title: Nociceptive trigeminocervical reflexes in healthy subjects.
abstract: OBJECTIVE
  Electrical stimulation of the supraorbital trigeminal nerve branch induces trigeminocervical reflex responses (TCRs) in the neck muscles. The purpose of this study was to elicit more nociceptive TCR responses through preferential activation of the nociceptive afferents with a concentric surface electrode.
  
  
  METHODS
  We recorded TCRs in 10 healthy subjects using both a standard (sTCR) and a nociceptive (nTCR) concentric surface electrode. We compared the baseline parameters, stimulus intensity/response, recovery, and habituation curves recorded for the two types of electrode, and assessed the effects of local anaesthesia.
  
  
  RESULTS
  Compared with the sTCRs, nTCRs showed a significantly longer latency of the late reflex component, as well as lower pain and higher reflex thresholds. They also showed a different recovery cycle and stimulus intensity/response curve, but similar habituation rate. Local anaesthesia attenuated by 85% the late reflex response to stimulation by the concentric electrode, and by only 15% the response to standard electrode stimulation.
  
  
  CONCLUSIONS
  The differences observed stimulating with these two electrode types may be due to their different activation of the afferent fibres.
  
  
  CONCLUSIONS
  If this study were extended to patients affected by primary headaches, TCR monitoring could emerge as a sensitive tool for detecting changes in nociceptive transmission at the level of trigeminocervical complex.
authors.affiliation: "Sapienza" University of Rome, Polo Pontino, Rome, Italy; IRCCS-Neuromed, Pozzilli, IS, Italy. Electronic address: mariano.serrao@uniroma1.it.
authors.forename: Mariano
authors.initials: M
authors.lastname: Serrao
authors.affiliation: G.B. Bietti Eye Foundation-IRCCS, Dept. of Neurophysiology of Vision and Neurophthalmology, Rome, Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Coppola
authors.affiliation: University Centre for Adaptive Disorders and Headache (UCADH), "Sapienza" University of Rome, Polo Pontino, I.C.O.T., Latina, Italy.
authors.forename: Cherubino
authors.initials: C
authors.lastname: Di Lorenzo
authors.affiliation: "Sapienza" University of Rome, Polo Pontino, Rome, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Di Fabio
authors.affiliation: Don Carlo Gnocchi Onlus Foundation, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Padua
authors.affiliation: University Centre for Adaptive Disorders and Headache (UCADH), IRCCS C. Mondino Foundation, Pavia, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Sandrini
authors.affiliation: University Centre for Adaptive Disorders and Headache (UCADH), "Sapienza" University of Rome, Polo Pontino, I.C.O.T., Latina, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Pierelli
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001703:Biophysics / Q000379:methods; D004558:Electric Stimulation / Q000379:methods; D004576:Electromyography / Q000379:methods; D006185:Habituation, Psychophysiologic; D006801:Humans; D008297:Male; D009334:Neck Muscles / Q000294:innervation; D009619:Nociceptors / Q000502:physiology*; D010147:Pain Measurement; D011930:Reaction Time / Q000502:physiology; D012018:Reflex / Q000502:physiology*; D012684:Sensory Thresholds / Q000502:physiology; D014276:Trigeminal Nerve / Q000502:physiology*; D055815:Young Adult