title: A relationship between bruxism and orofacial-dystonia? A trigeminal electrophysiological approach in a case report of pineal cavernoma.
abstract: BACKGROUND
  In some clinical cases, bruxism may be correlated to central nervous system hyperexcitability, suggesting that bruxism may represent a subclinical form of dystonia. To examine this hypothesis, we performed an electrophysiological evaluation of the excitability of the trigeminal nervous system in a patient affected by pineal cavernoma with pain symptoms in the orofacial region and pronounced bruxism.
  
  
  METHODS
  Electrophysiological studies included bilateral electrical transcranial stimulation of the trigeminal roots, analysis of the jaw jerk reflex, recovery cycle of masseter inhibitory reflex, and a magnetic resonance imaging study of the brain.
  
  
  RESULTS
  The neuromuscular responses of the left- and right-side bilateral trigeminal motor potentials showed a high degree of symmetry in latency (1.92 ms and 1.96 ms, respectively) and amplitude (11 mV and 11.4 mV, respectively), whereas the jaw jerk reflex amplitude of the right and left masseters was 5.1 mV and 8.9 mV, respectively. The test stimulus for the recovery cycle of masseter inhibitory reflex evoked both silent periods at an interstimulus interval of 150 ms. The duration of the second silent period evoked by the test stimulus was 61 ms and 54 ms on the right and left masseters, respectively, which was greater than that evoked by the conditioning stimulus (39 ms and 35 ms, respectively).
  
  
  CONCLUSIONS
  We found evidence of activation and peripheral sensitization of the nociceptive fibers, the primary and secondary nociceptive neurons in the central nervous system, and the endogenous pain control systems (including both the inhibitory and facilitatory processes), in the tested subject. These data suggest that bruxism and central orofacial pain can coexist, but are two independent symptoms, which may explain why numerous experimental and clinical studies fail to reach unequivocal conclusions.
authors.affiliation: Epochè "Orofacial Pain Center", Rome, Italy. frisardi@tin.it.
authors.forename: Gianni
authors.initials: G
authors.lastname: Frisardi
authors.forename: Cesare
authors.initials: C
authors.lastname: Iani
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Sau
authors.forename: Flavio
authors.initials: F
authors.lastname: Frisardi
authors.forename: Carlo
authors.initials: C
authors.lastname: Leornadis
authors.forename: Aurea
authors.initials: A
authors.lastname: Lumbau
authors.forename: Paolo
authors.initials: P
authors.lastname: Enrico
authors.forename: Donatella
authors.initials: D
authors.lastname: Sirca
authors.forename: Enrico Maria
authors.initials: EM
authors.lastname: Staderini
authors.forename: Giacomo
authors.initials: G
authors.lastname: Chessa
mesh_terms: D000328:Adult; D001932:Brain Neoplasms / Q000473:pathology / Q000503:physiopathology*; D002012:Bruxism / Q000473:pathology / Q000503:physiopathology*; D020821:Dystonic Disorders / Q000473:pathology / Q000503:physiopathology*; D019054:Evoked Potentials, Motor / Q000502:physiology; D020786:Hemangioma, Cavernous, Central Nervous System / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008406:Masseter Muscle / Q000503:physiopathology; D010870:Pineal Gland / Q000473:pathology / Q000503:physiopathology*; D011930:Reaction Time / Q000502:physiology; D050781:Transcranial Magnetic Stimulation; D014276:Trigeminal Nerve / Q000503:physiopathology*