Puri B K, Smith H C, Cox I J, Sargentoni J, Savic G, Maskill D W, Frankel H L, Ellaway P H, Davey N J
Robert Steiner MRI Unit, Imperial College School of Medicine, Hammersmith Hospital, London, UK.
J Neurol Neurosurg Psychiatry. 1998 Nov;65(5):748-54. doi: 10.1136/jnnp.65.5.748.
(1) A biochemical investigation of the motor cortex in patients with incomplete spinal cord injury and normal control subjects using proton magnetic resonance spectroscopy (MRS). (2) To relate any altered biochemistry with the physiological changes in corticospinal function seen after spinal cord injury.
A group of six patients with incomplete spinal cord injury who showed good recovery of motor function were selected. The patients were compared with five healthy control subjects. Electromyographic (EMG) responses of thenar muscles to transcranial magnetic stimulation (TMS) of the motor cortex showed that inhibition of cortical output was weaker in the patients than the controls. Proton MRS data were collected from a plane at the level of the centrum semiovale. Two 4.5 cm3 voxels in the motor cortex and a third voxel in the ipsilateral occipital cortex were examined in the patients and control subjects.
The mean level of N-acetylaspartate (NAA), expressed relative to the creatine (Cr) peak (NAA/Cr), was significantly increased in the motor cortex of the patients compared with their ipsilateral occipital cortex or either cortical area in the controls. No differences between patients and controls were seen for any of the other metabolite peaks (choline (Cho), glutamate/glutamine (Glx) or the aspartate component of NAA (AspNAA)) relative to Cr. Choline relative to Cr (Cho/Cr) was higher in the motor cortex of the control subjects than in their ipsilateral occipital cortex. This difference was not present in the patients.
Raised NAA/Cr in the motor cortex of the patients probably results from increased NAA rather than a decrease in the more stable Cr. The possible relevance of a raised NAA/Cr ratio is discussed, particularly with regard to the changed corticospinal physiology and the functional recovery seen in the patients.
(1) 采用质子磁共振波谱（MRS）对不完全性脊髓损伤患者和正常对照者的运动皮层进行生化研究。(2) 将任何生化改变与脊髓损伤后皮质脊髓功能的生理变化相关联。
选取一组6例运动功能恢复良好的不完全性脊髓损伤患者。将这些患者与5名健康对照者进行比较。对运动皮层进行经颅磁刺激（TMS）时，小鱼际肌的肌电图（EMG）反应显示，患者的皮质输出抑制比对照者弱。从半卵圆中心水平的平面收集质子MRS数据。在患者和对照者中，对运动皮层中的两个4.5 cm³体素以及同侧枕叶皮层中的第三个体素进行了检查。
与同侧枕叶皮层或对照者的任一皮层区域相比，患者运动皮层中相对于肌酸（Cr）峰的N-乙酰天门冬氨酸（NAA）平均水平（NAA/Cr）显著升高。相对于Cr，患者和对照者在任何其他代谢物峰（胆碱（Cho）、谷氨酸/谷氨酰胺（Glx）或NAA的天冬氨酸成分（AspNAA））方面均未观察到差异。相对于Cr的胆碱（Cho/Cr）在对照者的运动皮层中高于其同侧枕叶皮层。患者中不存在这种差异。
患者运动皮层中升高的NAA/Cr可能是由于NAA增加而非更稳定的Cr减少所致。讨论了升高的NAA/Cr比值的可能相关性，特别是关于患者中观察到的皮质脊髓生理学改变和功能恢复。
