Degeneration of the mid-cingulate cortex in amyotrophic lateral sclerosis detected in vivo with MR spectroscopy

Abstract

Background and purpose: Various lines of evidence implicate cerebral involvement beyond the motor cortex in ALS, including the cingulate gyrus and the thalamus. The purpose of this study was to assess neurodegeneration in these regions in vivo by using MRSI.

Materials and methods: Fourteen patients with ALS and 14 healthy controls underwent MRSI by using a coronal acquisition scheme. The NAA/Cho ratio was quantified in the MCC, thalamus, and motor cortex (PCG).

Results: NAA/Cho was reduced in the MCC in patients with ALS compared with the controls (P = .0004). There was no difference in NAA/Cho in the thalamus (P = .59). We also found a strong correlation of NAA/Cho among the PCG, MCC, and the thalamus in controls, which was absent in patients with ALS.

Conclusions: Neurodegeneration beyond the motor cortex is present in the MCC in ALS. The significant correlation of NAA/Cho among the PCG, MCC, and the thalamus in healthy subjects likely reflects the neuronal connectivity among these regions. The loss of these relationships in patients with ALS suggests that such connectivity is not responsible for the pattern of degeneration in these regions.

Fig 1.

Spectroscopic imaging. A coronal MR image is shown on the left demonstrating placement of the volume of interest (thick white border). Voxels identified for analysis included those in the PCG (squares), MCC (open circles), and thalamus (closed circles). A representative spectrum from each of these regions is presented on the right from a control subject and a patient with ALS.

Fig 2.

Loss of neurochemical associations among regions in patients with ALS. Strong correlations of NAA/Cho are present among regions in healthy control subjects (open circles); whereas, in patients (closed circles, regression coefficients not displayed) significant correlations are not observed.