The Light Cupula: An Emerging New Concept for Positional Vertigo

Benign paroxysmal positional vertigo (BPPV) is the most common type of positional vertigo. A canalolithiasis-type of BPPV involving the lateral semicircular canal (LSCC) shows a characteristic direction-changing positional nystagmus (DCPN) which beats towards the lower ear (geotropic) on turning the head to either side in a supine position. Because geotropic DCPN in LSCC canalolithiasis is transient with a latency of a few seconds, the diagnosis can be challenging if geotropic DCPN is persistent without latency. The concept of “light cupula” has been introduced to explain persistent geotropic DCPN, although the mechanism behind it requires further elucidation. In this review, we describe the characteristics of the nystagmic pattern in light cupula and discuss the current evidence for possible mechanisms explaining the phenomenon.

Persistent Positional Vertigo in a Patient with Sudden Sensorineural Hearing Loss: A Case Report

Because inner ear organs are interconnected through the endolymph and surrounding endolymphatic membrane, the patients with sudden sensorineural hearing loss (SSNHL) often complain of vertigo. In this study, we report a patient with SSNHL accompanied by persistent positional vertigo, and serial findings of head-roll tests are described. At acute stage, head-roll test showed persistent geotropic direction-changing positional nystagmus (DCPN), which led to a diagnosis of SSNHL and ipsilateral light cupula. Although vertigo symptom gradually improved, positional vertigo lasted for more than 3 weeks. At this chronic stage, persistent apogeotropic DCPN was observed in a head roll test, which led to a diagnosis of the heavy cupula. Although the mechanism for the conversion of nystagmus direction from geotropic to apogeotropic persistent DCPN is unclear, the change of specific gravity of the endolymph might be one of the plausible hypothetical explanations.

Positional Nystagmus in Acute and Subacute Vestibular Neuritis / 대한평형의학회지

BACKGROUND AND OBJECTIVES: By understanding the typical pattern of nystagmus during diverse positional change, we might be able to diagnose the subacute vestibular neuritis (VN) more accurately. The aim of this study was to identify the typical pattern of positional nystagmus in compensated and uncompensated VN patients. MATERIALS AND METHODS: The videonystagmography of 182 patients who were diagnosed as VN were reviewed retrospectively. The patients were classified into two groups by the presence or absence of spontaneous nystagumus (SN). The amplitude of nystagmus evoked by head roll test (HRT) and body roll test (BRT) were compared between the lesion side (ipsilateral, i) and the healthy side (contralateral, c). RESULTS: In the VN patients with SN, positional nystagmus was stronger on the iHRT and iBRT compared to the cHRT and cBRT, respectively. But in the VN patients without SN, this pattern of nystagmus was not evident. Although a stronger nystagmus was found in the iBRT compared to the cBRT, the mean amplitude of nystagmus was not significantly different. Also there was no difference in the nystagmus between the iHRT and cHRT. CONCLUSION: The typical pattern of positional nystagmus which can be found in the VN with SN was not evident in VN without SN. Positional nystagmus may not be able to give us useful information on diagnosing subacute VN.