Читать книгу Vestibular Disorders - Группа авторов - Страница 17

Spontaneous nystagmus can enhance during positional testing, leading to an incorrect diagnosis of BPV, especially in the emergency room. For example, a subject with left vestibular neuritis could demonstrate dramatic enhancement of a spontaneous right-beating nystagmus in either Hallpike position. If the primary position spontaneous nystagmus is subtle and missed (during examination without Frenzel glasses in a brightly lit emergency department), then enhanced spontaneous nystagmus could be mistaken for BPV and inappropriately treated with repositioning manoeuvres, which would only lead to increasing nausea and motion sensitivity. This enhanced spontaneous nystagmus is so distinctly different from BPV in that it would seem unlikely that it could be mistaken for BPV. First, BPV is paroxysmal while enhanced spontaneous nystagmus is persistent. Horizontal Canal BPV when tested with either ear down, changes direction whereas enhanced spontaneous nystagmus remains unidirectional (e.g., the same right-beating nystagmus is observed with the right ear down and with the left ear down).