Aleksanderek Izabela, Stevens Todd K, Goncalves Sandy, Bartha Robert, Duggal Neil
Department of Medical Biophysics and.
Centre for Functional and Metabolic Mapping, Robarts Research Institute, Western University; and.
J Neurosurg Spine. 2017 May;26(5):547-553. doi: 10.3171/2016.9.SPINE151507. Epub 2017 Feb 3.
OBJECTIVE The goal of this study was to compare the recovery of neuronal metabolism and functional reorganization in the primary motor cortex (M1) between mild and moderate cervical spondylotic myelopathy (CSM) following surgical intervention. METHODS Twenty-eight patients with CSM underwent 3-T MRI scans that included spectroscopy and functional MRI, before surgery and 6 months postsurgery. The classification of severity was based on the modified Japanese Orthopaedic Association questionnaire. Mild and moderate myelopathy were defined by modified Japanese Orthopaedic Association scores > 12 of 18 (n = 15) and 9-12 (n = 13), respectively. Ten healthy control subjects underwent 2 MRI scans 6 months apart. Metabolite levels were measured in the M1 contralateral to the greater deficit side in patients with CSM and on both sides in the controls. Motor function was assessed using a right finger-tapping paradigm and analyzed with BrainVoyager QX. RESULTS Patients with mild CSM had a lower preoperative N-acetylaspartate to creatine (NAA/Cr) ratio compared with moderate CSM, suggesting mitochondrial dysfunction. Postsurgery, NAA/Cr in moderate CSM decreased to the levels observed in mild CSM. Preoperatively, patients with mild CSM had a larger volume of activation (VOA) in the M1 than those with moderate CSM. Postoperatively, the VOAs were comparable between the mild and moderate CSM groups and had shifted toward the primary sensory cortex. CONCLUSIONS The NAA/Cr ratio and VOA size in the M1 can be used to discriminate between mild and moderate CSM. Postsurgery, the metabolite profile of the M1 did not recover in either group, despite significant clinical improvement. The authors proposed that metabolic impairment in the M1 may trigger the recruitment of adjacent healthy cortex to achieve functional recovery.
目的 本研究旨在比较轻度和中度脊髓型颈椎病（CSM）患者手术干预后初级运动皮层（M1）神经元代谢恢复情况及功能重组。方法 28例CSM患者在手术前及术后6个月接受了3-T磁共振成像（MRI）扫描，包括磁共振波谱成像和功能MRI。严重程度分类基于改良日本骨科学会问卷。轻度和中度脊髓病分别由改良日本骨科学会评分>12分（共18分，n = 15）和9 - 12分（n = 13）定义。10名健康对照者相隔6个月接受2次MRI扫描。在CSM患者中，于M1中与较大功能缺损侧对侧测量代谢物水平，在对照组中则测量双侧代谢物水平。使用右手手指敲击范式评估运动功能，并通过BrainVoyager QX进行分析。结果 与中度CSM相比，轻度CSM患者术前N-乙酰天门冬氨酸与肌酸（NAA/Cr）比值较低，提示线粒体功能障碍。术后，中度CSM患者的NAA/Cr降至轻度CSM患者术前观察到的水平。术前，轻度CSM患者M1中的激活体积（VOA）大于中度CSM患者。术后，轻度和中度CSM组的VOA相当，且已向初级感觉皮层转移。结论 M1中的NAA/Cr比值和VOA大小可用于区分轻度和中度CSM。术后，尽管临床有显著改善，但两组M1的代谢物谱均未恢复。作者提出，M1中的代谢损伤可能会促使邻近健康皮层的募集以实现功能恢复。
