Presymptomatic spinal cord neurometabolic findings in SOD1-positive people at risk for familial ALS

Objectives: It has been speculated that amyotrophic lateral sclerosis (ALS) is characterized by a premanifest period during which neurodegeneration precedes the appearance of clinical manifestations. Magnetic resonance spectroscopy (MRS) was used to measure rations of neurometabolites in the cervical spine of asymptomatic individuals with a mutation in the SOD1 gene (SOD1+) and compare their neurometabolic ratios to patients with ALS and healthy controls. Methods: A cross-sectional study of (1)H-MRS of the cervical spine was performed on 24 presymptomatic SOD1+ volunteers, 29 healthy controls, and 23 patients with ALS. All presymptomatic subjects had no symptoms of disease, normal forced vital capacity, and normal electromyographic examination. Relative concentrations of choline (Cho), creatine (Cr), myo-inositol (Myo), and N-acetylasparate (NAA) were determined. Results: NAA/Cr and NAA/Myo rations are reduced in both SOD1+ subjects (39.7%, p = 0.001 and 18.0%, p = 0.02) and patients with ALS (41.2%, p < 0.001 and 24.0%, p = 0.01) compared to controls. Myo/Cr is reduced (10.3%, p = 0.02) in SOD1+ subjects compared to controls, but no difference was found between patients with ALS and controls. By contrast, NAA/Cho is reduced in patients with ALS (24.0%, p = 0.002), but not in presymptomatic SOD1+ subjects compared to controls. Conclusions: Changes in neurometabolite ratios in the cervical spinal cord are evident in presymptomatic SOD1+ individuals in advance of symptoms and clinical or electromyographic changes in this population resemble changes observed in patients with clinically apparent ALS. This suggest that neurometabolic changed occur early in the course of the disease process. Neurology (R) 2011;77:1370-1375