ABSTRACT
Intratympanic (IT) steroid therapy is a mainstay treatment for sudden sensorineural hearing loss (SSNHL) for both initial therapy and salvage therapy. We report a rare case of iatrogenic perilymphatic fistula that resulted from trauma during an IT steroid injection for SSNHL. We discuss the diagnosis and treatment in the current case and compare it with previous reports from the literature. Laryngoscope, 131:2088-2090, 2021.
Subject(s)
Hearing Loss, Sensorineural/diagnosis , Hearing Loss, Sudden/drug therapy , Semicircular Canals/pathology , Steroids/adverse effects , Aged, 80 and over , Audiometry, Pure-Tone/methods , Female , Fistula/etiology , Humans , Iatrogenic Disease , Injection, Intratympanic , Perilymph , Salvage Therapy , Semicircular Canals/injuries , Stapes Surgery/adverse effects , Steroids/administration & dosage , Steroids/therapeutic use , Treatment Outcome , Vertigo/diagnosis , Vertigo/etiology , Vestibular Diseases/complicationsABSTRACT
Objective:To evaluate the frequency characteristics of semicircular canal injury in patients with vestibular neuritis. Method:Fifty-three patients with vestibular neuritis were respectively evaluated by caloric test(CT)ï¼head shaking test(HST),video head impulse test (vHIT),which reflects semicircular canal function in the low, middle, high frequency region. The asymmetric value of CT unilateral semicircular canal reaction (UW), head shaking nystagmus induced by HST, gain value of VHIT (VHIT-G) and presence or absence of saccade (VHIT-S) were used as observation indicators. The data were analyzed by SPSS 17.0 statistical software.The characteristics of the results of the three tests in patients with vestibular neuritis was analyzed and the functional status of the high, middle and low frequency regions of the semicircular canal was evaluated. Result:The positive rates of CT, HST, VHIT-G and VHIT-S in 53 patients with vestibular neuritis were 94.3%ï¼50/53ï¼,75.5%ï¼40/53ï¼,81.1%ï¼43/53ï¼,96.2%ï¼51/53ï¼,respectively. The positive rates of CT, HST, VHIT-G and VHIT-S were 92.9%ï¼26/28ï¼,89.3%ï¼25/28ï¼,92.9%ï¼26/28ï¼,96.4%ï¼27/28ï¼in 28 cases with disease course ≤ 7 days, and the positive rates in 25 patients with disease course >7 days were 96.0%ï¼24/25ï¼,60.0%ï¼15/25ï¼,68.0%ï¼17/25ï¼,96.0%ï¼24/25ï¼,respectively. Compared with the positive rate of each index, CT and VHIT-G (Pî=0.076), HST and VHIT-G (P=0.480) had no statistical significance. The difference between CT and HST (P=0.015), VHIT-G and VHIT-S(P=0.032) was statistically significant. The positive rates of CT, HST, VHIT-G and VHIT-saccade in patients with course of disease ≤7 days were compared, and there was no significant difference. In patients with disease course >7 days, except HST and VHIT-G, there were statistical differences in other indexes. The correlation test between VHIT-G and VHIT-Sï¼r=-0.437, P=0.006. Conclusion:The vestibular injury in patients with vestibular neuritis showed in a manner of full frequency injury. The multi-frequency detection technique is helpful for the clinical diagnosis of vestibular neuritis, and also can reflect the compensation and recovery of vestibular function.
Subject(s)
Semicircular Canals , Vestibular Neuronitis , Caloric Tests , Head Impulse Test , Humans , Semicircular Canals/injuries , Vertigo , Vestibular Neuronitis/complicationsABSTRACT
The rate of hearing preservation after vestibular schwannoma surgery is variable and is not as high as expected, possibly due to injuries to the posterior semicircular canal while exposing the tumor. The aim of this study was to estimate the risk of posterior semicircular canal injuries using temporal bone computed tomography (CT) scan findings. Temporal bone CT scans of 30 patients selected between 2013 and 2015 were studied. The median age of the patients was 40 years. Two planes were studied: (1) the axial plane that shows the common crus of the posterior semicircular canal and (2) the coronal plane that shows the two crura of the posterior semicircular canal. Five lines were drawn and four angles and three distances were measured. In this study, we divided the patients into three groups consisting of 10 patients each: (1) patients with no evidence of inflammatory or neoplastic disease, (2) those with chronic ear disease, and (3) those with vestibular schwannomas. The portion of the internal auditory canal that was exposed by drilling while preserving the posterior semicircular canal was 53 to 64% and 61 ± 9% in whole temporal bones in the three groups. The mean angle of vision with an endoscope was less than 105° in 56% of cases, which means even with a 30° endoscope, the fundus could not be visualized. Therefore, according to our data, it seemed impossible to expose the whole length of the internal auditory canal from the porus to the fundus without causing injury to the posterior semicircular canal. However, the use of endoscopes may help to prevent injury.
Subject(s)
Endoscopy/adverse effects , Neuroma, Acoustic/surgery , Semicircular Canals/injuries , Semicircular Canals/surgery , Tomography, X-Ray Computed/methods , Adult , Endoscopy/methods , Female , Hearing Loss/etiology , Humans , Male , Postoperative Complications/etiology , Risk Assessment/methods , Semicircular Canals/diagnostic imaging , Temporal Bone/diagnostic imagingABSTRACT
Introducción: la dehiscencia del canal semicircular superior es una alteración del oído interno caracterizada por la ausencia parcial de la cobertura ósea de dicho canal. En condiciones normales, el oído interno solamente tiene dos ventanas: la oval y la redonda, ambas cerradas elásticamente; cuando hay una dehiscencia del canal semicircular superior, existe una tercera ventana en el laberinto, lo que cambia la fisiología del oído interno. Objetivo: describir el síndrome de dehiscencia del canal semicircular superior como forma de presentación de la vestibulopatía periférica. Método: consulta y discusión de la literatura médica. Conclusión: en la actualidad, a pesar de la resolución de los métodos de diagnóstico por imagen, existen discrepancias sobre la prevalencia real de dicho síndrome(AU)
Subject(s)
Humans , Audiometry , Ear, Inner , Semicircular Canals/injuriesABSTRACT
A 28-year-old female diver presented with dizziness and difficulty clearing her left ear whilst scuba diving. Her pure-tone audiometry and tympanometry were normal. Testing of Eustachian tube function revealed tubal stenosis. Video-oculography revealed a predominantly torsional nystagmus while the patient was in the lordotic position. Fistula signs were positive. High-resolution computed tomography (HRCT) of the temporal bone revealed a diagnosis of bilateral superior semicircular canal dehiscence (SCDS). Cervical vestibular-evoked myogenic potential (cVEMP) testing showed that the amplitude of the cVEMP measured from her left ear was larger than that from the right. In electronystagmography (ENG), nose-pinched Valsalva manoeuvres caused eye movements to be mainly directed counterclockwise with a vertical component. Tullio phenomenon was also positive for both ears. SCDS patients tend to be misdiagnosed and misunderstood; common misdiagnoses in these cases are alternobaric vertigo (AV), inner ear barotrauma, and inner-ear decompression sickness. It is difficult to diagnose vertigo attacks after scuba diving as SCDS; however, when the patient develops sound- and/or pressure-induced vertical-torsional nystagmus, HRCT should be conducted to confirm a diagnosis of SCDS.
Subject(s)
Barotrauma/diagnosis , Diving/adverse effects , Semicircular Canals/injuries , Adult , Barotrauma/complications , Diving/injuries , Electrophysiological Phenomena , Female , Humans , Nystagmus, Pathologic/diagnosis , Semicircular Canals/diagnostic imaging , Tomography, X-Ray Computed/methods , Valsalva Maneuver/physiology , Vestibular Evoked Myogenic Potentials/physiologyABSTRACT
Objective:The aim of this study is to retrospective analysis the clinic features of 118 cases of benign paroxysmal positional vertigo after trauma. Method:Analyzes clinic features of injury in 118 cases of benign paroxysmal positional vertigo after trauma, and classified and localized the craniocerebral trauma. The 118 cases were tested with different positioning tests in the sequence of Dix hallpike test and rolling test. Then, proper otolith manual reduction was given. Result:In 118 cases of BPPV after trauma including 35 cases of skull fracture, 6 cases of concussion, 17 cases of scalp hematoma, 28 cases of scalp laceration, 14 cases of mild brain contusion and 18 cases of head combined injury. The distributions of head injury were 57 at front temporal, 24 at top, 22 at occipital and 15 at maxillofacial region. The latency of BPPV after head injury varies from 1day to 1month. The incidence of 3-7 day after head injury was the highest, followed by 7-14 days, 0-3 days, and the lowest incidence rate of 14 day to 1 month. Canal type 118 BPPV patients after head injury accounting for up to 57.6% of the horizontal semicircular canal accounted for 33.1%, mixed 9.3%. Conclusion:The patients with front temporal trauma and skull fracture were prone to have BPPV. The peak incidence of BPPV was 3-14 days after head injury. The most common type of BPPV was PC BPPV, and the HC BPPV was the second type. A good curative effect can be manipulative reduction after trauma BPPV.î.
Subject(s)
Benign Paroxysmal Positional Vertigo/etiology , Wounds and Injuries/complications , Benign Paroxysmal Positional Vertigo/physiopathology , Humans , Otolithic Membrane/injuries , Retrospective Studies , Scalp , Semicircular Canals/injuriesABSTRACT
OBJECTIVE: A clinical description of post-traumatic benign paroxysmal positional vertigo (t-BPPV) in a large cohort is reported, sometimes caused by apparently insignificant minor head traumas. The aim of the study was to carefully assess the prevalence of t-BPPV and the main outcomes belonging to specific traumatic events. DESIGN: Retrospective analysis of medical records of t-BPPV cases among patients suffering from BPPV. STUDY SAMPLE: Among 3060 patients with a clinical diagnosis of BPPV, we reviewed 716 clinical cases in which a clear association to a traumatic event was present. RESULTS: A traumatic event was identified in 23.4% of total enrolled BPPV patients. Some minor head traumas could be more prone to determine BPPV in females. We confirmed that t-BPPV appeared significantly more difficult to treat than idiopathic form. Posterior canal t-BPPV cases required more treatment sessions before obtaining therapeutic success, while horizontal ones recovered at most after two repositioning maneuvers. CONCLUSION: Post-traumatic BPPV is considered one of the most common known etiologies. An accurate understanding of trauma mechanism, gender prevalence, and therapeutic success rates of each event, could be useful in adequately treating and planning follow-up examinations.
Subject(s)
Benign Paroxysmal Positional Vertigo/etiology , Craniocerebral Trauma/complications , Adult , Aged , Benign Paroxysmal Positional Vertigo/therapy , Female , Humans , Male , Middle Aged , Retrospective Studies , Semicircular Canals/injuries , Sex FactorsABSTRACT
Objetivos: Determinar si la existencia de un canal semicircular superior o posterior dehiscente se asocia con el adelgazamiento de la cubierta ósea en el resto de los canales verticales (superior o posterior). Métodos: Se estudia mediante tomografía computarizada y se compara estadísticamente el espesor de los canales semicirculares superiores y posteriores contralaterales a una dehiscencia. Resultados: Cuando un canal semicircular superior presentaba una dehiscencia, el canal contralateral mostraba un adelgazamiento significativo de su espesor con una media de 0,5mm (DE:0,3mm). No sucede lo mismo con los posteriores que no modifican su grosor de 2,1mm (DE: 1,2mm; p=0,49).Cuando un canal semicircular posterior presentaba dehiscencia no se observó adelgazamiento significativo en los canales semicirculares superiores 1mm (DE:0,4), ni en el posterior contralateral 1,3mm (DE:0,3). Conclusión: La existencia de una dehiscencia del canal semicircular superior se asocia al adelgazamiento del hueso del canal del lado contrario, pero no de los canales semicirculares posteriores. No ocurre lo mismo si la dehiscencia es del canal semicircular posterior, que no altera de manera significativa el espesor del canal del lado contralateral ni en los superiores (AU)
Objectives: Our objective was to determine if the existence of dehiscence in the superior or posterior semicircular canal was associated with the thinning of the bone roof in the rest of the vertical canals (superior or posterior). Methods: The thickness of the superior and posterior semicircular canals contralateral to a dehiscence was studied using computerized tomography and compared statistically. Results: When a superior semicircular canal had a dehiscence, the contralateral canal showed a significant mean decrease in its thickness of 0.5mm (SD: 0.3mm). This was not the case if the dehiscence was in the posterior semicircular canal, where the thickness of 2.1 mm remained unchanged (SD: 1.2mm; P=0.49).When a posterior semicircular canal showed dehiscence, no significant thinning was shown in the superior semicircular (1mm; SD: 0.4) or in the posterior contralateral (1.3mm; SD: 0.3) canals. Conclusion: The existence of a dehiscence in the superior semicircular canal is associated with bone thinning in the canal on the opposite side, but not with the posterior semicircular canal. In contrast, if the dehiscence is in the posterior semicircular canal, contralateral and superior canal thickness is not modified (AU)
Subject(s)
Humans , Semicircular Canals/injuries , Ear Ossicles/injuries , Ear Canal/anatomy & histologyABSTRACT
Posterior semicircular canal dehiscence is a rare otologic entity that presents with third window signs and symptoms. Petrous apex cholesteatoma, fibrous dysplasia, high riding jugular bulb, and eosinophilic granuloma have been reported to be associated with posterior semicircular canal dehiscence. Here we report a case of development of posterior semicircular canal dehiscence following an endolymphatic sac surgery for the first time.
Subject(s)
Endolymphatic Sac/surgery , Iatrogenic Disease , Meniere Disease/surgery , Middle Ear Ventilation/adverse effects , Semicircular Canals/injuries , Endolymphatic Sac/physiopathology , Follow-Up Studies , Humans , Male , Meniere Disease/diagnosis , Middle Aged , Middle Ear Ventilation/methods , Postoperative Complications/diagnostic imaging , Postoperative Complications/physiopathology , Semicircular Canals/pathology , Tomography, X-Ray Computed/methodsABSTRACT
OBJECTIVE: Determine if aging and menopause, known to be associated with bone resortion, also are associated with superior semicircular canal dehiscence. DESIGN: Observational study. SETTING: Study conducted in 3 tertiary Spanish hospitals. PATIENTS: Nonselected consecutive patients of all ages. INTERVENTIONS: Thin-section multi-detector row computed tomographic scan of the temporal bones. MAIN OUTCOME MEASURE: The minimum thickness of the bone covering the roof of the superior semicircular canal (SSC) measured in each temporal bone. The outcome was studied both as a continuous and as a dichotomous variable: thin (<0.6 mm) and normal (≥ 0.6 mm). RESULTS: Five hundred eighty-two ears of 312 patients were included in the study. Fifty-five percent of the sample were women. Patient's age ranged from 2 to 88 years. A 40-year age difference between ears was associated with a decreased thickness of bone covering the SSC of 0.10 mm, which is 10% of the average thickness of such bone. The thickness of the bone overlying the SSC of subjects younger than 45 years was an average of 1.14 mm (SD, 0.52 mm), whereas that of the subjects older than 45 years was equal to 1.02 mm (SD, 0.45 mm; p = 0.006). The percentage of ears with thin bone coverage of SSC was 7.1% in subjects younger than 45 years and 13.8% in those older than 45 years (p = 0.013). CONCLUSION: Our data support the hypothesis that there is a slight osteopenia of the roof of the superior semicircular canal associated with aging, and this effect seems to be more pronounced in menopausal women.
Subject(s)
Menopause , Semicircular Canals/pathology , Temporal Bone/pathology , Adolescent , Adult , Age Factors , Aged , Aged, 80 and over , Child , Child, Preschool , Female , Humans , Male , Middle Aged , Semicircular Canals/diagnostic imaging , Semicircular Canals/injuries , Temporal Bone/diagnostic imaging , Tomography, X-Ray Computed , Young AdultABSTRACT
The literature about bony defects in the semicircular canal system is highly inconsistent. Therefore, we analyzed a series of 700 high-resolution multislice CT examinations of the temporal bone for semicircular canal dehiscencies. An unselected group of ENT patients with different clinical symptoms and variable age was chosen. We found semicircular canal dehiscence in 9.6% of temporal bones, superior semicircular canal was affected mostly (8%), less common posterior semicircular canal (1.2%); only in 3 cases (0.4%), lateral semicircular canal showed dehiscence. In 60% of SSC dehiscence, we registered bilateral manifestation. The so-called "third mobile window" in semicircular canal dehiscence causes a great variety of clinical symptoms like vertigo, nystagmus, oscillopsies, hearing loss, tinnitus and autophonia. Comparison with anatomic studies shows that CT examination implies the risk of considerable overestimation; this fact emphasizes the important role of clinical and neurophysiological testing.
Subject(s)
Labyrinth Diseases/diagnostic imaging , Meniere Disease/diagnostic imaging , Multidetector Computed Tomography , Semicircular Canals/diagnostic imaging , Temporal Bone/diagnostic imaging , Adolescent , Adult , Aged , Aged, 80 and over , Child , Child, Preschool , Cholesteatoma, Middle Ear/complications , Cholesteatoma, Middle Ear/diagnostic imaging , Cholesteatoma, Middle Ear/epidemiology , Cross-Sectional Studies , Humans , Infant , Labyrinth Diseases/epidemiology , Labyrinthitis/complications , Labyrinthitis/diagnostic imaging , Labyrinthitis/epidemiology , Meniere Disease/epidemiology , Middle Aged , Risk Factors , Semicircular Canals/injuries , Temporal Bone/injuries , Young AdultABSTRACT
INTRODUCTION AND OBJECTIVE: The aetiology of the superior semicircular canal dehiscence is currently unknown. Our objective was to analyse and discuss different hypotheses about the origin of this pathology. METHODS: In this study performed on 295 temporal bones, one case of partial alteration of the bony roof in the right superior semicircular canal was described from the anatomical and radiological points of view, and compared with the temporal bone on the other side. RESULTS: Macroscopically, the superior semicircular canal shows deterioration in the bony roof, which consists exclusively of the inner or endosteal layer that separates the canal from the superior semicircular conduct. The Pöschl plane reconstruction showed a whole bony roof, but its thickness decreased from the canal curvature to the defect (from 0.6 to 0.3mm). CONCLUSION: The presence of partial defects in the bony roof of the superior semicircular canal with absence of the external and middle layers, besides its lesser thickness, makes the canal susceptible to suffering a second event. This could produce its fracture and a dehiscence.
Subject(s)
Semicircular Canals/abnormalities , Temporal Bone/abnormalities , Cephalometry , Child , Hearing Loss/etiology , Humans , Image Processing, Computer-Assisted , Male , Postural Balance , Semicircular Canals/anatomy & histology , Semicircular Canals/diagnostic imaging , Semicircular Canals/embryology , Semicircular Canals/injuries , Sensation Disorders/etiology , Temporal Bone/diagnostic imaging , Temporal Bone/embryology , Temporal Bone/injuries , Tomography, Spiral ComputedABSTRACT
Superior canal dehiscence syndrome is a recently described vestibular and hearing condition caused by an absence of bone over the arc of the superior semicircular canal. Patients with the condition present with a variety of perplexing symptoms including conductive hearing loss, hyperacusis, vertigo, autophony, and eye movement in response to sound. This article presents the case of a patient with the condition, discusses how it is distinct from other vestibular and hearing disorders, and describes how patients with this disorder can be diagnosed and treated.
Subject(s)
Hearing Loss, Sensorineural/etiology , Hyperacusis/etiology , Meniere Disease/etiology , Semicircular Canals/injuries , Bone Conduction , Diagnosis, Differential , Hearing Loss, Sensorineural/diagnosis , Humans , Hyperacusis/diagnosis , Male , Meniere Disease/diagnosis , Middle Aged , Semicircular Canals/pathology , SyndromeABSTRACT
The endolymphatic calcium concentration [Ca2+] is essential for acoustic transduction. This study investigated the changes in cochlear function caused by vestibular labyrinth destruction in the acute phase by measurement of the endocochlear potential and endolymphatic [Ca2+].Hartley guinea pigs underwent lateral semicircular canal transection with suctioning of the perilymph, ampullectomy, or destruction of the lateral part of the vestibule. The endocochlear potential and endolymphatic [Ca2+] showed mild change after lateral semicircular canal transection with suctioning or ampullectomy. However, the endocochlear potential decreased drastically and permanently, and the endolymphatic [Ca2+] elevated suddenly but finally normalized after vestibulotomy. Elevated endolymphatic [Ca2+] is important in the disturbance of the mechanism of cochlear function caused by vestibular labyrinth destruction.
Subject(s)
Calcium/metabolism , Cochlea/physiopathology , Endolymph/metabolism , Vestibule, Labyrinth/injuries , Animals , Guinea Pigs , Hair Cells, Ampulla/physiology , Male , Membrane Potentials , Perilymph , Semicircular Canals/injuries , Semicircular Canals/physiopathology , Time FactorsABSTRACT
OBJECTIVE: The objectives of this study were 1) to assess the influence of a cochlear implantation on peripheral vestibular receptor function in the inner ear in the implant and in the nonimplant side, and 2) to analyze a possible correlation with resulting vertigo symptoms. STUDY DESIGN: Prospective clinical study. SETTING: Cochlear implant center at tertiary referral hospital. SUBJECTS AND METHODS: A total of 32 patients, aged 15 to 83 years, undergoing cochlear implantation were assessed pre- and postoperatively for caloric horizontal semicircular canal response and vestibular-evoked myogenic potentials of the sacculus, and postoperatively for subjective vertigo symptoms. Patients with vertigo were compared with patients without symptoms with regard to the findings of the vestibular function tests. RESULTS: Cochlear implantation represents a significant risk factor for horizontal semicircular canal impairment (P < 0.001) and sacculus impairment (P = 0.047) in the implanted ear. In eight of 16 patients with preoperatively preserved caloric response, this response was decreased postoperatively. Before surgery, 14 of 30 patients had regular vestibular-evoked myogenic responses. Two months after implantation, six patients had a new loss and another six showed depression of sacculus function on vestibular-evoked myogenic potentials testing. The impaired vestibular function did not correlate with vertigo symptoms. Function on the contralateral side remains unaffected (P > 0.05). CONCLUSION: Cochlear implantation is a relevant risk factor for damage of peripheral vestibular receptor function. Therefore, preservation not only of residual hearing function but also of vestibular function should be aimed for, by using minimally invasive surgical techniques.
Subject(s)
Cochlear Implantation/adverse effects , Semicircular Canals/injuries , Adolescent , Adult , Aged , Aged, 80 and over , Evoked Potentials , Female , Hearing Loss, Sensorineural/surgery , Humans , Male , Middle Aged , Postoperative Complications/epidemiology , Prospective Studies , Saccule and Utricle/physiology , Vertigo/epidemiology , Vertigo/etiologyABSTRACT
OBJECTIVES/HYPOTHESIS: Iatrogenic semicircular canal (SC) transection during mastoidectomy for chronic otitis media often leads to profound hearing loss. AM-111, an apoptosis inhibitor, has been shown to mitigate hearing loss resulting from a variety of inner ear injuries. The goal of this study was to determine if round window application of AM-111 following SC transection in the presence of Pseudomonas aeruginosa otitis media (PA-OM) may reduce the associated hearing loss. STUDY DESIGN: Prospective, randomized, controlled study in an animal model. METHODS: PA-OM was induced bilaterally in 34 guinea pigs. After 3 days, both bullae were opened and the lateral SC of one ear was transected. AM-111 or vehicle was applied topically to the round window of the ear that had undergone SC transection. Hearing was assessed with auditory brainstem responses. RESULTS: The mean change in hearing thresholds was significantly less in transected ears treated with AM-111 than those receiving vehicle alone when testing with clicks (22.1 dB vs. 35.0 dB; P = .019) and at 4kHz (11.3 dB vs. 40.0 dB; P = .021). A similar trend was shown with 16 kHz tone pips (27.7 dB vs. 41.1 dB; P = .119). CONCLUSIONS: AM-111 prevents hearing loss from SC transection in the guinea pig model of PA-OM.
Subject(s)
Apoptosis/drug effects , Hearing Loss/prevention & control , Otitis Media/complications , Peptides/therapeutic use , Semicircular Canals/injuries , Administration, Topical , Animals , Guinea Pigs , Hearing Loss/etiology , Peptides/administration & dosage , Prospective Studies , Pseudomonas Infections/complications , Pseudomonas aeruginosa , Random AllocationABSTRACT
Spontaneous regeneration of vestibular and auditory receptors and their innervating afferents in birds, reptiles, and amphibians are well known. Here, we produced a complete vestibular receptor loss and epithelial denervation using an ototoxic agent (streptomycin), after which we quantitatively characterized the afferent innervation of the horizontal semicircular canals following completed regeneration. We found that calyx, dimorph, and bouton afferents all regenerate in a manner the recapitulates the epithelial topography of normal birds, but over a slow time course. Similar to previous findings in the vestibular otolith maculae, regeneration occurs according to a three-stage temporal sequence. Bouton afferents regenerate during the first month of regeneration, followed by calyceal-bearing afferents in the second and third months. Calyx afferents were the last to regenerate in the final stage of recovery after 3 mo. We also found that regenerated afferents exhibited terminal morphologies that are significantly smaller, less complex, and innervate fewer receptor cells over smaller epithelial areas than those that develop through normative morphogenesis. These structural fiber changes in afferent innervation correlate to alterations in gaze responses during regeneration, although the exact underlying mechanisms responsible for behavioral changes remain unknown. Plasticity in central vestibular neurons processing motion information seem to be required to explain the observed morphologic and response adaptations observed in regenerating vestibular systems.
Subject(s)
Nerve Regeneration/physiology , Neurons, Afferent/physiology , Neurons, Afferent/ultrastructure , Semicircular Canals/physiology , Analysis of Variance , Animals , Cell Count , Columbidae , Hair Cells, Vestibular/drug effects , Hair Cells, Vestibular/physiology , Hair Cells, Vestibular/ultrastructure , Microscopy, Electron, Scanning , Neuronal Plasticity/physiology , Neurons, Afferent/drug effects , Photomicrography , Semicircular Canals/injuries , Semicircular Canals/ultrastructure , Streptomycin , Time Factors , Vestibular Diseases/chemically inducedABSTRACT
The objective of this study was to assess the influence of a cochlear implant (CI) on horizontal semicircular canal (hSCC) function, to test the correlation with symptomatic vertigo and to identify possible risk factors for a postoperative vestibular impairment. In a prospective observational study design, forty-seven adult patients who had undergone cochlear implantation at Cochlear Implant Center at a tertiary referral university hospital, Munich, between 2003 and 2007, were studied. Postoperative vertigo symptoms were assessed using a questionnaire followed by a structured interview. Patients were subjected to caloric and rotational chair vestibular function tests pre- and postoperatively. The CI operation was performed with a retroauricular transmastoidal approach by three different surgeons. Thirty-six implants were Cochlear Nucleus 24 devices and 11 implants were MedEl devices. Twenty-one (45%) patients reported vertigo symptoms after CI. Functional testing of the hSCC yielded valid results in 45 of the 47 patients. Thirty-two percent of patients had a substantially reduced hSCC function after CI. Responses of caloric irrigation showed a significant worsening postoperatively in the CI ears. No direct correlation between a decrease in caloric response and risk of postoperative vertigo symptoms could be established. For the criteria age, sex, implant type, surgeon, cause of deafness, petrous bone CT findings and preoperative vertigo, there were no significant differences between the patients with and the patients without postoperative vertigo. Besides morphological changes, a cochlear implantation also causes functional damage of vestibular parts of the labyrinth. Our study showed a significant worsening of the caloric response. However, this alteration did not lead to vertigo complaints in all patients. It is therefore presumed that additional damage to sensory or visual afferents and central vestibular compensatory mechanisms play a role.
Subject(s)
Cochlear Implantation/methods , Cochlear Implants/adverse effects , Deafness/surgery , Semicircular Canals/injuries , Vertigo/etiology , Vestibular Diseases/etiology , Vestibule, Labyrinth/injuries , Adolescent , Adult , Aged , Caloric Tests , Deafness/etiology , Female , Humans , Interviews as Topic , Male , Middle Aged , Prospective Studies , Risk Factors , Surveys and Questionnaires , Vertigo/physiopathology , Vestibular Diseases/physiopathology , Vestibular Function TestsABSTRACT
HYPOTHESIS: Irrigation of the mastoid with a quinolone antibiotic-steroid solution may mitigate hearing loss caused by iatrogenic semicircular canal injury in the presence of Pseudomonas aeruginosa (PA) otitis media (OM). BACKGROUND: Studies have shown the cochlea to be more vulnerable to semicircular canal transection (SCT)-related hearing loss in the presence of PA OM. Prophylactic systemic antibiotics and steroids may decrease this hearing loss, but SCT is usually not planned. The aim of this study was to determine if irrigation with ciprofloxacin-dexamethasone (cipro-dex) could improve hearing outcomes following SCT in PA OM. METHODS: PA OM was induced in 28 animals. After three to five days, unilateral SCT was performed in each animal, with sham SCT on the contralateral ear. At surgery, half of the animals (n = 14) underwent irrigation of the both mastoid bullae with cipro-dex; the second group of animals (n = 14) underwent irrigation of the bullae with sterile saline. Auditory thresholds were obtained immediately prior to SCT and 7-10 days after SCT. RESULTS: SCT ears treated with cipro-dex showed a mean click threshold improvement of 4.6 dB from pre-transection to 7-10 days post-transection, whereas thresholds in the SCT ears treated with saline worsened by 7.5 dB (p = 0.15). CONCLUSION: Irrigation of the guinea pig bulla with cipro-dex following SCT in the setting of PA OM appears safe and may yield beneficial effects on hearing.
