Mesial prefrontal cortex degeneration in amyotrophic lateral sclerosis: a high-field proton MR spectroscopy study.

BACKGROUND AND PURPOSE

Frontotemporal lobar degeneration is responsible for the cognitive abnormalities seen in patients with ALS. We sought to evaluate the in vivo neurochemical changes associated with this pathology indicative of neuronal loss and gliosis.

MATERIALS AND METHODS

Twenty-four patients with ALS (2 with ALS-FTD) and 15 healthy controls were studied. High-field proton MR spectroscopy of the mesial prefrontal cortex was used to determine concentrations of NAA and mIns, markers of neuronal integrity and gliosis, respectively. Metabolite concentrations were correlated with cognitive tests (verbal fluency, ACE).

RESULTS

NAA/mIns was decreased 17% (P =.002). Abnormalities were present to a lesser degree in the individual metabolites NAA (decreased 9%; P =.08) and mIns (increased 11%; P =.06) than the ratio of the 2 metabolites. These measures did not correlate significantly with verbal fluency or the ACE.

CONCLUSIONS

Prefrontal lobe degeneration exists in patients with ALS as indicated by an abnormal mesial prefrontal cortex neurochemical profile. Further study is necessary to determine the potential utility of the NAA/mIns ratio as a biomarker for frontal lobe degeneration in ALS.