1/34. Pontine cryptococcoma in a nonimmunocompromised individual: MRI characteristics.The case of a pontine cryptococcoma in a nonimmunocompromised, previously healthy 16-year-old boy is presented. The patient had slowly progressive brainstem signs with right cranial nerves V, VII, and VIII palsies, and contralateral corticospinal and spinothalamic deficits. Magnetic resonance images (MRI) revealed, within the right pons, a 1-cm diameter round mass lesion, hypointense on T1-weighted images, hyperintense on T2-weighted images, and with rim enhancement after infusion of gadopentetate dimeglumine. This is the only report of the MRI findings in an isolated pontine cryptococcoma in an immunocompetent patient. Early recognition of this specific MRI pattern is essential, because complete recovery can be achieved with prompt antifungal treatment.- - - - - - - - - - ranking = 1keywords = brain (Clic here for more details about this article) |
2/34. Vestibular function in auditory neuropathy.Auditory neuropathy is characterized by mild-to-moderate pure-tone hearing loss, poor speech discrimination out of proportion with this loss, absent or abnormal auditory brainstem responses and normal outer hair cell function as measured by otoacoustic emissions and cochlear microphonics. We followed three patients in our clinic whom we classified as auditory neuropathy patients. These patients also complained of balance disorders and we report our auditory and vestibular system analyses of these patients. The data presented herein include results of audiometric tests (serial pure-tone audiometry and speech discrimination tests), otoacoustic emissions, auditory-evoked brainstem responses and vestibular function tests (clinical tests of balance, electronystagmography, damped rotation tests and vestibular-evoked myogenic potentials). In all patients, pure-tone audiometry revealed mild-to-moderate sensorineural hearing loss, markedly poor speech discrimination scores and absent auditory-evoked brainstem responses, all in the presence of normal otoacoustic emissions. Balance tests (caloric tests and damped rotation test) were abnormal. saccades, smooth pursuit eye movements and optokinetic nystagmus were normal in all patients. Neurological and motor system evaluations were normal in all patients. These three auditory neuropathy patients manifest a disorder of cochlear nerve function in the presence of normal outer hair cell activity. They additionally manifest a disorder of the vestibular nerve and its end organs. We conclude that, in patients with isolated auditory neuropathy, the vestibular branch of the VIIIth cranial nerve and its innervated structures may also be affected. We suggest the use of the term "cochlear neuropathy" to characterize those patients with involvement of only the auditory branch of the VIIIth cranial nerve and its innervation.- - - - - - - - - - ranking = 3keywords = brain (Clic here for more details about this article) |
3/34. An isolated and sporadic auditory neuropathy (auditory nerve disease): report of five patients.Five patients of various ages with difficulty in speech discrimination were evaluated. All showed evidence of abnormal auditory brainstem responses (ABRs) beginning with the VIIIth cranial nerve. Broad summating potentials were evoked on their electrocochleograms (EcochGs) and they all exhibited almost normal cochlear outer hair cell function by otoacoustic emissions (OAEs) recordings. Behavioural audiometric testing revealed a mild to moderate elevation of pure-tone threshold in all patients. The shape of their pure-tone losses varied, being predominantly low-frequency in four patients (rising slope pattern) and flat across all frequencies in one patient. speech intelligibility scores of all patients were poor and out of proportion to what would have been expected if threshold elevation of pure-tone was of cochlear origin (i.e. markedly poor scores on the speech audiogram with good scores on the auditory comprehension test). patients were neurologically normal when the hearing impairment was first manifested. We suggest that this type of hearing impairment is due to an isolated and sporadic disorder of auditory nerve function. It occurs in isolation and does not seem to be part of a generalized neuropathological process.- - - - - - - - - - ranking = 1keywords = brain (Clic here for more details about this article) |
4/34. Hearing habilitation with auditory brainstem implantation in two children with cochlear nerve aplasia.patients with aplasia and hypoplasia of the cochlear nerve have no chance of having their hearing restored by stimulating the periphery of the auditory system using the traditional cochlear implant. A possible approach to auditory rehabilitation may be direct electrical stimulation of the cochlear nuclei with an auditory brainstem implant (ABI). Recently, two children, aged 4 and 3 years, respectively, with bilateral severe cochlear malformations and cochlear nerve aplasia received an ABI. The present paper reports the technique and the preliminary results of this experience. The classic retrosigmoid approach was used. The correct position of the electrodes was estimated with the aid of EABRs and neural response telemetry (NRT). No postoperative complications were observed. High-resolution CT scans with a bone algorithm reconstruction technique were taken postoperatively to evaluate electrode placement before discharge. The ABI was activated 30 days after implantation in both patients. To date 16 and 13 electrodes, respectively, have been activated in the two children. Three months after activation the first patient had achieved good environmental sound awareness, good speech detection and some speech discrimination. The second child, 1 month after activation, had achieved good environmental sound awareness and moderate speech detection. To the best of our knowledge this is the first report of patients with hypoplasia of the cochlea and aplasia of the cochlear nerve, aged below 5 years and treated with an ABI.- - - - - - - - - - ranking = 5keywords = brain (Clic here for more details about this article) |
5/34. Auditory neuropathy in children.Auditory neuropathy is a sensorineural disorder characterized by absent or abnormal auditory brainstem evoked potentials and normal cochlear outer hair cell function. A variety of processes is thought to be involved in its pathophysiology and their influence on hearing may be different. We present here the diagnostic sequence and management of two new cases of auditory neuropathy in breastfeeding children.- - - - - - - - - - ranking = 1keywords = brain (Clic here for more details about this article) |
6/34. Electrocochleography in auditory neuropathy.Auditory neuropathy (AN) is a disorder characterized by the absence or the severe impairment of the auditory brainstem responses (ABRs) together with the preservation of otoacoustic emissions and/or cochlear microphonic (CM). We recorded transtympanic electrocochleography (ECohG) evoked by 0.1 ms clicks in one young adult and in four children having distortion product otoacoustic emissions and absent ABRs. In all but one patient CM and summating potential (SP) were present with normal threshold, and their amplitudes appeared comparable to or higher than the values obtained from subjects with normal hearing. The compound action potential (CAP) was absent in two patients while in one subject CM and SP were followed by a highly desynchronized neural activity. A broad CAP was found in two children and the threshold appeared clearly elevated in one of them, while it showed only a mild elevation in the other. No correlation was found between CAP and behavioral thresholds. These results suggest that ECohG can be useful in AN diagnoses since it is the only reliable tool in evaluating the auditory peripheral function in the presence of a desynchronized ABR.- - - - - - - - - - ranking = 1keywords = brain (Clic here for more details about this article) |
7/34. osteoma of the internal auditory canal.Osteomas of the internal auditory canal, inaccesible to clinical examination, are rare lesions. There are only 14 cases of osteomas and exostoses of the internal auditory canal reported in the international medical literature. A patient with an osteoma of the internal auditory canal is presented, along with differential diagnosis and possible etiologic factors for the lesion. The auditory brainsteam evoked response testing showed increased absolute latencies of 1 wave and discrepancy of the wave morphology due to bony compression of the eight nerve in the internal auditory canal. Computed tomography showed a bony growth in the internal auditory canal. Magnetic response showed no abnormalities. No surgery was performed since the symptoms improved by conservative therapy.- - - - - - - - - - ranking = 1keywords = brain (Clic here for more details about this article) |
8/34. Screening and follow up assessment in three cases of auditory neuropathy.Three children with auditory neuropathy are described. Two were detected via a targeted neonatal hearing screening programme based on auditory brain stem response testing, and one via the routine health Visitor Distraction Test. Auditory neuropathy is an important but poorly understood disorder which has implications on planning future hearing screening policy and management of hearing impairment.- - - - - - - - - - ranking = 1keywords = brain (Clic here for more details about this article) |
9/34. cochlear implantation in patients with auditory neuropathy of varied etiologies.OBJECTIVES/HYPOTHESIS: Auditory neuropathy is a relatively recently described pattern of hearing loss characterized by preservation of outer hair cell function despite absent brainstem auditory evoked responses. Intact outer hair cell function is demonstrated by the presence of otoacoustic emissions and/or a measurable cochlear microphonic on electrocochleography, whereas no synchronous neural activity (absent action potentials) is seen on acoustically evoked brainstem auditory evoked response testing. The study reviews the authors' experience with six patients diagnosed with auditory neuropathy, four of whom have undergone cochlear implantation. MATERIALS AND methods: A retrospective review of all medical and audiological charts at the University of virginia hospitals (Charlottesville, VA) was performed to identify patients who have undergone cochlear implantation or have been diagnosed with auditory neuropathy, or both. RESULTS: Six patients with hearing loss attributable to auditory neuropathy were identified, four of whom have undergone cochlear implantation. Causes varied, including congenital, infectious, and idiopathic origins. Adults demonstrated subjective auditory perception on promontory stimulation, whereas no repeatable brainstem auditory evoked response waveforms could be demonstrated on pediatric promontory stimulation testing. patients with implants demonstrated implant-evoked brainstem auditory evoked responses and improved audiological performance. CONCLUSIONS: The six cases presented in the study represent varied causes and, probably, varied sites of lesions of auditory neuropathy. Promontory stimulation has been valuable, particularly in adults. cochlear implantation allows the opportunity to provide a supraphysiological electrical stimulation to the auditory nerve, with the hope of reintroducing synchronous neural activity. Greater confidence and enthusiasm for cochlear implantation in appropriately selected patients with auditory neuropathy are gained through experience with such diverse cases.- - - - - - - - - - ranking = 4keywords = brain (Clic here for more details about this article) |
10/34. Auditory neuropathy in friedreich ataxia. A report of two cases.friedreich ataxia (FA) is a hereditary neurodegenerative disease with autosomical recessive inheritance. The purpose of this paper is to present two cases of FA with auditory neuropathy, demonstrated by Otoacoustic emissions (OAE) and brainstem auditory evoked potentials (BAEP). The patients were two adolescent girls. Both patients underwent behavioral pure-tone audiometry, BAEP, OAE, motor nerve conduction measurement, and magnetic resonance image studies. Both girls showed at least five of nine clinical criteria for FA. They also showed abnormal BAEP and normal OAE indicating auditory neuropathy. One patient showed normal thresholds on behavioral pure-tone audiometry, whereas the other patient showed a mild sensorineural hearing loss. In one case there was absence of peripheral caloric vestibular response, and electronystagmographic abnormalities compatible with cerebellar dysfunction. Cochlear function as assessed by OAE had not been reported previously in cases of FA. We conclude that auditory neuropathy should be considered in patients diagnosed as FA. Furthermore, BAEP and OAE should be included in the diagnostic routine in these patients.- - - - - - - - - - ranking = 1keywords = brain (Clic here for more details about this article) |
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