Predictors of central vestibular disorders from videonystagmography tests

Background The diagnosis of central vestibular lesion is challenging and sometimes there is an overlap in symptoms and signs with a peripheral vestibular lesion. In some selected cases, dizziness is the only presenting symptom and in other patients, mild neurological symptoms as numbness are ignored. Videonystagmography (VNG) is considered a useful method for diagnosing vertigo of peripheral origin; however, not all the patients with central vertigo can be diagnosed easily. Benign paroxysmal positional vertigo and central positional vertigo share common criteria. The aim of the present study is to assess the usefulness of different VNG tests as predictors of central vestibular disorders, to determine the criteria that differentiate central positional nystagmus from the peripheral type, and to attempt to relate the abnormality in different VNG tests to certain central nervous system (CNS) levels. Materials and methods A retrospective study was carried out on 51 patients with possible central vestibular disorders from VNG tests battery and were referred for an MRI for further assessment. According to MRI results, the patients were divided into group A (31 patients), the group with manifest MRI findings, and group B, the group with free MRI (20 patients). Different VNG tests were compared between both groups. Results Three predictors of CNS lesion by VNG were determined: fixation index (FI), oculomotor tests, and central positional nystagmus; there was a statistically significant difference between both groups in FI, oculomotor tests, and central positional nystagmus, and apogeotropic criteria or nystagmus in multiple plains. There was no relation between any of those predictors and specific levels in the CNS. Conclusion VNG tests are a good diagnostic tool to differentiate between peripheral and central vestibular lesions. The inclusion of FI and positional tests to the oculomotor tests increases the sensitivity of the VNG. In some cases, it is difficult to distinguish between benign paroxysmal positional vertigo and central positional vertigo; apogeotropic nystagmus and nystagmus in multiple plains should raise the suspicion of CNS lesion. Anterior circulation ischemia may lead to chronic vertigo symptoms. Central vestibular vertigo could be caused by dysfunction or excitation of various structures in the CNS including the vestibular cortex.