title: The falcine trigeminocardiac reflex: case report and review of the literature.
abstract: BACKGROUND
  Trigeminocardiac reflex (TCR), the reproducible hypotension and bradycardia upon stimulation of the trigeminal nerve, has been reported during craniofacial surgery and during surgery within the cerebellopontine angle, petrosal sinus, orbit, and trigeminal ganglion. Whereas the falx cerebri is known to be innervated by the nervus tentorii, a recurrent branch of V1, there have been no reports to date of this response upon mechanical stimulation of the falx.
  
  
  METHODS
  We report a case of immediate, reproducible, and reflexive response of asystole upon stimulation of the falx cerebri during operative resection of a parafalcine meningioma in a 53-year-old woman. Upon recognition of the reproducible relationship between falcine stimulation and increased vagal tone, the patient was given glycopyrrolate in an effort to block cholinergic hyperactivity. After glycopyrrolate was given, no further dysrhythmias occurred.
  
  
  CONCLUSIONS
  In this patient, mechanical stimulation of the falx likely resulted in the hyperactivity of the trigeminal ganglion, thereby triggering TCR. The dorsal region of the spinal trigeminal tract includes neurons from hypoglossal and vagus nerves, and projections have been seen between the vagus and trigeminal nuclei. The vagus provides parasympathetic innervation to the heart, vascular smooth muscle, and abdominal viscera. Vagal stimulation via these connections after trigeminal nerve activation likely accounts for the reflexive response of asystole seen in this patient. This is confirmed by the observation that the reflex was inhibited by the anticholinergic effects of glycopyrrolate. Awareness of TCR allows for early detection and appropriate treatment.
authors.affiliation: University of Michigan Medical School, Ann Arbor, MI 48109, USA.
authors.forename: David F
authors.initials: DF
authors.lastname: Bauer
authors.forename: Andrew
authors.initials: A
authors.lastname: Youkilis
authors.forename: Christine
authors.initials: C
authors.lastname: Schenck
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Turner
authors.forename: B Gregory
authors.initials: BG
authors.lastname: Thompson
mesh_terms: D001794:Blood Pressure / Q000502:physiology; D001919:Bradycardia / Q000209:etiology; D003388:Cranial Fossa, Posterior; D004388:Dura Mater / Q000502:physiology*; D005260:Female; D006323:Heart Arrest / Q000209:etiology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007002:Hypoglossal Nerve / Q000502:physiology; D007022:Hypotension / Q000209:etiology; D007431:Intraoperative Complications / Q000209:etiology*; D008577:Meningeal Neoplasms / Q000601:surgery*; D008579:Meningioma / Q000601:surgery*; D008875:Middle Aged; D010275:Parasympathetic Nervous System / Q000502:physiology; D010812:Physical Stimulation; D012018:Reflex / Q000502:physiology*; D014276:Trigeminal Nerve / Q000502:physiology*; D014630:Vagus Nerve / Q000502:physiology