Departmental Unit of Audiology and Phoniatrics, "G. Rummo" Hospital, Benevento, Italy.
Acta Otorhinolaryngol Ital. 2011 Feb;31(1):17-26.
The Hyperventilation Test is widely used in the "bed-side examination" of vestibular patients. It can either activate a latent nystagmus in central or peripheral vestibular diseases or it can interact with a spontaneous nystagmus, by reducing it or increasing it. Aims of this study were to determine the incidence, patterns and temporal characteristics of Hyperventilation-induced nystagmus in patients suffering from vestibular diseases, as well as its contribution to the differential diagnosis between vestibular neuritis and neuroma of the 8(th) cranial nerve, and its behaviour in some central vestibular diseases. The present study includes 1202 patients featuring, at vestibular examination, at least one sign of vestibular system disorders or patients diagnosed with a "Migraine-related vertigo" or "Chronic subjective dizziness". The overall incidence of Hyperventilation-induced nystagmus was 21.9%. It was detected more frequently in retrocochlear vestibular diseases rather than in end-organ vestibular diseases: 5.3% in Paroxysmal Positional Vertigo, 37.1% in Menière's disease, 37.6% in compensated vestibular neuritis, 77.2% in acute vestibular neuritis and 91.7% in neuroma of the 8(th) cranial nerve. In acute vestibular neuritis, three HVIN patterns were observed: Paretic pattern: temporary enhancement of the spontaneous nystagmus; Excitatory pattern: temporary inhibition of the spontaneous nystagmus; Strong excitatory pattern: temporary inversion of the spontaneous nystagmus. Excitatory patterns proved to be time-dependent in that they disappeared and were replaced by the paretic pattern over a period of maximum 18 days since the beginning of the disorder. In acoustic neuroma, Hyperventilation-induced nystagmus was frequently observed (91.7%), either in the form of an excitatory pattern (fast phases towards the affected site) or in the form of a paretic pattern (fast phases towards the healthy side). The direction of the nystagmus is only partially related to tumour size, whereas other mechanisms, such as demyelination or a break in nerve fibres, might have an important role in triggering the situation. Hyperventilation-induced nystagmus has frequently been detected in cases of demyelinating diseases and in cerebellar diseases: in multiple sclerosis, hyperventilation inhibits a central type of spontaneous nystagmus or evokes nystagmus in 75% of patients; in cerebellar diseases, hyperventilation evokes or enhances a central spontaneous nystagmus in 72.7% of patients. In conclusion the Hyperventilation Test can provide patterns of oculomotor responses that indicate a diagnostic investigation through cerebral magnetic resonance imaging enhanced by gadolinium, upon suspicion of neuroma of the 8(th) cranial nerve or of a central disease. In our opinion, however, Hyperventilation-induced nystagmus always needs to be viewed within the more general context of a complete examination of the vestibular and acoustic system.
过度通气试验广泛应用于前庭患者的“床边检查”。它可以激活中枢或外周前庭疾病中的潜在眼震，或者通过减少或增加眼震来与自发性眼震相互作用。本研究的目的是确定前庭疾病患者过度通气诱发眼震的发生率、模式和时间特征，以及其在前庭神经炎和第 8 颅神经神经瘤鉴别诊断中的作用，以及在一些中枢性前庭疾病中的行为。本研究包括 1202 名患者，在前庭检查中至少有一项前庭系统疾病的体征，或被诊断为“偏头痛相关性眩晕”或“慢性主观性头晕”。过度通气诱发眼震的总发生率为 21.9%。它在耳蜗后前庭疾病中的发生率高于终末器官前庭疾病：阵发性位置性眩晕为 5.3%，梅尼埃病为 37.1%，代偿性前庭神经炎为 37.6%，急性前庭神经炎为 77.2%，第 8 颅神经神经瘤为 91.7%。在急性前庭神经炎中，观察到三种 HVIN 模式：麻痹模式：自发性眼震暂时增强；兴奋模式：自发性眼震暂时抑制；强兴奋模式：自发性眼震暂时反转。兴奋模式随着时间的推移而消失，在疾病开始后最长 18 天内被麻痹模式取代。在听神经瘤中，过度通气诱发的眼震很常见（91.7%），表现为兴奋模式（快相朝向受影响部位）或麻痹模式（快相朝向健康侧）。眼震的方向仅部分与肿瘤大小有关，而脱髓鞘或神经纤维断裂等其他机制可能在引发这种情况方面发挥重要作用。脱髓鞘疾病和小脑疾病中经常检测到过度通气诱发的眼震：多发性硬化症中，过度通气抑制中枢型自发性眼震或在 75%的患者中引起眼震；小脑疾病中，过度通气引起或增强 72.7%的患者的中枢性自发性眼震。总之，过度通气试验可以提供眼动反应模式，表明怀疑第 8 颅神经神经瘤或中枢性疾病时，通过增强钆的脑磁共振成像进行诊断性检查。然而，我们认为，过度通气诱发的眼震始终需要在更全面的前庭和听觉系统检查的背景下进行观察。
