Acute isolated vertigo with vertical up-beating nystagmus: A rare case of nucleus intercalatus of Staderini ischemia

The role of intercalatus nucleus of Staderini (INS), the most caudal of the perihypoglossal nuclei, is much debated. Last research seems to suggest that this nucleus plays a role as a vertical eyes movements integrator. The few clinical reports present in the literature that describe isolated lesions of the INS have described patients presenting in acute with up-beating vertical spontaneous nystagmus. Isolated acute lesion of INS is, in fact, much rare, and, without other neurological signs, is exceptional. We present a case of acute isolated vertigo with no other neurological signs or symptoms, due to INS ischemia provoked by vertebral artery stenosis. The patient presented with spontaneous vertical up-beating nystagmus that showed at videonystagmographic recording, a clear exponential decay of angular slow-phase velocity, that is considered a typical sign of neural integrator impairment. This case seems to represent a further confirm that INS is part, as a vertical-to-position neural integrator, of the neural circuit controlling the vertical eyes movements.