title: Evaluation of the pathophysiology of classical trigeminal neuralgia by blink reflex study and current perception threshold testing.
abstract: We recruited 49 patients with classical trigeminal neuralgia (TN) according to the latest guidelines of the International Classification of Headache Disorders, and divided them into an acute (</=30 days onset; 13 patients) and a chronic (>30 days onset; 36 patients) group. We used blink reflex study and current perception threshold (CPT) testing to evaluate the painful facial areas and contralateral non-painful areas of patients with classical TN. CPT 5 Hz examinations, which correlate with unmyelinated fiber function, showed significantly decreased CPTs in the acute stage (11.62 +/- 6.99 vs. 18.69 +/- 9.66, P = 0.025), but significantly increased CPTs in the chronic stage (26.67 +/- 18.65 vs. 19.69 +/- 13.70, P = 0.010) on the painful side when compared with the contralateral non-painful side. However, CPTs at 250 Hz (Adelta) and 2000 Hz (Abeta) examinations did not show significant differences between the painful and non-painful sides. In contrast, only three (3/49) patients showed an abnormal trigeminal nerve stimulation on the ipsilateral painful side by blink reflex study. The findings suggest that classical TN is not a simple large-myelinated nerve fiber dysfunction but a more complex process with a main dysfunction of unmyelinated nerve fibers.
authors.affiliation: Department of Neurology, Linkou Headquarters, Chang Gung Memorial Hospital and College of Medicine, Chang-Gung University, 199 Tung Hwa North Road, Taipei, Taiwan.
authors.forename: Ming Feng
authors.initials: MF
authors.lastname: Liao
authors.forename: Meng
authors.initials: M
authors.lastname: Lee
authors.forename: Mei Jen
authors.initials: MJ
authors.lastname: Hsieh
authors.forename: Mei Yun
authors.initials: MY
authors.lastname: Cheng
authors.forename: Jiann Der
authors.initials: JD
authors.lastname: Lee
authors.forename: Hsu Huei
authors.initials: HH
authors.lastname: Weng
authors.forename: Long Sun
authors.initials: LS
authors.lastname: Ro
mesh_terms: D000328:Adult; D000368:Aged; D001767:Blinking / Q000502:physiology*; D003943:Diagnostic Techniques, Neurological; D004568:Electrodiagnosis / Q000379:methods*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009413:Nerve Fibers, Myelinated / Q000502:physiology; D036421:Nerve Fibers, Unmyelinated / Q000502:physiology; D009619:Nociceptors / Q000502:physiology; D010147:Pain Measurement / Q000379:methods*; D017288:Pain Threshold / Q000502:physiology; D010812:Physical Stimulation / Q000379:methods; D011237:Predictive Value of Tests; D012021:Reflex, Abnormal / Q000502:physiology; D012680:Sensitivity and Specificity; D011984:Sensory Receptor Cells / Q000502:physiology; D055698:Touch Perception / Q000502:physiology; D014276:Trigeminal Nerve / Q000503:physiopathology; D014277:Trigeminal Neuralgia / Q000175:diagnosis* / Q000503:physiopathology*