Cases reported "Labyrinth Diseases"

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1/87. Vestibular-evoked myogenic potentials in patients with dehiscence of the superior semicircular canal.

    Recently Minor and co-workers described patients with sound- and pressure-induced vertigo due to dehiscence of bone overlying the superior semicircular canal. Identifying patients with this "new" vestibular entity is important, not only because the symptoms can be very incapacitating, but also because they are surgically treatable. We present symptoms and findings for three such patients. On exposure to sounds, especially in the frequency range 0.5-1 kHz, they showed vertical/torsional eye movements analogous to a stimulation of the superior semicircular canal. They also showed abnormally large sound-induced vestibular-evoked myogenic potentials (VEMP), i.e. the short latency sternomastoid muscle response considered to be of saccular origin. The VEMP also had a low threshold, especially in the frequency range 0.5-1 kHz. However, in response to saccular stimulation by skull taps, i.e. when the middle ear route was bypassed, the VEMP were not enlarged. This suggests that the relation between the sound-induced and the skull tap-induced responses can differentiate a large but normal VEMP from an abnormally large response due to dehiscence of bone overlying the labyrinth, because only the latter would produce large sound-induced VEMP compared to those induced by skull taps.
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keywords = vertigo
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2/87. sound- and pressure-induced vertigo associated with dehiscence of the roof of the superior semicircular canal.

    In many types of peripheral vertigo, imaging is not part of the initial evaluation. We present a patient with sound- and pressure-induced vertigo associated with bony dehiscence of the roof of the superior semicircular canal. The diagnosis of this new entity can only be made by high-resolution coronal CT imaging of the temporal bones. In patients with this symptom complex, CT should be performed early in the diagnostic workup.
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keywords = vertigo
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3/87. Rotational vertebral artery occlusion syndrome with vertigo due to "labyrinthine excitation".

    Leftward head rotations in a patient with a rotational vertebral artery occlusion syndrome elicited recurrent uniform attacks of severe rotatory vertigo and tinnitus in the right ear. These attacks were accompanied by a mixed clockwise torsional downbeat nystagmus with a horizontal component toward the right. A transient ischemia of the right labyrinth probably induced the attacks and led to a combined transient excitation of the right anterior and horizontal semicircular canals as well as the cochlea.
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keywords = vertigo
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4/87. Clinical features of sudden hearing loss associated with a high signal in the labyrinth on unenhanced T1-weighted magnetic resonance imaging.

    We report on five patients with high signals in the labyrinth on unenhanced magnetic resonance imaging who developed sudden hearing loss and vertigo. Weissman et al. (1992) suggested the possibility that such high signals were caused by hemorrhage. We assessed these patients using audiograms, caloric tests, and auditory brainstem responses to investigate the possibility of inner ear hemorrhage. Most of the patients were found to have severe and irreversible impairment of both cochlear and vestibular function. These findings were consistent with the hypothesis that their symptoms were caused by inner ear hemorrhage.
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keywords = vertigo
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5/87. Traumatic perilymphatic fistulas in children: etiology, diagnosis and management.

    Post-traumatic perilymphatic fistulas have been described following ear and temporal bone injury, particularly in the setting of temporal bone fractures. However, indications for exploratory surgery in cases of trauma without temporal bone fracture are vague and not well described. We describe three children who presented with symptoms suggestive of perilymphatic fistula (PLF) without an associated temporal bone fracture: two with penetrating tympanic membrane injuries and one with blunt temporal bone trauma. All had symptoms of hearing loss and vestibular disturbance. Two of the children cooperated with ear-specific audiologic assessment, which demonstrated sensorineural hearing loss (SNHL) on the traumatized side. The third child showed audiometric evidence of a SNHL on the injured side, but due to his age, the degree of severity of the SNHL was unable to be appropriately addressed prior to the patient being surgically managed. All three children underwent exploratory surgery and were found to have bony defects in the region of the oval window. All were repaired with fascial grafts to the oval and round windows with complete resolution of vestibular symptoms. However, two of the three patients with documented post-operative audiograms suffered from persistent SNHL on the injured side. We conclude that exploratory middle ear surgery is indicated in patients suffering from blunt or penetrating temporal bone or middle ear trauma who demonstrate persistent vestibular symptoms, sensorineural hearing loss or radiographic evidence of oval window pathology. As this is a limited number of patients, a larger series may be warranted to study the actual incidence of post-traumatic PLF in the child with persistent hearing loss and vertigo after head or ear trauma.
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keywords = vertigo
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6/87. Vestibular-evoked myogenic potentials in the diagnosis of superior canal dehiscence syndrome.

    patients with superior canal dehiscence (SCD) syndrome have vertigo and oscillopsia induced by loud noises and by stimuli that result in changes in middle ear or intracranial pressure. We recorded vestibular-evoked myogenic potentials (VEMP responses) in 10 patients with SCD syndrome. The diagnosis had been confirmed in each case by evoked eye movements and by high-resolution CT scans of the temporal bones that showed a dehiscence overlying the affected superior canal. For the 8 patients without prior middle ear disease, the VEMP threshold from the dehiscent ears measured 72 /- 8 dB NHL (normal hearing level) whereas the threshold from normal control subjects was 96 /- 5 dB NHL (p < 0.0001). The VEMP threshold measured from the contralateral ear in patients with unilateral dehiscence was 98 /- 4 dB NHL (p > 0.9 with respect to normal controls). Two patients with apparent conductive hearing loss from middle ear disease, and SCD, had VEMP responses from the affected ears. In the absence of dehiscence, VEMP responses would not have been expected in the setting of conductive hearing loss. These findings confirm earlier studies demonstrating that patients with SCD syndrome have lowered VEMP thresholds. Conditions other than SCD syndrome may also lead to lowered VEMP thresholds. Rather than being based upon a single test, the diagnosis of SCD syndrome is best established when the characteristic symptoms, signs, VEMP response, and CT imaging all indicate SCD.
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keywords = vertigo
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7/87. Positional down beating nystagmus in 50 patients: cerebellar disorders and possible anterior semicircular canalithiasis.

    OBJECTIVES: To clarify the clinical significance of positional down beat nystagmus (pDBN). methods: A discussion of the neuro-otological findings in 50 consecutive patients with pDBN. RESULTS: In 38 patients there was evidence of CNS disease (central group) but in 12 there was not (idiopathic group). In the CNS group, presenting symptoms were gait, speech, and autonomic dysfunction whereas in the idiopathic group patients mostly reported positional vertigo. The main neurological and oculomotor signs in the CNS group were explained by cerebellar dysfunction, including 13 patients with multiple system atrophy. In patients with multiple system atrophy with a prominent extrapyramidal component, the presence of pDBN was helpful in the differential diagnosis of atypical parkinsonism. No patient with pDBN had the arnold-chiari malformation, a common cause of constant down beat nystagmus (DBN). In the idiopathic group, the pDBN had characteristics which suggested a peripheral labyrinthine disorder: vertigo, adaptation, and habituation. In six patients an additional torsional component was found (concurrently with the pDBN in three). Features unusual for peripheral disorder were: bilateral positive Dix-Hallpike manoeuvre in nine of 12 patients and selective provocation by the straight head-hanging manoeuvre in two. CONCLUSION: It is argued that some patients with idiopathic pDBN have benign paroxysmal positional vertigo (BPPV) with lithiasis of the anterior canal. The torsional component may be weak, because of the predominantly sagittal orientation of the anterior canal, and may not be readily seen clinically. Nystagmus provocation by bilateral Dix-Hallpike and straight head-hanging may be explained by the vertical upwards orientation of the ampullary segment of the anterior canal in the normal upright head position. Such orientation makes right-left specificity with the Dix-Hallpike manoeuvre less important than for posterior canal BPPV. This orientation requires a further downwards movement of the head, often achieved with the straight head-hanging position, to provoke migration of the canaliths. The straight head-hanging manoeuvre should be carried out in all patients with a history of positional vertigo and a negative Dix-Hallpike manoeuvre.
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ranking = 4
keywords = vertigo
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8/87. MR findings in intralabyrinthine schwannomas.

    AIM: Intralabyrinthine schwannomas (ILS) are rare benign tumours. They are not always recognized on routine magnetic resonance imaging (MRI). We aimed to study the clinical presentation and MRI findings in our patients with ILS. MATERIALS AND methods: Retrospective analysis of patients with vestibular schwannomas treated at this center. RESULTS: Of 144 vestibular schwannomas studied at this centre, three patients had an ILS. The most common presenting symptoms were unilateral hearing loss, tinnitus and vertigo. Two patients demonstrated a progressive sensorineural hearing loss (SNHL). The third patient had a severe SNHL at presentation. MRI enhanced with contrast medium was positive in the two patients with progressive SNHL and negative in the patient with the severe SNHL. CONCLUSION: This series demonstrates the ability of MRI to identify schwannomas filling the labyrinth, and also its inability to identify extremely small ILS. It underlines the importance of sending the cristae of patients undergoing labyrinthectomy for presumed Meniere's disease for histological examination.
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ranking = 1
keywords = vertigo
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9/87. Unexpected complication of posterior canal occlusion surgery for benign paroxysmal positional vertigo.

    OBJECTIVE: The purpose of this report was to illustrate how an unusual complication of posterior canal occlusion surgery for benign paroxysmal positional vertigo (BPPV) may be recognized and prevented. recurrence of BPPV after occlusion surgery of the posterior semicircular canal has not previously been reported in the literature, to the authors' knowledge. Failure of occlusion not only permits the continued symptoms of BPPV but also burdens the patient with the additional morbidity of a fistula of the PSCC. The authors describe the successful treatment of a patient with recurrent and incapacitating BPPV after the failure of occlusion surgery of the posterior semicircular canal, when the patient was simultaneously crippled by the distressing morbidity of an iatrogenic fistula. DESIGN: Case report. SETTING: Tertiary care referral center. INTERVENTION: Surgical excision of the fistulous segment of the membranous posterior semicircular canal. OUTCOME MEASURES: The BPPV was resolved. The distressing symptom of a fistula was eliminated. Hearing was preserved. CONCLUSION: Failure to completely occlude the posterior semicircular canal during posterior canal occlusion surgery results in recurrence of BPPV and an iatrogenic fistula, both of which are preventable. The occurrence of such an event is described, its management is outlined, and some thoughts are offered about its prevention.
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ranking = 5
keywords = vertigo
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10/87. Caloric-eye tracking pattern test: I. Visual suppression and the possibility of simplified differential diagnosis between peripheral and central vertigo.

    During the examination of patients who complain of vertigo or who have equilibrium disorders, it is often difficult to determine the etiology of the disorders, that is, to determine whether it is dependent on a peripheral or central vestibular disorder. To attempt to guess the etiology in these cases, we devised a new method: the caloric eye-tracking pattern test. In normal subjects and in patients with peripheral disorders, as is well known, caloric nystagmus has little influence on the eye-tracking pattern. In contrast, in patients with central vestibular disorders, caloric nystagmus evoked abnormalities on the eye-tracking pattern, either superimposed or saccades, in spite of the fact that the eye-tracking pattern before the caloric stimulation is normal. These findings result from the visual suppression mechanism to the vestibular nystagmus. We can say that the visual suppression to the vestibular nystagmus is evoked more strongly bu pursuing a moving visual stimulus than by gazing at a stationary target. These results are interesting, not only form the physiological view point, but also from the clinical view point. There is a possibility of the differential diagnosis between peripheral and central vertigo.
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ranking = 6
keywords = vertigo
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