Glomus jugulare tumor is a rare, benign paraganglioma of the skull base that forms in the jugular fossa of the temporal bone and is made up of glomus cells which are neural crest cell derivatives.
Glomus jugulare tumor (GJT) is uncommon and has been shown to develop primarily between the fourth and seventh decades of life [1] [2]. It has a higher prevalence in females than males and is sometimes inherited familially [1].
Slow growing and non-malignant nature of GJT results in a negative outcome, as the presentation is delayed with gradual onset of symptoms [3]. Symptoms are due to the direct encroachment of the tumor into neighboring structures, and both the size and location of GJT is important for classification purposes [4]. As these tumors arise from the temporal bone, the middle ear is impinged on, causing tinnitus (pulsatile), sensorineural and conductive hearing loss, vertigo, ear discharge, pain, and a reddish-bluish discoloration of the eardrum by an inconspicuous mass on otoscopy. Due to their extensive vasculature, a bruit may be heard upon auscultation of the temporal bone.
The jugular foramen is the aperture through which the internal jugular vein, and cranial nerves IX, X, and XI exit the skull. Compression of the cranial nerves results in dysphagia, hoarseness, change in voice, weakness in the sternocleidomastoid and trapezius muscles leading to the jugular foramen syndrome [2] [5].
The spread of a glomus jugulare tumor into the cranial vault consequently manifests as headaches, accumulation of cerebrospinal fluid and other features of raised intracranial pressure [6]. The brain stem may be affected, giving rise to signs such as loss of coordination, ataxia, loss of balance, and involvement of multiple cranial nerves [6]. Unilateral facial weakness is unusual but has been reported [5].
Most GJTs do not release any hormones. In some instances, however, they secrete adrenalin, noradrenalin, and dopamine, and have been referred to as complex GJTs [7]. Ensuing sympathetic hyperstimulation can induce tachycardia, tachypnea, diaphoresis, and elevated blood pressure; similar to the presentation of adrenal gland tumors. Malignant change is uncharacteristic for these tumors, noted in only a minority of cases [8].
Imaging is the mainstay of diagnosis and monitoring in this type of tumor. Computerized tomography (CT) and magnetic resonance imaging (MRI) scans are most frequently used. CT scans and MRI scans help to visualize tumor extension into the bone, as well as spread to adjacent intracranial structures respectively [6]. X-rays of the skull can also be done, and will show signs of abnormal growth around the jugular fossa, but are not as helpful as CT and MRI scans. The aforementioned rich blood supply of glomus jugulare tumors necessitates arteriography and is especially important if tumor resection is planned. Radionuclide scan using meta-iodobenzyl-guanidine (MIBG) has also been used with success, in assessing these masses [9]. If there are indications of sympathetic predominance, urine catecholamine levels can be measured to determine whether tumors are secretory or not [10].