ARTICLE IN PRESS

YBJOM-5194; No. of Pages 2

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ScienceDirect British Journal of Oral and Maxillofacial Surgery xxx (2017) xxx–xxx

Letter to the Editor Pitfalls in monitoring of the facial nerve during operations for parotid cancer Sir, The facial nerve splits into branches within the parotid gland and innervates the muscles of facial expression. Damage to it can result in temporary or permanent facial deformity, asymmetry of the smile, and ocular keratosis. Studies have shown that intraoperative use of a facial nerve monitor can reduce paralysis of the nerve. A 60-year-old man with parotid cancer that involved the lower branches of the facial nerve had a resection of the right parotid and a neck dissection with curative intent. Using the NIM-Response 3.0 (Medtronic, Dublin, Ireland) facial nerve monitor we located a large, rounded, discoloured facial nerve trunk intraoperatively, and when we stimulated both it and the distal cervicomandibular branches, there were no signals and his face did not twitch (Fig. 1). A response was elicited on the nerve monitor and facial twitching was seen only when we stimulated the distal segments of the frontozygomatic and temporal branches of the nerve (Fig. 2). These were found in parotid tissue that was macroscopically tumour-free.

Fig. 1. No response from stimulation of the facial nerve trunk when the parotid gland was retracted medially. (Published with the patient’s consent).

We had cross-checked the monitor consistently throughout the procedure, replaced the probe, and used a testing unit to ensure optimum function. The lower branches of the facial nerve were sacrificed as part of the resection of the tumour. If we had relied on the facial nerve monitor alone, then the upper branches may also have been lost. This case shows the shortcomings of monitoring devices in cancerous tissue. A conduction block in the portion of the involved nerve stops the facial nerve monitor working proximal to that point. This highlights the danger of relying on it during parotid surgery. Studies have shown that in primary parotid surgery, facial nerve monitoring helps to reduce temporary postoperative facial weakness, but does not affect the long-term outcome.1 A facial nerve monitor is of greater benefit during primary total parotidectomy than a superficial parotidectomy or revision.2 Despite the progress of technology, the mainstay of nerve protection should be the use of anatomical landmarks, careful dissection techniques, and gentle manual stimulation while observing facial twitching during operation.

Fig. 2. Response from stimulation of the temporal branch of the facial nerve, after the parotid gland had been resected (published with the patient’s consent).

http://dx.doi.org/10.1016/j.bjoms.2017.06.001 0266-4356/© 2017 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Please cite this article in press as: Kassam S, et al. Pitfalls in monitoring of the facial nerve during operations for parotid cancer. Br J Oral Maxillofac Surg (2017), http://dx.doi.org/10.1016/j.bjoms.2017.06.001

ARTICLE IN PRESS

YBJOM-5194; No. of Pages 2

2

Letter to the Editor / British Journal of Oral and Maxillofacial Surgery xxx (2017) xxx–xxx

Conflict of interest

2. Guntinas-Lichius O, Eisele DW. Facial nerve monitoring. Adv Otorhinolaryngol 2016;78:46–52.

We have no conflicts of interest.

Ethics statement/confirmation of patient’s permission Ethics approval not needed. We have obtained the patient’s permission.

S. Kassam S. Chegini ∗ M. Kumar Northwick Park Hospital, Watford Rd, Harrow HA1 3UJ ∗ Corresponding author. E-mail address: [email protected] (S. Chegini)

References 1. Sood AJ, Houlton JJ, Nguyen SA, et al. Facial nerve monitoring during parotidectomy: a systematic review and meta-analysis. Otolaryngol Head Neck Surg 2015;152:631–7.

Please cite this article in press as: Kassam S, et al. Pitfalls in monitoring of the facial nerve during operations for parotid cancer. Br J Oral Maxillofac Surg (2017), http://dx.doi.org/10.1016/j.bjoms.2017.06.001

Pitfalls in monitoring of the facial nerve during operations for parotid cancer.

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