For the patient, sudden deafness can be terrifying. For the specialist, this disorder can be most challenging for the cause of sudden deafness cannot be readily determined by use of the most advanced diagnostic tests.
Several complementary tests are used, such as audiological, biochemical, otoneurological, and imaging studies. Now a research team has elected to choose Magnetic resonance imaging (MRI) for a detailed study of the structures of the inner ear, the internal auditory meatus (IAM), and the cerebellopontine angle, the angle formed at the junction of the cerebellum, pons, and medulla, and most likely location of an acoustic neuroma.
Past research has revealed that in an MRI examination of 495 sudden deafness cases, 22 showed evidence of intra-axial lesions. This gave a research team a central etiologic basis for the deafness; the possibility of lesions in the audiovestibular pathway has been considered by other researchers to be one of the principal causes of sudden hearing loss.
A new study reports on the abnormalities found after an MRI examination of patients with sudden deafness. The authors of “Magnetic Resonance Imaging in Sudden Deafness,” are Hugo Valter Lisboa Ramos MD, Flávia Alencar de Barros, Hélio Yamashita MD PhD, Wellington Yugo Yamaoka MD, Ana Cláudia Valério de Souza MD, and Norma de Oliveira Penido MD PhD, all from the Federal University of São Paulo - Paulista Medical School, São Paulo, Brazil. findings are being presented at the American Academy of Otolaryngology-Head and Neck Surgery Foundation Annual Meeting & OTO EXPO, being held September 19-22, 2004, at the Jacob K. Javits Convention Center, New York City, NY.
Methodology:
This prospective study examined 49 patients, 23 male and 26 female, ranging in age from 15 to 91 years (average 45.4 years). Thirty-four were racially white, ten were mixed-race, two black, and three Asian. Only five of the 49 patients studied had MRI performed before clinical treatment with prednisone and pentoxiphylline. In 23 patients, the deafness was on the left side, 26 on the right side.
An audiometric test and acoustic impedance audiometry were performed on patients who complained of a sudden loss of hearing. Sudden deafness was defined as a sensorineural loss of audition greater than or equal to 30 dB in at least three contiguous audiometric frequencies occurring within three days or less.
The patients studied underwent MRI of the temporal bone and brain. The test was complemented with use of axial slices of the cranium in concentrated sequences obtained by a Fluid Attenuation Inversion Recovery (FLAIR) system with the objective of evaluating the encephalic mass. The researchers determined peripheral alterations to be those limited to the inner ear, and central alterations to be those located in the internal auditory meatus or in the central nervous system. The results were analyzed descriptively.
Results: