[Clinico-experimental study on parapharyngeal space invasion of head and neck cancer]

We studied the incidence and mode of development of parapharyngeal space invasion from head and neck cancers by both retrospective examination of our 172 patients and tracing the dynamics of lymph flows to the parapharyngeal space from the hypopharynx, the mesopharynx and the posterior portion of oral cavity. Of the patients examined 23 (13.4%) were found the parapharyngeal invasions (20% in mesopharyngeal cancers, 17.3% in hypopharyngeal cancers, 11.9% in cancers of posterior portion of oral cavity). Parapharyngeal space invasions occur frequently in a direct or indirect way when meso- or hypo-pharyngeal cancers or those of posterior parts of oral cavity invade deeply into the muscle layers and extend to the palatine arch, retromolar region, pharyngoepiglottic fold, lateral base of tongue, or posterior buccal mucosa. These invasions frequently induced such symptoms as trismus (47.8%), swelling of the lateral pharyngeal wall (39.1%), otalgia (34.8%), swelling of infra-auricular and submandibular regions (34.8%, 26.1%) and facial palsy (26.1%). Computed tomography was very useful to the diagnosis of the parapharyngeal space invasion. The parapharyngeal space invasions were successfully removed under a wide surgical field without injuring the important nerves and vessels and with preservation of mandibular function by our modification of Attia's technique. The lymph flow from the hypopharynx was chiefly upward and reached terminally to the parapharyngeal space including the retropharyngeal lymph nodes. The lymph flow from the mesopharynx revealed to drain chiefly into the lower internal jugular nodes. The lymph flow from the posterior parts of oral cavity was divided into anterior and posterior groups. Anterior groups of lymphatic drained into the root of tongue and reached terminally to the vallecula and posterior groups drained into the internal jugular nodes. We should cover all routes for extension of head and neck cancers, including the parapharyngeal space, in the diagnosis and the management of these conditions.