A lateralized reduction of NAA in a case of corticobasal degeneration (CBD): Application of proton magnetic resonance spectroscopy (¹H-MRS)

We studied the application of proton magnetic resonance spectroscopy (¹H-MRS) in a case of corticobasal degeneration. A 73-year-old woman was referred to our hospital for dysarthria and clumsiness in right arm movement. Intelligence was normal and neither ideational apraxia or ideomotor apraxia were observed. Her speech was slurred and extremely slow. Neurological findings showed a limitation of ocular upward gaze movement, impaired smooth pursuit in the horizontal gaze, rigidity, limb kinetic apraxia and cortical sensory disturbance in the right arm. Magnetic resonance imaging (MRI) showed diffuse brain atrophy, especially in the left fronto-parietal cortex around the central sulcus. A positron emission tomography (PET) study showed diffuse decrement of cerebral blood flow, dominantly in the left hemisphere. The decrease in the uptake of ¹⁸F-Fluoro-deoxyglucose also revealed glucose hypo-metabolism, especially ill the left frontal and parietal lobe. ¹H-MRS by the multivoxel method showed a decrease in N-acetylaspartate (NAA)/Creatine to 1.0 in the left basal ganglia and temporal lobe, compared to the values between 1.4 and 1.7 in the right basal ganglia. These findings indicated that ¹H-MRS might detect neuronal loss or degeneration when MRI showed minimal cortical atrophy. This study, the first application of ¹H- MRS in a case of corticobasal degeneration, showed that this method was useful for the evaluation of pathophysiological changes in corticobasal degeneration.