Pathological Study of Light Cupula Syndrome on a Visual Bionic Semicircular Canal.

A type of persistent direction-changing positional nystagmus with a null point during head position deflection is known as light cupula syndrome (LCS) in the clinic. To date, the pathogenesis and biomechanical response of human semicircular canals with light cupula syndrome (LCS) (HSCs-LCS) are still unclear. In this study, based on the anatomical structure and size of the one-dimensional human semicircular canal (HSC) and imitating the pathological changes of the endolymph in HSC with LCS, a visual bionic semicircular canal (BSC) with LCS was fabricated using three-dimensional printing technology, hydrogel modification, and target tracking technology. Through theoretical derivation, mathematical models of the HSC-LCS perception process were established. By conducting in vitro experiments on the bionic model, the biomechanical response process of HSC-LCS was studied, and the mathematical models were validated. The results of pulse acceleration stimulation showed that the pathological changes in the density and viscosity of the endolymph could reduce the deformation of the cupula of the BSC-LCS and increase the time constant. The results of the sinusoidal acceleration stimulation showed that the amplitude-frequency gain of the BSC-LCS decreased and the phase difference increased. The BSC-LCS can be used as a tool for pathological research of the HSC-LCS. The results of this study can provide a theoretical basis for clinical diagnosis.

[Benign paroxysmal positional vertigo : Typical and unusual clinical findings]. / Benigner peripherer paroxysmaler Lagerungsschwindel : Typische und ungewöhnliche klinische Befunde.

Benign paroxysmal positional vertigo (BPPV) is the most frequent form of vertigo seen in patients attending emergency departments. Leading symptoms are short attacks of vertigo provoked by head or body rotations. BPPV is caused by small calcium crystals, so-called otoconia, which are dislocated from the macula of the utricle mostly into the posterior semicircular canal. Free floating otoconia can move under the influence of gravity inside the semicircular canal (canalolithiasis) or adhere to the cupula (cupulolithiasis) causing displacement of the cupula. This results in positional nystagmus, whose directions and time courses are characteristic for the affected semicircular canal and the underlying cause. In recent years, however, a number of cases were reported, in which direction and times course of nystagmus differed from typical clinical findings. This may cause diagnostic problems.

[Benign paroxysmal positional vertigo : Typical and unusual clinical findings]. / Benigner peripherer paroxysmaler Lagerungsschwindel : Typische und ungewöhnliche klinische Befunde.

Benign paroxysmal positional vertigo (BPPV) is the most frequent form of vertigo seen in patients attending emergency departments. Leading symptoms are short attacks of vertigo provoked by head or body rotations. BPPV is caused by small calcium crystals, so-called otoconia, which are dislocated from the macula of the utricle mostly into the posterior semicircular canal. Free floating otoconia can move under the influence of gravity inside the semicircular canal (canalolithiasis) or adhere to the cupula (cupulolithiasis) causing displacement of the cupula. This results in positional nystagmus, whose directions and time courses are characteristic for the affected semicircular canal and the underlying cause. In recent years, however, a number of cases were reported, in which direction and times course of nystagmus differed from typical clinical findings. This may cause diagnostic problems.

Neutral position of persistent direction-changing positional nystagmus.

The aim of this study was to measure the neutral position of direction-changing apogeotropic positional nystagmus (heavy cupula of the horizontal semicircular canal) and persistent direction-changing geotropic positional nystagmus (light cupula of the horizontal semicircular canal). We conducted a prospective case series study on 31 patients with heavy cupula (12 males, 19 females; mean age, 64.3 years) and 33 patients with light cupula (10 males, 23 females; mean age, 60.9 years). We measured the angle of the neutral position in patients with heavy cupula (θ 1) and that in patients with light cupula (θ 2) using a large protractor. The mean value and standard deviation of θ 1 was 31.6 ± 22.4°, minimum value was 5°, and maximum value was 89°. The mean value and standard deviation of θ 2 was 44.4 ± 20.5°, minimum value was 5°, and maximum value was 85°. θ 2 was significantly greater than θ 1 (p < 0.05). The neutral position varies widely. Some patients exhibit a great angle (more than 40°); therefore, examiners should make patients adopt a completely lateral position in the supine head roll test and should confirm the direction of nystagmus in order to avoid mistaking positional nystagmus for spontaneous nystagmus.

Light cupula of the horizontal semicircular canal occurring alternately on both sides: a case report.

BACKGROUND: The light cupula is a condition wherein the cupula of the semicircular canal has a lower specific gravity than its surrounding endolymph. It is characterized by a persistent geotropic direction-changing positional nystagmus in the supine head-roll test, and the identification of a null plane with slight head-turning to either side. CASE PRESENTATION: This study describes a case of recurring light cupula that occurred alternately on both sides. At the first episode, a null plane was identified on the right side, which led to the diagnosis of a light cupula on the right side. At the second episode, a null plane was identified on the left side, leading to the diagnosis of a light cupula on the left side. CONCLUSION: This is the first case report of recurring light cupula alternately involving both sides. Although the pathophysiology is not entirely understood yet, the light cupula should be considered as one of causes of recurrent positional vertigo.

Clinical characteristics and lateralization of the horizontal semicircular canal light cupula.

Introduction: Positional vertigo and nystagmus are the main symptoms and signs of dizziness, respectively. Despite the clinical utility of the supine roll test (SRT) and null point (NP) in diagnosing light cupula, a type of positional vertigo, there exists a notable gap in the literature concerning the comprehensive evaluation of lateralization values based on various nystagmus characteristics and the intensity of direction-changing positional nystagmus (DCPN) in the SRT, particularly in comparison to the NP. Additionally, limited data on abnormal canal paresis (CP) in light cupula patients underscores the need for further research with a larger patient population to elucidate this mechanism. This study aims to investigate the characteristics of positional nystagmus and lateralization of the horizontal semicircular canal (HSCC) light cupula, which is a type of positional vertigo and nystagmus that is poorly understood. Methods: Eighty-five patients (17 males, 68 females; mean age, 60.9 years) with light cupula were reviewed. We summarized the characteristics of spontaneous nystagmus and positional nystagmus, including supine positioning nystagmus, bow nystagmus, and lean nystagmus. Then, the side of the NP was identified as the affected side, and the values of the fast phase direction of the spontaneous nystagmus, supine positioning nystagmus, bow nystagmus, and lean nystagmus, as well as the intensity of the DCPN in the SRT, were used to diagnose the affected sides. Caloric testing was also performed for some patients. Results: Light cupula was observed in 5.7% of the patients with positional nystagmus. The frequencies of supine positioning nystagmus (88.2%), bow nystagmus (90.6%), and lean nystagmus (83.5%) were higher than spontaneous nystagmus (61.2%) (p < 0.001). The second NP (NP2) (92.9%) and third NP (NP3) (83.5%) were readily detected, affecting the left and right sides in 38 and 47 patients, respectively. Lateralization through the fast phase directions of bow nystagmus and lean nystagmus did not significantly differ from that of NP (all p > 0.05). However, the accuracy rate of lateralization through the sides with more vigorous DCPN in the SRT was 63.5%, significantly lower than through NP (p < 0.001). Particularly in patients with supine positioning nystagmus (n = 75), the rate was only 58.7% (p < 0.001). However, the rate was 100% in patients without supine positioning nystagmus (n = 10). Among the 70 patients who underwent caloric testing, 37 had abnormal CP, and the sides of the reduced caloric reaction were ipsilateral to the affected sides of the light cupula in 83.8% of the patients. Conclusion: Besides utilizing the NP to determine the affected side, the fast phase direction of the bow nystagmus or lean nystagmus can also aid in identification. However, a simple comparison of the intensity of DCPN in SRT cannot provide accurate lateralization, especially in patients with supine positioning nystagmus. There is a high incidence of CP on the affected side of the light cupula.

The Light Cupula Phenomenon: A Scoping Review.

Direction-changing positional nystagmus (DCPN), which refers to the change in the direction of nystagmus with different head positions, is a well-known characteristic of horizontal semicircular canal BPPV. The supine head roll test is commonly used to diagnose horizontal canal BPPV. However, persistent geotropic DCPN observed during this test cannot be explained by the conventional explanations of canalolithiasis or cupulolithiasis. To account for this unique nystagmus, the concept of a "light cupula" has been recently introduced. In this review, we provide an overview of the historical background, clinical features and diagnostic methods, proposed mechanisms, and treatment strategies associated with the light cupula phenomenon based on the available literature to date.

Posterior canal benign paroxysmal positional vertigo with long duration: Heavy or light cupula?

Objective: To investigate the characteristics of positional nystagmus in posterior semicircular canal (PSCC) benign paroxysmal positional vertigo (BPPV) patients with longer durations, and to discuss the possible underlying mechanism of this nystagmus. Methods: We conducted a retrospective review, and enrolled 118 consecutive patients with unilateral PSCC BPPV. The duration of nystagmus during a Dix-Hallpike test was classified into short (<1 min) and long (≥1 min) durations. For the identification of a neutral point in PSCC BPPV patients with long durations, the patient's head was turned 45° to the lesioned side to set the affected PSCC on the sagittal plane, and the disappearance of positional nystagmus was investigated in a pitch plane. Results: Among 118 patients with PSCC BPPV, positional nystagmus during a Dix-Hallpike test showed short durations (<1 min) in 112 patients and long durations (≥1 min) in 6 patients. Of 6 PSCC BPPV patients with a long duration, a neutral point was identified in 5 patients whose nystagmus lasted for longer than 2 min; interestingly, a neutral point was observed when the patient's head was slightly tilted backward in all 5 patients. Conclusion: Considering that a neutral position was identified when the patient's head was slightly tilted backward while keeping the head turned 45° to the right or left, we assume that the light cupula condition of the ipsilateral PSCC or the contralateral anterior semicircular canal, and not PSCC BPPV cupulolithiasis, could be responsible for the occurrence of persistent torsional-upbeating nystagmus in a Dix-Hallpike test. Level of Evidence: 4.

Clinical Characteristics of persistent geotropic horizontal direction-changing positional nystagmus: Experience in 189 participants.

BACKGROUND: The etiology and mechanism of persistent geotropic horizontal direction-changing positional nystagmus (DCPN) are still unclear. Whether this pattern of nystagmus is a subtype of benign paroxysmal positional vertigo (BPPV) remains controversial. OBJECTIVE: The goal of this study was to observe the clinical characteristics of persistent geotropic horizontal DCPN involving the lateral semicircular canal. METHODS: The analysis was performed to participants with episodic positional vertigo in our clinic from 2014 to 2021. Participants were included via positional test. We observed and summarized the distribution data, vertigo history, follow-up tests, and recurrence situations of 189 persistent geotropic horizontal DCPN participants. RESULTS: The mean age at the first time showing of persistent geotropic horizontal DCPN was 56±14.7 and more women than men were affected by persistent geotropic horizontal DCPN (female-to-male ratio 2.4 : 1). Overall, 58.7% (57/94) of participants who came for the first-week follow-up test were asymptomatic. Thirty-three participants experienced recurrence (female-to-male ratio: 4.5 : 1). Fifty-three (28.0%) participants experienced the conversion of the patterns of DCPN in the history, the follow-up tests and the recurrence compared to the first showing of persistent geotropic horizontal DCPN. 24(12.1%) participants still experienced persistent geotropic horizontal DCPN attack in the follow-up tests and the recurrences without benign paroxysmal positional vertigo history. CONCLUSION: Persistent geotropic horizontal DCPN affected more women than men. The persistent geotropic horizontal DCPN that with conversion to transient geotropic horizontal DCPN or to persistent apogeotropic horizontal DCPN might be a subtype of BPPV or in a stage of BPPV process. However, the persistent geotropic horizontal DCPN without conversion might be an independent disease that is not related to BPPV.

Paroxysmal Positional Nystagmus in Acoustic Neuroma Patients.

The association between acoustic neuroma and positional vertigo with paroxysmal positional nystagmus is relatively rare, but, when present, it certainly represents a challenge for the otoneurologist. There are few reports in the literature on this particular issue, and some questions are still unanswered, particularly regarding the characteristics of positional nystagmus that may distinguish between a true benign paroxysmal vertigo and a positional nystagmus associated with the tumor. We present the videonystagmographic patterns of seven patients with acoustic tumor who had paroxysmal positional nystagmus and analyzed its features. A concomitant true benign paroxysmal positional vertigo may be present during the follow-up of a non-treated patient, as the paroxysmal positional vertigo may be the first symptom of the tumor, and it may show characteristics that are very similar to a posterior semicircular canal canalolithiasis or a horizontal canal "heavy or light cupula". The possible mechanisms are discussed.

Subjective visual vertical deviation in patients with early-onset direction-changing horizontal positional nystagmus.

OBJECTIVE: Otolithic dysfunction is investigated in cases of direction-changing horizontal positional nystagmus (DCHPN) due to peripheral vestibular disorders. METHODS: The static-subjective visual vertical (S-SVV) was conducted in DCHPN cases within 48 h after onset. RESULTS: The absolute values of S-SVV deviations of patients with Light cupula and lateral canal-benign paroxysmal positional vertigo-cupulolithiasis (L-BPPV-Cup) were significantly different from those of healthy subjects (p < 0.001, p < 0.05, respectively), whereas there were no significant differences in those of patients with L-BPPV-Canalolithiasis-geotropic (L-BPPV-Can-g) or L-BPPV-Can-ageotropic (L-BPPV-Can-a) versus healthy subjects. Significant differences were found in S-SVV (+: deviation to the affected side, -: deviation to the unaffected side) between patients with Light cupula and those with L-BPPV-Can-g, L-BPPV-Can-a and L-BPPV-Cup (p < 0.01, p < 0.05, and p < 0.001, respectively), as well as between those with L-BPPV-Can-g and L-BPPV-Cup (p < 0.01). The S-SVV in patients with Light cupula, L-BPPV-Can-g, and L-BPPV-Can-a deviated more to the affected side, whereas that in patients with L-BPPV-Cup deviated more to the unaffected side. CONCLUSION: Mild otolithic dysfunctions were found in patients with DCHPN due to the presence of peripheral vestibular disorders within 48 h after onset. The extent of otolithic (utricular) disorders in patients with DCHPN is estimated in decreasing order as follows: Light cupula > L-BPPV-Cup > L-BPPV-Can-g and L-BPPV-Can-a. Many patients with L-BPPV-Cup likely suffer from disorders of the pars externa of the utricular macula, whereas many patients with L-BPPV-Can-g likely suffer from disorders of the pars interna of the utricular macula. L-BPPV-Can-a and L-BPPV-Can-g must be induced by a common mild utricular disorder.

Analysis of persistent geotropic and apogeotropic positional nystagmus of the lateral canal benign paroxysmal positional vertigo.

Objective: This study aims to analyze the clinical characteristics of persistent geotropic and apogeotropic positional nystagmus of LC-BPPV in view of light and heavy cupula discussion. Material and method: The study group includes 184 patients with LC BPPV (98 apogeotropic, 86 geotropic type) who have been examined between 2009 and 2020. Ninety-nine females and 85 males, aged between 16 and 92 years were included (Ageotropic 49.32 ± 14.12, geotropic 44.49 ± 13.90 years). Average slow phase velocity (SPV) of positional nystagmus was documented and those with persistent direction-changing positional nystagmus lasting more than a minute were grouped separately. Age, gender difference, side of involvement, and recurrence pattern were particularly reviewed. Chi-square and One way ANOVA tests were used to compare the difference between groups. Statistical significance was set at P < 0.05. Results: Thirty-seven patients with apogeotropic nystagmus (30.7%; 37/98) and 18 patients with geotropic nystagmus (20.9%; 18/86) had persistent nystagmus (p ˂0.05). Comparison of slow phase velocity (SPV) of persistent and non-persistent geotropic and apogeotropic positional nystagmus of the affected side was significant (p ˂0.05). Comparison of average age, male to female ratio, side of involvement, and the recurrence rate in patients with persistent and non-persistent geotropic and apogeotropic type positional nystagmus groups were not significant (p = 0.177, p = 0.521, p = 0.891, p = 0.702). Conclusion: Persistent geotropic and apogeotropic positional nystagmus is mostly correlated with the size, amount, and position of otoconial debris. It is difficult to justify the light cupula as a new geotropic variant of cupular pathology. Patients with persistent positional nystagmus present similar therapeutic outcomes and recurrence rates.

Variants of benign paroxysmal positional vertigo in relation to head position during sleep.

BACKGROUND: Patients with posterior- and lateral-(canal)-benign paroxysmal positional vertigo (BPPV)-canalolithiasis sleep in the affected-ear-down head position. Posterior-BPPV-canalolithiasis typically affects the right than left ear; sleeping in the right-ear-down head position may be causal. OBJECTIVE: To investigate the relationship between habitual head position during sleep and the onset of BPPV variants. METHODS: Among 1,170 cases of BPPV variants with unknown etiology, the affected ears, habitual head positions during sleep based on interviews, and relationships among them were investigated. RESULTS: Posterior-BPPV-canalolithiasis and lateral-BPPV-canalolithiasis-geotropic affected the right ear significantly more often. Significantly more patients with posterior-BPPV-canalolithiasis and lateral-BPPV-canalolithiasis-apogeotropic habitually slept in the right-ear-down head position. Patients with posterior- and lateral-BPPV-canalolithiasis and light cupula were more likely to sleep habitually in the affected-ear-down position than in the healthy-ear-down head position; no relationship was observed in patients with posterior- and lateral-BPPV-cupulolithiasis. In patients with posterior-BPPV-canalolithiasis and lateral-BPPV-canalolithiasis-geotropic, the proportion of right-affected ears in those sleeping habitually in the right-ear-down head position was significantly greater than that for the left-affected ear. CONCLUSIONS: A habitual affected-ear-down head position during sleep may contribute to BPPV-canalolithiasis and light cupula onset, but not BPPV-cupulolithiasis onset. However, habitual sleeping in the right-ear-down head position cannot explain the predominance of right-affected ears.

Atypical Positional Vertigo: Definition, Causes, and Mechanisms.

Paroxysmal positional vertigo is a frequent cause for consultation. When approaching these patients, we try to differentiate central from peripheral causes, but sometimes we find manifestations that generate diagnostic doubts. In this review, we address atypical paroxysmal positional vertigo, reviewing the literature on the subject and giving a provisional definition of atypical positional vertigo as well as outlining its causes and pathophysiological mechanisms.

[Clinical and pathogenetic aspects of positional nystagmus]. / Kliniko-patogeneticheskie aspekty pozitsionnogo nistagma.

Positional nystagmus (PN) is a heterogeneous clinical phenomenon. Most often it develops in benign positional paroxysmal vertigo as a result of otolithiasis. Rarely PN is observed in cases of lesion location in the cerebellum and brainstem. Recently a theory of light cupula was suggested to explain persisting geotropic PN. It explains the development of nystagmus by the changes in the ratio of the density of cupula to the density of endolymph, making the former sensitive to gravitational forces. Several theories were suggested: lighter cupula theory, heavier endolymph theory, theories of light debris and of density difference between perilymph and endolymph. However, the exact mechanism of light cupula syndrome is unclear. Clear diagnosis of the causes of PN requires detailed evaluation of neurological status with the use of diagnostic tests and additional research methods.

Recurrence in patients with benign paroxysmal positional vertigo of the lateral semicircular canal.

OBJECTIVES: There are 3 subtypes of lateral canal benign paroxysmal positional vertigo. Persistent geotropic positional nystagmus is due to a light cupula, heavy cupula produces apogeotropic positional nystagmus, and canalolithiasis accounts for transient geotropic positional nystagmus. The aims of this study were to determine the recurrence rate and to examine the number of times of recurrence in each of the 3 subtypes. METHODS: Subjects were patients with light cupula (n = 47), heavy cupula (n = 48), and canalolithiasis (n = 45). We investigated the number of times of recurrence and determined the subtypes of a recurrent vertigo attack over the period of 5 years. RESULTS: The subtype of a recurrent vertigo attack was not always the same as the subtype at the first visit. The recurrence rate of light cupula group was 72.3%, that of heavy cupula group was 20.8%, and that of canalolithiasis group was 28.9%. Some patients experienced recurrence more than once. The mean value and standard deviation of the number of times of recurrence in light cupula group was 2.5 ±â€¯1.3 times, that in heavy cupula group was 1.5 ±â€¯0.7 times, and that in canalolithiasis group was 1.5 ±â€¯0.7 times. CONCLUSIONS: The recurrence rate in patients with light cupula is much higher than that in patients with heavy cupula or canalolithiasis. The number of times of recurrence in patients with light cupula is greater than that in patients with heavy cupula or canalolithiasis.

Light Cupula: To Be Or Not to Be?

Benign paroxysmal positional vertigo (BPPV) represents the most common form of positional vertigo. It is caused by dislodged otoconia that freely float in the semicircular canals (canalolithiasis) or attach to the cupula (cupulolithiasis). A cupulolithiasis-type (or a heavy cupula-type) of BPPV implicating the lateral semicircular canal (LSCC) exhibits persistent ageotropic direction-changing positional nystagmus (DCPN) in a head-roll test. However, in some cases, unlike any type of BPPV, persistent geotropic DCPN cannot be explained by any mechanisms of BPPV, and don't fit the current classifications. Recently, the notion of light cupula has been introduced to refer to the persistent geotropic DCPN. In this study, we looked at the clinical features of light cuplula and discussed the possible mechanisms and therapeutic strategies of the condition. The notion of light cupula is a helpful addition to the theory of peripheral positional vertigo and nystagmus.

Characteristics of positional nystagmus in patients with horizontal canal canalolithiasis or cupulopathy.

OBJECTIVES: Positional nystagmus can be related to various kinds of disorders. The current study aims to compare the direction-changing horizontal positional nystagmus (DCPN) characteristics in horizontal canal canalolithiasis (HC-canalolithiasis), heavy cupula of the horizontal canal (HC-Hcu), and light cupula of the horizontal canal (HC-Lcu), especially the temporal patterns of positional nystagmus in three disorders. METHODS: 52 patients (22 males, 30 females; mean age, 49.6 years) presenting with geotropic or apogeotropic DCPN were enrolled, and they were divided into HC-canalolithiasis, HC-Hcu, or HC-Lcu groups according their nystagmus characteristics. We compared their latency, time constant, peak slow-phase velocity (SPV), time to reach peak SPV intensity (Tpeak), and time to decay to half-peak intensity (T1/2peak). RESULTS: The time to reach peak SPV did not differ significantly between the HC-Hcu (23.1 ± 8.6 s) and HC-Lcu (24.4 ± 9.9 s) groups (p = 0.733), but was significantly longer than that of the HC-canalolithiasis group (5.4 ± 3.5 s; p ≤ 0.001). The peak intensity did not differ among the canalolithiasis (36.4 ± 20.6º/s), HC-Hcu (30.1 ± 23.6º/s), and HC-Lcu (21.4 ± 12.7º/s) groups (p = 0.133). The onset latency also had no statistical difference among three groups (p = 0.200). The nystagmus patterns of HC-Lcu and HC-Hcu groups were similar, including latency, peak SPV intensity, Tpeak, T1/2peak, and SPV in 20 s, 40 s, 60 s, 80 s. CONCLUSIONS: The nystagmus characteristics of HC-Hcu and HC-Lcu are similar, except for the fact that movement was in opposite directions, suggesting that HC-Hcu and HC-Lcu may result from a similar pathophysiological mechanism (cupulopathy) differing from that underlying canalolithiasis.

Clinical Findings in Patients With Persistent Positional Nystagmus: The Designation of "Heavy and Light Cupula".

Objective: Direction-changing positional nystagmus (DCPN) had been observed as persistent horizontal apogeotropic and was considered as "cupulolithiasis or heavy cupula. " Recently, the concept of "light cupula" exhibiting persistent geotropic DCPN has been introduced. However, the light cupula is not systematically described, while the identification and diagnosis of "light cupula" should be improved. Here we investigated the underlying characteristics and therapeutic options designed to the "light" and "heavy" cupula, respectively; and summarized the clinical characteristics and therapeutic effect in the two groups. Methods: A total of 359 cases with vertigo and bilateral DCPN were found in the supine roll test. Only 25 patients with persistent DCPN were enrolled and followed up. According to the direction of nystagmus, we further divided the patients into "heavy cupula" (apogeotropic) and "light cupula" (geotropic) groups. We compared the incidence, characteristics of nystagmus and the efficacy of repositioning maneuver in the two groups. Results: Nine patients with persistent horizontal geotropic DCPN were confirmed as "light cupula," other 16 patients with persistent horizontal ageotropic DCPN were confirmed as heavy cupula. All 25 patients had null plane; the mean value and standard deviation of the null plane in light cupula and heavy cupula was 25.67 ± 9.31° and 27.06 ± 6.29°, respectively. The mean value and standard deviation of the termination plane in light cupula was 28.78 ± 10.00°, and 30.25 ± 6.53° in heavy cupula. There was no statistical significance between the two groups. We found that the direction of evoked nystagmus in the supine position was toward the intact side in light cupula, while in heavy cupula, it was toward the lesion side. The null plane appeared on the lesion side. For light cupula patients, the effect was not obvious at Day-7 after the treatment, however, treatment for most heavy cupula patients were effective. All patients recovered after 30 days of treatment. Conclusion: The null plane is crucial in determining the lesion side for light or heavy cupula. Although the short-term therapeutic effect of the light cupula is not as promising as the effect seen in heavy cupula, the long-term prognosis in both groups is comparable; with all patients recovered after 30 days of treatment. Study design: This is a retrospective cohort study.

[Persistent geotropic direction-changing positional nystagmus: an independent disease entity?]

Persistent geotropic direction-changing positional nystagmus (DCPN) has been described in recent years as no latency or fatigability but a null plane when head is turned toward the affected side. Different from the canalolithiasis of horizontal semicircular canal, it is similar with cupulolithiasis, but the direction of nystagmus are opposite. Light cupula theory has been used to explain the characteristics of this unique nystagmus. In this paper, the characteristics, possible etiologies, pathogenesis, related diseases, diagnosis, treatment and prognosis of DCPN are reviewed.