title: Cognitive event-related potentials in multiple sclerosis: Correlation with MRI and neuropsychological findings.
abstract: BACKGROUND
  Cognitive event-related potentials (ERPs) have been previously correlated with T2 lesion load (Τ2LL) in patients with multiple sclerosis (MS). It is currently unknown, however, whether ERPs also correlate with brain atrophy or the presence of T1 hypointense lesions ("black holes") which reflect tissue destruction and axonal loss. The primary aim of the current study is to explore the effect of neuroradiological parameters such as brain atrophy, T1 and T2 lesion load on auditory ERPs in MS patients. In addition, we correlated cognitive impairment with neurophysiological (ERP) and neuroradiological (MRI) variables and investigated whether a combination of ERP and MRI parameters is capable of distinguishing patients suffering from secondary progressive (SP), primary progressive (PP) and relapsing-remitting (RR) MS.
  
  
  METHODS
  The study sample consisted of fifty nine MS patients (mean age±SD: 37.82±1.38 years; average disease duration: 6.76±5.3 years) and twenty six age-matched controls (mean age±SD: 41.42±15.39 years). The patients' EDSS and NRS scores were 3.77±2.14 (range: 1-7.5) and 75.88±11.99 (range: 42-94) respectively. ERPs were recorded using the auditory "odd-ball" paradigm. T1 and T2 lesions were automatically segmented using an edge-finding tool and total lesion volumes were calculated. MRI measures of brain atrophy included third ventricle width (THIRDVW) and the ratio of mid-sagittal corpus callosum area to the mid-sagittal intracranial skull surface area (CC/MISS). Statistical analysis was performed using multiple regression, principal component (PCA) and discriminant analysis.
  
  
  RESULTS
  T1 lesion load emerged as the most significant predictor of P300 and N200 latency. The rest of the endogenous ERPs parameters (P300 amplitude, N200 amplitude) were not significantly correlated with the MRI variables. PCA of pooled neuroradiological and neurophysiological markers suggested that four components accounted for 64.6% of the total variability. Discriminant analysis based on ERP & MRI markers classified correctly 79.63% of patients in RR, PP and SP subgroups.
  
  
  CONCLUSIONS
  T1 lesion load is the most significant MRI correlate of auditory ERPs in MS patients. Importantly, ERPs in combination with MRI variables can be usefully employed for distinguishing patients with different subtypes of MS.
authors.affiliation: Laboratory of Clinical Neurophysiology, AHEPA Hospital, Aristotle University of Thessaloniki, Greece.
authors.forename: Vasilios K
authors.initials: VK
authors.lastname: Kimiskidis
authors.affiliation: Laboratory of Clinical Neurophysiology, AHEPA Hospital, Aristotle University of Thessaloniki, Greece. Electronic address: vpapal@auth.gr.
authors.forename: Vasileios
authors.initials: V
authors.lastname: Papaliagkas
authors.affiliation: Laboratory of Mathematics and Statistics, Agricultural University of Athens, Greece.
authors.forename: Kyriaki
authors.initials: K
authors.lastname: Sotirakoglou
authors.affiliation: Department of Psychology, Aristotle University of Thessaloniki, Greece.
authors.forename: Zoi K
authors.initials: ZK
authors.lastname: Kouvatsou
authors.affiliation: 3rd Department of Neurology, Aristotle University of Thessaloniki, "G Papanikolaou" General Hospital, Exohi, Greece.
authors.forename: Victoria K
authors.initials: VK
authors.lastname: Kapina
authors.affiliation: Department of Radiology, Faculty of Medicine, University of Crete, University Hospital, Heraklion 71110 Stavrakia, Greece.
authors.forename: Efrosini
authors.initials: E
authors.lastname: Papadaki
authors.affiliation: 3rd Department of Neurology, Aristotle University of Thessaloniki, "G Papanikolaou" General Hospital, Exohi, Greece.
authors.forename: Vaia
authors.initials: V
authors.lastname: Tsimourtou
authors.affiliation: Department of Psychology, Aristotle University of Thessaloniki, Greece.
authors.forename: Elvira
authors.initials: E
authors.lastname: Masoura
authors.affiliation: 3rd Department of Neurology, Aristotle University of Thessaloniki, "G Papanikolaou" General Hospital, Exohi, Greece.
authors.forename: Dimitrios A
authors.initials: DA
authors.lastname: Kazis
authors.affiliation: 3rd Department of Neurology, Aristotle University of Thessaloniki, "G Papanikolaou" General Hospital, Exohi, Greece.
authors.forename: Sotirios
authors.initials: S
authors.lastname: Papayiannopoulos
authors.affiliation: Department of Radiology, "G Papanikolaou" General Hospital, Exohi, Greece.
authors.forename: Triantafyllos
authors.initials: T
authors.lastname: Geroukis
authors.affiliation: 3rd Department of Neurology, Aristotle University of Thessaloniki, "G Papanikolaou" General Hospital, Exohi, Greece.
authors.forename: Sevasti
authors.initials: S
authors.lastname: Bostanjopoulou
mesh_terms: D000328:Adult; D000375:Aging / Q000502:physiology / Q000523:psychology; D001284:Atrophy; D001307:Auditory Perception / Q000502:physiology; D001921:Brain / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology*; D003071:Cognition / Q000502:physiology*; D003937:Diagnosis, Differential; D004185:Disability Evaluation; D016002:Discriminant Analysis; D004569:Electroencephalography; D005071:Evoked Potentials; D006801:Humans; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D009103:Multiple Sclerosis / Q000145:classification / Q000000981:diagnostic imaging* / Q000503:physiopathology* / Q000523:psychology; D009483:Neuropsychological Tests; D009929:Organ Size
keywords: Brain atrophy; Cognitive impairment; Event-related potentials; MRI; Multiple sclerosis