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Change of nystagmus direction during a head-roll test in lateral semicircular canal cupulolithiasis
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ANL-2118; No. of Pages 5 Auris Nasus Larynx xxx (2016) xxx–xxx Contents lists available at ScienceDirect
Auris Nasus Larynx journal homepage: www.elsevier.com/locate/anl
Change of nystagmus direction during a head-roll test in lateral semicircular canal cupulolithiasis Jung Eun Shin, Kyung-Hwa Jeong, Sung Hwan Ahn, Chang-Hee Kim * Department of Otorhinolaryngology-Head and Neck Surgery, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul, Republic of Korea
A R T I C L E I N F O
A B S T R A C T
Article history: Received 21 December 2015 Accepted 1 April 2016 Available online xxx
Objective: To demonstrate positional nystagmus during a head-roll test in two patients with lateral semicircular canal (LSCC) cupulolithiasis who presented with spontaneous detachment of otoliths from the LSCC cupula, and to confirm that otoliths may adhere to both the utricle and canal sides of the cupula. Patients and methods: Using video nystagmography, positional nystagmus was evaluated in two patients with LSCC cupulolithiasis who showed the change of nystagmus direction during a headroll test. Results: Both patients presented with persistent left-beating and right-beating nystagmus when the head was bent forward and backward, respectively. This suggests the presence of either cupulolithiasis on the right side or light cupula on the left side of the LSCC. In Case 1, transformation from cupulolithiasis to canalolithiasis occurred, implicating the detachment of otoliths from the canal side of the right LSCC cupula. In Case 2, vigorous right-beating nystagmus was followed by persistent left-beating nystagmus when the head was rolled to the left. Following this, direction-fixed left-beating nystagmus was observed at all positions, which may indicate that otoliths attached on utricle side of the right LSCC cupula were detached and fell into the utricle under the influence of gravity. A conversion of nystagmus direction may be explained by an expression of short-term adaptation of vestibular tone. Conclusions: Otoliths can be attached to either side of the cupula in LSCC cupulolithiasis. Because it is difficult to determine the attached side at the time of diagnostic maneuver, the therapeutic approach should include maneuvers designed to detach otolith particles from both the utricle and canal side. ß 2016 Elsevier Ireland Ltd. All rights reserved.
Keywords: Benign paroxysmal positional vertigo Direction-changing positional nystagmus Lateral semicircular canal Cupulolithiasis Otolith particles
1. Introduction Benign paroxysmal positional vertigo (BPPV) is one of the most common causes of vertigo, and it has been reported that approximately 5.1–52.1% of BPPV cases originate from the
* Corresponding author at: Department of Otorhinolaryngology-Head and Neck Surgery, Konkuk University Medical Center, Konkuk University School of Medicine, 120-1 Neungdong-ro (Hwayang-dong), Gwangjin-gu, Seoul 143729, Republic of Korea. Tel.: +82 2 2030 7666; fax: +82 2 2030 5299. E-mail address: [email protected] (C.-H. Kim).
lateral semicircular canal (LSCC) [1–4]. For patients with LSCC BPPV, direction-changing positional nystagmus (DCPN) is typically observed in a head-roll test. When DCPN is directed toward the lowermost ear (geotropic), gravitydependent movement of otolith particles within the LSCC has been accepted as a possible mechanism (canalolithiasis). In such cases, the nystagmus lasts transiently and shows fatigability. When DCPN beats toward the uppermost ear (apogeotropic) during a head-roll test, otolith debris adhering to the cupula is known to be a cause (cupulolithiasis), and the nystagmus is persistent without latency or fatigability. It has
http://dx.doi.org/10.1016/j.anl.2016.04.001 0385-8146/ß 2016 Elsevier Ireland Ltd. All rights reserved.
Please cite this article in press as: Shin JE, et al. Change of nystagmus direction during a head-roll test in lateral semicircular canal cupulolithiasis. Auris Nasus Larynx (2016), http://dx.doi.org/10.1016/j.anl.2016.04.001
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been reported that LSCC BPPV may show transition between canalolithiasis and cupulolithiasis [5,6]. In the present study, we report two patients with LSCC cupulolithiasis who presented with a change of nystagmus direction during a head-roll test. Possible mechanisms involved in the change of nystagmus direction will be addressed, and a conjecture will be made as to which side of the cupula the otolith particles are attached. 2. Presentation of cases 2.1. Case 1 A previously healthy 42-year-old man developed severe positional vertigo 3 days prior to admission. Vertigo was aggravated when the patient turned his head to either side in the supine position. He reported no past medical history of hypertension, diabetes mellitus, or neurologic disorders. A head
impulse test and a head-shaking nystagmus test were negative, and no focal neurologic deficit was found. The patient did not complain of audiologic symptoms, such as hearing loss, tinnitus, or ear fullness, and pure tone audiometry revealed normal hearing on both sides. Caloric test revealed no canal paresis, and subjective visual vertical was normal. Weak spontaneous right-beating nystagmus was observed. When the patient bent his head forward over 908 in a sitting position, persistent left-beating nystagmus was observed (Fig. 1A, Supplemental Video 1). Persistent right-beating nystagmus was observed when the patient leaned his head backwards over 608 (Fig. 1B, Supplemental Video 1). Turning the head 908 to the right in a supine position elicited left-beating nystagmus, which only lasted for about 80 s (Fig. 1C, Supplemental Video 1). The patient’s head was then turned 908 to the left in the supine position, and left-beating nystagmus, which lasted for about 40 s, was observed (Fig. 1D, Supplemental Video 1). After gently bringing the
Fig. 1. Video nystagmography of horizontal eye movement in Case 1, with right lateral semicircular canal (LSCC) cupulolithiasis. In the upper panels, the view from the top of patient’s head and magnified LSCC are depicted. Note that the otolith particles are attached on the canal side of the cupula, and the otolith particles are spontaneously detached from the cupula. In the bending forward position (A), persistent left-beating nystagmus was observed due to utriculofugal deflection of the cupula. In the leaning backward position (B), the cupula is ampulopetally deviated, resulting in right-beating nystagmus. When the head was turned to the right in the supine position (C), left-beating (apogeotropic) nystagmus was observed. The nystagmus lasted only for 80 s, and it was speculated that the otolith particles had been detached from the cupula. Turning the head to the left (D) in the supine position elicited transient left-beating (geotropic) nystagmus, which was caused by the movement of otolith particles under the influence of gravity. Following this, turning the head to the right (E) in the supine position elicited vigorous right-beating (geotropic) nystagmus, which lasted only transiently.
Please cite this article in press as: Shin JE, et al. Change of nystagmus direction during a head-roll test in lateral semicircular canal cupulolithiasis. Auris Nasus Larynx (2016), http://dx.doi.org/10.1016/j.anl.2016.04.001
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head back to the starting position, the patient’s head was turned again 908 to the right, which elicited transient right-beating nystagmus (Fig. 1E, Supplemental Video 1). The findings of positional nystagmus may indicate that a conversion of cupulolithiasis to canalolithiasis occurred on the right side, possibly owing to a large otolith particle attached to the canal side of the LSCC cupula that was detached by the influence of gravity when the head was rolled to the left (see discussion). After one session of conducting canalith-repositioning maneuvers, positional vertigo and nystagmus disappeared. Supplementary Video 1 related to this article can be found, in the online version, at http://dx.doi.org/10.1016/j.anl.2016. 04.001. 2.2. Case 2 A previously healthy 46-year-old man developed severe positional vertigo 1 week prior to admission. He reported a head trauma on the left parietal area, caused by a fall from a bicycle. He denied any previous history of inner ear diseases, neurologic disorders, or other chronic medical conditions, such as hypertension or diabetes mellitus. The patient did not complain of audiologic symptoms, such as hearing loss, tinnitus, and ear fullness. A head impulse test revealed no catch-up saccade, and
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a thorough neurologic examination showed no focal neurologic deficit. While sitting upright, spontaneous nystagmus was not observed. Persistent left-beating nystagmus was observed when the patient bent his head forward over 908 in a sitting position (Fig. 2A, Supplemental Video 2). When the patient leaned his head backwards over 608 in a sitting position, persistent rightbeating nystagmus was observed (Fig. 2B, Supplemental Video 2). Turning the head 908 to the right in a supine position elicited persistent left-beating nystagmus (Fig. 2C, Supplemental Video 2). Then, after gently bringing the head back to the starting position, the patient’s head was turned 908 to the left in the supine position, which elicited vigorous right-beating nystagmus. After 40 s, the right-beating nystagmus changed to persistent left-beating nystagmus (Fig. 2D, Supplemental Video 2). Following this, direction-fixed left-beating nystagmus was persistently present in every head position, including when the head was rolled to the right (Fig. 2E, Supplemental Video 2). The patient’s symptoms were considerably relieved, even though he continued to present with weak spontaneous leftbeating nystagmus. From the findings of positional nystagmus in this patient, we speculated that a large otolith particle attached to the utricular side of the right LSCC cupula was detached when the head was rolled to the left, and
Fig. 2. Video nystagmography of horizontal eye movement in Case 2, in which the patient presented with right lateral semicircular canal (LSCC) cupulolithiasis. In the upper panels, the view from the top of the patient’s head and the magnified LSCC are depicted. Note that the otolith particles adhere to the utricle side of the cupula, and the otolith particles are spontaneously detached from the cupula. In the bending forward position (A), persistent left-beating nystagmus was observed due to utriculofugal deflection of the cupula. In the backward leaning position (B), the cupula was ampulopetally deviated, resulting in right-beating nystagmus. When the head was turned to the right in the supine position (C), persistent left-beating (apogeotropic) nystagmus was observed. When the head was turned to the left (D) in the supine position, right-beating (apogeotropic) nystagmus occurred, which was then followed by left-beating nystagmus. It was speculated that detachment of otolith particles from the cupula leads to the spontaneous resolution of the cupulolithiasis. The direction-fixed right-beating nystagmus persisted regardless of the head position, including when the head was turned to the right (E).
Please cite this article in press as: Shin JE, et al. Change of nystagmus direction during a head-roll test in lateral semicircular canal cupulolithiasis. Auris Nasus Larynx (2016), http://dx.doi.org/10.1016/j.anl.2016.04.001
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cupulolithiasis was spontaneously resolved (see discussion). Direction-fixed left-beating nystagmus can be explained by the short-term adaptation of vestibular tone following the abrupt resolution of severe vestibular imbalance [7]. Supplementary Video 2 related to this article can be found, in the online version, at http://dx.doi.org/10.1016/j.anl.2016. 04.001. 3. Discussion In cupulolithiasis-type LSCC BPPV, otolith particles attached to the cupula make the LSCC gravity sensitive. The otolith particles can be attached to either side of the cupula, i.e., the utricle or canal side [5,8]. Baloh et al. reported three patients with persistent apogeotropic DCPN, and suggested that otolith particles originated as a result of the otoliths adhering to the utricle side of the LSCC cupula [8]. Steddin et al. reported two patients who presented with a transformation from geotropic to apogeotropic nystagmus during treatment, and suggested otolith particles within the LSCC attached to the canal side of the cupula as a possible cause [5]. It has been reported that cupulolithiasis of the utricle side is more frequent than that of the canal side [9,10]. Nystagmus patterns are the same regardless of the side that is attached in cupulolithiasis; therefore, determining the side to which the otolith particles are attached, which is important in the selection of treatment maneuver, is difficult at the time of diagnosis. In the present study, we treated two patients with cupulolithiasis of the LSCC in which the otolith particles were detached during a diagnostic maneuver. Both patients presented with persistent left-beating or right-beating nystagmus when bending the head forward or leaning the head backward, respectively. This may suggest the presence of cupulopathy (either cupulolithiasis on the right side, or light cupula on the left side) [11]. Rolling the head to the right in the supine position elicited left-beating nystagmus, which was indicative of cupulolithiasis on the right side of the LSCC. In Case 1, the nystagmus was not persistent and lasted for approximately 80 s. It can therefore be speculated that otolith particles on the canal side of LSCC cupula were detached by the influence of gravity when the head was turned to the right (Fig. 1C). Turning the head to the left and right elicited transient geotropic DCPN, indicating that transformation from cupulolithiasis to canalolithiasis occurred. Imai et al. described two patients who showed transformation from cupulolithiasis to canalolithiasis by detachment of otolith particles attached onto the canal side of the LSCC cupula [12], which, as observed in Case 1, showed transient positional nystagmus beating toward the healthy side on head-rolling to the affected side because the otolith particles are detached from the cupula by the influence of gravity and then settled in the most dependent position within the LSCC. We considered the orientation of LSCC within the temporal bone and the direction of cupular axis within the LSCC in evaluating the direction of positional nystagmus and determining the affected side, which is in line with observation of previous studies [12,13]. While Imai et al. determined the affected side by observing the direction of nystagmus in the supine position [12], we determined the affected side by evaluating the directions of
nystagmus both in bowing and leaning positions. Previous studies using mathematical models have reported that the intensity of positional nystagmus is greater in canalolithiasis than cupulolithiasis [14,15], and the time constant of positional nystagmus is longer in cupulolithiasis than canalolithiasis [5,8]. Imai et al. investigated the change in the intensity and time constant of positional nystagmus when the patient’s head was turned to the affected side in a supine position, and estimated the time of otoliths detachment [12]. In Case 2, vigorous rightbeating nystagmus, which lasted for 40 s, was followed by persistent left-beating nystagmus when the head was turned to the left (Fig. 2D). Following this, direction-fixed left-beating nystagmus was observed at all positions. We speculated that otolith particles attached to the utricle side of the right LSCC cupula were detached and fell into the utricle under the influence of gravity when the head was rolled to the left. A conversion of nystagmus direction may be explained by an expression of shortterm adaptation of the vestibular tone, resulting from the abrupt cessation of vigorous LSCC stimulation following the spontaneous resolution of cupulolithiasis. In an animal study, the direction of nystagmus was reversed when electrical stimulation of the vestibular nerve was stopped [7]. In addition, rightward nystagmus elicited by the left head-rolling was stronger than leftward nystagmus elicited by the right head-rolling in Case 2, which is much greater than that can be expected by Ewald’s second law. This difference may be explained by the detachment of otolith particles during the left head-rolling inducing much stronger nystagmus by canalolithiasis because positional nystagmus induced by canalolithiasis was reported to be larger than that induced by cupulolithiasis [14,15]. Cupulolithiasis in the LSCC has been reported to have poorer treatment outcomes than canalolithiasis following canalith repositioning maneuvers [16,17]. This may be attributed to the difficulty in determining which side of the cupula the otolith particles are attached to. These difficulties may be a cause of the wide variety of treatment maneuvers for LSCC cupulolithiasis [18]. It is reasonable that different therapeutic approaches should be applied according to the location of otoliths attachment. However, because identifying the side of attachment is impossible during a diagnostic maneuver, therapeutic approaches attempting to resolve both sides of the cupula provide better outcomes [19]. The limitation of this study is that only two cases were included in the present study, and a study of more cases may be needed to draw more valid conclusion. 4. Conclusion Our study indirectly confirmed that otolith particles can be attached to either side of the cupula in LSCC cupulolithiasis. Therapeutic approaches for LSCC cupulolithiasis should include maneuvers to detach otolith particles from both the utricle and canal side of the cupula. Conflicts of interest The authors declare no financial or other conflicts of interests.
Please cite this article in press as: Shin JE, et al. Change of nystagmus direction during a head-roll test in lateral semicircular canal cupulolithiasis. Auris Nasus Larynx (2016), http://dx.doi.org/10.1016/j.anl.2016.04.001
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Acknowledgment This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (2015R1C1A1A01055849). References [1] Honrubia V, Baloh RW, Harris MR, Jacobson KM. Paroxysmal positional vertigo syndrome. Am J Otol 1999;20:465–70. [2] Cakir BO, Ercan I, Cakir ZA, Civelek S, Sayin I, Turgut S. What is the true incidence of horizontal semicircular canal benign paroxysmal positional vertigo? Otolaryngol Head Neck Surg 2006;134:451–4. [3] Moon SY, Kim JS, Kim BK, Kim JI, Lee H, Son SI, et al. Clinical characteristics of benign paroxysmal positional vertigo in Korea: a multicenter study. J Korean Med Sci 2006;21:539–43. [4] Kim CH, Kim MB, Ban JH. Persistent geotropic direction-changing positional nystagmus with a null plane: the light cupula. Laryngoscope 2014;124:E15–9. [5] Steddin S, Ing D, Brandt T. Horizontal canal benign paroxysmal positioning vertigo (h-BPPV): transition of canalolithiasis to cupulolithiasis. Ann Neurol 1996;40:918–22. [6] Vannucchi P, Pecci R. About nystagmus transformation in a case of apogeotropic lateral semicircular canal benign paroxysmal positional vertigo. Int J Otolaryngol 2011;2011:687921. [7] Lewis RF, Nicoucar K, Gong W, Haburcakova C, Merfeld DM. Adaptation of vestibular tone studied with electrical stimulation of semicircular canal afferents. J Assoc Res Otolaryngol 2013;14:331–40. [8] Baloh RW, Yue Q, Jacobson KM, Honrubia V. Persistent directionchanging positional nystagmus: another variant of benign positional nystagmus? Neurology 1995;45:1297–301.
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[9] Chu LC, Yang CC, Tsai HT, Lin HC. A simple algorithm for treating horizontal benign paroxysmal positional vertigo. Otol Neurotol 2014;35:1621–5. [10] Chiou WY, Lee HL, Tsai SC, Yu TH, Lee XX. A single therapy for all subtypes of horizontal canal positional vertigo. Laryngoscope 2005;115: 1432–5. [11] Kim CH, Shin JE, Kim YW. A new method for evaluating lateral semicircular canal cupulopathy. Laryngoscope 2015;125:1921–5. [12] Imai T, Takeda N, Sato G, Sekine K, Ito M, Nakamae K, et al. Changes in slow phase eye velocity and time constant of positional nystagmus at transform from cupulolithiasis to canalolithiasis. Acta Otolaryngol 2008;128:22–8. [13] Bisdorff AR, Debatisse D. Localizing signs in positional vertigo due to lateral canal cupulolithiasis. Neurology 2001;57:1085–8. [14] Squires TM, Weidman MS, Hain TC, Stone HA. A mathematical model for top-shelf vertigo: the role of sedimenting otoconia in BPPV. J Biomech 2004;37:1137–46. [15] Rajguru SM, Ifediba MA, Rabbitt RD. Biomechanics of horizontal canal benign paroxysmal positional vertigo. J Vestib Res 2005;15:203–14. [16] Casani AP, Vannucci G, Fattori B, Berrettini S. The treatment of horizontal canal positional vertigo: our experience in 66 cases. Laryngoscope 2002;112:172–8. [17] Imai T, Takeda N, Ito M, Inohara H. Natural course of positional vertigo in patients with apogeotropic variant of horizontal canal benign paroxysmal positional vertigo. Auris Nasus Larynx 2011;38:2–5. [18] Riga M, Korres S, Korres G, Danielides V. Apogeotropic variant of lateral semicircular canal benign paroxysmal positional vertigo: is there a correlation between clinical findings, underlying pathophysiologic mechanisms and the effectiveness of repositioning maneuvers? Otol Neurotol 2013;34:1155–64. [19] Kim SH, Jo SW, Chung WK, Byeon HK, Lee WS. A cupulolith repositioning maneuver in the treatment of horizontal canal cupulolithiasis. Auris Nasus Larynx 2012;39:163–8.
Please cite this article in press as: Shin JE, et al. Change of nystagmus direction during a head-roll test in lateral semicircular canal cupulolithiasis. Auris Nasus Larynx (2016), http://dx.doi.org/10.1016/j.anl.2016.04.001
ANL-2118; No. of Pages 5 Auris Nasus Larynx xxx (2016) xxx–xxx Contents lists available at ScienceDirect
Auris Nasus Larynx journal homepage: www.elsevier.com/locate/anl
Change of nystagmus direction during a head-roll test in lateral semicircular canal cupulolithiasis Jung Eun Shin, Kyung-Hwa Jeong, Sung Hwan Ahn, Chang-Hee Kim * Department of Otorhinolaryngology-Head and Neck Surgery, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul, Republic of Korea
A R T I C L E I N F O
A B S T R A C T
Article history: Received 21 December 2015 Accepted 1 April 2016 Available online xxx
Objective: To demonstrate positional nystagmus during a head-roll test in two patients with lateral semicircular canal (LSCC) cupulolithiasis who presented with spontaneous detachment of otoliths from the LSCC cupula, and to confirm that otoliths may adhere to both the utricle and canal sides of the cupula. Patients and methods: Using video nystagmography, positional nystagmus was evaluated in two patients with LSCC cupulolithiasis who showed the change of nystagmus direction during a headroll test. Results: Both patients presented with persistent left-beating and right-beating nystagmus when the head was bent forward and backward, respectively. This suggests the presence of either cupulolithiasis on the right side or light cupula on the left side of the LSCC. In Case 1, transformation from cupulolithiasis to canalolithiasis occurred, implicating the detachment of otoliths from the canal side of the right LSCC cupula. In Case 2, vigorous right-beating nystagmus was followed by persistent left-beating nystagmus when the head was rolled to the left. Following this, direction-fixed left-beating nystagmus was observed at all positions, which may indicate that otoliths attached on utricle side of the right LSCC cupula were detached and fell into the utricle under the influence of gravity. A conversion of nystagmus direction may be explained by an expression of short-term adaptation of vestibular tone. Conclusions: Otoliths can be attached to either side of the cupula in LSCC cupulolithiasis. Because it is difficult to determine the attached side at the time of diagnostic maneuver, the therapeutic approach should include maneuvers designed to detach otolith particles from both the utricle and canal side. ß 2016 Elsevier Ireland Ltd. All rights reserved.
Keywords: Benign paroxysmal positional vertigo Direction-changing positional nystagmus Lateral semicircular canal Cupulolithiasis Otolith particles
1. Introduction Benign paroxysmal positional vertigo (BPPV) is one of the most common causes of vertigo, and it has been reported that approximately 5.1–52.1% of BPPV cases originate from the
* Corresponding author at: Department of Otorhinolaryngology-Head and Neck Surgery, Konkuk University Medical Center, Konkuk University School of Medicine, 120-1 Neungdong-ro (Hwayang-dong), Gwangjin-gu, Seoul 143729, Republic of Korea. Tel.: +82 2 2030 7666; fax: +82 2 2030 5299. E-mail address: [email protected] (C.-H. Kim).
lateral semicircular canal (LSCC) [1–4]. For patients with LSCC BPPV, direction-changing positional nystagmus (DCPN) is typically observed in a head-roll test. When DCPN is directed toward the lowermost ear (geotropic), gravitydependent movement of otolith particles within the LSCC has been accepted as a possible mechanism (canalolithiasis). In such cases, the nystagmus lasts transiently and shows fatigability. When DCPN beats toward the uppermost ear (apogeotropic) during a head-roll test, otolith debris adhering to the cupula is known to be a cause (cupulolithiasis), and the nystagmus is persistent without latency or fatigability. It has
http://dx.doi.org/10.1016/j.anl.2016.04.001 0385-8146/ß 2016 Elsevier Ireland Ltd. All rights reserved.
Please cite this article in press as: Shin JE, et al. Change of nystagmus direction during a head-roll test in lateral semicircular canal cupulolithiasis. Auris Nasus Larynx (2016), http://dx.doi.org/10.1016/j.anl.2016.04.001
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been reported that LSCC BPPV may show transition between canalolithiasis and cupulolithiasis [5,6]. In the present study, we report two patients with LSCC cupulolithiasis who presented with a change of nystagmus direction during a head-roll test. Possible mechanisms involved in the change of nystagmus direction will be addressed, and a conjecture will be made as to which side of the cupula the otolith particles are attached. 2. Presentation of cases 2.1. Case 1 A previously healthy 42-year-old man developed severe positional vertigo 3 days prior to admission. Vertigo was aggravated when the patient turned his head to either side in the supine position. He reported no past medical history of hypertension, diabetes mellitus, or neurologic disorders. A head
impulse test and a head-shaking nystagmus test were negative, and no focal neurologic deficit was found. The patient did not complain of audiologic symptoms, such as hearing loss, tinnitus, or ear fullness, and pure tone audiometry revealed normal hearing on both sides. Caloric test revealed no canal paresis, and subjective visual vertical was normal. Weak spontaneous right-beating nystagmus was observed. When the patient bent his head forward over 908 in a sitting position, persistent left-beating nystagmus was observed (Fig. 1A, Supplemental Video 1). Persistent right-beating nystagmus was observed when the patient leaned his head backwards over 608 (Fig. 1B, Supplemental Video 1). Turning the head 908 to the right in a supine position elicited left-beating nystagmus, which only lasted for about 80 s (Fig. 1C, Supplemental Video 1). The patient’s head was then turned 908 to the left in the supine position, and left-beating nystagmus, which lasted for about 40 s, was observed (Fig. 1D, Supplemental Video 1). After gently bringing the
Fig. 1. Video nystagmography of horizontal eye movement in Case 1, with right lateral semicircular canal (LSCC) cupulolithiasis. In the upper panels, the view from the top of patient’s head and magnified LSCC are depicted. Note that the otolith particles are attached on the canal side of the cupula, and the otolith particles are spontaneously detached from the cupula. In the bending forward position (A), persistent left-beating nystagmus was observed due to utriculofugal deflection of the cupula. In the leaning backward position (B), the cupula is ampulopetally deviated, resulting in right-beating nystagmus. When the head was turned to the right in the supine position (C), left-beating (apogeotropic) nystagmus was observed. The nystagmus lasted only for 80 s, and it was speculated that the otolith particles had been detached from the cupula. Turning the head to the left (D) in the supine position elicited transient left-beating (geotropic) nystagmus, which was caused by the movement of otolith particles under the influence of gravity. Following this, turning the head to the right (E) in the supine position elicited vigorous right-beating (geotropic) nystagmus, which lasted only transiently.
Please cite this article in press as: Shin JE, et al. Change of nystagmus direction during a head-roll test in lateral semicircular canal cupulolithiasis. Auris Nasus Larynx (2016), http://dx.doi.org/10.1016/j.anl.2016.04.001
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head back to the starting position, the patient’s head was turned again 908 to the right, which elicited transient right-beating nystagmus (Fig. 1E, Supplemental Video 1). The findings of positional nystagmus may indicate that a conversion of cupulolithiasis to canalolithiasis occurred on the right side, possibly owing to a large otolith particle attached to the canal side of the LSCC cupula that was detached by the influence of gravity when the head was rolled to the left (see discussion). After one session of conducting canalith-repositioning maneuvers, positional vertigo and nystagmus disappeared. Supplementary Video 1 related to this article can be found, in the online version, at http://dx.doi.org/10.1016/j.anl.2016. 04.001. 2.2. Case 2 A previously healthy 46-year-old man developed severe positional vertigo 1 week prior to admission. He reported a head trauma on the left parietal area, caused by a fall from a bicycle. He denied any previous history of inner ear diseases, neurologic disorders, or other chronic medical conditions, such as hypertension or diabetes mellitus. The patient did not complain of audiologic symptoms, such as hearing loss, tinnitus, and ear fullness. A head impulse test revealed no catch-up saccade, and
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a thorough neurologic examination showed no focal neurologic deficit. While sitting upright, spontaneous nystagmus was not observed. Persistent left-beating nystagmus was observed when the patient bent his head forward over 908 in a sitting position (Fig. 2A, Supplemental Video 2). When the patient leaned his head backwards over 608 in a sitting position, persistent rightbeating nystagmus was observed (Fig. 2B, Supplemental Video 2). Turning the head 908 to the right in a supine position elicited persistent left-beating nystagmus (Fig. 2C, Supplemental Video 2). Then, after gently bringing the head back to the starting position, the patient’s head was turned 908 to the left in the supine position, which elicited vigorous right-beating nystagmus. After 40 s, the right-beating nystagmus changed to persistent left-beating nystagmus (Fig. 2D, Supplemental Video 2). Following this, direction-fixed left-beating nystagmus was persistently present in every head position, including when the head was rolled to the right (Fig. 2E, Supplemental Video 2). The patient’s symptoms were considerably relieved, even though he continued to present with weak spontaneous leftbeating nystagmus. From the findings of positional nystagmus in this patient, we speculated that a large otolith particle attached to the utricular side of the right LSCC cupula was detached when the head was rolled to the left, and
Fig. 2. Video nystagmography of horizontal eye movement in Case 2, in which the patient presented with right lateral semicircular canal (LSCC) cupulolithiasis. In the upper panels, the view from the top of the patient’s head and the magnified LSCC are depicted. Note that the otolith particles adhere to the utricle side of the cupula, and the otolith particles are spontaneously detached from the cupula. In the bending forward position (A), persistent left-beating nystagmus was observed due to utriculofugal deflection of the cupula. In the backward leaning position (B), the cupula was ampulopetally deviated, resulting in right-beating nystagmus. When the head was turned to the right in the supine position (C), persistent left-beating (apogeotropic) nystagmus was observed. When the head was turned to the left (D) in the supine position, right-beating (apogeotropic) nystagmus occurred, which was then followed by left-beating nystagmus. It was speculated that detachment of otolith particles from the cupula leads to the spontaneous resolution of the cupulolithiasis. The direction-fixed right-beating nystagmus persisted regardless of the head position, including when the head was turned to the right (E).
Please cite this article in press as: Shin JE, et al. Change of nystagmus direction during a head-roll test in lateral semicircular canal cupulolithiasis. Auris Nasus Larynx (2016), http://dx.doi.org/10.1016/j.anl.2016.04.001
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cupulolithiasis was spontaneously resolved (see discussion). Direction-fixed left-beating nystagmus can be explained by the short-term adaptation of vestibular tone following the abrupt resolution of severe vestibular imbalance [7]. Supplementary Video 2 related to this article can be found, in the online version, at http://dx.doi.org/10.1016/j.anl.2016. 04.001. 3. Discussion In cupulolithiasis-type LSCC BPPV, otolith particles attached to the cupula make the LSCC gravity sensitive. The otolith particles can be attached to either side of the cupula, i.e., the utricle or canal side [5,8]. Baloh et al. reported three patients with persistent apogeotropic DCPN, and suggested that otolith particles originated as a result of the otoliths adhering to the utricle side of the LSCC cupula [8]. Steddin et al. reported two patients who presented with a transformation from geotropic to apogeotropic nystagmus during treatment, and suggested otolith particles within the LSCC attached to the canal side of the cupula as a possible cause [5]. It has been reported that cupulolithiasis of the utricle side is more frequent than that of the canal side [9,10]. Nystagmus patterns are the same regardless of the side that is attached in cupulolithiasis; therefore, determining the side to which the otolith particles are attached, which is important in the selection of treatment maneuver, is difficult at the time of diagnosis. In the present study, we treated two patients with cupulolithiasis of the LSCC in which the otolith particles were detached during a diagnostic maneuver. Both patients presented with persistent left-beating or right-beating nystagmus when bending the head forward or leaning the head backward, respectively. This may suggest the presence of cupulopathy (either cupulolithiasis on the right side, or light cupula on the left side) [11]. Rolling the head to the right in the supine position elicited left-beating nystagmus, which was indicative of cupulolithiasis on the right side of the LSCC. In Case 1, the nystagmus was not persistent and lasted for approximately 80 s. It can therefore be speculated that otolith particles on the canal side of LSCC cupula were detached by the influence of gravity when the head was turned to the right (Fig. 1C). Turning the head to the left and right elicited transient geotropic DCPN, indicating that transformation from cupulolithiasis to canalolithiasis occurred. Imai et al. described two patients who showed transformation from cupulolithiasis to canalolithiasis by detachment of otolith particles attached onto the canal side of the LSCC cupula [12], which, as observed in Case 1, showed transient positional nystagmus beating toward the healthy side on head-rolling to the affected side because the otolith particles are detached from the cupula by the influence of gravity and then settled in the most dependent position within the LSCC. We considered the orientation of LSCC within the temporal bone and the direction of cupular axis within the LSCC in evaluating the direction of positional nystagmus and determining the affected side, which is in line with observation of previous studies [12,13]. While Imai et al. determined the affected side by observing the direction of nystagmus in the supine position [12], we determined the affected side by evaluating the directions of
nystagmus both in bowing and leaning positions. Previous studies using mathematical models have reported that the intensity of positional nystagmus is greater in canalolithiasis than cupulolithiasis [14,15], and the time constant of positional nystagmus is longer in cupulolithiasis than canalolithiasis [5,8]. Imai et al. investigated the change in the intensity and time constant of positional nystagmus when the patient’s head was turned to the affected side in a supine position, and estimated the time of otoliths detachment [12]. In Case 2, vigorous rightbeating nystagmus, which lasted for 40 s, was followed by persistent left-beating nystagmus when the head was turned to the left (Fig. 2D). Following this, direction-fixed left-beating nystagmus was observed at all positions. We speculated that otolith particles attached to the utricle side of the right LSCC cupula were detached and fell into the utricle under the influence of gravity when the head was rolled to the left. A conversion of nystagmus direction may be explained by an expression of shortterm adaptation of the vestibular tone, resulting from the abrupt cessation of vigorous LSCC stimulation following the spontaneous resolution of cupulolithiasis. In an animal study, the direction of nystagmus was reversed when electrical stimulation of the vestibular nerve was stopped [7]. In addition, rightward nystagmus elicited by the left head-rolling was stronger than leftward nystagmus elicited by the right head-rolling in Case 2, which is much greater than that can be expected by Ewald’s second law. This difference may be explained by the detachment of otolith particles during the left head-rolling inducing much stronger nystagmus by canalolithiasis because positional nystagmus induced by canalolithiasis was reported to be larger than that induced by cupulolithiasis [14,15]. Cupulolithiasis in the LSCC has been reported to have poorer treatment outcomes than canalolithiasis following canalith repositioning maneuvers [16,17]. This may be attributed to the difficulty in determining which side of the cupula the otolith particles are attached to. These difficulties may be a cause of the wide variety of treatment maneuvers for LSCC cupulolithiasis [18]. It is reasonable that different therapeutic approaches should be applied according to the location of otoliths attachment. However, because identifying the side of attachment is impossible during a diagnostic maneuver, therapeutic approaches attempting to resolve both sides of the cupula provide better outcomes [19]. The limitation of this study is that only two cases were included in the present study, and a study of more cases may be needed to draw more valid conclusion. 4. Conclusion Our study indirectly confirmed that otolith particles can be attached to either side of the cupula in LSCC cupulolithiasis. Therapeutic approaches for LSCC cupulolithiasis should include maneuvers to detach otolith particles from both the utricle and canal side of the cupula. Conflicts of interest The authors declare no financial or other conflicts of interests.
Please cite this article in press as: Shin JE, et al. Change of nystagmus direction during a head-roll test in lateral semicircular canal cupulolithiasis. Auris Nasus Larynx (2016), http://dx.doi.org/10.1016/j.anl.2016.04.001
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Please cite this article in press as: Shin JE, et al. Change of nystagmus direction during a head-roll test in lateral semicircular canal cupulolithiasis. Auris Nasus Larynx (2016), http://dx.doi.org/10.1016/j.anl.2016.04.001