Tumours in the salivary gland tend to form very close to, and sometimes on top of, the facial nerve, which makes salivary gland operations a rather risky and delicate type of surgery. For this reason, surgery to remove salivary gland tumours carries a risk of damaging the facial nerve, which can result in complete or partial facial paralysis; in most cases the weakness is temporary.1,2
Why the facial nerve is at risk
The facial nerve moves the muscles of the face; it controls the smile and the eyelids. It passes directly through the parotid gland, the salivary gland in front of the ear, and splits into smaller branches inside it. This makes it hard to remove the deeper part of the gland without pulling and pushing the nerve, which can bruise it and cause temporary weakness.2
The signs of facial paralysis are being unable to blink, raise the eyebrows, close the eyes or smile.3
How often it happens
Facial nerve paralysis is a common complication after salivary gland surgery, even with benign lesions. This complication can seriously affect a patient’s quality of life, so the risk factors should be identified before the operation, and the operation should be planned around them. In one published series, the risk was higher with tumours 3 cm or more long or 2 cm or more deep, and with a second operation for a tumour that had come back.4
The figures that ENT UK publishes for parotid surgery are these:
- Part of the gland removed (partial parotidectomy): temporary weakness in around 20 of 100 operations; permanent weakness in up to 7 of 100.2
- Whole gland removed (total parotidectomy): temporary weakness in around 40 of 100 operations; permanent weakness in up to 9 of 100.2
These are published figures, not the results of one surgeon or one practice, and the same source notes that reported complication rates vary widely. According to it, the facial nerve usually works normally after surgery; permanent weakness tends to affect one or more branches of the nerve, and permanent weakness of all the branches is rare.2
How the nerve is protected during the operation
This operation calls for a thorough knowledge of the anatomy of the face, including the salivary gland and the facial nerve. Knowing exactly where the facial nerve lies in relation to the salivary gland tumour is the first prerequisite for avoiding damage to the nerve.
The surgeon finds the main trunk of the nerve from fixed anatomical landmarks, then follows its branches one by one, separating the gland tissue from them. During surgery, a facial nerve monitor helps to identify the main nerve trunk and to follow the branches of the nerve, and in this way to protect the facial nerve and its branches. In a pooled analysis of seven published studies, weakness straight after the operation was less frequent when the nerve was monitored; the rate of permanent weakness was not statistically different.5,6,7
The United Kingdom guidelines state that, when the face moves normally before the operation, every attempt should be made to preserve the nerve, and that immediate microsurgical repair should be considered if the nerve is divided during the operation.1
Recovery and protecting the eye
Facial movement is checked as soon as you wake up. Some weakness may be seen, particularly after removal of the whole gland; when all the branches have been identified and preserved, it typically resolves with time, though full recovery can take many months.7
In one published series of 84 operations on the superficial part of the gland for a benign tumour, 14 patients had weakness afterwards; all recovered fully, the first within two weeks and the last in the 36th week.4
While the face is weak, the eye on that side may not close fully; this is usually temporary. An eye that stays open dries out and its surface can become inflamed, so eye closure is assessed and the eye is protected with eye drops or lubricants, and with an eye patch or tape at night.7,8
When to contact your surgeon
After the operation, tell your surgeon or the team looking after you if you feel unwell or are worried about anything, and in particular if:8
- you have a lot of bleeding from the wound8
- you have signs of an infection: a high temperature, shivering, feeling generally unwell, or swelling or redness around the wound8
- you have pain that does not settle8
References
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Sood S, McGurk M, Vaz F. Management of salivary gland tumours: United Kingdom National Multidisciplinary Guidelines. J Laryngol Otol. 2016;130(S2):S142-S149. doi:10.1017/S0022215116000566 ↩
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ENT UK. Parotidectomy – surgery to remove a lump [Internet]. London: ENT UK; 2023 Aug 24 [cited 2026 Oct 5]. Available from: entuk.org ↩
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Facial Palsy UK. Symptoms of facial palsy [Internet]. Peterborough: Facial Palsy UK; [reviewed 2026 Jul 29; cited 2026 Oct 12]. Available from: facialpalsy.org.uk ↩
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Bittar RF, Ferraro HP, Ribas MH, Lehn CN. Facial paralysis after superficial parotidectomy: analysis of possible predictors of this complication. Braz J Otorhinolaryngol. 2016;82(4):447-451. doi:10.1016/j.bjorl.2015.08.024 ↩
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Eren SB, Dogan R, Ozturan O, Veyseller B, Hafiz AM. How deleterious is facial nerve dissection for the facial nerve in parotid surgery: an electrophysiological evaluation. J Craniofac Surg. 2017;28(1):56-60. doi:10.1097/SCS.0000000000003186 ↩
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Sood AJ, Houlton JJ, Nguyen SA, Gillespie MB. Facial nerve monitoring during parotidectomy: a systematic review and meta-analysis. Otolaryngol Head Neck Surg. 2015;152(4):631-637. doi:10.1177/0194599814568779 ↩
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El Sayed Ahmad Y, Winters R. Parotidectomy. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 [cited 2026 Oct 13]. Available from: ncbi.nlm.nih.gov ↩
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Cancer Research UK. Possible problems after salivary gland cancer surgery [Internet]. London: Cancer Research UK; [reviewed 2026 May 8; cited 2026 Oct 5]. Available from: cancerresearchuk.org ↩