I appreciate Schipke et al for their interesting report on ‘Computer-assisted paranasal sinus operation induces diving bradycardia’ . In this, the authors have mentioned about the first description of trigeminal nerve associated acute hemodynamic changes (bradycardia, hypotension and asystole) during nasal preparation . However, similar finding was reported by a senior author in 2008. They had reported a case of 29-year-old woman with prolactinoma in which 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/paranasal mucosa for a transsphenoidal approach under general anaesthesia . These hemodynamic alterations lasted for a few seconds and further managed by atropine. The possible mechanism was attributed to trigeminal cardiac reflex (TCR), which, usually manifests as bradycardia, hypotension, asystole and gastric hyper motility. TCR is a brainstem reflex that may be incited by stimulation of any sensory branch of trigeminal nerve along its course. Therefore TCR is described in all neurosciences disciplines. There exist different subtypes of TCR: peripheral TCR, central TCR and Ganglion Gasseri TCR . On the other hand, the diving reflex (DR) in humans is characterized by breath-holding, slowing of the heart rate, and decrease in cardiac output with sympathetic mediated peripheral vasoconstriction. What differ is that in TCR there is a secondary decrease in MABP, whereas in DR the MABP gradually increases . At present it is still not clear whether this increase in MABP is specific for all peripheral TCR or only for a more central subgroup. DR may be a peripheral component of TCR. Both the reflexes cannot be completely blocked by the pretreatment with local anesthetics and therefore suggest different sensitivities and different receptors mediated interactions as plausible causes .

Therefore, the present case is the mere reflection of peripheral TCR which has already been described in the literature; however, it is important to know about this unique reflex, which, is considered to be neuroprotective mechanism on one hand but may produce grave consequences on the other hand.