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Vestibular Evoked Myogenic Potentials in Subject With Superior Canal Dehiscence Syndrome  [PDF]
Feray GüLE?,Ne?e ?ELEBISOY
Journal of Neurological Sciences , 2012,
Abstract: Superior canal dehiscence syndrome (SCDS) is characterized by absence of the roof of the superior semicircular canal. Sound stimuli of higher decibels can cause vertigo and oscillopsia in these patients. A 38-year-old lady complaining about vertigo attacks associated with loud sounds as well as coughing and sneezing was evaluated. Her audiogram revealed a mild conductive type hearing loss on the left side. The caloric responses were normal. Vestibular evoked myogenic potential (VEMP) latencies recorded from the sternocleidomastoid muscles (SCM) were normal bilaterally ( p13 and n 23 latencies were 13.0 ms, 20.7 ms on the left side and 12.7 ms, 22.6 ms on the right side). The amplitude of the n13-p23 potential was 204 μV on the left and 78 μV on the right side. Repeated recordings showed that the amplitude asymmetry was persisting. Dehiscence of the superior canal acts as a third window and causes pressure and sound sensitivity. VEMPs can be recorded easily in patients with the abovementioned complaints to support the diagnosis before a high resolution temporal bone CT is performed.
A patient with superior semicircular canal dehiscence presenting with Tullio's phenomenon: a case report
Richard JD Hewitt, Anthony O Owa
Journal of Medical Case Reports , 2009, DOI: 10.1186/1752-1947-3-22
Abstract: A 45-year-old Caucasian man presented with vertigo induced by sound or pressure. Subsequent investigation revealed dehiscence of the superior semicircular canal and the patient underwent a surgical repair.Surgery to repair or resurface the dehiscence represents an effective treatment modality, offering a resolution of symptoms with no detrimental effect on hearing or long-term sequelae. A five-layer composite repair consisting of temporalis fascia – bone pate – conchal cartilage – bone pate – temporalis fascia has been found to be safe and effective.Dehiscence of bone overlying the superior semi-circular canal was described in 1998 by Minor et al. [1] as a cause of sound and pressure induced vertigo. The condition of superior semicircular canal dehiscence has subsequently been the topic of numerous articles exploring the clinical presentation, investigation and management of the disorder. The incidence of dehiscent bone has been reported in cadaveric analysis to lie between 0.4 and 0.5%, with thinning of the bone to <0.1 mm in a further 1.4% [2].Symptoms include one or more of the following: sound induced vertigo, often in a vertical-torsional plane; conductive hyperacusis; and chronic feelings of disequilibrium and motion intolerance [3]. Clinical evaluation with a patient exposed to sound or pressure, wearing Frenzel's glasses, reveals nystagmus of an upward and anticlockwise nature in a right-sided lesion, and upward and clockwise in a left-sided lesion [2]. Radiological imaging, with high resolution computed tomograms of the temporal bones, has a high sensitivity for the diagnosis of superior semicircular canal dehiscence but needs to be correlated with patient history, clinical examination and audiological and vestibular assessment to achieve a high specificity.The treatment is either conservative, with the avoidance of causative stimuli, or surgical, if the symptoms are uncontrollable. Surgical repair or resurfacing of the dehiscence area of bone is the recomm
Dehiscencia del canal semicircular superior: Estudio de la incidencia anatómica Dehiscence in the superior semicircular canal: Anatomic incidence study  [cached]
Jaime Whyte O,Claudio Martínez M,Ana Cisneros G,Jesús Obón N
Revista de Otorrinolaringología y Cirugía de Cabeza y Cuello , 2011,
Abstract: Introducción: La presencia de dehiscencia de canal semicircular superior presenta una notable diferencia entre la incidencia radiológica (del 1% al 19%) y la anatómica (entre 0,4% y 0,6%). Objetivo: El objetivo del trabajo es determinar la incidencia anatómica de la dehiscencia del canal semicircular superior y compararla con la incidencia radiológica. Material y método: Se estudia la incidencia de dehiscencia de canal semicircular superior en 80 cráneos (160 temporales). Resultados: Hemos observado la presencia de una dehiscencia del canal semicircular superior en un cráneo de los 80 estudiados, lo que representó una incidencia del 0,6%. Se discute las posibles causas porque la prevalencia de los estudios radiológicos es marcadamente superior a la de los estudios anatómicos. Conclusión: Es evidente que se realiza un "sobrediagnóstico" de dehiscencias del canal semicircular superior ya que los hallazgos anatómicos están muy lejos de los resultados obtenidos con técnicas de imagen. Introduction: The presence of dehiscence in the superior semicircular canal shows a remarkable difference between radiological (from 1%% to 19%%) and anatomical incidence (between 0,4% and 0,6%) Aim: To determine the incidence anatomical superior semicircular canal dehiscence. Material and method: The incidence of dehiscence in superior semicircular canal in 80 skulls (160 temporal bones) is studied. Results: We have observed the presence of one dehiscence in the superior semicircular canal in one skull from the 80 studied, representing an incidence of 0.6%. The possible causes are discussed because of the prevalence of the radiological studies is highly superior to anatomical studies. Conclusion: It is obvious the over-diagnosis performed about the dehiscences in the superior semicircular canal since anatomical finds are quite different from the results obtained by means of image technics.
Superior semicircular canal dehiscence in East Asian women with osteoporosis  [cached]
Yu Alexander,Teich Douglas L,Moonis Gul,Wong Eric T
BMC Ear, Nose and Throat Disorders , 2012, DOI: 10.1186/1472-6815-12-8
Abstract: Background Superior semicircular canal dehiscence (SSCD) may cause Tullio phenomenon (sound-induced vertigo) or Hennebert sign (valsalva-induced vertigo) due to the absence of bone overlying the SSC. We document a case series of elderly East Asian women with atypical SSCD symptoms, radiologically confirmed dehiscence and concurrent osteoporosis. Methods A retrospective record review was performed on patients with dizziness, vertigo, and/or imbalance from a neurology clinic in a community health center serving the East Asian population in Boston. SSCD was confirmed by multi-detector, high-resolution CT of the temporal bone (with P schl and Stenvers reformations) and osteoporosis was documented by bone mineral density (BMD) scans. Results Of the 496 patients seen in the neurology clinic of a community health center from 2008 to 2010, 76 (17.3%) had symptoms of dizziness, vertigo, and/or imbalance. Five (6.6%) had confirmed SSCD by multi-detector, high-resolution CT of the temporal bone with longitudinal areas of dehiscence along the long axis of SSC, ranging from 0.4 to 3.0 mm, as seen on the P schl view. Two of the 5 patients experienced motion-induced vertigo, two fell due to disequilibrium, and one had chronic dizziness. None had a history of head trauma, otologic surgery, or active intracerebral disease. On neurological examination, two patients had inducible vertigo on Dix-Hallpike maneuver and none experienced cerebellar deficit, Tullio phenomenon, or Hennebert sign. All had documented osteoporosis or osteopenia by BMD scans. Three of them had definite osteoporosis, with T-scores < 2.5 in the axial spine, while another had osteopenia with a T-score of 2.3 in the left femur. Conclusions We describe an unusual presentation of SSCD without Tullio phenomenon or Hennebert sign in a population of elderly, East Asian women. There may be an association of SSCD and osteoporosis in this population. Further research is needed to determine the incidence and prevalence of this disorder, as well as the relationship of age, race, osteoporosis risk, and the development of SSCD.
Turning Semicircular Canal Function on Its Head: Dinosaurs and a Novel Vestibular Analysis  [PDF]
Justin A. Georgi, Justin S. Sipla, Catherine A. Forster
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0058517
Abstract: Previous investigations have correlated vestibular function to locomotion in vertebrates by scaling semicircular duct radius of curvature to body mass. However, this method fails to discriminate bipedal from quadrupedal non-avian dinosaurs. Because they exhibit a broad range of relative head sizes, we use dinosaurs to test the hypothesis that semicircular ducts scale more closely with head size. Comparing the area enclosed by each semicircular canal to estimated body mass and to two different measures of head size, skull length and estimated head mass, reveals significant patterns that corroborate a connection between physical parameters of the head and semicircular canal morphology. Head mass more strongly correlates with anterior semicircular canal size than does body mass and statistically separates bipedal from quadrupedal taxa, with bipeds exhibiting relatively larger canals. This morphologic dichotomy likely reflects adaptations of the vestibular system to stability demands associated with terrestrial locomotion on two, versus four, feet. This new method has implications for reinterpreting previous studies and informing future studies on the connection between locomotion type and vestibular function.
Superior canal dehiscence in a patient with three failed stapedectomy operations for otosclerosis: a case report
Martin Lehmann, J?rg Ebmeyer, Tahwinder Upile, Holger H Sudhoff
Journal of Medical Case Reports , 2011, DOI: 10.1186/1752-1947-5-47
Abstract: We present the case of a 48-year-old German Caucasian woman presenting with hearing loss on the left side and vertigo. She had undergone three previous stapedectomies for hearing improvement. Reformatted high-resolution computed tomographic scanning and the patient's history confirmed the diagnosis of concurrent canal dehiscence syndrome.Failure of hearing improvement after otosclerosis surgery may indicate an alternative underlying diagnosis which should be explored by further appropriate evaluation.Superior semicircular canal dehiscence is an abnormal exposure of the vestibular membranous labyrinth in the middle cranial fossa. Superior semicircular canal dehiscence syndrome (SCD) occurs when a loss of the bone normally covering the superior semicircular canal in the middle cranial fossa produces one or more of the following symptoms: conductive hearing loss, acute pressure- and sound-evoked vestibular symptoms and chronic dysequilibrium [1]. The correlation between these symptoms and bony dehiscence of the superior semicircular canal in the floor of the middle cranial fossa was first recognized and described by Minor [2].We present the case of a 48-year-old German Caucasian woman who presented with hearing loss on the left side and vertigo. The patient had a history of three previous stapedectomy operations carried out elsewhere to improve her hearing loss (Figure 1). The first operation was performed for the diagnosis of otosclerosis. The next two operations were performed to improve her persistent hearing loss and vertigo.After the third operation, the patient came to our unit with persistent amblyacousia as well as severe vertigo and headache. Pure tone audiometry showed a maximal conductive hearing loss. The patient located in her left ear the sound of a tuning fork pressed on the right ankle. This phenomenon suggested SCD. Further high-resolution computed tomographic (CT) scans and audiometery were performed. A CT scan revealed superior semicircular canal deh
Optimizing the vertebrate vestibular semicircular canal: could we balance any better?  [PDF]
Todd M. Squires
Physics , 2004, DOI: 10.1103/PhysRevLett.93.198106
Abstract: The fluid-filled semicircular canals (SCCs) of the vestibular system are used by all vertebrates to sense angular rotation. Despite masses spanning seven decades, all mammalian SCCs are nearly the same size. We propose that the SCC represents a sensory organ that evolution has `optimally designed'. Four geometric parameters are used to characterize the SCC, and `building materials' of given physical properties are assumed. Identifying physical and physiological constraints on SCC operation, we find that the most sensitive SCC has dimensions consistent with available data.
Dehiscencia del canal semicircular superior: Estudio de la incidencia anatómica
Whyte O,Jaime; Martínez M,Claudio; Cisneros G,Ana; Obón N,Jesús; Gracia-Tello,Borja; Crovetto D,Miguel ángel;
Revista de otorrinolaringología y cirugía de cabeza y cuello , 2011, DOI: 10.4067/S0718-48162011000100006
Abstract: introduction: the presence of dehiscence in the superior semicircular canal shows a remarkable difference between radiological (from 1%% to 19%%) and anatomical incidence (between 0,4% and 0,6%) aim: to determine the incidence anatomical superior semicircular canal dehiscence. material and method: the incidence of dehiscence in superior semicircular canal in 80 skulls (160 temporal bones) is studied. results: we have observed the presence of one dehiscence in the superior semicircular canal in one skull from the 80 studied, representing an incidence of 0.6%. the possible causes are discussed because of the prevalence of the radiological studies is highly superior to anatomical studies. conclusion: it is obvious the over-diagnosis performed about the dehiscences in the superior semicircular canal since anatomical finds are quite different from the results obtained by means of image technics.
Procedures for restoring vestibular disorders
Walther, Leif Erik
GMS Current Topics in Otorhinolaryngology, Head and Neck Surgery , 2005,
Abstract: This paper will discuss therapeutic possibilities for disorders of the vestibular organs and the neurons involved, which confront ENT clinicians in everyday practice. Treatment of such disorders can be tackled either symptomatically or causally. The possible strategies for restoring the body's vestibular sense, visual function and co-ordination include medication, as well as physical and surgical procedures. Prophylactic or preventive measures are possible in some disorders which involve vertigo (bilateral vestibulopathy, kinetosis, height vertigo, vestibular disorders when diving (Tables 1 and 2). Glucocorticoid and training therapy encourage the compensation of unilateral vestibular loss. In the case of a bilateral vestibular loss, it is important to treat the underlying disease (e.g. Cogan's disease). Although balance training does improve the patient's sense of balance, it will not restore it completely.In the case of Meniere's disease, there are a number of medications available to either treat bouts or to act as a prophylactic (e.g. dimenhydrinate or betahistine). In addition, there are non-ablative (sacculotomy) as well as ablative surgical procedures (e.g. labyrinthectomy, neurectomy of the vestibular nerve). In everyday practice, it has become common to proceed with low risk therapies initially. The physical treatment of mild postural vertigo can be carried out quickly and easily in outpatients (repositioning or liberatory maneuvers). In very rare cases it may be necessary to carry out a semicircular canal occlusion. Isolated disturbances of the otolith function or an involvement of the otolith can be found in roughly 50% of labyrinth disturbances. A specific surgical procedure to selectively block the otolith organs is currently being studied. When an external perilymph fistula involving loss of perilymph is suspected, an exploratory tympanotomy involving also the round and oval window niches must be carried out. A traumatic rupture of the round window membrane can, for example, also be caused by an implosive inner ear barotrauma during the decompression phase of diving. Dehiscence of the anterior semicircular canal, a relatively rare disorder, can be treated conservatively (avoiding stimuli which cause dizziness), by non-ablative resurfacing" or by plugging" the semicircular canal. A perilymph fistula can cause a Tullio-phenomenon resulting from a traumatic dislocation or hypermobility of the stapes, which can be surgically corrected. Vestibular disorders can also result from otosurgical therapy. When balance disorders persist following stap
Functional Implications of Ubiquitous Semicircular Canal Non-Orthogonality in Mammals  [PDF]
Jeri C. Berlin, E. Christopher Kirk, Timothy B. Rowe
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0079585
Abstract: The ‘canonical model’ of semicircular canal orientation in mammals assumes that 1) the three ipsilateral canals of an inner ear exist in orthogonal planes (i.e., orthogonality), 2) corresponding left and right canal pairs have equivalent angles (i.e., angle symmetry), and 3) contralateral synergistic canals occupy parallel planes (i.e., coplanarity). However, descriptions of vestibular anatomy that quantify semicircular canal orientation in single species often diverge substantially from this model. Data for primates further suggest that semicircular canal orthogonality varies predictably with the angular head velocities encountered in locomotion. These observations raise the possibility that orthogonality, symmetry, and coplanarity are misleading descriptors of semicircular canal orientation in mammals, and that deviations from these norms could have significant functional consequences. Here we critically assess the canonical model of semicircular canal orientation using high-resolution X-ray computed tomography scans of 39 mammal species. We find that substantial deviations from orthogonality, angle symmetry, and coplanarity are the rule for the mammals in our comparative sample. Furthermore, the degree to which the semicircular canals of a given species deviate from orthogonality is negatively correlated with estimated vestibular sensitivity. We conclude that the available comparative morphometric data do not support the canonical model and that its overemphasis as a heuristic generalization obscures a large amount of functionally relevant variation in semicircular canal orientation between species.
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