title: Differences between episodic and chronic tension-type headaches in nociceptive-specific trigeminal pathways.
abstract: BACKGROUND
  The trigeminal nociceptive system plays a pivotal role in the pathophysiology of tension-type headaches (TTH).
  
  
  OBJECTIVE
  This study investigated and compared nociceptive-specific trigeminal pathways in patients with episodic and chronic TTH (ETTH and CTTH, respectively) using the nociceptive blink reflex (nBR) and nociceptive trigeminocervical reflex (nTCR).
  
  
  METHODS
  We recorded nBR and nTCR in patients with ETTH and CTTH, and healthy controls using concentric electrodes and subsequently compared the threshold (i.e. sensory, pain) and parameters of reflex (i.e. the R2 component of the nBR and the late responses of the nTCR).
  
  
  RESULTS
  Women with ETTH ( N  = 40) and CTTH ( N  = 32) and age-matched controls ( N  = 40) were recruited. CTTH patients displayed significantly lower amplitude and area under the curve (AUC) values of the R2 component for the nBR compared with those displayed by ETTH patients and controls ( P  < 0.05). Moreover, the amplitude and AUC of the R2 component was negatively correlated with the frequency of headaches, whereas the latency of the R2 component for the nBR was positively correlated with the frequency and duration of headaches in the TTH groups ( P  < 0.05). However, no significant differences in the late response parameters (i.e. latency, duration, amplitude, or AUC) were noted between the groups in terms of the nTCR.
  
  
  CONCLUSIONS
  R2 suppression associated with CTTH suggests decreased brainstem excitability. This may be the result of excessive descending inhibitory influences.
authors.affiliation: Department of Neurology, Hallym University College of Medicine, Chuncheon Sacred Heart Hospital, Chuncheon, Republic of Korea. deepfoci@hallym.or.kr
authors.forename: Jong Hee
authors.initials: JH
authors.lastname: Sohn
authors.forename: Hui Chul
authors.initials: HC
authors.lastname: Choi
authors.forename: Chul Ho
authors.initials: CH
authors.lastname: Kim
mesh_terms: D004558:Electric Stimulation; D005260:Female; D006801:Humans; D008875:Middle Aged; D009434:Neural Pathways / Q000503:physiopathology*; D010146:Pain / Q000503:physiopathology*; D017288:Pain Threshold / Q000502:physiology*; D012018:Reflex; D018781:Tension-Type Headache / Q000503:physiopathology*; D014276:Trigeminal Nerve / Q000503:physiopathology*; D014278:Trigeminal Nuclei / Q000503:physiopathology