Anatomical Characteristics of Facial Nerve and Cochlea Interaction

Objective: The aim was to study the relationship between the labyrinthine portion (LP) of the facial canal and the cochlea in human inner ear molds and temporal bones using micro-CT and 3D rendering. A reduced cochlea-facial distance may spread electric currents from the cochlear implant to the LP and cause facial nerve stimulation. Influencing factors may be the topographic anatomy and otic capsule properties. Methods: An archival collection of human temporal bones underwent micro-CT and 3D reconstruction. In addition, cochlea-facial distance was assessed in silicone and polyester resin molds, and the association between the LP and upper basal turn of the cochlea was analyzed. Results: Local thinning of the otic capsule and local anatomy may explain the development of cochlea-facial dehiscence, which was found in 1.4%. A reduced cochlea-facial distance was noted in 1 bone with a superior semicircular canal dehiscence but not in bones with superior semicircular canal “blue line.” The otic capsule often impinged upon the LP and caused narrowing. Conclusion: Micro-CT with 3D rendering offers new possibilities to study the topographic anatomy of the human temporal bone. The varied shape of the cross-section of the LP could often be explained by an “intruding” cochlea.

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Anatomo-radiological study of the superior semicircular canal dehiscence of 37 cadaver temporal bones

Surgical and Radiologic Anatomy ◽

10.1007/s00276-012-0992-1 ◽

2012 ◽

Vol 35 (1) ◽

pp. 55-59 ◽

Cited By ~ 18

Author(s):

Michel Mondina ◽

Damien Bonnard ◽

Xavier Barreau ◽

Vincent Darrouzet ◽

Valérie Franco-Vidal

Keyword(s):

Semicircular Canal ◽

Superior Semicircular Canal Dehiscence ◽

Radiological Study ◽

Superior Semicircular Canal ◽

Temporal Bones ◽

Canal Dehiscence

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Superior semicircular canal dehiscence simulating otosclerosis

The Journal of Laryngology & Otology ◽

10.1258/002221503322113003 ◽

2003 ◽

Vol 117 (7) ◽

pp. 553-557 ◽

Cited By ~ 59

Author(s):

G. Michael Halmagyi ◽

Swee T. Aw ◽

Leigh A. McGarvie ◽

Michael J. Todd ◽

Andrew Bradshaw ◽

...

Keyword(s):

Semicircular Canal ◽

Vestibular Evoked Myogenic Potentials ◽

Patient Needs ◽

Vestibular Evoked Myogenic Potential ◽

Superior Semicircular Canal Dehiscence ◽

Superior Semicircular Canal ◽

Acoustic Reflexes ◽

Temporal Bones ◽

Conductive Hearing ◽

Canal Dehiscence

This is a report of a patient with an air-bone gap, thought 10 years ago to be a conductive hearing loss due to otosclerosis and treated with a stapedectomy. It now transpires that the patient actually had a conductive hearing gain due to superior semicircular canal dehiscence. In retrospect for as long as he could remember the patient had experienced cochlear hypersensitivity to bone-conducted sounds so that he could hear his own heart beat and joints move, as well as a tuning fork placed at his ankle. He also had vestibular hypersensitivity to air-conducted sounds with sound-induced eye movements (Tullio phenomenon), pressure-induced nystagmus and low-threshold, high-amplitude vestibular-evoked myogenic potentials. Furthermore some of his acoustic reflexes were preserved even after stapedectomy and two revisions. This case shows that if acoustic reflexes are preserved in a patient with an air-bone gap then the patient needs to be checked for sound- and pressure-induced nystagmus and needs to have vestibular-evoked myogenic potential testing. If there is sound- or pressure-induced nystagmus and if the vestibular-evoked myogenic potentials are also preserved, the problem is most likely in the floor of the middle fossa and not in the middle ear, and the patient needs a high-resolution spiral computed tomography (CT) of the temporal bones to show this.

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‘Honeycomb’ tegmen: multiple tegmen defects associated with superior semicircular canal dehiscence

The Journal of Laryngology & Otology ◽

10.1017/s0022215109991411 ◽

2009 ◽

Vol 124 (5) ◽

pp. 560-563 ◽

Cited By ~ 32

Author(s):

R Suryanarayanan ◽

T H Lesser

Keyword(s):

Semicircular Canal ◽

Case Reports ◽

Relevant Literature ◽

Developmental Defect ◽

Middle Fossa ◽

Superior Semicircular Canal Dehiscence ◽

Superior Semicircular Canal ◽

Temporal Bones ◽

Honeycomb Appearance ◽

Canal Dehiscence

AbstractObjective:To report the coexistence of multiple tegmen defects, forming a ‘honeycomb’ pattern, together with dehiscence of the superior semicircular canal.Case reports:We describe three cases in which the above findings were noted, and we review the relevant literature.Conclusion:Superior semicircular canal dehiscence is defined as the absence of portions of bone over the canal along the floor of the middle fossa. Most published articles describe the defect as an isolated finding which is either unilateral or bilateral. Studies on temporal bones show either a defect over the superior semicircular canal or isolated defects over the tegmen. We describe three cases in which we found multiple tegmen defects, giving a characteristic honeycomb appearance, coexisting with dehiscence over the superior semicircular canal. This finding, which supports the theory of a developmental defect as the origin of the condition, has not previously been reported. A literature review is presented, with discussion of the aetiology and management of superior semicircular canal dehiscence.

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Mondini-like malformation mimicking otosclerosis and superior semicircular canal dehiscence

The Journal of Laryngology & Otology ◽

10.1017/s0022215106000934 ◽

2006 ◽

Vol 120 (5) ◽

pp. 419-422 ◽

Cited By ~ 13

Author(s):

M Karlberg ◽

M Annertz ◽

M Magnusson

Keyword(s):

Hearing Loss ◽

Semicircular Canal ◽

Bone Conduction ◽

Low Frequency ◽

Acoustic Energy ◽

Vestibular Evoked Myogenic Potentials ◽

Superior Semicircular Canal Dehiscence ◽

Superior Semicircular Canal ◽

Temporal Bones ◽

Canal Dehiscence

In 2003, it was reported that superior semicircular canal dehiscence can mimic otosclerosis because of low-frequency bone conduction hearing gain and dissipation of air-conducted acoustic energy through the dehiscence. We report the case of a 17-year-old girl with left-sided combined hearing loss thought to be due to otosclerosis. Bone conduction thresholds were −10 dB at 250 and 500 Hz and she had a 40 dB air–bone gap at 250 Hz. When a tuning fork was placed at her ankle she heard it in her left ear. Acoustic reflexes and vestibular evoked myogenic potentials could be elicited bilaterally. Imaging of the temporal bones showed no otosclerosis, superior semicircular canal dehiscence or large vestibular aqueduct, but a left-sided, Mondini-like dysplasia of the cochlea with a modiolar deficiency could be seen. Mondini-like cochlear dysplasia should be added to the causes of inner-ear conductive hearing loss.

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