Glomus jugulare tumour

A glomus jugulare tumour is a paraganglioma of the head and neck that is confined to the jugular fossa. While it is a rare tumour, it is the most common of the jugular fossa tumours.

Epidemiology

The relative prevalence of glomus jugulare with respect to other head and neck paraganglioma of the head and neck varies from publication to publication and depending on definition of the terms jugulare, tympanicum and jugulotympanicum. Most agree however that they are more common than glomus vagale ³. 

These tumours are seen in adults, typically between 40 and 60 years of age, with a moderate female predilection ³.

Clinical presentation

Presentation depends on the degree of middle ear involvement. When significant involvement is present then pulsatile tinnitus and hearing loss.

Additionally a number of patterns of cranial nerve palsies have been described due to involvement of the nerves at the jugular foramen. These include ^3-4:

• Vernet syndrome (motor paralysis of cranial nerves IX, X, and XI)
• Collet-Sicard syndrome (Vernet syndrome with additional involvement of cranial nerve XII) (46), and
• Horner syndrome

Pathology

For a general discussion on the pathology of these tumours please refer to the generic article pertaining to paragangliomas.

Glomus jugulare tumours are defined according to location (i.e. origin at the jugular foramen) rather than anatomic origin and may arise from Jacobson's nerve, Arnold's nerve of the jugular bulb ³.

Radiographic features

Growth of these tumour is in a number of directions. Typically they extend into the mastoid air-cells and middle ear and Eustachian tube. 

CT

CT is most useful at assessing the bony margins of the tumour, which are typically irregularly eroded with a moth-eaten pattern. Eventually as the tumour enlarges the jugular spine is eroded and the mass extends into the middle ear, as well as inferiorly into the infratemporal fossa.  CT is excellent at assessing the integrity of the ossicles and bony labyrinth ³.

MRI

• T1 : low signal ³
• T2 : high signal
• T1 C+ (Gd) : marked intense enhancement ^2-4

Salt and pepper appearance is seen on both T1 and T2 weighted sequences; the salt representing blood products from haemorrhage or slow flow and the pepper representing flow voids due to high vascularity. It should be noted that this appearance is sometimes encountered in other lesions (e.g. hypervascular metastases) and is not typically seen in smaller glomus tumours ³.

DSA - angiography

Angiography demonstrates an intense tumour blush, with the most common feeding vessel being the ascending pharyngeal ³. Early draining veins are also noted due to intra-tumoural shunting ⁴.

Angiography also has a role to play in preoperative embolisation, which is typically carried out 1-2 days prior to surgery, however care must be taken to fully evaluate feeding vessels. Familiarity with vascular anatomy of the region is essential if complications are to be avoided ³.

Nuclear medicine

Indium-111 labelled octreotide accumulates in these tumours due to the presence of receptors for somatostatin, best visualised with SPECT, but requires the tumour to be greater than 1.5cm in diameter.

Treatment and prognosis

Surgery is the treatment of choice and if complete resection is achieved a cure can be expected. Complications are however not uncommon due to the large number of sensitive structures in the region and include:

• cranial nerve deficits
• CSF / endolymphatic leak

Although most cervical paragangliomas (e.g. carotid body tumours) are considered relatively radioresistant, base of skull paragangliomas are radiosensitive, and thus large inoperable tumours or tumours in elderly and frail patients are often treated with radiotherapy.

Recurrence and local invasion is common, occurring in 40-50% of cases ³. Malignant transformation is less common, seen in 2-13% of cases ³.

Differential diagnosis

• jugular schwannoma
  • sharply demarcated smooth bony margins ¹
  • no internal flow voids
  • not very vascular on angiography
  • no salt and pepper appearance
  • Indium-111 labelled octreotide negative ³
• bony metastases
  • hypervascular tumours may be very similar in appearances (e.g. RCC, thyroid cancer)
• meningioma
• normal anatomical variation
  • asymmetry of jugular foramen size
  • high riding or dehiscent jugular bulb
• jugular bulb thrombosis