title: Prolongation of the tibialis anterior CMAP duration in chronic inflammatory demyelinating polyneuropathy.
abstract: OBJECTIVE
  To assess the duration of the distal compound muscle action potential (dCMAP) recording from the tibialis anterior (TA) as a supportive electrodiagnostic feature in chronic inflammatory demyelinating polyneuropathy (CIDP).
  
  
  METHODS
  We performed peroneal motor conduction studies with recording from the TA in 35 CIDP patients, 30 normal controls, and 21 disease controls. The normal cut-off for the TA dCMAP duration was determined to be 14 ms.
  
  
  RESULTS
  Prolonged TA dCMAP durations were detected in 34% of CIDP patients (12/35) and in 33% (2/6) of patients in whom only one demyelinating lesion was identified by conventional motor conduction studies. Prolonged TA dCMAP durations were present in 28% (5/18) of patients with normal duration dCMAPs recorded from the abductor hallucis (AH) and in 42% (5/12) of patients with normal duration dCMAPs recorded from the extensor digitorum brevis (EDB). In patients with AH or EDB dCMAP amplitudes <1 mV, TA dCMAP durations were prolonged in 28% and 23% of patients, respectively.
  
  
  CONCLUSIONS
  Determination of TA dCMAP duration appears to be useful for detecting demyelination in CIDP, especially when there is significant coexisting axon loss.
  
  
  CONCLUSIONS
  In patients with potential CIDP and limited electrodiagnostic abnormalities by routine studies, the finding of additional demyelinating findings, such as increased TA dCMAP duration, could allow for improved diagnostic sensitivity.
authors.affiliation: Peripheral Neuropathy Center, Department of Neurology, Weill Cornell Medical College, New York, NY, USA. hnodera@bidmc.harvard.edu
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nodera
authors.forename: Norman
authors.initials: N
authors.lastname: Latov
authors.forename: Bridget
authors.initials: B
authors.lastname: Carey
authors.forename: Jennifer
authors.initials: J
authors.lastname: Langsdorf
authors.forename: Veronica
authors.initials: V
authors.lastname: Bedoya
authors.forename: Svetla
authors.initials: S
authors.lastname: Tacheva
authors.forename: Russell L
authors.initials: RL
authors.lastname: Chin
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D020277:Polyradiculoneuropathy, Chronic Inflammatory Demyelinating / Q000175:diagnosis* / Q000503:physiopathology*; D011446:Prospective Studies; D012189:Retrospective Studies; D013997:Time Factors; D055815:Young Adult