title: Is total duration of distal compound muscle action potential better than negative peak duration in the diagnosis of chronic inflammatory demyelinating polyneuropathy?
abstract: BACKGROUND
  The diagnosis of chronic inflammatory demyelinating polyneuropathy (CIDP) is difficult, and the role of electrophysiology is crucial. Distal compound muscle action potential (CMAP) duration is a useful tool that is assessed by measuring negative peak duration (NP). The value of total distal CMAP duration (T), which seems more precise from a physiological standpoint, has not been studied.
  
  
  METHODS
  We reviewed retrospectively the records of 50 patients with CIDP and 50 controls with chronic axonal neuropathy. We constructed ROC curves for NP and T.
  
  
  RESULTS
  Comparison of AUC for T vs. NP showed an advantage for the former (P=0.026 for the fibular nerve). Our derived cut-offs offered a sensitivity of 42.3% for T vs. 35.3% for NP.
  
  
  CONCLUSIONS
  This study suggests a slight advantage for T over NP duration of the distal CMAP in the diagnosis of CIDP. However, the clinical relevance of this result must be weighed against the feasibility of this measurement.
authors.affiliation: Département de Neurophysiologie Clinique, AP-HP, Groupe Hospitalier Pitié-Salpêtrière, 47-83 Boulevard de l'Hôpital, 75651 Paris cedex 13, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Lagarde
authors.forename: Karine
authors.initials: K
authors.lastname: Viala
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Fournier
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D016022:Case-Control Studies; D004594:Electrophysiology; D005260:Female; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000502:physiology*; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000294:innervation*; D009431:Neural Conduction / Q000502:physiology; D010543:Peroneal Nerve / Q000502:physiology*; D020277:Polyradiculoneuropathy, Chronic Inflammatory Demyelinating / Q000175:diagnosis* / Q000503:physiopathology; D012372:ROC Curve; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013979:Tibial Nerve / Q000502:physiology*; D013997:Time Factors; D014459:Ulnar Nerve / Q000502:physiology*
keywords: CIDP; diagnostic criteria; distal CMAP duration; distal demyelination; electrophysiology