title: fNIRS evaluation during a phonemic verbal task reveals prefrontal hypometabolism in patients affected by myotonic dystrophy type 1.
abstract: OBJECTIVE
  Myotonic dystrophy type 1 (DM1), the most common muscular dystrophy in adults, is characterized by a multisystem involvement. Cognitive involvement predominantly affecting frono-temporal functions is an established clinical feature in this disorder. Brain imaging and metabolic studies showed a predominant involvement of fronto-temporal regions in DM1 patients, yet correlation studies among these findings and neuropsychological data gave contrasting results. In order to contribute to clarify the relationship between the metabolic changes documented in the frontal cortex of DM1 patients and a related cognitive task, we applied the functional near-infrared spectroscopy (fNIRS) during the execution of a phonemic verbal fluency task (pVFT).
  
  
  METHODS
  We enrolled 29 consecutive right-handed DM1 patients and 30 controls. A 2-channel fNIRS imaging system was used to investigate changes in oxygenated [O2Hb] and deoxygenated [HHb] hemoglobin concentrations in the prefrontal cortex (PFC) during a pVFT. [O2Hb] and [HHb] baseline-corrected activation values were calculated (respectively [O2Hb]c and [HHb]c).
  
  
  RESULTS
  In the control group [O2Hb] significantly increased and [HHb] significantly decreased during the pVFT, in the DM1 group no significant variation was found for both parameters revealing no activation of both PFCs during the task. On the other hand, in the DM1 sample, statistical analysis revealed a direct correlation between [O2Hb]c of the left PFC and the pVFT score, while no correlation was observed in the control group.
  
  
  CONCLUSIONS
  Our study reveals that DM1 patients show prefrontal hypometabolism during a specific frontal cognitive task compared to controls. Moreover the rapid temporal discrimination of fNIRS allows revealing the correlation between the PFC hypometabolism and the cognitive performance in DM1 patients.
  
  
  CONCLUSIONS
  fNIRS can be helpful to understand the functional correlates of the frontal cognitive impairment in DM1.
authors.affiliation: Department of Geriatrics-Neuroscience-Orthopaedics-Physiatrics, Institute of Neurology, Catholic University, Rome, Italy. Electronic address: p.caliandro@rm.unicatt.it.
authors.forename: Pietro
authors.initials: P
authors.lastname: Caliandro
authors.forename: Gabriella
authors.initials: G
authors.lastname: Silvestri
authors.forename: Luca
authors.initials: L
authors.lastname: Padua
authors.forename: Maria Laura Ester
authors.initials: ML
authors.lastname: Bianchi
authors.forename: Chiara
authors.initials: C
authors.lastname: Simbolotti
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Russo
authors.forename: Marcella
authors.initials: M
authors.lastname: Masciullo
authors.forename: Paolo Maria
authors.initials: PM
authors.lastname: Rossini
mesh_terms: D000328:Adult; D005260:Female; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009223:Myotonic Dystrophy / Q000378:metabolism*; D010700:Phonetics; D017397:Prefrontal Cortex / Q000378:metabolism*; D012660:Semantics; D019265:Spectroscopy, Near-Infrared; D014705:Verbal Behavior / Q000502:physiology
chemical_list: D006454:Hemoglobins; C100003:deoxyhemoglobin
keywords: Myotonic dystrophy; Prefrontal cortex; fNIRS