormalities were observed in the MN-SCEPs and TES-SCEPs；and upper limb sensory type, only the MN-SCEPs were abnormal. Thirteen (65％) of the 20 patients were grouped into the transverse type, 4 into the posterolateral type, and 3 into the upper limb sensory type. Although the involvement of the anterior spinal tract was not determined, the present study showed that the posterolateral area of the posterior column associated with upper limb sensation was more vulnerable than the corticospinal area. Finger numbness in mild CSM at an early stage may originate from posterior column lesions associated with the upper limbs.