内リンパ水腫―画像評価とその意義―

抄録

　We have developed imaging analysis to visualize the endolymphatic space using 3-T magnetic resonance imaging (MRI) after intratympanic or intravenous injection of gadolinium (Gd). Investigation into the existence of endolymphatic hydrops (EH) among patients with Meniere's disease (MD) diagnosed according to the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) criteria revealed that EH was frequently observed in patients with definite MD, suggesting MRI evaluation as a promising alternative to histologic confirmation of EH. Another investigation into the relationships between EH and other otological examinations, including vestibular evoked myogenic potential (VEMP), electrocochleography, and caloric response, demonstrated that results were related not only to the degree of EH, but also to the persistence of EH, i.e., duration of the disease. EH was detected on the MRI findings of patients with sudden deafness or fluctuating hearing loss, besides in those with MD. Moreover, EH was also found in patients with tinnitus or sensation of ear fullness, suggesting these symptoms as a potential first sign of early EH. MRI examination of EH can also be applied for preoperative evaluation for middle ear surgery, particularly otosclerosis. The existence of EH is a risk factor for severe vertigo following stapes surgery. The presence of EH in cases with otosclerosis could be clearly visualized in ears with and without EH-related symptoms. MRI is a sensitive technique for detecting EH, and could provide useful information to manage related symptoms and prevent complications following middle ear surgery.