Cogan's Syndrome. High resolution MRI indicators of activity.

In the chronic-relapsing form of Cogan's syndrome, it can be difficult to evaluate the activity of the disease. In contrast to the initial stage, routine diagnostic techniques sometimes fail to indicate progression in the chronic stage. To determine whether high-resolution magnetic resonance imaging (HR-MRI) can be used to differentiate between active and inactive stages, we examined three patients with Cogan's syndrome (one during an acute relapse, two with chronic audiovestibular deficits), all of whom had antibodies to inner ear tissue (cochlea, vestibular labyrinth). Unenhanced T1-, T2, gadolinium-enhanced T1-weighted, and three-dimensional constructive interference in steady stage (CISS) images were used. Abnormal MRI signals of the inner ear were related to the activity of the disease. The patient studied during an acute exacerbation showed abnormal MRI signals in the vestibule, semicircular canals, vestibular nerve, and cochlea, which disappeared after the relapse. These abnormalities included high signal in the membranous labyrinth, the vestibule, and cochlea, with enhancement on T1-weighted images, indicating gadolinium leakage through the abnormal labyrinthine membrane into the perilymphatic spaces. In contrast, the other two patients with chronic audiovestibular deficits but no clinical signs of an acute relapse, had narrowing or occlusion of semicircular canals of the cochlea on the 3D-CISS images, but no high signal lesions (T1) and no enhancement. We conclude that sequential gadolinium-enhanced MRI can identify the active stage of Cogan's syndrome. The combination of HR-MRI and antibodies to inner ear antigens are helpful in the diagnosis of acute, sequential, bilateral audiovestibular impairment of autoimmune origin.