Sustained trigeminocardiac reflex following balloon embolization of carotico-cavernous fistula

Recently, a double-balloon technique for the embolisation of direct caroticocavernous fistula (CCF) was suggested by Niu et al.¹ Balloon embolisation is a cost-effective and feasible method of treating these direct fistulas that are predominantly post-traumatic and high flow in nature. Authors have described a very useful technique of inflating two balloons simultaneously to completely close the fistula. However, we must be aware of possible complications during such a procedure. Inflating multiple balloons in the region of the cavernous sinus can potentially cause reflex autonomic changes. We describe a patient who developed sustained trigeminocardiac reflex (TCR) following balloon embolisation of CCF. A middle-aged male patient with no previous co-morbid illness presented with post-traumatic left-sided direct CCF with possible rent involving a horizontal segment of the cavernous ICA and draining anteriorly into the bilateral superior ophthalmic vein (SOV) (Figure 1). No antegrade flow was seen into the distal ICA and cross-filling was seen across the anterior communicating artery. Balloon embolisation was attempted using a single Goldbal 4 balloon attached to a co-axial catheter. Following inflation of the balloon, near complete embolisation of the fistula was seen with re-establishment of antegrade flow within the left ICA. However, sustained periodical reduction in heart rate (HR) was seen following inflation of the balloon. Baseline values decreased gradually over seconds by more than 20% and after a few seconds showed similar gradual increase (not reaching baseline values). This fluctuation in HR was seen to persist in the immediate post-embolisation period. No significant associated changes in blood pressure were noted. The patient was closely monitored and in view of stable blood pressure and lack of asystole, no treatment was initially given. Subsequently he developed a couple of episodes of vomiting and his HR decreased further, prompting treatment with intravenous atropine. Fluctuating sinus bradycardia was seen to reverse following atropine and his HR remained stable thereafter. The rest of his post-operative stay was uneventful. This could represent a form of central TCR due to mechanical irritation of trigeminal nerve sensory afferents in the region of the left cavernous sinus. This is predominantly a brainstem reflex secondary to stimulation of any branch of the trigeminal nerve along its course while response is mediated by the parasympathetic efferent fibres of the vagus. Incidence of TCR following endovascular embolisation reported in literature is around 11%.² The majority of case reports describing TCR during endovascular procedures have been related to injection of dimethyl sulfoxide (DMSO) and Onyx injection since it was first described.³ There are very few reports of TCR following balloon embolisation, possibly because of routine preanaesthetic medication with atropine and clinical variants showing minimal variations in HR would not be routinely recognised. The TCR seen in our patient was most likely due to mechanical irritation of trigeminal afferents in the region of the cavernous sinus following inflation of the balloon. Interestingly, TCR seen in our patient was sustained in immediate post-procedural period till it was treated with intravenous atropine. Possible reasons would have been the continuous mechanical stimulation by the balloon and lack of preanaesthetic medication during the procedure, which was performed under conscious sedation. The average HR in our patient prior to the procedure was around 56–60/min and following balloon inflation, this dropped to 38/min. However, mean arterial blood pressure (MABP) in our patient remained stable and no significant alterations were seen. Blood pressure is a highly regulated hemodynamic variable and multiple autonomic reflex loops are involved in its control. Additionally, it has been shown that changes in mean blood pressure vary between different forms of TCR.⁴ Hence balloon embolisation of CCF can be associated with TCR, and use of multiple balloons might increase its risk. We need to anticipate such complications during the procedure, including the risk of TCR during inflation of the balloons, and expedite its management.

Figure 1.

Left ICA injection (a) showing direct CCF with drainage through the left SOV and no antegrade flow. Balloon inflated in situ (b) within the left paracavernous sac and post-procedural injection (c) showing complete embolisation of fistula with distal flow in the ICA. Post-procedural patient monitor, which shows bradycardia following balloon inflation due to central TCR (d).

ICA: internal carotid artery; CCF: caroticocavernous fistula; TCR: trigeminocardiac reflex.

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.