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Audiological signs in pediatric cases with dehiscence of the bony labyrinth caused by a high jugular bulb
International Journal of Pediatric Otorhinolaryngology 76 (2012) 447–451
Contents lists available at SciVerse ScienceDirect
International Journal of Pediatric Otorhinolaryngology journal homepage: www.elsevier.com/locate/ijporl
Case report
Audiological signs in pediatric cases with dehiscence of the bony labyrinth caused by a high jugular bulb Michihiko Sone a,*, Naomi Katayama a, Shinji Naganawa b, Tadao Yoshida a, Masaaki Teranishi a, Tsutomu Nakashima a a b
Department of Otorhinolaryngology, Nagoya University Graduate School of Medicine, Nagoya, Japan Department of Radiology, Nagoya University Graduate School of Medicine, Nagoya, Japan
A R T I C L E I N F O
A B S T R A C T
Article history: Received 20 October 2011 Received in revised form 5 December 2011 Accepted 7 December 2011 Available online 5 January 2012
Clinical findings were assessed in three pediatric cases of dehiscence of the bony labyrinth caused by a high jugular bulb (HJB). Two children had two dehiscent lesions, which included posterior semicircular canal dehiscence (PSCD) and vestibular aqueduct dehiscence (VAD). One child had VAD alone. Two subjects with PSCD, but not with VAD alone, had mixed hearing loss and showed wave motion of the baseline on tympanometry and acoustic reflex testing, and a reduced response on otoacoustic emission. These findings may reflect jugular venous pulsations transmitted through the PSC and represent characteristics of cases with PSCD caused by HJB. ß 2011 Elsevier Ireland Ltd. All rights reserved.
Keywords: High jugular bulb Posterior semicircular canal Vestibular aqueduct Dehiscence Pulsatile tinnitus Hearing loss
1. Introduction The clinical characteristics of bony labyrinth dehiscence have been explained by the concept of a pathological third window [1– 8], which accompanies mixed hearing loss with air-bone gaps (ABG) at lower frequencies. Superior semicircular canal dehiscence (SSCD), which was first described by Minor et al. [6], is the most frequently demonstrated syndrome in these lesions. A high jugular bulb (HJB) is one of the causes of posterior semicircular canal dehiscence (PSCD). HJB may also induce vestibular aqueduct dehiscence (VAD). A temporal bone study showed that the overall incidence of HJB was 16.0% [9]. Typical symptoms in patients with bony labyrinth dehiscence caused by a HJB are hearing loss with ABG or pulsatile tinnitus [2]. Compared with SSCD, otological disturbances in cases with PSCD caused by HJB are less reported in the literature [2,10–12], especially in children. There might be a tendency to overlook the disease in children, as pediatric patients complain less than adults, especially for diseases related to vestibular dysfunction [12].
* Corresponding author at: Department of Otorhinolaryngology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan. Tel.: +81 52 744 2323; fax: +81 52 744 2325. E-mail address: [email protected] (M. Sone). 0165-5876/$ – see front matter ß 2011 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijporl.2011.12.007
Three recent pediatric cases with bony labyrinth dehiscence caused by HJB are reported, and their characteristic findings, which may represent diagnostic clues of the disease that could be used to avoid needless middle ear surgery, are described.
2. Methods Three pediatric patients with dehiscence of the bony labyrinth caused by HJB (confirmed by computer tomography (CT; Asteion and Aquilion, Toshiba, Tokyo, Japan) using sequential 0.5-mmthick slices) were studied. Hearing levels were evaluated using an audiometer (Model AA78, Rion, Tokyo, Japan) in a sound-attenuated room. Impedance audiometry, which included tympanometry (TM) and acoustic reflex (AR), and otoacoustic emission (OAE) were performed using an RS-22 and ILO292-USB (Rion, Tokyo, Japan), respectively. The caloric test was performed with cool air stimulation (15 8C, 6 l/min, 60 s) using an FAC-700 (DAIICHI Medical, Tokyo, Japan). The vestibular-evoked myogenic potential (VEMP) test was performed as follows: surface myogenic potentials in the sternocleidomastoid muscle were added 150 times using a reference electrode over the sternum, while clicks (105 dB) were presented to the ipsilateral ear, and white noise (75 dB) was presented to the contralateral ear (Synax 2100, NEC Medical Systems, Tokyo, Japan), as described elsewhere [13].
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M. Sone et al. / International Journal of Pediatric Otorhinolaryngology 76 (2012) 447–451
3. Clinical observations 3.1. Case 1 A seven-year-old boy was referred to our hospital with hearing loss in his left ear that had been detected during a preschool medical examination. He had no other symptoms, including disequilibrium. The left tympanic membrane appeared normal, and the pure-tone audiogram (PTA) revealed the presence of mixed hearing loss (MHL) of 50–70 dB, with ABG that was prominent in the low-frequency range (Fig. 1A). TM yielded type A tympanograms bilaterally; however, the baseline on the left side exhibited wave motion (Fig. 1B), and responses on AR showed wave motion of the left ear (Fig. 1C). OAE of the left ear showed no response, except at high frequencies. Caloric testing showed a normal response. The VEMP test revealed a 1.47-fold increase in amplitude
for the left ear compared with the right ear. CT revealed the presence of HJB on the left side, which was dehiscent to the posterior semicircular canal (PSC) and to the vestibular aqueduct (VA) (Fig. 2). The HJB was not dehiscent into the middle ear cavity. 3.2. Case 2 Another seven-year-old boy had been treated for otitis media with effusion for 2 years; however, hearing loss in his left ear continued, even after the disease was cured, and he was referred to our hospital. He had no complaints indicative of inner ear disturbance. The tympanic membrane of his left ear appeared normal, and PTA revealed the presence of MHL of 40–60 dB, with AGB that was most prominent in the low-frequency range (Fig. 3A). TM yielded type A tympanograms bilaterally; however, the baseline on the left ear showed wave motion (Fig. 3B). Responses
Fig. 1. Pure-tone audiogram (PTA), tympanogram, and acoustic reflex (AR) in case 1. PTA shows mixed hearing loss with air-bone gaps, which are prominent in the lowfrequency range (A). Baseline waves are observed in the tympanogram (arrow in B) and AR (C) of the left ear.
M. Sone et al. / International Journal of Pediatric Otorhinolaryngology 76 (2012) 447–451
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Fig. 2. High-resolution computed tomography (CT) in case 1. The high jugular bulb (asterisk) observed on the left side is dehiscent to the vestibular aqueduct (arrow in A) and the posterior semicircular canal (arrowhead in B).
Fig. 3. Pure-tone audiogram (PTA), tympanogram, and acoustic reflex (AR) in case 2. PTA shows mixed hearing loss with air-bone gaps, which are prominent in the lowfrequency range (A). Baseline waves are observed in the tympanogram (arrow in B) and AR (C) of the left ear.
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M. Sone et al. / International Journal of Pediatric Otorhinolaryngology 76 (2012) 447–451
Fig. 4. High-resolution computed tomography (CT) in case 2. The large jugular bulb diverticulum (asterisk) detected on the left side is dehiscent to the posterior semicircular canal (arrowhead), which occupies the vestibular aqueduct portion.
on AR exhibited wave motion on the left (Fig. 3C). OAE of the left ear showed a reduced response, except at high frequencies. Caloric testing was normal; however, the VEMP test of the left ear revealed a 2.39-fold increase in amplitude compared with on the right ear. CT revealed the presence of a large HJB diverticulum on the left side, which was dehiscent to the PSC and to the VA (Fig. 4). The HJB was not dehiscent into the middle ear cavity. 3.3. Case 3 An 11-year-old boy was referred by a pediatrician to our department; he complained of headache, disequilibrium, and ‘intermittent but not pulsatile’ tinnitus that had persisted for 2 months. Bilateral tympanic membranes appeared normal, and audiological testing showed no obvious abnormality. TM yielded type A tympanograms bilaterally. Slight spontaneous nystagmus to the left was observed. Caloric testing was normal. The VEMP test showed a 1.32-fold increase in amplitude for the right ear compared with the left ear. Magnetic resonance imaging appeared normal; however, CT revealed the presence of HJB on the right side, which was dehiscent to the VA (Fig. 5). 4. Discussion Third-window lesions in the inner ear have been demonstrated in several lesions, such as dehiscence of the three semicircular canals or the large VA, dehiscence between the cochlea and the carotid canal, or X-linked deafness with stapes gusher [1]. These conditions result in a mobile third window on the vestibular portion and cause low-frequency ABG by elevation of the thresholds for air-conducted sounds and reduction of the thresholds for bone-conducted sounds [4,5]. Clues for accurate diagnosis of these lesions include the presence of a low-frequency ABG, AR, VEMP, and OAE, as well as vestibular manifestations, including sound-induced or pressure-induced vertigo [1,14]. Imaging analysis, especially CT, confirms the final diagnosis. The jugular bulb (JB) is considered high when it extends above the inferior tympanic annulus [15], and HJB can be a cause of PSCD or VAD. There are only a few cases reported of PSCD caused by HJB in children [2,12], and no definite pediatric cases of VAD in addition to PSCD. The most common symptoms in patients with bony labyrinth dehiscence caused by a JB abnormality are hearing loss with ABG or pulsatile tinnitus [2]. This pulsatile tinnitus is considered to be due most likely to transmission of the turbulent venous blood flow within the JB to the inner ear via the bony
Fig. 5. High-resolution computed tomography (CT) in case 3. The high jugular bulb (asterisk) observed on the right side is dehiscent to the vestibular aqueduct (arrow).
dehiscence [2]. In the present cases, the two patients with PSCD had low-frequency MHL; however, none of the three patients seemed to have this type of tinnitus. A vestibular symptom was observed exclusively in the patient with VAD only. This may be due to the lesser complaints of vestibular dysfunction in children compared with adults [12,16]. Most cases with SSCD show no abnormalities on TM [7], and cases with PSCD reported previously also showed normal responses on TM [2,12]. However, in the present two cases with PSCD and VAD, wave motion of the baseline was observed on TM, which was not found in the case with VAD only. Hourani et al. [15] speculated that jugular venous pulsations might be transmitted to the VA and to the endolymphatic sac, which could cause aberrant transmission of signals to the vestibular and cochlear nerve, thereby producing symptoms. The waving of the baseline on TM observed in the present cases might be elicited during the test, because the motion could not be visible on otoscopic examinations. A similar wave motion of the baseline was also found on AR in cases with PSCD and VA. Recently, vascular pulsations on impedance audiometry have been reported in a subject with SSCD as a sign of a third-window lesion [17], probably caused by a mechanism similar to that observed in the present cases. The VEMP test, which shows a characteristic response in cases with SSCD [1], is also useful in cases with PSCD [18]. Patients with PSCD exhibit a reduced threshold or high amplitude on the affected side compared with the unaffected side [2,12]. High amplitudes of VEMP on the affected side were observed in the present cases, especially in the subject with a very large HJB diverticulum (case 2). VEMP thresholds were not measured in the three cases; however, the large amplitude on the symptomatic side would indicate vestibular hypersensitivity to sounds, even though the subject had no related complaints. The presence of an OAE response is a characteristic feature in cases of SSCD, which differentiates this syndrome from middle ear pathology [4]. The present two cases with PSCD showed reduced responses, except at high frequencies; in contrast, OAE responses were observed in the case with VAD alone. A reduced response on OAE may be due to the severity of the hearing loss in cases with PSCD, or it may reflect damage of the outer hair cells caused by the pressure of jugular venous pulsations transmitted through the PSC and the VA. 5. Conclusion In addition to MHL and high amplitude on the VEMP test, wave motion of the baseline elicited on TM or AR may reflect jugular venous pulsations through the PSC and the VA. These findings may
M. Sone et al. / International Journal of Pediatric Otorhinolaryngology 76 (2012) 447–451
be characteristics of cases with PSCD and VAD caused by HJB, which could provide clues for the diagnosis of these lesions. Disclosures No financial disclosures. Conflict of interest None. References [1] S.N. Merchant, J.J. Rosowski, Conductive hearing loss caused by third-window lesions of the inner ear, Otol. Neurotol. 29 (2008) 282–289. [2] D.R. Friedmann, B.T. Le, B.K. Pramanik, A.K. Lalwani, Clinical spectrum of patients with erosion of the inner ear by jugular bulb abnormalities, Laryngoscope 120 (2010) 365–372. [3] J.J. Rosowski, J.E. Songer, H.H. Nakajima, K.M. Brinsko, S.N. Merchant, Clinical experimental, and theoretical investigations of the effect of superior semicircular canal dehiscence on hearing mechanisms, Otol. Neurotol. 25 (2004) 323–332. [4] A.A. Mikulec, M.J. McKenna, M.J. Ramsey, J.J. Rosowski, B.S. Herrmann, R. Hugh, et al., Superior semicircular canal dehiscence presenting as conductive hearing loss without vertigo, Otol. Neurotol. 25 (2004) 121–129. [5] S.N. Merchant, H.H. Nakajima, C. Halpin, J.B. Nadol, D.J. Lee, W.P. Innis, et al., Clinical investigation and mechanism of air-bone gaps in large vestibular aqueduct syndrome, Ann. Otol. Rhinol. Laryngol. 116 (2007) 532–541.
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[6] L.B. Minor, D. Solomon, J. Zinreich, D.S. Zee, Sound- and/or pressure-induced vertigo due to bone dehiscence of the superior semicircular canal, Arch. Otolaryngol. Head Neck Surg. 124 (1998) 249–258. [7] F.L. Chi, D.D. Ren, C.F. Dai, Variety of audiologic manifestations in patients with superior semicircular canal dehiscence, Otol. Neurotol. 31 (2010) 2–10. [8] H.W. Yuen, R. Boeddinghaus, R.H. Eikelboom, M.D. Atlas, The relationship between the air-bone gap and the size of superior semicircular canal dehiscence, Otolaryngol. Head Neck Surg. 141 (2009) 689–694. [9] H. Kawano, T. Tono, P.A. Schachern, M.M. Paparella, S. Komune, Petrous high jugular bulb: a histological study, Am. J. Otolaryngol. 21 (2000) 161–168. [10] K. Wadin, L. Thomander, H. Wilbrand, Effects of a high jugular fossa and jugular bulb diverticulum of the inner ear, Acta Radiol. Diagn. (Stockh.) 27 (1986) 629–636. [11] S. Yetiser, M. Kertmen, A. Yildirim, An analysis of correlation between the unusual location of the jugular bulb and audiovestibular symptoms, Auris Nasus Larynx 31 (2007) 369–377. [12] Q. Gopen, G. Zhou, D. Poe, M. Kenna, D. Jones, Posterior semicircular canal dehiscence: first reported case series, Otol. Neurotol. 31 (2010) 339–344. [13] N. Katayama, M. Yamamoto, M. Teranishi, S. Naganawa, S. Nakata, M. Sone, et al., Relationship between endolymphatic hydrops and vestibular-evoked myogenic potential, Acta Otolaryngol. 130 (2010) 917–923. [14] L.B. Minor, J.P. Carey, P.D. Cremer, L.R. Lusting, S.O. Streubel, Dehiscence of bone overlying the superior canal as a cause of apparent conductive hearing loss, Otol. Neurotol. 24 (2003) 270–278. [15] R. Hourani, J. Carey, D.M. Yousem, Dehiscence of the jugular bulb and vestibular aqueduct. Finding on 200 consecutive temporal bone computed tomography scans, J. Comput. Assist. Tomogr. 29 (2005) 657–662. [16] G. Phillips, M. Raske, L. Vega, D. Peterson, K.C.Y. Sie, Semicircular canal dehiscence in the pediatric population, Int. J. Pediatr. Otorhinolaryngol. 73 (2009) 321–327. [17] T.E. Hullar, Vascular pulsations on impedance audiometry as a sign of a thirdmobile window lesion, Otol. Neurotol. 31 (2010) 565–566. [18] A.A. Mikulec, S.P. Dennis, Operative management of a posterior semicircular canal dehiscence, Laryngoscope 116 (2006) 375–378.
Contents lists available at SciVerse ScienceDirect
International Journal of Pediatric Otorhinolaryngology journal homepage: www.elsevier.com/locate/ijporl
Case report
Audiological signs in pediatric cases with dehiscence of the bony labyrinth caused by a high jugular bulb Michihiko Sone a,*, Naomi Katayama a, Shinji Naganawa b, Tadao Yoshida a, Masaaki Teranishi a, Tsutomu Nakashima a a b
Department of Otorhinolaryngology, Nagoya University Graduate School of Medicine, Nagoya, Japan Department of Radiology, Nagoya University Graduate School of Medicine, Nagoya, Japan
A R T I C L E I N F O
A B S T R A C T
Article history: Received 20 October 2011 Received in revised form 5 December 2011 Accepted 7 December 2011 Available online 5 January 2012
Clinical findings were assessed in three pediatric cases of dehiscence of the bony labyrinth caused by a high jugular bulb (HJB). Two children had two dehiscent lesions, which included posterior semicircular canal dehiscence (PSCD) and vestibular aqueduct dehiscence (VAD). One child had VAD alone. Two subjects with PSCD, but not with VAD alone, had mixed hearing loss and showed wave motion of the baseline on tympanometry and acoustic reflex testing, and a reduced response on otoacoustic emission. These findings may reflect jugular venous pulsations transmitted through the PSC and represent characteristics of cases with PSCD caused by HJB. ß 2011 Elsevier Ireland Ltd. All rights reserved.
Keywords: High jugular bulb Posterior semicircular canal Vestibular aqueduct Dehiscence Pulsatile tinnitus Hearing loss
1. Introduction The clinical characteristics of bony labyrinth dehiscence have been explained by the concept of a pathological third window [1– 8], which accompanies mixed hearing loss with air-bone gaps (ABG) at lower frequencies. Superior semicircular canal dehiscence (SSCD), which was first described by Minor et al. [6], is the most frequently demonstrated syndrome in these lesions. A high jugular bulb (HJB) is one of the causes of posterior semicircular canal dehiscence (PSCD). HJB may also induce vestibular aqueduct dehiscence (VAD). A temporal bone study showed that the overall incidence of HJB was 16.0% [9]. Typical symptoms in patients with bony labyrinth dehiscence caused by a HJB are hearing loss with ABG or pulsatile tinnitus [2]. Compared with SSCD, otological disturbances in cases with PSCD caused by HJB are less reported in the literature [2,10–12], especially in children. There might be a tendency to overlook the disease in children, as pediatric patients complain less than adults, especially for diseases related to vestibular dysfunction [12].
* Corresponding author at: Department of Otorhinolaryngology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan. Tel.: +81 52 744 2323; fax: +81 52 744 2325. E-mail address: [email protected] (M. Sone). 0165-5876/$ – see front matter ß 2011 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijporl.2011.12.007
Three recent pediatric cases with bony labyrinth dehiscence caused by HJB are reported, and their characteristic findings, which may represent diagnostic clues of the disease that could be used to avoid needless middle ear surgery, are described.
2. Methods Three pediatric patients with dehiscence of the bony labyrinth caused by HJB (confirmed by computer tomography (CT; Asteion and Aquilion, Toshiba, Tokyo, Japan) using sequential 0.5-mmthick slices) were studied. Hearing levels were evaluated using an audiometer (Model AA78, Rion, Tokyo, Japan) in a sound-attenuated room. Impedance audiometry, which included tympanometry (TM) and acoustic reflex (AR), and otoacoustic emission (OAE) were performed using an RS-22 and ILO292-USB (Rion, Tokyo, Japan), respectively. The caloric test was performed with cool air stimulation (15 8C, 6 l/min, 60 s) using an FAC-700 (DAIICHI Medical, Tokyo, Japan). The vestibular-evoked myogenic potential (VEMP) test was performed as follows: surface myogenic potentials in the sternocleidomastoid muscle were added 150 times using a reference electrode over the sternum, while clicks (105 dB) were presented to the ipsilateral ear, and white noise (75 dB) was presented to the contralateral ear (Synax 2100, NEC Medical Systems, Tokyo, Japan), as described elsewhere [13].
448
M. Sone et al. / International Journal of Pediatric Otorhinolaryngology 76 (2012) 447–451
3. Clinical observations 3.1. Case 1 A seven-year-old boy was referred to our hospital with hearing loss in his left ear that had been detected during a preschool medical examination. He had no other symptoms, including disequilibrium. The left tympanic membrane appeared normal, and the pure-tone audiogram (PTA) revealed the presence of mixed hearing loss (MHL) of 50–70 dB, with ABG that was prominent in the low-frequency range (Fig. 1A). TM yielded type A tympanograms bilaterally; however, the baseline on the left side exhibited wave motion (Fig. 1B), and responses on AR showed wave motion of the left ear (Fig. 1C). OAE of the left ear showed no response, except at high frequencies. Caloric testing showed a normal response. The VEMP test revealed a 1.47-fold increase in amplitude
for the left ear compared with the right ear. CT revealed the presence of HJB on the left side, which was dehiscent to the posterior semicircular canal (PSC) and to the vestibular aqueduct (VA) (Fig. 2). The HJB was not dehiscent into the middle ear cavity. 3.2. Case 2 Another seven-year-old boy had been treated for otitis media with effusion for 2 years; however, hearing loss in his left ear continued, even after the disease was cured, and he was referred to our hospital. He had no complaints indicative of inner ear disturbance. The tympanic membrane of his left ear appeared normal, and PTA revealed the presence of MHL of 40–60 dB, with AGB that was most prominent in the low-frequency range (Fig. 3A). TM yielded type A tympanograms bilaterally; however, the baseline on the left ear showed wave motion (Fig. 3B). Responses
Fig. 1. Pure-tone audiogram (PTA), tympanogram, and acoustic reflex (AR) in case 1. PTA shows mixed hearing loss with air-bone gaps, which are prominent in the lowfrequency range (A). Baseline waves are observed in the tympanogram (arrow in B) and AR (C) of the left ear.
M. Sone et al. / International Journal of Pediatric Otorhinolaryngology 76 (2012) 447–451
449
Fig. 2. High-resolution computed tomography (CT) in case 1. The high jugular bulb (asterisk) observed on the left side is dehiscent to the vestibular aqueduct (arrow in A) and the posterior semicircular canal (arrowhead in B).
Fig. 3. Pure-tone audiogram (PTA), tympanogram, and acoustic reflex (AR) in case 2. PTA shows mixed hearing loss with air-bone gaps, which are prominent in the lowfrequency range (A). Baseline waves are observed in the tympanogram (arrow in B) and AR (C) of the left ear.
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M. Sone et al. / International Journal of Pediatric Otorhinolaryngology 76 (2012) 447–451
Fig. 4. High-resolution computed tomography (CT) in case 2. The large jugular bulb diverticulum (asterisk) detected on the left side is dehiscent to the posterior semicircular canal (arrowhead), which occupies the vestibular aqueduct portion.
on AR exhibited wave motion on the left (Fig. 3C). OAE of the left ear showed a reduced response, except at high frequencies. Caloric testing was normal; however, the VEMP test of the left ear revealed a 2.39-fold increase in amplitude compared with on the right ear. CT revealed the presence of a large HJB diverticulum on the left side, which was dehiscent to the PSC and to the VA (Fig. 4). The HJB was not dehiscent into the middle ear cavity. 3.3. Case 3 An 11-year-old boy was referred by a pediatrician to our department; he complained of headache, disequilibrium, and ‘intermittent but not pulsatile’ tinnitus that had persisted for 2 months. Bilateral tympanic membranes appeared normal, and audiological testing showed no obvious abnormality. TM yielded type A tympanograms bilaterally. Slight spontaneous nystagmus to the left was observed. Caloric testing was normal. The VEMP test showed a 1.32-fold increase in amplitude for the right ear compared with the left ear. Magnetic resonance imaging appeared normal; however, CT revealed the presence of HJB on the right side, which was dehiscent to the VA (Fig. 5). 4. Discussion Third-window lesions in the inner ear have been demonstrated in several lesions, such as dehiscence of the three semicircular canals or the large VA, dehiscence between the cochlea and the carotid canal, or X-linked deafness with stapes gusher [1]. These conditions result in a mobile third window on the vestibular portion and cause low-frequency ABG by elevation of the thresholds for air-conducted sounds and reduction of the thresholds for bone-conducted sounds [4,5]. Clues for accurate diagnosis of these lesions include the presence of a low-frequency ABG, AR, VEMP, and OAE, as well as vestibular manifestations, including sound-induced or pressure-induced vertigo [1,14]. Imaging analysis, especially CT, confirms the final diagnosis. The jugular bulb (JB) is considered high when it extends above the inferior tympanic annulus [15], and HJB can be a cause of PSCD or VAD. There are only a few cases reported of PSCD caused by HJB in children [2,12], and no definite pediatric cases of VAD in addition to PSCD. The most common symptoms in patients with bony labyrinth dehiscence caused by a JB abnormality are hearing loss with ABG or pulsatile tinnitus [2]. This pulsatile tinnitus is considered to be due most likely to transmission of the turbulent venous blood flow within the JB to the inner ear via the bony
Fig. 5. High-resolution computed tomography (CT) in case 3. The high jugular bulb (asterisk) observed on the right side is dehiscent to the vestibular aqueduct (arrow).
dehiscence [2]. In the present cases, the two patients with PSCD had low-frequency MHL; however, none of the three patients seemed to have this type of tinnitus. A vestibular symptom was observed exclusively in the patient with VAD only. This may be due to the lesser complaints of vestibular dysfunction in children compared with adults [12,16]. Most cases with SSCD show no abnormalities on TM [7], and cases with PSCD reported previously also showed normal responses on TM [2,12]. However, in the present two cases with PSCD and VAD, wave motion of the baseline was observed on TM, which was not found in the case with VAD only. Hourani et al. [15] speculated that jugular venous pulsations might be transmitted to the VA and to the endolymphatic sac, which could cause aberrant transmission of signals to the vestibular and cochlear nerve, thereby producing symptoms. The waving of the baseline on TM observed in the present cases might be elicited during the test, because the motion could not be visible on otoscopic examinations. A similar wave motion of the baseline was also found on AR in cases with PSCD and VA. Recently, vascular pulsations on impedance audiometry have been reported in a subject with SSCD as a sign of a third-window lesion [17], probably caused by a mechanism similar to that observed in the present cases. The VEMP test, which shows a characteristic response in cases with SSCD [1], is also useful in cases with PSCD [18]. Patients with PSCD exhibit a reduced threshold or high amplitude on the affected side compared with the unaffected side [2,12]. High amplitudes of VEMP on the affected side were observed in the present cases, especially in the subject with a very large HJB diverticulum (case 2). VEMP thresholds were not measured in the three cases; however, the large amplitude on the symptomatic side would indicate vestibular hypersensitivity to sounds, even though the subject had no related complaints. The presence of an OAE response is a characteristic feature in cases of SSCD, which differentiates this syndrome from middle ear pathology [4]. The present two cases with PSCD showed reduced responses, except at high frequencies; in contrast, OAE responses were observed in the case with VAD alone. A reduced response on OAE may be due to the severity of the hearing loss in cases with PSCD, or it may reflect damage of the outer hair cells caused by the pressure of jugular venous pulsations transmitted through the PSC and the VA. 5. Conclusion In addition to MHL and high amplitude on the VEMP test, wave motion of the baseline elicited on TM or AR may reflect jugular venous pulsations through the PSC and the VA. These findings may
M. Sone et al. / International Journal of Pediatric Otorhinolaryngology 76 (2012) 447–451
be characteristics of cases with PSCD and VAD caused by HJB, which could provide clues for the diagnosis of these lesions. Disclosures No financial disclosures. Conflict of interest None. References [1] S.N. Merchant, J.J. Rosowski, Conductive hearing loss caused by third-window lesions of the inner ear, Otol. Neurotol. 29 (2008) 282–289. [2] D.R. Friedmann, B.T. Le, B.K. Pramanik, A.K. Lalwani, Clinical spectrum of patients with erosion of the inner ear by jugular bulb abnormalities, Laryngoscope 120 (2010) 365–372. [3] J.J. Rosowski, J.E. Songer, H.H. Nakajima, K.M. Brinsko, S.N. Merchant, Clinical experimental, and theoretical investigations of the effect of superior semicircular canal dehiscence on hearing mechanisms, Otol. Neurotol. 25 (2004) 323–332. [4] A.A. Mikulec, M.J. McKenna, M.J. Ramsey, J.J. Rosowski, B.S. Herrmann, R. Hugh, et al., Superior semicircular canal dehiscence presenting as conductive hearing loss without vertigo, Otol. Neurotol. 25 (2004) 121–129. [5] S.N. Merchant, H.H. Nakajima, C. Halpin, J.B. Nadol, D.J. Lee, W.P. Innis, et al., Clinical investigation and mechanism of air-bone gaps in large vestibular aqueduct syndrome, Ann. Otol. Rhinol. Laryngol. 116 (2007) 532–541.
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