title: Frontal lobe abnormalities on MRS correlate with poor letter fluency in ALS.
abstract: OBJECTIVE
  To examine whether frontal lobe abnormalities on magnetic resonance spectroscopy (MRS) in amyotrophic lateral sclerosis (ALS) correlate with poor letter fluency (LF).
  
  
  METHODS
  Twenty-five patients with ALS (20 with definite, probable, or possible ALS and 5 with progressive muscular atrophy) performed an LF task, involving F word generation in 1 minute, and underwent MRS. Comparisons were made between patients with ALS with impaired LF and unimpaired LF based on an empirically derived cutoff score. A Spearman correlation was performed between the patient's N-acetyl acetate/creatinine-phosphocreatinine ratio (NAA/Cr) and the number of F words generated.
  
  
  RESULTS
  LF was impaired in 50% of patients with ALS. Patients with impaired LF had reduced NAA/Cr in the DLPFC compared with those with unimpaired LF (p = 0.007). There was a significant correlation between LF and NAA/Cr in the DLPFC (r = 0.51, p = 0.0009). The ALS Functional Rating Scale score, clinical region of motor onset, and disease category had no effect on LF or NAA/Cr in the DLPFC.
  
  
  CONCLUSIONS
  A reduced NAA/Cr in the DLPFC of patients with ALS is a marker of neuronal dysfunction and correlates with impaired performance on a clinical measure of executive function.
authors: Department of Neurology, University of Pennsylvania, PA, USA. colincq@gmail.com
authors: Colin
authors: C
authors: Quinn
authors: Lauren
authors: L
authors: Elman
authors: Leo
authors: L
authors: McCluskey
authors: Katelin
authors: K
authors: Hoskins
authors: Chafic
authors: C
authors: Karam
authors: John H
authors: JH
authors: Woo
authors: Harish
authors: H
authors: Poptani
authors: Sumei
authors: S
authors: Wang
authors: Sanjeev
authors: S
authors: Chawla
authors: Scott E
authors: SE
authors: Kasner
authors: Murray
authors: M
authors: Grossman
mesh_terms: D000690:Amyotrophic Lateral Sclerosis / Q000150:complications / Q000503:physiopathology*; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D013060:Speech; D013064:Speech Disorders / Q000209:etiology / Q000503:physiopathology*