Utility and Prognostic Value of Intraoperative Blink Reflex in Trigeminal or Facial Nerve Monitoring in Skull Base Surgeries: A Systematic Review

Abstract

Blink reflex (BR) is an oligosynaptic reflex that involves the ophthalmic branch of the trigeminal nerve (TN), ipsilateral main sensory and trigeminospinal nuclei, bilateral facial nuclei, and the facial nerves (FN). Theoretically, as it tests the function of both TN and FN simultaneously, it is an ideal tool for monitoring the status of TN and FN during skull base surgeries. Nevertheless, it is only recently utilized in surgeries as the use of anesthesia limits its use. Two authors inputted the search terms: [(Blink Reflex) AND (Intraoperative Neuromonitoring OR Neuro Intraoperative Monitoring OR Intraoperative OR NIOM OR IONM) AND (skull base surgery OR Facial Nerve OR Trigeminal Nerve OR Microvascular Decompression OR Hemifacial Spasm)] in Medline through its Pubmed interface and other search engines. Papers that fulfilled the inclusion and exclusion criteria were obtained and scrutinized. Only 7 observational papers with a total of 437 participants were included in the current systematic review. All studies (n=5) involving the use of BR in FN surgery noted that IOBR is beneficial, safe, sensitive, specific, and predictive of outcomes while all 2 papers involving trigeminal neuralgia patients recommended BR's use in microvascular decompression (MVD) of TN. IOBR is a sensitive, specific and safe monitoring technique that has good predictability of facial paresis and paresthesia among patients undergoing MVD for trigeminal neuralgia and primary hemifacial spasm and those who are for cerebellopontine angle tumor resection.