parapharyngeal

Parapharyngeal space refers to a paired deep neck space located on each side of the pharynx, extending from the base of the skull to the level of the hyoid bone. The space is classically divided by the tensor veli palatini muscle into two compartments: prestyloid (anterior) and retrostyloid (posterior). Its boundaries are the medial wall formed by the pharyngeal constrictors, the lateral aspect by the mandible and pterygomandibular space, the posterior fascia by the prevertebral layer, and the superior extent at the skull base with inferior contact near the hyoid bone.

The prestyloid compartment contains mainly adipose tissue, with some contribution from the deep lobe of the parotid gland and minor lymphatic tissue. The retrostyloid compartment houses vital neurovascular structures within the carotid sheath, including the internal carotid artery, internal jugular vein, and cranial nerves IX through XII, as well as the sympathetic chain. The retrostyloid space can also harbor lymph nodes and various neurogenic or vascular lesions.

Clinically, parapharyngeal space pathology is often recognized as a lateral oropharyngeal mass, presenting with oropharyngeal fullness, dysphagia, muffled voice, or referred otalgia. Tumors are predominantly benign and include pleomorphic adenomas of the deep lobe of the parotid, as well as neurogenic tumors such as schwannomas and paragangliomas in the retrostyloid region. Infections or inflammatory processes may produce abscesses within the space.

Diagnosis relies on imaging, with MRI and CT providing delineation of extent and relationship to surrounding structures. Management is typically multidisciplinary, with surgical excision being the mainstay for many lesions; approaches vary from transcervical to combined transmandibular or skull-base routes depending on location and involvement of adjacent structures.