Arnold-Chiari malformation and the otolaryngologist: place of magnetic resonance imaging and electronystagmography.

The Arnold-Chiari malformation (ACM) is a rare congenital condition in which there is a downward displacement of the cerebellum through the foramen magnum. Patients with this condition frequently develop symptoms of ataxia, imbalance, or vertigo. As a result the patient is often referred to an otolaryngologist. Such a case is reported. A patient presented with imbalance, had downbeating nystagmus on down gaze, and had other eye movement abnormalities recorded on electronystagmography (ENG) which were strongly suggestive of central pathology. Although her computerized tomography (CT) scan was normal, the eye findings and neurological evaluation were strongly suggestive of an ACM. A repeat CT scan with intrathecal metrizamide was abnormal. A definite diagnosis of ACM was confirmed using the new investigative technique of magnetic resonance imaging (MRI).