[Diagnosis of Arnold-Chiari malformation by electronystagmography]

3 patients with Arnold-Chiari malformation with vertigo as the sole clinical presentation are described. 2 of them had been undiagnosed for many years despite repeated examinations, including CT scans. The third patient was diagnosed 2 weeks following the initial vertiginous attack. Downbeating nystagmus demonstrated by electronystagmography, indicating a pathological lesion at the craniocervical junction, was the key finding that led to the diagnoses. Following this finding, CT scan directed to the craniocervical junction showed the typical image of Arnold-Chiari malformation. The cases presented emphasize the important contribution of electronystagmography in the evaluation of vertigo due to intracranial lesions. However, computerized imaging examination remains the main diagnostic tool for intracranial pathologic processes.