Lee Yeo Jin, Shin Jung Eun, Park Mun Su, Kim Jae Myeong, Na Bo Ra, Kim Chang-Hee, Park Hong Ju
Department of Otorhinolaryngology-Head and Neck Surgery, Konkuk University School of Medicine, Seoul, Korea.
Audiol Neurootol. 2012;17(4):228-34. doi: 10.1159/000336958. Epub 2012 Apr 5.
Although biphasic head-shaking nystagmus (HSN) is a basic response to head shaking in patients with unilateral vestibular loss, monophasic HSN is commonly seen in patients with dizziness of undetermined etiology. Since the clinical significance of HSN remains unclear, we sought to characterize different types of HSN in patients with vestibular neuritis (VN) during the acute stage (within 7 days after the onset of vertigo) and at follow-up (about 2 months after the onset of vertigo), and to compare HSN and caloric responses. We analyzed HSN, spontaneous nystagmus and caloric tests in 66 patients with VN. Overall, HSN showed high abnormal rates (94 and 89%) during the acute and follow-up stages and could detect vestibular hypofunction even when canal paresis (CP) had normalized at follow-up. All patients in the acute stage and most patients at follow-up showed HSN with the slow phase to the lesioned side (paretic). Biphasic HSN was common at follow-up, and many patients with a monophasic paretic pattern during the acute stage had evolved to a biphasic paretic pattern at follow-up. Initial slow-phase eye velocities (SPVs) in biphasic HSN were larger than those in monophasic HSN at follow-up. Absence of HSN or reversal of its direction was closely related to normalized caloric responses, but SPVs of HSN did not correlate with the severity of CP. These findings indicate that the HSN test is a sensitive detector of vestibular hypofunction upon 2-Hz head rotation. HSN may reveal previous vestibular hypofunction in the 2-Hz frequency range even at follow-up, when caloric responses detecting vestibular hypofunction in the low-frequency range had normalized. The two tests utilize different mechanisms to assess vestibular hypofunction and are complementary. Biphasic paretic HSN is the most common pattern at follow-up and occurs when the initial SPVs induced by head rotation are large enough to induce the adaptation of primary vestibular afferent activity. Monophasic HSN, which is commonly found in dizzy patients, indicates less severe vestibular hypofunction than biphasic HSN in the 2-Hz frequency range, and the caloric tests can provide further information about the side and presence of vestibular hypofunction at lower frequencies.
虽然双相摇头性眼震（HSN）是单侧前庭功能丧失患者对摇头的基本反应，但单相HSN常见于病因不明的头晕患者。由于HSN的临床意义尚不清楚，我们试图对急性前庭神经炎（VN）患者（眩晕发作后7天内）及随访时（眩晕发作后约2个月）不同类型的HSN进行特征描述，并比较HSN和冷热试验结果。我们分析了66例VN患者的HSN、自发性眼震和冷热试验。总体而言，HSN在急性期和随访期显示出较高的异常率（分别为94%和89%），即使在随访时半规管麻痹（CP）已恢复正常，HSN仍能检测到前庭功能减退。所有急性期患者及大多数随访期患者的HSN慢相指向患侧（麻痹侧）。随访时双相HSN常见，许多急性期呈单相麻痹型的患者在随访时已演变为双相麻痹型。随访时双相HSN的初始慢相眼速（SPV）大于单相HSN。HSN缺失或方向反转与冷热试验结果恢复正常密切相关，但HSN的SPV与CP的严重程度无关。这些发现表明，HSN试验是2 Hz头部旋转时前庭功能减退的敏感检测方法。即使在随访时，低频范围检测前庭功能减退的冷热试验结果已恢复正常，HSN仍可能显示2 Hz频率范围内既往的前庭功能减退。这两种试验利用不同机制评估前庭功能减退且具有互补性。双相麻痹型HSN是随访时最常见的类型，当头部旋转诱发的初始SPV足够大以诱导前庭初级传入活动适应时出现。单相HSN常见于头晕患者，在2 Hz频率范围内，其前庭功能减退程度比双相HSN轻，冷热试验可提供关于较低频率前庭功能减退的侧别及存在情况的进一步信息。
