Metabolite and functional profile of patients with cervical spondylotic myelopathy.
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.
Department of Medical Biophysics and.|Centre for Functional and Metabolic Mapping, Robarts Research Institute, Western University; and.
Izabela
I
Aleksanderek
Centre for Functional and Metabolic Mapping, Robarts Research Institute, Western University; and.
Todd K
TK
Stevens
Department of Medical Biophysics and.|Centre for Functional and Metabolic Mapping, Robarts Research Institute, Western University; and.
Sandy
S
Goncalves
Department of Medical Biophysics and.|Centre for Functional and Metabolic Mapping, Robarts Research Institute, Western University; and.
Robert
R
Bartha
Department of Medical Biophysics and.|Department of Clinical Neurological Sciences, University Hospital, London Health Sciences Centre, London, Ontario, Canada.
Neil
N
Duggal
D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D002574:Cervical Vertebrae / Q000601:surgery*; D003401:Creatine / Q000378:metabolism; D019299:Decompression, Surgical; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D009044:Motor Cortex / Q000000981:diagnostic imaging / Q000378:metabolism*; D009473:Neuronal Plasticity / Q000502:physiology; D011446:Prospective Studies; D020127:Recovery of Function; D012720:Severity of Illness Index; D013003:Somatosensory Cortex / Q000000981:diagnostic imaging / Q000378:metabolism; D013118:Spinal Cord Diseases / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000601:surgery*; D055009:Spondylosis / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000601:surgery*; D011795:Surveys and Questionnaires; D016896:Treatment Outcome
D001224:Aspartic Acid; C000179:N-acetylaspartate; D003401:Creatine
BA = Brodmann area; COG = center of gravity; CSM = cervical spondylotic myelopathy; Cr = creatine; FDR = false discovery rate; M1 = primary motor cortex; MRS = MR spectroscopy; N-acetylaspartate; NAA = N-acetylaspartate; VOA = volume of activation; brain plasticity; cervical spondylotic myelopathy; fMRI = functional MRI; functional MRI; mJOA = modified Japanese Orthopaedic Association; magnetic resonance spectroscopy