Trigemino-cardiac reflex in humans initiated by peripheral stimulation during neurosurgical skull-base operations....

The trigemino-cardiac reflex (TCR) is a well-recognised phenomenon (first described in skull base surgery by the authors in 1999) that consists of bradycardia, arterial hypotension, apnoea, and gastric hypermobility. TCR occurs during skull base surgery at or around structures that are innervated by any sensory branch of the trigeminal nerve. Thus far, it has not been shown that peripheral stimulation of a trigeminal nerve can also cause this reflex.

The TCR was defined as clinical hypotension with a drop in mean arterial blood pressure (MABP) and in heart rate (HR) of more than 20% compared to the baseline level and coinciding with the surgical manipulation at or around any branches of the trigeminal nerve. The anaesthesiological and the operative techniques that were used were standardised.

We describe here a 29-year-old woman with an endocrinological and imaging-proved micro-prolactinoma in which a TCR with a decrease in "arterial blood pressure" (130/70 mmHg up to a 100/40 mmHg) and an accompanying decrease of the HR (70 beats/min to 50 beats/min) was seen during preparation of the nasal mucosa for a transsphenoidal approach under general anaesthesia, lasting a few seconds until normalisation. After immediate application of atropine, the surgical procedure and the post-operative course was uneventful.

We present the first report of peripheral stimulation of a sensory branch of the trigeminal nerve that leads to a TCR under general anaesthesia according to our strict criteria as defined in 1999. The present finding is therefore a key research development and gives substantial evidence that TCR is coincident enhancement of sympathetic and parasympathetic outflows to the heart, suggesting that genetic differences may affect the susceptibility for TCR.