Introduction
The vagus nerve is a motor and sensory nerve. It is the only cranial nerve extending into the chest and abdomen.
It provides:
- Motor parasympathetic supply to all viscera except the adrenals (e.g. heart rate, peristalsis, sweating)
- Motor innervation to the muscles of the pharynx and larynx
- Sensory innervation to the outer ear (auricular nerve)
Vagus nerve palsy will cause hoarseness (recurrent laryngeal nerve) and difficulties with swallowing.
There may be uvula deviation to the opposite side. There are usually no parasympathetic effects evident. There may be loss of sensation over part of the ear.
The vagus nerve originates in the medulla, traverses the jugular foramen, then descends in the carotid sheath to innervate the neck, chest and abdomen.
Nerves IX and X are tested together.
Needs the same investigations as CN IX, but additionally consider CT chest to look for apical lung tumours and mediastinal tumours.
Examine the neck for tumours.
Trauma to the neck may rarely cause a CN X palsy.
Lateral medullary/Wallenbergs syndrome (brainstem stroke involving the vertebral or posterior inferior cerebellar artery) can cause palsies of CN X and XI.
Aortic aneurysm or tumours (mediastinal or lung carcinoma) can cause compression of the vagus nerve in the chest.
It can also be damaged at the base of skull (jugular foramen syndrome).
The nerve can be damaged in the neck, either by trauma or neck surgery.