title: Motor excitability measurements: the influence of gender, body mass index, age and temperature in healthy controls.
abstract: OBJECTIVE
  The technique of threshold tracking to test axonal excitability gives information about nodal and internodal ion channel function. We aimed to investigate variability of the motor excitability measurements in healthy controls, taking into account age, gender, body mass index (BMI) and small changes in skin temperature.
  
  
  METHODS
  We examined the left median nerve of 47 healthy controls using the automated threshold-tacking program, QTRAC. Statistical multiple regression analysis was applied to test relationship between nerve excitability measurements and subject variables.
  
  
  RESULTS
  Comparisons between genders did not find any significant difference (P>0.2 for all comparisons). Multiple regression analysis showed that motor amplitude decreases with age and temperature, stimulus-response slope decreases with age and BMI, and that accommodation half-time decrease with age and temperature.
  
  
  CONCLUSIONS
  The changes related to demographic features on TRONDE protocol parameters are small and less important than in conventional nerve conduction studies. Nonetheless, our results underscore the relevance of careful temperature control, and indicate that interpretation of stimulus-response slope and accommodation half-time should take into account age and BMI. In contrast, gender is not of major relevance to axonal threshold findings in motor nerves.
authors.affiliation: Clinical and translational physiology unit, physiology institute, faculty of medicine, Instituto de Medicina Molecular, university of Lisbon, avenue Professor Egas Moniz, 1649-028 Lisbon, Portugal.
authors.forename: I
authors.initials: I
authors.lastname: Casanova
authors.affiliation: Clinical and translational physiology unit, physiology institute, faculty of medicine, Instituto de Medicina Molecular, university of Lisbon, avenue Professor Egas Moniz, 1649-028 Lisbon, Portugal.
authors.forename: A
authors.initials: A
authors.lastname: Diaz
authors.affiliation: Clinical and translational physiology unit, physiology institute, faculty of medicine, Instituto de Medicina Molecular, university of Lisbon, avenue Professor Egas Moniz, 1649-028 Lisbon, Portugal.
authors.forename: S
authors.initials: S
authors.lastname: Pinto
authors.affiliation: Clinical and translational physiology unit, physiology institute, faculty of medicine, Instituto de Medicina Molecular, university of Lisbon, avenue Professor Egas Moniz, 1649-028 Lisbon, Portugal. Electronic address: mamedemg@mail.telepac.pt.
authors.forename: M
authors.initials: M
authors.lastname: de Carvalho
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001369:Axons / Q000502:physiology*; D015992:Body Mass Index; D005260:Female; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000502:physiology*; D008875:Middle Aged; D012737:Sex Factors; D012881:Skin Temperature; D055815:Young Adult
keywords: Age; Body mass index; Excitabilité nerveuse; Gender; Indice de masse corporelle; Nerve excitability; Sexe; Temperature; Température; Âge