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At least 1,081 records · Page 60Linked to original sources
PubMed1994

Particle repositioning maneuver for benign paroxysmal positional vertigo.

The recent demonstration of free-floating particles in the endolymph of the posterior semicircular canal in patients with benign paroxysmal positional vertigo (BPPV) has renewed interest in the physiology and treatment of this entity. The particle repositioning maneuver (PRM) relocates the free-floating particles from the posterior semicircular canal back into the utricle, relieving the patient of bothersome, often long-standing vertigo. This report represents a prospective study of 27 consecutive patients seen with a diagnosis of BPPV. Eighty-four percent of the patients treated with the particle repositioning maneuver who had no other associated pathology were cured or significantly improved with this new technique. Two patients who failed conservative management went on to surgical intervention with the posterior semicircular canal occlusion. The authors find the particle repositioning maneuver effective for many patients with benign positional vertigo and recommend it as the first-line treatment modality for BPPV.

Adult↗
PubMed1997

Postoperative radiographic assessment of the Combi 40 cochlear implant.

OBJECTIVE: The aims of this study were to establish a plain radiographic technique for the assessment of the postoperative appearance, position, and insertion depth of the Combi 40 cochlear implant and to correlate the radiologic findings with surgical reports. SUBJECTS AND METHODS: In an experimental study, an electrode of the Combi 40 device was inserted into the cochlea of a cadaveric skull. Digital radiographs were obtained in a modified Chausse III projection, in which the skull was placed supine on the radiography table with the infraorbitomeatal line strictly perpendicular to the film cassette. The skull was then rotated 30 degrees away from the side to be examined, and the central X-ray beam was angled 15 degrees cephalad to the infraorbitomeatal line. On these radiographs, the point of cochleostomy was marked by a needle tip and was projected inferior to the vestibule and on a line drawn through the superior semicircular canal and the vestibule. The appearance and position of the electrode was evaluated. An electrode was defined as completely inserted if all electrode contacts projected medial to the line drawn through the superior semicircular canal and the vestibule. We also studied cochlear implant insertion of the Combi 40 device in 37 patients. Postoperative digital radiographs of these patients were obtained and analyzed for the criteria as defined in the cadaveric study. In addition, the insertion depth of the electrode and the angle of insertion were measured on the radiographs. This depth was correlated with depth of insertion as estimated at surgery. RESULTS: The cadaveric study showed that the completely inserted electrode was seen on radiographs as a nonoverlapping spiral within the cochlea. All electrode contacts projected medial to the line drawn through the superior semicircular canal and the vestibule. In all 37 patients, the electrode could be seen without overlapping. According to our criteria, a completely inserted electrode was seen in 32 patients. In these patients, the insertion depth ranged from 21 to 34 mm and the angle of insertion ranged from 350 degrees to 810 degrees. In two patients, we saw a completely inserted electrode with a bend. In three patients, an incompletely inserted electrode was seen. Excellent correlation existed between the radiologic and surgical results with regard to insertion depth (r = .92). CONCLUSION: Digital radiographs obtained in the modified Chausse III projection allow clear depiction of the electrode and avoid overlapping. Such radiographs enable a reliable and accurate assessment of the position and insertion depth of the electrode of this new cochlear implant. Such images can serve as a baseline for further radiographic examinations when extrusion or slippage of the electrode is clinically suspected.

Adult↗
PubMed2004

Otolith and canal reflexes in human standing.

We used galvanic vestibular stimulation (GVS) to identify human balance reflexes of the semicircular canals and otolith organs. The experiment used a model of vestibular signals arising from GVS modulation of the net signal from vestibular afferents. With the head upright, the model predicts that the GVS-evoked canal signal indicates lateral head rotation while the otolith signal indicates lateral tilt or acceleration. Both signify body sway transverse to the head. With the head bent forward, the model predicts that the canal signal indicates body spin about a vertical axis but the otolith signal still signifies lateral body motion. Thus, we compared electromyograms (EMG) in the leg muscles and body sway evoked by GVS when subjects stood with the head upright or bent forward. With the head upright, GVS evoked a large sway in the direction of the anodal electrode. This response was abolished with the head bent forward leaving only small, oppositely directed, transient responses at the start and end of the stimulus. With the head upright, GVS evoked short-latency (60-70 ms), followed by medium-latency (120 ms) EMG responses, of opposite polarity. Bending the head forward abolished the medium-latency but preserved the short-latency response. This is compatible with GVS evoking separate otolithic and canal reflexes, indicating that balance is controlled by independent canal and otolith reflexes, probably through different pathways. We propose that the short-latency reflex and small transient sway are driven by the otolith organs and the medium-latency response and the large sway are driven by the semicircular canals.

Adult↗
PubMed2005

Effectiveness of treatment techniques in 923 cases of benign paroxysmal positional vertigo.

OBJECTIVE: To present treatment effectiveness of 923 consecutive cases of benign paroxysmal positional vertigo (BPPV) using canalith repositioning, liberatory, and log roll maneuvers combined with redistribution exercises. STUDY DESIGN: Retrospective case review. METHODS: Patients presented with either posterior semicircular canal (P-SCC) BPPV or horizontal semicircular canal (H-SCC) BPPV. Diagnosis was based on patient history of transient paroxysmal vertigo and a positive Dix-Hallpike response with either torsional or horizontal nystagmus. Patients with P-SCC BPPV numbered 840, and 83 patients had H-SCC BPPV. In the original study, there were 1,000 patients; however, 77 patients were dropped from the study because of lack of follow-through. Intervention was canalith repositioning, liberatory maneuvers, log roll maneuvers, and redistribution exercises. Patients numbering 607 were treated with canalith repositioning, 233 patients had liberatory maneuvers, and 83 received log roll maneuvers. All patients received redistribution exercises before treatment maneuvers. After intervention, patients were reassessed at 6 months. RESULTS: There were 601 women and 322 men from ages 12 to 94 (median 55) years. The average duration of symptoms before intervention was 30 months. Outcome measures were considered met when symptoms of BPPV had abated and patients demonstrated a negative Dix-Hallpike response. In the repositioning group, 94% of patients were symptom free or improved, 98% in the liberatory maneuver group and 100% in the log roll group. The average number of sessions was three for all groups. Recurrence of symptoms was demonstrated in 140 (16%) patients at 6 months. CONCLUSIONS: Treatment of BPPV can be effective using either repositioning, liberatory, or log roll maneuvers in combination with redistribution exercises.

Adolescent↗
PubMed1976

Temporal bone findings in Pierre Robin syndrome.

This is the first complete report on the histopathologic study of the temporal bones from an infant with a well-documented Pierre Robin syndrome (micrognathia, glossoptosis and cleft palate), demonstrating multiple middle and inner ear anomalies. The anomalies are basically architectural malformations rather than neutral or end organ developmental anomalies. The anomalies in this case, except for a few points, are somewhat similar in both ears. Multiple anomalies include: abnormal narrowing of the crus commune-utricle junction, superiorly located crus commune and posterior semicircular canal, underdeveloped modiolus, absence of the bony septum between the middle and apical coil (existence of scala communis in left ear), abnormally small internal auditory meatus, and abnormal direction of internal auditory canal, large cartilaginous mass around the superior semicircular canal and in the tympanic end of the fissula ante fenestram, small facial nerve, large facial bony canal dehiscence, anomalic stapes, etc.

Ear, Inner↗
PubMedDate not supplied

Vestibulo-ocular reflex in eccentric rotation in squirrel monkeys.

In addition to angular acceleration, eccentric rotation (ECR) imparts linear acceleration to the head positioned eccentric to the axis of rotation. Using ECR in squirrel monkeys, the effects of otolith organ stimulation by linear acceleration on vestibulo-ocular reflex (VOR) gain were investigated. With the animal's head facing away from the rotation axis, ECR significantly enhanced VOR gain over that seen in centric rotation (CR) at 1.0 Hz, but not at 0.5 Hz. However, no enhancement of VOR gain at 1.0 Hz was observed in eccentriclateral rotation when the animal faced tangentially. After bilateral ablation of the otolith organs (sacculectomy and utricular neurectomy), the ECR did not increase VOR gain, even at 1.0 Hz. In animals in which the lateral and posterior semicircular canals were plugged bilaterally, horizontal sinusoidal eye movements were induced by ECR at 1.0 Hz; no clear compensatory eye movement occurred during CR at 1.0 Hz. These findings demonstrate that during ECR, tangential acceleration along the interaural axis stimulates the utricular maculae, inducing horizontal eye movements in addition to those induced by the semicircular canal, thus resulting in an enhancement of VOR gain. Our results also suggest synergistic interactions of the otolith organs and semicircular canals. We conclude that ECR is a useful clinical test of the function of the otolith organs.

Animals↗
PubMed2003

The middle cranial fossa approach: an anatomical study.

Hearing preservation surgery has become an option for an increasing number of patients with vestibular schwannomas due to diagnosis at an earlier stage. The middle cranial fossa approach represents one such surgical approach for resection of vestibular schwannomas with hearing preservation. We have undertaken an anatomical study of the middle cranial fossa approach to the internal auditory meatus using 20 fresh temporal bones. By simulating the surgical approach it was possible to analyze critically two of the main recognized subapproaches to the internal acoustic meatus. The results confirmed that the angle subtended by the facial nerve and "blue-lined" semicircular canal was much less than 60 degrees but equally important was the degree of individual variability. Furthermore the roof of the geniculate fossa was not infrequently dehiscent. The distance measured from the inner table of the craniotomy to the superior semicircular canal was on average 22 mm, similar to previous reports and utilized by some in their approach in this challenging surgery. From this anatomical study it appears that safe dissection of this area is facilitated by observing the more acute angle between the facial nerve and superior semicircular canal and by taking advantage of the relationship between the inner table and important landmarks.

Cranial Fossa, Middle↗
PubMedDate not supplied

Does the endolymph pass through the base of the cupula?

Whether the endolymph of the semicircular canal passes the cupular partition or not was examined using the lateral semicircular canal system of adult pigeons (Columba livia). By applying various pressures by means of injection of a dye solution through the membranous canal, it was found that the dye solution, was seen to pass the cupula even under very low pressures when the pressure was increased gradually. When pulled by a magnet, the ultrafine particles of the dextran magnetite contained in the injected fluid were found to pass through the subcupular space without evident increase of the ampullary pressure.

Animals↗
PubMed2003

[Results in terms of hearing results after surgical closure of labyrinthine fistulas].

OBJECTIVES: We investigated the results achieved in terms of hearing in 36 patients who had each undergone resection of a cholesteatoma and closure of a labyrinthine fistula. PATIENTS AND METHODS: These patients included 28 who had a fistula of the semicircular canal, in 7 of them with an opened perilymphatic space. In 8 cases we found a fistula of the cochlea, with with a perilymphatic leak 7 in of them. We compared the sensorineural threshold before and after surgery and also the results in the two groups. Patients who were deaf preoperatively were excluded from further analysis. RESULTS: Hearing did not improve in any of the patients (n=5) who were deaf preoperatively. There was no significant difference in changes to the hearing threshold between patients with fistula of the cochlear and those with fistula of the semicircular canal with opened perilymphatic space; nor did patients with a fistula of the semicircular canal without perilymphatic leakage have a better outcome than patients with an open membranous labyrinth. CONCLUSIONS: The outcome of cholesteatoma resection and closure of the fistula in a single operation was good. Perilymphatic leakage seems to be predictive of a poorer result in terms of hearing.

Audiometry, Pure-Tone↗
PubMed1988

Sensory-to-motor transformations in the vestibular system.

The vestibulo-ocular reflex is a compensatory reflex that results in eye movements that are 180 degrees out of phase with movements of the head but that match head velocity. Because of these reflex eye movements that are equal, but opposite to head movement, the viewed object remains on the fovea of the retina during head movement, thus resulting in visual acuity that is not degraded by visual image slip on the retina. This reflex is compensatory over a large spectrum of head movements in any plane of space. This is accomplished by a spatial and temporal transformation of the input from the vestibular semicircular canals to the motoneurons that innervate the extraocular muscles. The reflex is a three-neuron arc. The middle leg of the reflex is accomplished by secondary vestibular neurons whose axons branch to innervate more than one extraocular muscle. These secondary neurons thus program an eye movement rather than the contraction of a single extraocular muscle. These programmed eye movements that match the plane of the particular semicircular canal that is the input to the reflex constitute the spatial transformation. Primary vestibular afferents innervating the semicircular canals have a broad range of response dynamics that either lead, lag or are in phase with head velocity. The predominant vestibular primary afferent input to the middle leg of the reflex, the same secondary neurons as mentioned above, is parcellated so that afferents more in phase with head velocity predominate.(ABSTRACT TRUNCATED AT 250 WORDS)

Head↗
PubMed1992

[Labyrinth fistula in chronic otitis with cholesteatoma].

The authors studied 116 surgically treated patients with labyrinthine fistulae due to cholesteatoma. The fistulae were most commonly localized on the lateral semicircular canal (75%) and much less frequently involved only the oval window area (7%) and the promontory (4%). The multiple fistulae were found in 14% patients. The closed technique was used, while the open technique was adopted only when the ear was deaf preoperatively, in cases of multiple fistulae and associated intracranial complications. The cholesteatoma matrix was not removed from the fistula of the oval window area or the promontory or in the cases of multiple fistulae and large fistulae of the lateral semicircular canal if the cholesteatoma matrix had penetrated into the labyrinth. The fistulae on the lateral semicircular canal were covered by a piece of fascia. Postoperatively deafness occurred only very exceptionally.

Adolescent↗
PubMedDate not supplied

Endolymphatic hydrops in perilymphatic fistula.

Cochlear hydrops was produced either by injecting artificial perilymph into the subarachnoid space or by sucking perilymph through the round window membrane. The animals were either vitally fixed immediately or kept alive for 1 to 3 months before fixation. Conventional celloidin embedding method was used for serial sectioning. Animals with cochlear hydrops were selected from among 56 guinea pigs; 13 animals were used for the present observation. The cochleas of these animals showed slight to moderate hydrops, while the vestibule and semicircular canals demonstrated either a normal or collapsed endolymphatic space. The pars superior does not develop hydrops. Changes in the saccular wall were not pronounced. One animal developed marked cochlear hydrops with atrophy of both Corti's organ and stria vascularis. The vestibule and semicircular canals showed marked collapse. The ductus reuniens and the saccule were completely obstructed. Marked cochlear hydrops was produced by blocking the longitudinal flow of endolymph. It is assumed that there may be cochlear hydrops in clinical cases of perilymphatic fistula, with various pathologies of the endolymphatic space of the vestibule and semicircular canals.

Animals↗
PubMed2005

Communication between the perilymphatic scalae and spiral ligament visualized by in vivo MRI.

We evaluated the transport of Gadolinium-diethylenetriaminepentaacetate-bismethylamide (Gd-DTPA-BMA) through the round window (RW) membrane into the perilymphatic space with 4.7-T MRI in an animal study and 1.5-T MRI in humans. After administration of Gd-DTPA-BMA onto the intact RW membrane of guinea pig, Gd-DTPA-BMA uptake was observed in the basal turn and part of the second turn within 40 min. The scala tympani, scala vestibuli, the fibrous part of the spiral ligament and semicircular canal all showed uptake of Gd-DTPA-BMA. All turns of the cochlea were filled with Gd within 10 min in the perforated RW membrane administration group and within 30 min in the intravenous administration group. In patients who accepted middle ear injection of Gd-DTPA-BMA, uptake was observed within 2 h in the basal turn and semicircular canal. After 12 h the apex did still not show any uptake. Gd-DTPA-BMA is transported from the RW to the semicircular canal, the scala tympani and scala vestibuli without passing the helicotrema.

Animals↗
PubMed2004

DAN directs endolymphatic sac and duct outgrowth in the avian inner ear.

Bone morphogenetic proteins (BMPs) are expressed in the developing vertebrate inner ear and participate in inner ear axial patterning and the development of its sensory epithelium. BMP antagonists, such as noggin, chordin, gremlin, cerberus, and DAN (differential screening-selected gene aberrative in neuroblastoma) inhibit BMP activity and establish morphogenetic gradients during the patterning of many developing tissues and organs. In this study, the role of the BMP antagonist DAN in inner ear development was investigated. DAN-expressing cell pellets were implanted into the otocyst and the periotic mesenchyme to determine the effects of exogenous DAN on otic development. Similar to the effects on the inner ear seen after exposure of otocysts to the BMP4 antagonist noggin, semicircular canals were truncated or eliminated based upon the site of pellet implantation. Unique to the DAN implantations, however, were effects on the developing endolymphatic duct and sac. In DAN-treated inner ears, endolymphatic ducts and sacs were merged with the crus or grew into the superior semicircular canal. Both the canal and endolymphatic duct and sac effects were rescued by joint implantation of BMP4-expressing cells. Electroporation of DAN antisense morpholinos into the epithelium of stage 15-17 otocysts, blocking DAN protein synthesis, resulted in enlarged endolymphatic ducts and sacs as well as smaller semicircular canals in some cases. Taken together, these data suggest a role for DAN both in helping to regulate BMP activity spatially and temporally and in patterning and partitioning of the medial otic tissue between the endolymphatic duct/sac and medially derived inner ear structures.

Animals↗
PubMed2005

[Histomorphological study of experimentally induced canalolithiasis].

Free otoconia in the posterior semicircular canal (pSCC) are regarded as the main reason for benign paroxysmal positional vertigo. We investigated the distribution of otoconia in the membranous labyrinth of guinea pigs (n = 34) after a defined rotatory/angular kinetic acceleration. The angular kinetic energy of the rotatory experiment produced a dislocation of the otoconia and sometimes of the complete gelatinous otolithic membrane of the utricular and saccular macula. The otoconia could be observed in all three semicircular canals but predominated in the dark cell areas of the utricular side of the lateral SCC. A total obstruction of the semicircular canal could never be seen. Close to the lateral crista, perilymphatic hemorrhage could frequently be observed. The saccular otoconia were located in the amalgamation between endolymphatic membrane and saccule. The results of this histological study can form the basis for different theories about the genesis of canalolithiasis and cupulolithiasis and the vertigo which accompanies them.

Acceleration↗
PubMed2000

[Vertical vestibuloocular reflexes in unilateral labyrinthine lesions (communication I)].

Vertical vestibuloocular reflexes (VVOR) were studied in 25 patients with unilateral labyrinthine lesions and in 22 healthy subjects. The technique of VVOR is based on stimulation of the internal semicircular canals of the labyrinth by active sagittal head subduction. Dysfunction of the vertical semicircular canals manifested with: VVOR asymmetry with stronger reflexes on the side of the labyrinth affection; predominance of upward VVOR; vertical components of the horizontal vestibuloocular reflexes were not so intensive as VVOR but had the same specific features.

Acute Disease↗
PubMed1991

Transport of heat in caloric vestibular stimulation. Conduction, convection or radiation?

Experiments in temporal bone specimens were carried out under strictly controlled conditions: temperature (37 degrees C) and humidity kept constant; standardized irrigation of the external ear canal by an automated system (in 15 s, 50 ml of water, 11 degrees C above temperature of specimen), thermistor probes of 0.2 mm diameter placed in different parts of the specimens. In the intact temporal bone such an irrigation causes a rise in temperature with a gradient from the external ear canal across the bony bridge to the lateral semicircular canal as expected with heat conduction. After removal of the bony bridge, which is the main route for heat conduction, the rise in temperature in the lateral semicircular canal is greater and faster than in the intact specimen. This effect again is drastically reduced by placing a reflecting shield between tympanic membrane and labyrinth. In the intact middle ear inserting a reflecting shield or filling the cavity with gel also reduces the heat transfer to the labyrinth, although the bony routes for heat conduction are left untouched. The experiments prove that radiation plays an important part in heat transfer in caloric stimulation.

Caloric Tests↗
PubMed1996

Update on posterior canal occlusion for benign paroxysmal positional vertigo.

Most, if not all, cases of BPPV appear to result from free-floating posterior semicircular canal endolymph particles. Particle repositioning alleviates symptoms and findings in the vast majority of patients. For the small intractable group of nonresponders, posterior semicircular canal occlusion remains a safe and highly efficacious procedure. This new technique has also paved the way for even newer and most invasive inner ear procedures.

Endolymph↗