Jugulotympanic Paraganglioma Presenting with Cerebellopontine Angle Cistern Involvement: Neuroradiological Evaluation on an Elucidative Case

A 76-years-old female patient presents at the emergency room with a frontotemporal headache, slight imbalance, and left deafness.  

Computed tomography (CT) shows an expansive lesion determining enlargement of the jugular foramen extending to the cerebellopontine angle cistern and tympanic cavity (Figs. 1,2,3,4).

MRI shows a jugular foramen-centred lesion with a heterogeneous signal on T1 and T2 (Figs. 5,6), with foci of hyper signal on T1 - extracellular methaemoglobin and some intermingled vascular flow voids - “salt and pepper” appearance (Fig. 5). In addition, Time-of-flight (TOF) magnetic resonance angiography demonstrates the extension to the left carotid space, determining an anterior displacement of the carotid artery, which has a normal thickness (Fig. 7).

Fat-saturated post gadolinium T1 and 3D-T1 demonstrate intense contrast enhancement, indicating the hypervascular characteristic of the lesion (Figs. 8,9). The tumour extends to the cerebellopontine angle and left prepontine cistern, exerting slight compression on the left middle cerebellar peduncle (Fig. 10). It also extends into the proximal portion of the left internal auditory canal (Fig. 11).

Paragangliomas, also known as glomus tumours, arise from paraganglion cells, forming the basis of the extra-adrenal neuroendocrine system. They represent less than 0.5% of all head and neck masses [1].

These tumours are more common in females, arising in several locations along the carotid sheath and middle ear, including the carotid bifurcation, vagal ganglia, jugular bulb, and tympanic plexus [2]. They could be associated with Von Hippel-Lindau, Multiple endocrine neoplasia type 2, and neurofibromatosis type 1 [1,2,3].

Jugulotympanic paraganglioma is a jugular paraganglioma without clearly arising from either of these spaces. The most common symptoms include pulsatile tinnitus and aural fullness; however, due to their large size, patients may present deficits of IX and X cranial nerves (Vernet syndrome) and conductive hearing loss [2,3].

On CT, paragangliomas present as a well-defined soft tissue attenuation mass. These tumours most commonly demonstrate homogenous and avid contrast enhancement. In addition, CT imaging accurately evaluates osseous involvement, demonstrating local erosion of adjacent bony structures.

MRI can conspicuously demonstrate the characteristic findings of glomus tumours. For example, paragangliomas typically present with internal flow voids, given the vascular nature of these lesions. Frequently, T1 demonstrates areas of a hyper signal indicative of subacute haemorrhage: the hypointense flow voids and hyperintense areas of haemorrhage results in a characteristic “salt and pepper” appearance [4,5].

Dynamic contrast-enhanced (DCE) MRI helps evaluate blood flow hemodynamics by measuring the effect of intravascular contrast material as it passes through tissue over time, providing semiquantitative parameters. Paragangliomas demonstrate a higher peak enhancement, maximum signal-enhancement ratio, and shorter time to maximum enhancement than schwannomas, the crucial differential diagnosis [6].

Time-resolved imaging of contrast kinetics (TRICKS) is a keyhole technique that improves temporal resolution, obtaining dynamic images during the arterial, capillary, and venous phases. Hence, it is possible to acquire three-dimensional volumes during the gadolinium passage, to detect the vascularization of the region of interest over time, as seen in digital subtraction angiography [7]. These modalities evaluate tumour vascular density and identify feeding vessels, which can guide subsequent embolization or surgical approaches. The most common feeding vessel is the ascending pharyngeal artery [3,4,5].

Treatment is usually by excision, and preoperative endovascular embolization can reduce tumour vascularity and aid the surgery. Palliative treatment includes radiotherapy for unresectable lesions [4,5,6].