Paragangliomas are rare tumours that grow from small nests of special cells, called paraganglia, which play a part in measuring and controlling the oxygen levels in the blood.

Paragangliomas usually occur at one of the following sites:

• the upper part of the neck just below the ear. These are often called carotid body tumours.
• in the bones of the skull, close to the middle ear. These are often called glomus tympanicum tumours.
• at the bottom of the skull, alongside the internal jugular vein. These are known as glomus jugulare tumours.

Paragangliomas are almost always benign (non-cancerous). They are usually very slow growing, often being present for years before they cause symptoms. Eventually, however, a paraganglioma will reach a size where it becomes troublesome, pressing on surrounding structures and causing problems like difficulty in swallowing and hoarseness of the voice (with carotid body tumours), deafness, ringing in the ears (tinnitus) and earache (with glomus tympanicum tumours) or paralysis of some nerves causing difficulty with swallowing and eye movements (with glomus jugulare tumours).

The usual treatment for these tumours is surgery which, provided they can be removed completely, results in a cure. Sometimes because of their position an operation is not possible and on these occasions radiotherapy is often a successful alternative treatment.