title: Electrophysiological and spinal imaging evidences for sensory dysfunction in amyotrophic lateral sclerosis.
abstract: OBJECTIVE
  The prevalence of sensory impairment at an early stage of amyotrophic lateral sclerosis (ALS) is still debated. The study aim was to investigate the anatomofunctional properties of sensory pathways in patients with ALS, combining spinal diffusion tensor imaging (DTI) and somatosensory evoked potentials (SEPs).
  
  
  METHODS
  Case-control study.
  
  
  METHODS
  ALS referral centre and laboratory of biomedical imaging (Paris, France).
  
  
  METHODS
  Well-characterised group of 21 patients with ALS with moderate disability (mean amyotrophic lateral sclerosis Functional Rating Scale (ALSFRS) score 39.3±1.0) and no clinical sensory signs and control group of 21 gender and age-matched healthy subjects.
  
  
  METHODS
  Fractional anisotropy and diffusivity of the dorsal columns at C5-T1 levels (DTI metrics) and SEPs after median and ulnar nerve stimulations (latency and amplitude of N9 and N20 components).
  
  
  RESULTS
  Abnormal DTI metrics indicated anatomical damages of ascending sensory fibres in ∼60% of patients (p<0.05). Raw SEPs (μV) were smaller in ∼40% of patients but the difference with healthy subjects was not significant (p>0.16). Their normalisation to prestimulus activity strengthened the difference between groups (p<0.05) and allowed identification of ∼60% of patients with abnormal values. According to N9 latency, the peripheral conduction time was normal in patients (p>0.32) but based on N20 latency, the central conduction time (between spinal cord and parietal cortex) was found to be slower (p<0.05). Significant correlation was found between DTI metrics and N9 amplitude (p<0.05). Altered SEPs were also correlated with the disease duration (p<0.05). Taken together, spinal imaging and electrophysiology helped to identify ∼85% of patients with subclinical sensory defect while separated methods revealed abnormal values in ∼60%.
  
  
  CONCLUSIONS
  Sensory impairments have been underestimated at early stages of ALS. These results show for the first time the interest to combine electrophysiology and imaging to assess non-motor system involvement in ALS.
  
  
  BACKGROUND
  IDRCB2012-A00016-37.
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS, INSERM, Laboratoire d'Imagerie Biomédicale, Paris, France.
authors.forename: Caroline
authors.initials: C
authors.lastname: Iglesias
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS, INSERM, Laboratoire d'Imagerie Biomédicale, Paris, France.
authors.forename: Sina
authors.initials: S
authors.lastname: Sangari
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS, INSERM, Laboratoire d'Imagerie Biomédicale, Paris, France.
authors.forename: Mohamed-Mounir
authors.initials: MM
authors.lastname: El Mendili
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS, INSERM, Laboratoire d'Imagerie Biomédicale, Paris, France.
authors.forename: Habib
authors.initials: H
authors.lastname: Benali
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS, INSERM, Laboratoire d'Imagerie Biomédicale, Paris, France.
authors.forename: Véronique
authors.initials: V
authors.lastname: Marchand-Pauvert
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS, INSERM, Laboratoire d'Imagerie Biomédicale, Paris, France Département des Maladies du Système Nerveux, AP-HP, Hôpital Pitié-Salpêtrière, Paris, France.
authors.forename: Pierre-François
authors.initials: PF
authors.lastname: Pradat
mesh_terms: D000328:Adult; D000368:Aged; D000690:Amyotrophic Lateral Sclerosis / Q000473:pathology / Q000503:physiopathology*; D016022:Case-Control Studies; D056324:Diffusion Tensor Imaging / Q000379:methods; D055724:Electrophysiological Phenomena; D005073:Evoked Potentials, Somatosensory; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011930:Reaction Time; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013003:Somatosensory Cortex / Q000503:physiopathology*