Introduction: The oculocardiac reflex (OCR) is a sudden decrease in heart rate resulting from mechanical manipulation of the orbit, especially due to traction on the extra-ocular muscles. In approaches to the skull base, utilizing the principle of retracting bone rather than brain, the orbitozygomatic (OZ) approaches are commonly used to approach multiple pathologies. The purpose of this study was to evaluate the occurrence of the OCR during OZ craniotomies to better prepare neurosurgeons and neuroanesthesiologists in the management of patients undergoing OZ craniotomies.
Methods: For the OZ craniotomy, electrocardiographic strips were collected prospectively from 108 patients depict the resting heart rate at stage 1 (control) and the heart rate at stage 2 (orbital manipulation). A deviation of 10 beats per minute or greater from the resting heart rate during orbital manipulation (stage 2) was recorded as an OCR event.
Results: In our 108 patients we detected bradycardia during stage 2 (orbital manipulation) 36% of the time compared with 6% of the time during the standard pterional portion of the craniotomy (p<0.001). No statistically significant occurrence of the OCR was found in analysis of the covariates of hypertension, hyperlidemia, diabetes mellitus, hypo/hyperthyroidism, beta-blocker use, calcium channel blocker use, or tobacco use. No patients required anti-cholinergic intervention as a result of OCR, and there were no post-operative ramifications of the OCR.
Conclusions: This prospective cohort study was able to show a 36% rate of OCR during orbital manipulation. These data are useful to both neurosurgeons and neuroanesthesiologists in anticipating cardiac arrhythmia during skull base surgeries.
Patient Care: This study allows neurosurgeons and neuroanesthesiologists to anticipate cardiac arrhythmia in patients undergoing OZ craniotomies.
Learning Objectives: By the conclusion of this session, participants should be able to 1) Describe the occulocardiac reflex. 2) Understand the frequency of the occurrence of the OCR. 3) Anticipate its occurrence and work with other providers to anticipate patient problems.