title: Ulnar sensory-motor amplitude ratio: a new tool to differentiate ganglionopathy from polyneuropathy.
abstract: The objective of this study was to evaluate if the ratio of ulnar sensory nerve action potential (SNAP) over compound muscle action potential (CMAP) amplitudes (USMAR) would help in the distinction between ganglionopathy (GNP) and polyneuropathy (PNP).
  
  
  METHODS
  We reviewed the nerve conductions studies and electromyography (EMG) of 18 GNP patients, 33 diabetic PNP patients and 56 controls. GNP was defined by simultaneous nerve conduction studies (NCS) and magnetic resonance imaging (MRI) abnormalities. PNP was defined by usual clinical and NCS criteria. We used ANOVA with post-hoc Tukey test and ROC curve analysis to compare ulnar SNAP and CMAP, as well as USMAR in the groups.
  
  
  RESULTS
  Ulnar CMAP amplitudes were similar between GNP x PNP x Controls (p=0.253), but ulnar SNAP amplitudes (1.6±3.2 x 11.9±9.1 × 45.7±24.7) and USMAR values (0.3±0.3 × 1.5±0.9 × 4.6±2.2) were significantly different. A USMAR threshold of 0.71 was able to differentiate GNP and PNP (94.4% sensitivity and 90.9% specificity).
  
  
  CONCLUSIONS
  USMAR is a practical and reliable tool for the differentiation between GNP and PNP.
authors.affiliation: Department of Neurology, School of Medicine, University of Campinas (UNICAMP), Campinas SP, Brazil.
authors.forename: Raphael Ubirajara
authors.initials: RU
authors.lastname: Garcia
authors.forename: João Adilson Gama
authors.initials: JA
authors.lastname: Ricardo
authors.forename: Cassiana Abreu
authors.initials: CA
authors.lastname: Horta
authors.forename: Solange Garcia
authors.initials: SG
authors.lastname: Garibaldi
authors.forename: Anamarli
authors.initials: A
authors.lastname: Nucci
authors.forename: Marcondes Cavalcante
authors.initials: MC
authors.lastname: França
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000328:Adult; D000704:Analysis of Variance; D016022:Case-Control Studies; D003929:Diabetic Neuropathies / Q000175:diagnosis; D003937:Diagnosis, Differential; D004576:Electromyography; D005260:Female; D005724:Ganglia / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction / Q000502:physiology; D011115:Polyneuropathies / Q000175:diagnosis*; D012372:ROC Curve; D015203:Reproducibility of Results; D014459:Ulnar Nerve / Q000503:physiopathology*