Magnetic resonance imaging and H-1-magnetic resonance spectroscopy in amyotrophic lateral sclerosis

We aimed to increase confidence in the combined use of MRI and proton MR sp ectroscopy (H-1-MRS) in diagnosis of amyotrophic lateral sclerosis (ALS). W e investigated 12 patients with ALS, seven definite and five probable, taki ng into account clinical measures of motor neuron function. On T2-weighted images we found high signal in the corticospinal tract in six and low signa l in the primary motor cortex in seven of the 12 patients. Atrophy of the p recentral gyrus was apparent in all the patients apart from one with probab le ALS. Absolute quantification of cerebral metabolites using 1H-MRS demons trated a significantly lower mean concentration of N-acetylaspartate (NAA) in the precentral gyrus of patients with probable and definite ALS (8.5 +/- 0.62) than in control subjects (10.4 +/- 0.71; P < 0.001). NAA concentrati on in primary motor cortex correlated with Norris scale scores (r = 0.30; P < 0.0001) but not with the ALS Functional Rating Scale score or disease du ration. Significantly lower levels of NAA were detected in patients with lo w signal in the motor cortex than in those without (P < 0.01). Mean choline (Cho) and creatine (Cr) values did not differ between patients with ALS an d controls.