Trigemino-cardiac reflex during microvascular trigeminal decompression in cases of trigeminal neuralgia

The trigemino-cardiac reflex (TCR) is a well-recognized phenomenon consisting of bradycardia, arterial hypotension, apnea, and gastric hypermotility during ocular surgery or other manipulations in and around the orbit. Thus far, it could bee shown that central stimulation of the trigeminal nerve during transsphenoidal surgery and surgery for tumors in the cerebellopontine angle can lead to TCR. In cases of microvascular trigeminal decompression for trigeminal neuralgia, no data of the possible occurrence of TCR are available. TCR was defined as a drop in mean arterial blood pressure (MABP) and the heart rate (HR) of more than 20% to the baseline values before the stimulus and coinciding with the manipulation of the trigeminal nerve. Electronic anesthetic recorded perioperative HR and MABP values were reviewed retrospectively in 28 patients who received microvascular trigeminal decompression in cases of trigeminal neuralgia and were divided into two subgroups on the basis of occurrence of TCR during surgery. Of the 28 patients, 5 (18%) showed evidence of TCR during manipulation at the trigeminal radix by separation from microvascular structures. Their HR fell 46% and their MABP 57% during operative procedures near the trigeminal nerve as compared with levels immediately before the stimulus. After cessation of manipulation, HR and MABP returned (spontaneously) to levels before the stimulus. Risk factors of TCR were compared with results from the literature. In conclusion, the present results give evidence of TCR during manipulation of the central part of the trigeminal nerve during microvascular trigeminal decompression in cases of trigeminal neuralgia under a standardized anesthetic protocol.