The unseen risk: a systematic review of the incidence, management, and outcomes of the trigeminocardiac reflex in skull-base surgery

Purpose: This study synthesizes contemporary evidence on the trigeminocardiac reflex (TCR) during skull-base and adjacent neurosurgical procedures, with emphasis on operative corridors, triggers, hemodynamic phenotypes, management, and the limits of current outcome evidence. Methods: Following PRISMA guidelines, we systematically searched PubMed, Scopus, Web of Science, and Embase through September 15, 2024. Eligible reports described intraoperative TCR or closely related trigeminal autonomic responses during skull-base surgery or adjacent procedures and reported event features, management, or outcomes. Results: Twenty-eight studies including 329 patients met inclusion criteria. Reported TCR events clustered in microvascular decompression for trigeminal neuralgia (n=168; 51.1%), CPA/posterior fossa or anterior skull-base tumor surgery (n=71; 21.6%), transsphenoidal pituitary procedures (n=47; 14.3%), and percutaneous trigeminal procedures (n=35; 10.6%). Immediate cessation of the provoking maneuver was the cornerstone of management, with anticholinergics, vasoactive agents, or temporary pacing required only in selected severe or recurrent cases. No TCR-attributable mortality was reported. However, evidence regarding long-term functional outcomes remains limited, inconsistently reported, and largely dependent on historical vestibular schwannoma and pituitary cohorts. A procedure-specific synthesis identifies high-risk maneuvers, preventive considerations, and escalation options for each operative corridor. Conclusions: TCR should be anticipated during trigeminal manipulation across skull-base surgical corridors and managed initially by immediate cessation or modification of the provoking stimulus, with pharmacologic or resuscitative escalation reserved for persistent or severe events. Although the available evidence supports a procedure-specific approach to prevention and preparedness, heterogeneous definitions, retrospective designs, and incomplete denominators preclude reliable incidence estimates or validated management recommendations.