Neuromonitoring in ENT surgery: From cochlear implants to parotidectomy
ENT surgery
ENT surgery is a diverse surgical field that deals with the surgical treatment of diseases, injuries and malformations of the ear as well as auditory processing disorders (e.g. cochlear implants), the upper and lower airways, the oral cavity, the pharynx, the larynx and the oesophagus. ENT surgery overlaps with neurosurgery, general and visceral surgery and also plastic surgery.
Importance of neuromonitoring for ENT surgery
Due to the sensitive and complex surgical field and varying course of the delicate nerves, the objective of today’s ENT surgery is to use more conservative endoscopic and minimally invasive procedures. Intraoperative neuromonitoring plays an important role in localisation and functional monitoring of nerves as well as the intraoperative preservation of nerve function. Nerve monitoring is also very useful during open surgery, e.g. during insertion of a cochlear implant.
Type of intervention and approach determine neuromonitoring measuring method
Depending on the intervention and type of approach, electromyography (EMG) is primarily used in ENT surgery to record the neuromonitoring signals, such as during cochlear implant surgery. However, evoked potentials, such as auditory evoked potentials (AEPs), are also used during certain interventions such as the resection of a vestibular schwannoma.
The facial nerve is at risk during parotid gland surgery (parotidectomy). The individual branches can be localised and monitored via electromyographic recording of the muscles they innervate. During thyroidectomy, the function of the recurrent laryngeal nerve is also monitored via an EMG recording on the vocal muscle.
When a tympanoplasty is performed or a cochlear implant is inserted, EMG neuromonitoring is a useful tool when milling near the bony facial canal to monitor the facial nerve.
EMG neuromonitoring is also used to minimise the risk of injury to the facial nerve during mastoidectomy when milling near the corresponding bony structure.
The following ENT procedures are most frequently accompanied by neuromonitoring:
>> Parotidectomy
>> Thyroidectomy
>> Vestibular schwannomas
>> Tympanoplasty
>> Mastoidectomy
>> Cochlear implants