glomus tympanicum

Glomus tympanicum paragangliomas (chemodectomas) are the most common middle ear tumour.

Epidemiology

There is a female predominance (M: F = 1:3); presentation is most common when patients are more than 40 years old .

Clinical presentation

May be incidental but symptomatic masses produce pulsatile tinnitus, otalgia, or conductive hearing loss .

Pathology

Glomus tympanicum paragangliomas arise from the Jacobson nerve at the cochlear promontory.

Radiographic features

CT is usually the best modality to assess these masses.

CT

• soft tissue mass lateral to the cochlear promontory
  • if large may fill the middle ear cavity, and invade the Eustachian tube or mastoid
• ossicles may or not be destroyed and may simply be encased
• surrounding bony destruction may be present in aggressive tumours
• intact jugular bulb

The Glasscock-Jackson and Fisch classifications of glomus tumours are based on the local extension of the tumour and their effect on mortality and morbidity. Glomus tympanicum paragangliomas are considered type A tumour, as they are limited to the middle ear cavity.

Treatment and prognosis

Surgical resection is the treatment of choice .

Differential diagnosis

On imaging consider:

• glomus jugulare paraganglioma
  • permeative destruction of the floor of the middle ear
  • involving the jugular foramen
  • presents with a dehiscent jugular bulb
• facial nerve schwannoma
  • pedunculated mass arising from the facial nerve
  • involving the tympanic segment of the facial nerve
• congenital cholesteatoma
  • no enhancement on post-contrast T1 MRI

See also

• paragangliomas of the head and neck

Siehe auch:

• Paragangliom
• Paragangliome von Kopf und Hals

und weiter:

• Paragangliom des Nervus vagus
• glomus jugulotympanicum tumour