Radiology of the parapharyngeal space.

The parapharyngeal space (PPS) is a central space in the deep neck. Intrinsic lesions within this space are limited. Other spaces in the neck are closely related to the PPS and the direction of displacement of this space often suggests the origin of a lesion. The morphology of a lesion, together with the site of origin, helps in narrowing the diagnostic possibilities. The behaviour of the PPS often helps to determine whether a lesion is an intrinsic abnormality or whether it arises from a neighbouring space. Such information is crucial in the planning of surgical approach and the placement of drains.