Otology & Neurotology 37:e192–e193 ß 2015, Otology & Neurotology, Inc.
Imaging Case of the Month
Lateral Semicircular Canal–enlarged Vestibular Aqueduct Fistula Associated With Paroxysmal Positional Nystagmus Mitsuya Suzuki, Yasushi Ota, Toshitake Tanaka, and Yutaka Ota Department of Otolaryngology, Toho University, Sakura Medical Center, Sakura City, Chiba, Japan
We report the case of a 48-year-old man with bilateral congenital hearing loss with an inner ear anomaly. He had been experiencing hearing loss with a 5-year history of paroxysmal vertigo when moving from a sitting to a supine position or vice versa. He also reported transient dizziness when lifting heavy objects. Otoscopy was normal. An audiogram showed profound bilateral sensorineural hearing loss. Positional nystagmus was recorded using an electronystagmogram (ENG) and a charge-coupled device video camera. The ENG and charge-coupled device video camera showed nystagmus toward the right side in a supine position, whereas nystagmus toward the left side was recorded in a sitting position (Fig. 1). The nystagmus observed toward the right side in a supine position did not change direction during the head roll test. When both nose-pinch and glottic Valsalva maneuvers were performed in a sitting position, nystagmus was elicited toward the right side. The caloric response was moderately reduced in both ears. The amplitude of the cervical vestibular myogenic potentials in the right ear was significantly greater than that in the left ear; the response threshold in the right ear was 65 dB SPL, whereas that in the left ear was 95 dB SPL.
The patient was instructed to initiate positional changes slowly, and this has been associated with a subjective reduction in symptoms. EVA syndrome occasionally accompanies other inner ear malformations such as a Mondini anomaly (1). Although a Mondini anomaly is sometimes complicated by a lateral semicircular canal that communicates widely with the vestibule (2,3), a Mondini anomaly accompanied by a lateral semicircular canal crista (LSCC)EVA fistula is rare. In our case, the direction of nystagmus did not change during the head roll test but differed in supine and sitting positions. The nystagmus featured horizontal rather than vertical torsional eye movements. These findings suggest that this positional nystagmus did not result from benign paroxysmal positional vertigo. The cervical vestibular myogenic potential findings were suggestive of a third window from the LSCC-EVA fistula, similar to the findings seen in superior semicircular canal dehiscence syndrome. In a labyrinthine-intracranial fistula, the direction of nystagmus induced by a nose-pinch Valsalva maneuver usually reverses with respect to that induced by a glottic Valsalva maneuver (4). In our patient, both the glottic and nose-pinch Valsalva maneuvers induced nystagmus toward the right side. These findings suggest that both Valsalva maneuvers caused ampullopetal flow in the right LSCC (5). Nystagmus toward the right side might have been caused by ampullopetal flow in the right LSCC, which was induced by an increase in intracranial pressure resulting from both the Valsalva maneuvers and the orientation of the head in a supine position. In contrast, nystagmus toward the left side could also be induced by ampullofugal flow in the right LSCC and caused by a decrease in intracranial pressure in a sitting position. Computed tomography showed extensions of the spiral foraminous tract. It suggests an enlargement of the cochlear nerve canal and a deformity of the cribriform area. We speculated that the inner ear fluid flow in our patient changed when passing through the LSCC-EVA fistula via the extended spiral foraminous tract according to changes in intracranial pressure.
HIGH-RESOLUTION COMPUTED TOMOGRAPHY AND MAGNETIC RESONANCE IMAGING Magnetic resonance imaging showed bilateral normalsize cochleae with a partial or complete lack of an interscalar septum (bilateral Mondini anomalies) and a right-sided fistula between a lateral semicircular canal deformity and an enlarged vestibular aqueduct (EVA) (Fig. 2, A–C).
Address correspondence and reprint requests to Mitsuya Suzuki, M.D., Department of Otolaryngology, Toho University, Sakura Medical Center, 564-1 Shimo-shizu, Sakura City, Chiba 285-0841, Japan; E-mail: [email protected] The authors disclose no conflicts of interest.
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Copyright © 2016 Otology & Neurotology, Inc. Unauthorized reproduction of this article is prohibited.
LSC-ENLARGED VA FISTULA ASSOCIATED WITH NYSTAGMUS
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FIG. 1. Positional nystagmus recorded on an ENG. Small arrows indicate nystagmus elicited by changes in head position. The large arrows indicate a moment when the patient changed to a sitting position from a supine position or changed to a supine position from a sitting position. Calibration was performed at 10-degree intervals. H indicates horizontal; V, vertical; MSPVN, maximum slow-phase velocity of nystagmus.
FIG. 2. Temporal bone imaging. A and B, Axial and coronal computed tomography imaging demonstrates bilateral Mondini malformations and a right-sided lateral semicircular canal deformity with an enlarged vestibular aqueduct. C, Axial T2-weighted magnetic resonance imaging shows a right-sided LSCC-EVA fistula. Asterisks indicate the ampulla of the lateral semicircular canal. White circles indicate the LSCC-EVA fistula. White arrows indicate extensions of the spiral foraminous tract. Black arrowheads indicate the EVA. IAM indicates internal auditory meatus.
REFERENCES 1. Valvassori GE, Clemis JD. The large vestibular aqueduct syndrome. Laryngoscope 1978;88:723–8. 2. Maekawa C, Kitahara T, Horii A, Miyabe J, Kubo T. Vestibular type of Mondini anomalies with BPPV and Me´nie`re’s disease–like symptoms. Auris Nasus Larynx 2009;36:218–20.
3. Ohtani I, Schuknecht HF. Temporal bone pathology in DiGeorge’s syndrome. Ann Otol Rhinol Laryngol 1984;93:220–4. 4. Minor LB. Superior canal dehiscence syndrome. Am J Otol 2000;21: 9–19. 5. Baloh RW, Honrubia V, Konrad HR. Ewald’s second law reevaluated. Acta Otolaryngol 1977;83:475–9.
Otology & Neurotology, Vol. 37, No. 6, 2016
Copyright © 2016 Otology & Neurotology, Inc. Unauthorized reproduction of this article is prohibited.
Imaging Case of the Month
Lateral Semicircular Canal–enlarged Vestibular Aqueduct Fistula Associated With Paroxysmal Positional Nystagmus Mitsuya Suzuki, Yasushi Ota, Toshitake Tanaka, and Yutaka Ota Department of Otolaryngology, Toho University, Sakura Medical Center, Sakura City, Chiba, Japan
We report the case of a 48-year-old man with bilateral congenital hearing loss with an inner ear anomaly. He had been experiencing hearing loss with a 5-year history of paroxysmal vertigo when moving from a sitting to a supine position or vice versa. He also reported transient dizziness when lifting heavy objects. Otoscopy was normal. An audiogram showed profound bilateral sensorineural hearing loss. Positional nystagmus was recorded using an electronystagmogram (ENG) and a charge-coupled device video camera. The ENG and charge-coupled device video camera showed nystagmus toward the right side in a supine position, whereas nystagmus toward the left side was recorded in a sitting position (Fig. 1). The nystagmus observed toward the right side in a supine position did not change direction during the head roll test. When both nose-pinch and glottic Valsalva maneuvers were performed in a sitting position, nystagmus was elicited toward the right side. The caloric response was moderately reduced in both ears. The amplitude of the cervical vestibular myogenic potentials in the right ear was significantly greater than that in the left ear; the response threshold in the right ear was 65 dB SPL, whereas that in the left ear was 95 dB SPL.
The patient was instructed to initiate positional changes slowly, and this has been associated with a subjective reduction in symptoms. EVA syndrome occasionally accompanies other inner ear malformations such as a Mondini anomaly (1). Although a Mondini anomaly is sometimes complicated by a lateral semicircular canal that communicates widely with the vestibule (2,3), a Mondini anomaly accompanied by a lateral semicircular canal crista (LSCC)EVA fistula is rare. In our case, the direction of nystagmus did not change during the head roll test but differed in supine and sitting positions. The nystagmus featured horizontal rather than vertical torsional eye movements. These findings suggest that this positional nystagmus did not result from benign paroxysmal positional vertigo. The cervical vestibular myogenic potential findings were suggestive of a third window from the LSCC-EVA fistula, similar to the findings seen in superior semicircular canal dehiscence syndrome. In a labyrinthine-intracranial fistula, the direction of nystagmus induced by a nose-pinch Valsalva maneuver usually reverses with respect to that induced by a glottic Valsalva maneuver (4). In our patient, both the glottic and nose-pinch Valsalva maneuvers induced nystagmus toward the right side. These findings suggest that both Valsalva maneuvers caused ampullopetal flow in the right LSCC (5). Nystagmus toward the right side might have been caused by ampullopetal flow in the right LSCC, which was induced by an increase in intracranial pressure resulting from both the Valsalva maneuvers and the orientation of the head in a supine position. In contrast, nystagmus toward the left side could also be induced by ampullofugal flow in the right LSCC and caused by a decrease in intracranial pressure in a sitting position. Computed tomography showed extensions of the spiral foraminous tract. It suggests an enlargement of the cochlear nerve canal and a deformity of the cribriform area. We speculated that the inner ear fluid flow in our patient changed when passing through the LSCC-EVA fistula via the extended spiral foraminous tract according to changes in intracranial pressure.
HIGH-RESOLUTION COMPUTED TOMOGRAPHY AND MAGNETIC RESONANCE IMAGING Magnetic resonance imaging showed bilateral normalsize cochleae with a partial or complete lack of an interscalar septum (bilateral Mondini anomalies) and a right-sided fistula between a lateral semicircular canal deformity and an enlarged vestibular aqueduct (EVA) (Fig. 2, A–C).
Address correspondence and reprint requests to Mitsuya Suzuki, M.D., Department of Otolaryngology, Toho University, Sakura Medical Center, 564-1 Shimo-shizu, Sakura City, Chiba 285-0841, Japan; E-mail: [email protected] The authors disclose no conflicts of interest.
e192
Copyright © 2016 Otology & Neurotology, Inc. Unauthorized reproduction of this article is prohibited.
LSC-ENLARGED VA FISTULA ASSOCIATED WITH NYSTAGMUS
e193
FIG. 1. Positional nystagmus recorded on an ENG. Small arrows indicate nystagmus elicited by changes in head position. The large arrows indicate a moment when the patient changed to a sitting position from a supine position or changed to a supine position from a sitting position. Calibration was performed at 10-degree intervals. H indicates horizontal; V, vertical; MSPVN, maximum slow-phase velocity of nystagmus.
FIG. 2. Temporal bone imaging. A and B, Axial and coronal computed tomography imaging demonstrates bilateral Mondini malformations and a right-sided lateral semicircular canal deformity with an enlarged vestibular aqueduct. C, Axial T2-weighted magnetic resonance imaging shows a right-sided LSCC-EVA fistula. Asterisks indicate the ampulla of the lateral semicircular canal. White circles indicate the LSCC-EVA fistula. White arrows indicate extensions of the spiral foraminous tract. Black arrowheads indicate the EVA. IAM indicates internal auditory meatus.
REFERENCES 1. Valvassori GE, Clemis JD. The large vestibular aqueduct syndrome. Laryngoscope 1978;88:723–8. 2. Maekawa C, Kitahara T, Horii A, Miyabe J, Kubo T. Vestibular type of Mondini anomalies with BPPV and Me´nie`re’s disease–like symptoms. Auris Nasus Larynx 2009;36:218–20.
3. Ohtani I, Schuknecht HF. Temporal bone pathology in DiGeorge’s syndrome. Ann Otol Rhinol Laryngol 1984;93:220–4. 4. Minor LB. Superior canal dehiscence syndrome. Am J Otol 2000;21: 9–19. 5. Baloh RW, Honrubia V, Konrad HR. Ewald’s second law reevaluated. Acta Otolaryngol 1977;83:475–9.
Otology & Neurotology, Vol. 37, No. 6, 2016
Copyright © 2016 Otology & Neurotology, Inc. Unauthorized reproduction of this article is prohibited.
