A Mathematical Model of Human Semicircular Canal Geometry: A New Basis for Interpreting Vestibular Physiology

Bradshaw, Andrew P.; Curthoys, Ian S.; Todd, Michael J.; Magnussen, John; Taubman, David; Aw, Swee T.; Hálmagyi, G. Michael

doi:10.1007/s10162-009-0195-6

Cited by 86 publications

(89 citation statements)

References 31 publications

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“…The persistence of such varying sensitivity patterns of the SC in three-toed sloths thus suggests that their functional architecture is not associated with a high level of selection on their shape. On the other hand, absence of left-right asymmetry in our sample of sloths, as usual in other mammals [7], indicates that intra-individual variation of the inner ear is limited, possibly in order to avoid vertigo pathophysiology [27], or as a result of a constraint at the level of individual development, which remains to be determined.…”

Section: Europaea)mentioning

confidence: 53%

High morphological variation of vestibular system accompanies slow and infrequent locomotion in three-toed sloths

et al. 2012

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The semicircular canals (SCs), part of the vestibular apparatus of the inner ear, are directly involved in the detection of angular motion of the head for maintaining balance, and exhibit adaptive patterns for locomotor behaviour. Consequently, they are generally believed to show low levels of intraspecific morphological variation, but few studies have investigated this assumption. On the basis of high-resolution computed tomography, we present here, to our knowledge, the first comprehensive study of the pattern of variation of the inner ear with a focus on Xenarthra. Our study demonstrates that extant three-toed sloths show a high level of morphological variation of the bony labyrinth of the inner ear. Especially, the variation in shape, relative size and angles of their SCs greatly differ from those of other, faster-moving taxa within Xenarthra and Placentalia in general. The unique pattern of variation in three-toed sloths suggests that a release of selection and/or constraints on their organ of balance is associated with the observed wide range of phenotypes. This release is coincident with their slow and infrequent locomotion and may be related, among other possible factors, to a reduced functional demand for a precise sensitivity to movement.

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Section: Europaea)mentioning

confidence: 53%

High morphological variation of vestibular system accompanies slow and infrequent locomotion in three-toed sloths

et al. 2012

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“…Seventeen (five bilateral, seven left and five right) SCD and one right PCD patients were diagnosed based on a combination of tests as shown in Table 1: (a) air-conducted single-click-evoked vestibulo-ocular reflex (click VOR) with magnitude and threshold below normal 110-dB normal hearing level (NHL; 145-dB sound pressure level) measurements (Aw et al 2006); (b) high-resolution, 0.625-mm multi-slice (64), temporal bone CT images (GE Medical Systems, USA) reformatted in semicircular canal planes (Williamson et al 2003;Aw et al 2006;Freidmann et al 2010;Bradshaw et al 2010) with estimation of the dehiscence arc and reconstruction in three dimensions, (c) threshold of cervical vestibular-evoked myogenic potentials from air-conducted single click (Rosengren et al 2008), (d) clinical vestibular assessment such as pure tone (0.25, 0.50, 1.0, and 2.0 kHz) at 110-dB NHL sound-induced nystagmus and pressure-induced nystagmus with the Hannebert and valsalva tests, (e) cochlear hypersensitivity symptoms such as autophonia/hyperacusis symptoms and pure-tone audiogram with crossed acoustic reflex. The patients' ViVORs were then compared with the above combination of tests elucidated in Table 1.…”

Section: Subjectsmentioning

confidence: 99%

“…Three-dimensional reconstruction and multiplanar reformatting of the CT images with a second-order planar fit to the semicircular canal centreline permitted the bony capsule's integrity to be examined over its entire circumference (Bradshaw et al 2010 …”

Section: Computed Axial Tomography Imagingmentioning

confidence: 99%

“…3) with equivalent SCD patients with normal conductive mechanism. 3-D reconstruction and reformation of their CT images in the plane of their left superior semicircular canals were performed on these SCD patients' left labyrinths and ossicular chains to confirm their left SCDs and left PORPs (Bradshaw et al 2010). Figure 3A compares the ViVORs from the left unilateral SCD (patient 11) with left ossicular chain dysfunction (left panels) with the left unilateral SCD patient with normal conductive mechanism (right panels).…”

Section: Vibrations Bypass the Ear's Conductive Mechanismmentioning

confidence: 99%

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Three-Dimensional Vibration-Induced Vestibulo-ocular Reflex Identifies Vertical Semicircular Canal Dehiscence

Todd

et al. 2011

JARO

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Vertical semicircular canal dehiscence (VSCD) due to superior canal dehiscence (SCD) or posterior canal dehiscence (PCD) of the temporal bone causes vestibular and cochlear hypersensitivity to sound. This study aimed to characterize the vibration-induced vestibulo-ocular reflex (ViVOR) in VSCD. ViVORs in one PCD and 17 SCD patients, confirmed by CT imaging reformatted in semicircular canal planes, were measured with dual-search coils as binocular three-dimensional eye rotations induced by skull vibrations from a bone oscillator (B71-10 ohms) at 7 ms, 500 Hz, 135-dB peak-force level (re: 1 μN). The ViVOR eye rotation axes were computed by vector analysis and referenced to known semicircular canal planes. Onset latency of the ViVOR was 11 ms. ViVOR from VSCD was up to nine times greater than normal. The ViVOR's torsional rotation was always contraversive-torsional (the eye's upper pole rotated away from the stimulated ear), i.e. its direction was clockwise from a left and counterclockwise from a right VSCD, thereby lateralizing the side of the VSCD. The ViVORs vertical component distinguishes PCD from SCD, being downwards in PCD and upwards in SCD. In unilateral VSCD, the ViVOR eye rotation axis aligned closest to the dehiscent vertical semicircular canal axis from either ipsilateral or contralateral mastoid vibrations. However, in bilateral VSCDs, the ViVOR eye rotation axis lateralized to the ipsilateral dehiscent vertical semicircular canal axis. ViVOR was evoked in ossicular chain dysfunction, even when air-conducted click vestibulo-ocular reflex (VOR) was absent or markedly reduced. Hence, ViVOR could be a useful measurement to identify unilateral or bilateral VSCD even in the presence of ossicular chain dysfunction.

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“…Recently, some preliminary results have also revealed the statistical difference in global morphology of the VS between right-thoracic AIS and normal controls [20]. The shape of the central contour of each canal for the VS surfaces has also been studied [2]. However, the complete geometry of the surface has not been fully analyzed.…”

Section: Introductionmentioning

confidence: 99%

Shape Analysis of Vestibular Systems in Adolescent Idiopathic Scoliosis Using Geodesic Spectra

Zeng

Lui

Shi

et al. 2010

Lecture Notes in Computer Science

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Abstract. Adolescent Idiopathic Scoliosis (AIS) characterized by the 3D spine deformity affects about 4% schoolchildren worldwide. One of the prominent theories of the etiopathogenesis of AIS was proposed to be the poor postural balance control due to the impaired vestibular function. Thus, the morphometry of the vestibular system (VS) is of great importance for studying AIS. The VS is a genus-3 structure situated in the inner ear and consists of three semicircular canals lying perpendicular to each other. The high-genus topology of the surface poses great challenge for shape analysis. In this work, we propose an effective method to analyze shapes of high-genus surfaces by considering their geodesic spectra. The key is to compute the canonical hyperbolic geodesic loops of the surface, using the Ricci flow method. The Fuchsian group generators are then computed which can be used to determine the geodesic spectra. The geodesic spectra effectively measure shape differences between highgenus surfaces up to the hyperbolic isometry. We applied the proposed algorithm to the VS of 12 normal and 15 AIS subjects. Experimental results show the effectiveness of our algorithm and reveal statistical shape difference in the VS between right-thoracic AIS and normal subjects.

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A Mathematical Model of Human Semicircular Canal Geometry: A New Basis for Interpreting Vestibular Physiology

Cited by 86 publications

References 31 publications

High morphological variation of vestibular system accompanies slow and infrequent locomotion in three-toed sloths

High morphological variation of vestibular system accompanies slow and infrequent locomotion in three-toed sloths

Three-Dimensional Vibration-Induced Vestibulo-ocular Reflex Identifies Vertical Semicircular Canal Dehiscence

Shape Analysis of Vestibular Systems in Adolescent Idiopathic Scoliosis Using Geodesic Spectra

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