ENT

Parotid gland tumours

Surgical interventions in the ENT field are particularly high risk, as injury to the fine nerve structures can often result in serious consequential damage for the patients. If a parotid gland tumour (parotid gland cancer) is surgically removed, the surgeons face the challenging task of preserving the function of the facial nerve. With intraoperative neuromonitoring, the nerves can be localised and their function monitored during surgery.

Parotid gland tumours belong to a rare subtype in the category of salivary gland tumours. The majority of all tumours of this type, about 70–80%,^[1] are benign; however, even a benign parotid gland tumour should always be removed, as in many cases it can become malignant. The parotid gland is located on both sides between the ear and the lower jaw.

Parotid gland tumours and the location of the facial nerve

Removing a parotid gland tumour is complicated by the anatomical course of the facial nerve. This nerve is responsible for the function of the mimic facial muscles and transmits activation signals from the brain to these muscles.

The facial nerve divides into a fine nerve branch in the area of the parotid gland. This nerve branch runs like a fan through the parotid gland, from where the individual branches continue to the different facial muscles. If a parotid gland tumour is removed, the risk of injury to these complex branching nerves during surgery can be increased, for example, by pressure, tension or bruising. Patients may suffer from temporary paralysis of individual muscles or even permanent hemiplegia of the mimic facial muscles.

For this reason, intraoperative nerve monitoring is an important protective technology for patients and doctors alike to avoid facial nerve damage.

Neuromonitoring procedure during parotid gland surgery

Depending on how far the parotid gland tumour has spread, the parotid gland is either partly or completely removed. Neuromonitoring is used in the following way:

>> Placement of needle electrodes in the facial muscles to record the “nerve signals” (muscle response)

>> Direct stimulation of the nerves via electrical impulses (stimuli) using a stimulation probe

>> Recording of response signals resulting from the contraction of the stimulated muscles

>> Visual and acoustic representation of the response signals by the neuromonitoring device

If a parotid gland tumour is surgically removed, the doctors can be warned of possible nerve damage at an early stage by using intraoperative neuromonitoring. The use of IONM can thus contribute significantly to patient safety.

In addition to parotid gland tumours and their surgical removal, IONM is also frequently used in spine surgery, e.g. for scoliosis.

References

1. Spiegel Online, Ohrspeicheldrüsenkrebs: Selten, aber tückisch (2013). Available at: http://www.spiegel.de/gesundheit/diagnose/ohrspeicheldruesenkrebs-eine-operation-ist-pflicht-a-888353.html. (Last accessed: 6 November 2025).

Stöhr, M. et al. Neuromonitoring (1999).

Zenner, H. Praktische Therapie von Hals-Nasen-Ohren-Krankheiten: Operationsprinzipien, konservative Therapie, Chemo- und Radiochemotherapie (2008).

Aage R. Møller, Intraoperative neurophysiological monitoring, 2nd ed (2006).

Yingling, C. „Selective dorsal rhizotomy“, Handbook of Clinical Neurophysiology 8; pp. 439–454 (2008).