Advanced magnetic resonance neuroimaging in bulbar and limb onset early amyotrophic lateral sclerosis

Abstract

Introduction:Amyotrophic lateral sclerosis (ALS) is a fatal and most common motor neuron disease, caused by progressive loss of motor neurons. Diffusion tensor imaging (DTI) and magnetic resonance spectroscopic (MRS) studies detect pathological changes in neuronal fibers in vivo. We evaluated the role of DTI and MRS in early course of the disease, which may prove beneficial in the early diagnosis and better management.Materials and Methods:Twenty-one patients with ALS and 13 age-matched controls received 1.5T DTI and three-dimensional multi-voxel MRS. Fractional anisotropy (FA), apparent diffusion coefficient, N-acetyl aspartate (NAA)/Creatine (Cr), and NAA/Choline (Ch) ratios were analyzed in various regions of the brain and compared with healthy controls. ALS patients were classified as definite, possible, and probable category, and patients were also studied in limb versus bulbar onset.Results:Decreased FA and increase mean diffusivity values in regions of corticospinal tract (CST) and corpus callosum (CC) was consistent finding in definite and probable disease category (P < 0.05). In possible disease, CC involvement was not significant. NAA/Cr and NAA/Ch ratios were lower in CC and regions of CST. However, in possible disease, CC involvement was not significant, while regions of CST were showing significant reduction in NAA/Cr and NAA/Ch ratios (P < 0.05).Conclusion:DTI and MRS detect changes associated with ALS even in the early phase of the disease. Bulbar onset and limb onset ALS patients show different pattern of involvement. Extramotor involvement suggested by CC involvement is a feature seen in bulbar onset patient and can suggest poor outcome in such patients. The present findings may be helpful for designing further studies in the direction of more early diagnosis of disease and its management.

Hippocampal Metabolic Alterations in Amyotrophic Lateral Sclerosis: A Magnetic Resonance Spectroscopy Study

“…There is now ample evidence that MRS is both sensitive to detect focal changes and exhibit good correlations with relevant clinical metrics and therefore should be incorporated in both future single-centre and multi-centre studies. The challenges of voxel placement consistency and ROI selection are likely to be overcome by emerging whole-brain, multi-voxel techniques that have already been successfully piloted in ALS [ 115 , 116 , 117 ].…”

Progressive Neurochemical Abnormalities in Cognitive and Motor Subgroups of Amyotrophic Lateral Sclerosis

“…MRS studies in ALS have consistently revealed abnormalities in the motor cortex, demonstrating reductions in NAA/Cr, 6,[23][24][25][26][27] NAA/Cho, 6,23,24,26,27 and NAA/Ino. 2,23 Previously, neurochemical correlates were reported with DPR for both NAA/ Cr 28 and NAA/Cho 3,26 in the motor region, which corroborate with the present study findings.…”

Clinical Measures of Bulbar Dysfunction in ALS

“…Emerging technologies such as quantitative neuroimaging, muscle ultrasound, electrical impedance myography (EIM), high-resolution manometry, videomanofluoroscopy, and speech acoustic monitoring are likely to soon complement our armamentarium of clinical tools. A number of promising imaging techniques have already been utilized to characterize the pathological substrate of bulbar impairment in ALS including diffusion tensor imaging (106, 107), cortical thickness measurements (50, 108, 109), morphometry-type analyses (49, 110), magnetization transfer ratio imaging (106), MR spectroscopy (111), MRI intensitometry (112), and task-based functional MRI (113, 114). Despite these advances, MRI-derived metrics remain underutilized in the clinical setting and as outcome measures in pharmacological trials.…”