[Trigeminocardiac reflex in pituitary surgery. A prospective pilot study].

BACKGROUND: The trigeminocardiac reflex (TCR) is a relatively recently described brainstem reflex in the fields of neurosurgery which leads to a simultaneous drop in mean arterial pressure (MAP) and heart rate of at least 20% from baseline levels after stimulation of a sensible branch of the trigeminal nerve. PATIENTS AND METHODS: The purpose of this study was to register prospectively for the first time the rate of TCR during trans-sphenoidal surgery and to describe possible predispositional factors. This was examined by determining selected biomarkers thought to correlate with possible intraoperative ischemic events after occurrence of TCR and furthermore with neuroprotective mechanisms ("ischemic tolerance").
RESULTS: Three of the 40 patients included (7.5%) demonstrated intraoperative occurrence of TCR after exposure of the cavernous sinus. One (2.5%) demonstrated a TCR during preparation of the nasal mucosa. Permanent cardiovascular damage or unfavorable postoperative outcome through the appearance of TCR was not found. There was a trend to lower C-reactive protein levels after occurrence of TCR (32 mg/dl vs 14 mg/dl) following normal values before operations in all cases. Considering that no clinical clue of ischemia was detected, this could mean that some neuroprotective cascades are initiated. There was a correlation between tumor necrosis factor A and noradrenalin levels with the size (invasivity) of the pituitary adenoma. The administration of atropine was necessary in only one patient with intraoperative occurrence of TCR.
CONCLUSION: On the basis of this study, it cannot be said to what extent neuroprotective mechanisms after TCR are activated, but a trend is still apparent. Considering the adverse effects and the reflex arc, prophylactic or therapeutic treatment with atropine is not justified.