Head and Neck Imaging

Parapharyngeal space, pathology

Intrinsic parapharyngeal space pathology
- Retrostyloid compartment
Apart from vascular pathology, such as internal carotid aneurysm, dissection or thrombosis and internal jugular vein thrombosis, tumoral pathology arising either from the lower cranial nerves (see neurogenic tumour, head and neck ) or from the glomus bodies ( glomus tumour ) may be seen in the retrostyloid compartment. Mass lesions in this location typically displace the internal carotid artery anteromedially and the internal jugular vein posterolaterally ( Fig. 1); carotid space, pathology .
- Prestyloid compartment
Lesions in the prestyloid compartment lie anterior to the internal carotid artery and internal jugular vein. Solid mass lesions are usually of accessory salivary gland origin. Anomalies from the branchial apparatus may be encountered.
Extrinsic parapharyngeal space pathology

The parapharyngeal space can be displaced or invaded by pathology arising from the surrounding spaces. The loose fatty parapharyngeal tissue may be used as a 'lift shaft' by pathological conditions originating from neighbouring structures.
- parotid space: tumours arising from the deep lobe of the parotid gland commonly extend into the prestyloid compartment. Differentiation from a primary prestyloid lesion may be difficult. The most reliable sign of a primary parapharyngeal tumour is the presence of a fat layer separating the tumour from the deep lobe of the gland; a more or less dumbbell-shaped mass widening of the stylomandibular tunnel, combined with anteromedial displacement of the parapharyngeal fat, suggests a primary parotid lesion (Fig. 2).
Parapharyngeal cellulitis may be seen secondary to parotitis ( parotid gland, pathology ).
- pharynx: pharyngitis may cause parapharyngeal cellulitis; malignant tumours from the oro- or nasopharynx may extend into the pre- and/or retrostyloid compartment (see oropharyngeal cancer ). Such an extension pattern is particularly common in nasopharyngeal cancer .
- masticator space, pathology : mass lesions from the masticator space may displace the parapharyngeal fat posteromedially.
- retropharyngeal space, pathology : large retropharyngeal adenopathies displace the parapharyngeal fat anterolaterally.
- mass lesions arising from the submandibular space, pathology or skull base may extend into the parapharyngeal space.

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Fig. 01a

Axial T1-weighted spin-echo image in a patient with known neurofibromatosis. A large enhancing soft tissue mass is seen in the retrostyloid compartment of the parapharyngeal space, displacing the internal carotid artery (arrow) anteromedially (the internal jugular vein cannot be identified on this image). The fat of the prestyloid compartment is displaced anteriorly (arrowhead).
Parapharyngeal space, pathology, Fig. 01a
Parapharyngeal space, pathology, Fig. 02a (a)
Parapharyngeal space, pathology, Fig. 02b (b)
Parapharyngeal space, pathology, Fig. 02c (c)