Distinct Syndrome of Isolated Central Vestibulopathy

Acute isolated vertigo has mostly been ascribed to inflammatory disorders, involving the peripheral vestibular labyrinth. Because the dorsal medulla contains the structures such as the vestibular nuclei (VN), nucleus prepositus hypoglossi (NPH), and inferior cerebellar peduncle (ICP) that are involved in conveying and processing the vestibular and ocular motor signals, lesions involving this area typically cause dizziness/vertigo and imbalance along with ocular motor abnormalities. However, the vestibular symptoms and signs from lesions involving the dorsal medulla have mostly been recognized as a constellation of the much more prevalent forms of infarctions involving the medial (medial medullary) or lateral (lateral medullary infarction or Wallenberg syndrome) portion of the medulla. Diagnosis of brain stem vestibular syndromes is straightforward when other signs of brain stem involvements are identified. However, isolated vestibular syndrome from infarctions restricted to this area provides a difficulty in differentiation from more benign disorders involving the inner ear or the peripheral vestibular nerve. Previously, clinical features of isolated vestibulopathy from strokes have mostly been reported in patients with cerebellar infarctions, and only a few anecdotal reports have described isolated vestibular syndrome from brain stem strokes. To aid in differentiation of the isolated vestibular syndrome from dorsal medullary infarction (DMI) from peripheral vestibular disorders, we analyzed the clinical features in 18 patients with isolated vestibular syndromes from infarctions restricted to the dorsal portion of the medulla. We hypothesized that DMI would present clinical features distinct from those observed in peripheral vestibular disorders depending on the structures involved. Background and Purpose—The characteristics of infarctions restricted to the dorsal medulla have received little attention. This study aimed to define the distinct clinical features of dorsal medullary infarction. Methods—Of the 172 patients with a diagnosis of medullary infarction at Seoul National University Bundang Hospital from 2003 to 2014, 18 patients with isolated dorsal medullary infarction were subjected to analyses of clinical and laboratory findings. Results—All patients presented acute isolated vestibular syndrome with dizziness/vertigo and imbalance. Almost all patients (17/18, 94%) showed the signs from involvements of the vestibular nuclei, nucleus prepositus hypoglossi, or inferior cerebellar peduncle, which included direction-changing gaze-evoked nystagmus (n=12), negative head-impulse tests (n=8), skew deviation (n=7), central patterns of head-shaking nystagmus (n=6), and spontaneous nystagmus (n=2). Initial magnetic resonance imagings including diffusion-weighted images were negative in 7 patients (39%). Twelve patients (67%) showed a progression and developed additional neurological abnormalities, but the neurological outcomes were favorable. Conclusions—The presence of central vestibular signs allows bedside differentiation of isolated vestibular syndrome because of dorsal medullary infarction from acute peripheral vestibular disorders. Because initially false-negative magnetic resonance imagings and subsequent progression are frequent in dorsal medullary infarction, early recognition through scrutinized evaluation is important for proper managements. (Stroke. 2015;46:00-00. DOI: 10.1161/ STROKEAHA.115.010972.)