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PubMedDate not supplied

Heat exchange in cryosurgery of Meniere's disease. Experimental and clinical studies.

The course of the temperature in the lateral semicircular canal and the heat exchange were measured on temporal-bone specimens when cooling with a cryoprobe on the lateral semicircular canal was performed. The measurements showed a correlation between the heat exchange, the cooling time and the temperature in the lateral semicircular canal. In 15 patients with unilateral Meniere's disease, this was utlized to achieve a controlled temperature course during cryosurgery on the lateral semicircular canal. The effect of the treatment on the attacks of vertigo and on the hearing in these patients is reported.

Cryosurgery↗
PubMed1999

[Diagnosis and therapeutic options in benign paroxysmal positional vertigo].

Benign paroxysmal positional vertigo (BPPV) is one of the most common and treatable causes of vertigo. We examined BPPV types and the effectiveness of physical therapy in each type. BPPV is caused by a utricular statoconium that blocks the semicircular canal. Statoconia can block any of the semicircular canals, but they generally affects the posterior canal. Diagnosis is based on a typical history and characteristic eye movements elicited by the Dix-Hallpike test. Treatment involves a physical maneuver designed to mobilize the free calcium particles from the semicircular canal to the utricle. Canalith repositioning is the mainstay of treatment. The maneuver is illustrated in detail and other forms of treatment and their indications are discussed.

Diagnosis, Differential↗
PubMed1999

Inertial processing of vestibulo-ocular signals.

New evidence for a central resolution of gravito-inertial signals has been recently obtained by analyzing the properties of the vestibulo-ocular reflex (VOR) in response to combined lateral translations and roll tilts of the head. It is found that the VOR generates robust compensatory horizontal eye movements independent of whether or not the interaural translatory acceleration component is canceled out by a gravitational acceleration component due to simultaneous roll-tilt. This response property of the VOR depends on functional semicircular canals, suggesting that the brain uses both otolith and semicircular canal signals to estimate head motion relative to inertial space. Vestibular information about dynamic head attitude relative to gravity is the basis for computing head (and body) angular velocity relative to inertial space. Available evidence suggests that the inertial vestibular system controls both head attitude and velocity with respect to a gravity-centered reference frame. The basic computational principles underlying the inertial processing of otolith and semicircular canal afferent signals are outlined.

Animals↗
PubMed2002

Patterns of canal and otolith afferent input convergence in frog second-order vestibular neurons.

Second-order vestibular neurons (2 degrees VN) were identified in the isolated frog brain by the presence of monosynaptic excitatory postsynaptic potentials (EPSPs) after separate electrical stimulation of individual vestibular nerve branches. Combinations of one macular and the three semicircular canal nerve branches or combinations of two macular nerve branches were stimulated separately in different sets of experiments. Monosynaptic EPSPs evoked from the utricle or from the lagena converged with monosynaptic EPSPs from one of the three semicircular canal organs in ~30% of 2 degrees VN. Utricular afferent signals converged predominantly with horizontal canal afferent signals (74%), and lagenar afferent signals converged with anterior vertical (63%) or posterior vertical (37%) but not with horizontal canal afferent signals. This convergence pattern correlates with the coactivation of particular combinations of canal and otolith organs during natural head movements. A convergence of afferent saccular and canal signals was restricted to very few 2 degrees VN (3%). In contrast to the considerable number of 2 degrees VN that received an afferent input from the utricle or the lagena as well as from one of the three canal nerves (~30%), smaller numbers of 2 degrees VN (14% of each type of 2 degrees otolith or 2 degrees canal neuron) received an afferent input from only one particular otolith organ or from only one particular semicircular canal organ. Even fewer 2 degrees VN received an afferent input from more than one semicircular canal or from more than one otolith nerve (~7% each). Among 2 degrees VN with afferent inputs from more than one otolith nerve, an afferent saccular nerve input was particularly rare (4-5%). The restricted convergence of afferent saccular inputs with other afferent otolith or canal inputs as well as the termination pattern of saccular afferent fibers are compatible with a substrate vibration sensitivity of this otolith organ in frog. The ascending and/or descending projections of identified 2 degrees VN were determined by the presence of antidromic spikes. 2 degrees VN mediating afferent utricular and/or semicircular canal nerve signals had ascending and/or descending axons. 2 degrees VN mediating afferent lagenar or saccular nerve signals had descending but no ascending axons. The latter result is consistent with the absence of short-latency macular signals on extraocular motoneurons during vertical linear acceleration. Comparison of data from frog and cat demonstrated the presence of a similar organization pattern of maculo- and canal-ocular reflexes in both species.

Animals↗
PubMed1998

Comparative review of the human bony labyrinth.

The bony labyrinth inside the petrous part of the temporal bone houses the organs of hearing and balance. Being functionally linked with sensory control of body movements and located in a part of the basicranium that is closely associated with the brain, this structure is of great interest in the study of human evolutionary history. However, few aspects of its morphology have been studied in nonhuman primates. This review compares the bony labyrinth of humans with that of the great apes and 37 other primate species based on data newly acquired with computed tomography combined with previous descriptions. With body mass taken into account, consistent differences are found between the size of the semicircular canals in humans, the great apes, and other primates. In particular, the arcs of the anterior and posterior canals are larger in humans than in the African apes. The functional implications of semicircular canal dimensions for registering angular head motion are evaluated in relation to locomotor behavior. Biophysical models, comparative studies, and some neurophysiological experiments all support a link between semicircular canal size and agility, or more specifically the frequency contents of natural head movements, but the evidence on the exact nature of this link is ambiguous. It is concluded that any link between the characteristic dimensions of the human canals and locomotion will be more complex than a simple association with the broad categories of quadrupedal vs. bipedal behavior. The functionally important planar orientations of the semicircular canals are similar in humans and the African apes as well as in many other species. In contrast, other aspects of the human labyrinth differ markedly in shape, following a pattern that seems to reflect the characteristic architecture of the human basicranium. Indeed, it is found that labyrinthine and basicranial shape are interspecifically correlated in the sample, and in most respects the human morphology is consistent with the general trend among primate species. Differences in brain growth and development are proposed as the predominant factor underlying both the unique shape of the human labyrinth as well as the interspecific labyrintho-basicranial correlations.

Anatomy, Comparative↗
PubMed1995

Three-dimensional (3-D) eye movement analysis in patients with positioning nystagmus.

Benign paroxysmal positioning vertigo (BPPV), and nystagmus (BPPN) is the commonest type of rotational vertigo. Typical BPPN is generally believed to arise from one posterior semicircular canal. If this is true, the syndrome would offer the unique possibility to study vestibular responses when just one single semicircular canal is excited. In this study we used search coils to measure 3-D eye positions in 3 patients with BPPN. We present a complete 3-D description of the eye movements induced in BPPN. We found that in our patients the eyes rotate rather precisely in the plane of one posterior semicircular canal, suggesting that BPPN in our cases is indeed solely produced by the posterior semicircular canal.

Adult↗
PubMed1995

Three-component analysis of benign paroxysmal positional nystagmus.

Three-component analysis of Benign Paroxysmal Positional Nystagmus (BPPN), focusing on the horizontal, vertical, and torsional, using a computerized eye movement analysis system, was carried out in 10 patients. Using a pendular rotation stimulus, we also measured three components of eye movement elicited from the vertical semicircular canals in normal subjects. We compared two components (vertical and torsional) of BPPN with that of eye movements elicited from the vertical semicircular canals. In BPPN, the torsional component of eye movements was larger than that of the vertical component. Conversely, the vertical component from the vertical semicircular canals was larger than that of the torsional component. From these results, by analysing the vestibulo-ocular reflex of the vertical semicircular canals, it is difficult to support the idea that the pathology of the BPPV is localized in the posterior semi-circular canal alone.

Electronic Data Processing↗
PubMed1996

Partial labyrinthectomy with hearing preservation: an experimental study in guinea pigs.

Recent advances in neurotologic surgery have challenged the traditional belief that violating the labyrinth is incompatible with hearing. Our aim in this study was to define the conditions that result in hearing preservation and hearing loss after surgery on the labyrinth. A guinea pig model was developed. Click-evoked auditory brain stem responses were used to determine hearing thresholds. Animals underwent surgical destruction of part or all of the vestibular labyrinth. Transection and plugging of the lateral semicircular canal resulted in normal hearing. Transection of multiple semicircular canals also resulted in hearing preservation. Intentional suctioning of perilymph from a transected canal led to transient hearing loss with complete recovery. Sequential destruction of the entire lateral semicircular canal resulted in preserved hearing as long as the vestibule was not opened. Wide vestibulotomy resulted in hearing loss. Preliminary histologic studies showed that cochlear hair cells were preserved in most cases. The results of our experiments demonstrate the feasibility of preservation of hearing after partial labyrinthectomy and provide physiologic criteria for developing new operations on the inner ear in human subjects.

Animals↗
PubMed1999

[The influence of dorsal neck proprioceptive inputs on vestibular compensation--by three-dimensional analysis of neck-induced nystagmus].

The influence of dorsal neck proprioceptive inputs on vestibular compensation was investigated in 21 patients with unilateral vestibular dysfunction. Subjects neither had history of spontaneous nystagmus nor of disequilibrium, indicating that they were in a good compensated stage. However, marked nystagmus was induced by applying vibratory stimulation to the dorsal neck of the patients, using a vibrator with a frequency of 110 Hz. The nystagmus was three-dimensional as analyzed by applying computerized eye movement analysis system. Twelve of 21 patients (57%) demonstrated three components of eye movement. All subjects showed a horizontal component directed towards the contralateral side of the vestibular lesion. Vertical and torsional components of the nystagmus were exhibited by 18 and 14 subjects, respectively. The average percentages of slow phase velocity of the horizontal, vertical and torsional components were 57%, 23% and 20%, respectively. No tendency towards any of the three components was observed. Furthermore, in order to investigate the relation between dorsal neck proprioceptive inputs and vestibular outputs, especially semicircular canal outputs, the author compared the direction of the nystagmus with the orientation of the semicircular canals. Normalized average velocity vectors of the nystagmus were calculated. In most subjects, the velocity vectors of the nystagmus were related to the horizontal semicircular canal. These results suggest that by controlling the neck proprioceptive inputs, neck vibration can cause discompensation in vestibularly well-compensated subjects with unilateral dysfunction secondary to vestibular lesion, and that neck proprioceptive inputs have a great influence on the horizontal vestibulo-ocular reflex pathways. However, in a few subjects the average vectors of the nystagmus were related to the vertical semicircular canals. This suggests that the proprioceptive inputs may also be related to the vertical vestibulo-ocular reflex pathways.

Adult↗
PubMed2003

Anterior canal failure: ocular torsion without perceptual tilt due to preserved otolith function.

A patient with anterior semicircular canal dehiscence syndrome underwent surgical patching that caused an isolated dysfunction of the left anterior semicircular canal postoperatively. He exhibited significant ocular torsion toward the side of the affected labyrinth (17 degrees excyclotropia of the ipsilateral eye), but no displacement of the subjective visual vertical. This dissociation suggests that an isolated ocular torsion may occur after an anterior semicircular canal lesion. A combined ocular torsion and subjective visual vertical tilt, which is usually seen with vestibular lesions, requires an associated otolith dysfunction.

Eye Diseases↗
PubMed1976

Menière's disease - roentgenologic diagnosis.

Radiologic diagnosis in Menière's disease should not be based on the vestibular aqueducts tomographic reproducibility. Instead, valuable preoperative information should be given about the size and location of the aqueducts external aperture in relation to the posterior and lateral semicircular canals. In saccotomy the semicircular canals are landmarks for identification of the endolymphatic sac. The periaqueductal pneumatization is demonstrated to be partly decisive for the vestibular aqueducts gross morphology. In Menière's disease either a sparse or a total lack of periaqueductal pneumatization is observed in most of all cases. The development of peri- and infralabyrinthine pneumatization is also decisive for the position of the foveate impression, which houses the extraosseous part of the endolymphatic sac. Its location and size can be evaluated by tomographic characterization of the vestibular aqueducts external aperture.

Humans↗
PubMed2003

Central projections of the vestibular nerve: a review and single fiber study in the Mongolian gerbil.

The primary purpose of this article is to review the anatomy of central projections of the vestibular nerve in amniotes. We also report primary data regarding the central projections of individual horseradish peroxidase (HRP)-filled afferents innervating the saccular macula, horizontal semicircular canal ampulla, and anterior semicircular canal ampulla of the gerbil. In total, 52 characterized primary vestibular afferent axons were intraaxonally injected with HRP and traced centrally to terminations. Lateral and anterior canal afferents projected most heavily to the medial and superior vestibular nuclei. Saccular afferents projected strongly to the spinal vestibular nucleus, weakly to other vestibular nuclei, to the interstitial nucleus of the eighth nerve, the cochlear nuclei, the external cuneate nucleus, and nucleus y. The current findings reinforce the preponderance of literature. The central distribution of vestibular afferents is not homogeneous. We review the distribution of primary afferent terminations described for a variety of mammalian and avian species. The tremendous overlap of the distributions of terminals from the specific vestibular nerve branches with one another and with other sensory inputs provides a rich environment for sensory integration.

Animals↗
PubMed1985

Site of lesion vestibular function testing.

The results of conventional electronystagmography (ENG) sometimes are confusing. The Hallpike alternate binaural bithermal (ABB) caloric test is helpful diagnostically except for the group of "sick patients that have a normal test." Conventional ENG tests also fall short in the area of objective confirmation of patient progress. What does each test tell us regarding site of lesion? 1. Alternate binaural bithermal stimulation gives us information about the semicircular canals -- particularly the horizontal semicircular canal -- pickup head. 2. Simultaneous binaural bithermal stimulation gives information brain stem connections -- switching and relay. 3. Rotation testing gives information about the processing by the brain -- central control.

Adult↗
PubMed1984

Harmonic acceleration as a measure of vestibular compensation.

The results of conventional electronystagmography (ENG) sometimes are confusing. The Hallpike alternate binaural bithermal (ABB) caloric test is helpful diagnostically except for the group of "sick patients that have a normal test". Conventional ENG tests also fall short in the area of objective confirmation of patient progress. What does each test tell us regarding site of lesion? Alternate binaural bithermal stimulation gives us information about the semicircular canals--particularly the horizontal semicircular canal--pickup head. Simultaneous binaural bithermal stimulation gives information about brain stem connections--switching and relay. Rotation testing gives information about the processing by the brain--central control.

Humans↗
PubMed2001

Mechanics of Coriolis stimulus and inducing factors of motion sickness.

To specify inducing factors of motion sickness comprised in Coriolis stimulus, or cross-coupled rotation, the sensation of rotation derived from the semicircular canal system during and after Coriolis stimulus under a variety of stimulus conditions, was estimated by an approach from mechanics with giving minimal hypotheses and simplifications on the semicircular canal system and the sensory nervous system. By solving an equation of motion of the endolymph during Coriolis stimulus, rotating angle of the endolymph was obtained, and the sensation of rotation derived from each semicircular canal was estimated. Then the sensation derived from the whole semicircular canal system was particularly considered in two cases of a single Coriolis stimulus and cyclic Coriolis stimuli. The magnitude and the direction of sensation of rotation were shown to depend on an angular velocity of body rotation and a rotating angle of head movement (amplitude of head oscillation when cyclic Coriolis stimuli) irrespective of initial angle (center angle) of the head relative to the vertical axis. The present mechanical analysis of Coriolis stimulus led a suggestion that the severity of nausea evoked by Coriolis stimulus is proportional to the effective value of the sensation of rotation caused by the Coriolis stimulus.

Acceleration↗
PubMed2002

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.

Electronystagmography↗
PubMed2004

A mesenchyme-free culture system to elucidate the mechanism of otic vesicle morphogenesis.

The vertebrate inner ear has been extensively studied as a model system of morphogenesis and differentiation. The interactions between epithelium and surrounding mesenchyme have not previously been studied directly, because an appropriate experimental system had not been established. Here we describe a mesenchyme-free culture system of E11.5 mouse otic vesicle which retains the ability for (1) formation of the cochlear loop, (2) emigration of ganglion cells from the epithelium and (3) invagination of semicircular canal epithelium. E10.5 otic vesicle was maintained using the same method, but morphogenesis was less successful. Culture of the E11.5 cochlear region alone resulted in regeneration of a structure with semicircular canal character from the cut end, indicating that region-specific cell fate within the otic vesicle is not irreversibly determined at this stage. Co-culturing otic vesicle with cochleovestibular ganglion (CVG) resulted in enhanced looping or ectopic diverticulum formation of the cochlear region, suggesting that the CVG provides a morphogenetic signal for cochlear looping. Cochlear looping was specifically blocked by inhibiting actin polymerization by cytochalasin D, while morphogenesis of the semicircular canal region remained intact. Hyaluronidase treatment inhibited semicircular canal morphogenesis, resulting in a cystic form of the otic vesicle. These data validate this culture system as a tool for elucidating the mechanism of morphogenesis of the otic vesicle.

Actins↗
PubMed2006

Resolving head rotation for human bipedalism.

Alignment of the body to the gravitational vertical is considered to be the key to human bipedalism. However, changes to the semicircular canals during human evolution suggest that the sense of head rotation that they provide is important for modern human bipedal locomotion. When walking, the canals signal a mix of head rotations associated with path turns, balance perturbations, and other body movements. It is uncertain how the brain uses this information. Here, we show dual roles for the semicircular canals in balance control and navigation control. We electrically evoke a head-fixed virtual rotation signal from semicircular canal nerves as subjects walk in the dark with their head held in different orientations. Depending on head orientation, we can either steer walking by "remote control" or produce balance disturbances. This shows that the brain resolves the canal signal according to head posture into Earth-referenced orthogonal components and uses rotations in vertical planes to control balance and rotations in the horizontal plane to navigate. Because the semicircular canals are concerned with movement rather than detecting vertical alignment, this result shows the importance of movement control and agility rather than precise vertical alignment of the body for human bipedalism.

Adult↗