The study of the electrophysiological properties of cranial nerves has long been of interest to otolaryngologists as it relates to both medical and surgical applications within the diverse field of otolaryngology. Expertise in managing conditions involving multiple cranial nerves has been acquired by otolaryngologists during residency and fellowship training as well as through basic science and clinical research. Residency programs teach this field as required by the RRC in conjunction with a common Core Curriculum and are tested on this subject matter by the American Board of Otolaryngology.
The facial nerve has important functions involved in protecting the eye and expressing emotion. Facial nerve weakness or paralysis is an emotionally devastating condition. Preservation of the facial nerve is a key component to otologic and neurotologic procedures. Identification of the facial nerve is a critical step in temporal bone procedures. Facial nerve injury is a potential complication of otologic and neurotologic procedures.
Iatrogenic facial nerve injury is a potentially devastating complication of temporal bone surgery. (1) Facial nerve repair and facial nerve grafting, while helpful, cannot restore natural, normal facial function; thus, prevention of injury is a primary goal.
Otolaryngologists have been exquisitely sensitive to the vulnerability of the facial nerve during operative procedures for decades. Initially, the technique for monitoring involved keeping the face exposed and asking for reports on any twitches while the surgeon was working. By the 1960s through the 1980s, electrical facial nerve monitoring was introduced and refined.
Intraoperative monitoring uses facial electromyography, with or without a stimulating probe. Otolaryngologists are trained to set up, monitor, interpret, and troubleshoot this equipment. Systemic neuromuscular blockade must be avoided to permit muscle stimulation and neural monitoring, and this fact must be communicated to the anesthesiologist.
While intraoperative monitoring is not a substitute for good surgical technique, in certain situations monitoring does improve facial nerve outcomes in skull base surgery and in temporal bone surgery.
Facial nerve monitoring is cost effective and beneficial for neurotologic and mastoid surgery, and its use, at the discretion of the operating surgeon, can reduce the risk of iatrogenic facial nerve injury. (2)
Drafted 9/29/2016
Submitted for Review 10/12/2016
Submitted for Review 12/6/2016
Adopted 3/12/2017
References
- Ruhl DS, Hong SS, Littlefield PD. Lessons learned in otologic surgery: 30 years of malpractice cases in the United States. Otology & neurotology: official publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology. 2013; 34(7):1173-1179.
- Wilson L, Lin E, Lalwani A. Cost-effectiveness of intraoperative facial nerve monitoring in middle ear or mastoid surgery. The Laryngoscope. 2003:113(10):1736-1745.
- Eshraghi AA, Connell SS, Chang RC, Telischi FF. Intraoperative Neurophysiologic Monitoring. In: Brachmann D, Shelton C, Arriaga M, eds. Otologic Surgery. 3rd ed. Philadelphia: Saunders Elsevier; 2010:773-784.
- Yingling C. Ashram YA. Intraoperative Monitoring of Cranial Nerves in Skull Base Surgery. In: Jackler RK, Brackmann DE, eds. Neurotology. 2nd ed. Philadelphia: Elsevier Mosby; 2005:958-993.
- Diaz RC, Poti SM, Dobie RA. Tests of Facial Nerve Function. In: Flint PW, Haughey BH, Lund VJ, et al., eds. Cummings Otolaryngology. Vol 3. 6th ed. Philadelphia: Elsevier Saunders; 2015:2604-2616.
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