| The most common clinical presentations of dural arteriovenous fistulas (DAVFs) are bruit, headache, increased intracranial pressure, and intracranial hemorrhage. In particular locations, such as the cavernous sinus or middle cranial fossa, cranial nerve involvement due to dural arterial steal or venous occlusion may develop. A case in which a DAVF is associated with hearing loss, however, has not previously been reported. The authors report a case in which an intraosseous DAVF and associated hearing loss probably resulted from cochlear nerve or vascular compression caused by the draining vein or nidus of the DAVF. ( info) |
12/54. Central hearing loss with a bilateral inferior colliculus lesion. A case is presented of a 43-year-old man with bilateral lesions of the inferior colliculus (IC) due to central nervous system lymphoma. Our patient was found to have relatively normal pure-tone averages with severely reduced bilateral word recognition scores. This case illustrates that the presentation of a partial bilateral IC lesion may be of severely reduced word recognition accompanied by nearly normal pure-tone hearing. ( info) |
13/54. Cortical auditory disorder caused by bilateral strategic cerebral bleedings. Analysis of two cases. The authors present the anatomical and clinical features of cortical auditory dysfunction in two patients, in whom hypertensive bleedings destroyed the cortical auditory centres in both hemispheres. The second haemorrhage occurred four years after the first bleeding in both cases. The bleedings isolated the cortical hearing centres due to the destruction of the right and left temporal white matter. During the clinical course the symptomatology has changed in both patients: pure word deafness has transformed to cortical deafness and generalised auditory agnosia. Normal pattern of brain stem auditory evoked potentials suggested intact auditory pathways. Authors conclude that transformation of clinical forms of cortical auditory disorder can be explained by the tissue reaction to the subcortical bleeding in the cortical auditory centres. ( info) |
14/54. Postoperative hearing recovery in a case of delayed hearing loss after acoustic neurinoma removal. Delayed postoperative hearing loss after acoustic neurinoma removal is seldom observed. The presented case illustrates the phenomenon of delayed postoperative hearing loss which was observed 4 days after removal of a large acoustic neurinoma. Intraoperative brainstem auditory evoked potentials (BAEP) revealed a gradual loss of wave V with preservation of wave I. In animal experiments a dissociated loss of BAEP has been associated with impairment of microcirculation due to secondary edema. Vasoactive treatment was initiated and after 11 days a partial hearing recovery could be documented. Transient disturbance in microcirculation of vasa nervorum of the cochlear nerve is assumed to be responsible for postoperative hearing fluctuation. ( info) |
15/54. cochlear implantation in a Mandarin Chinese-speaking child with auditory neuropathy. Auditory neuropathy (AN) is a hearing disorder characterized by the preservation of outer hair cell function despite the absence of auditory brainstem responses. The pathophysiology and etiology of this condition remain unknown. Recent studies have shown that some patients with AN benefit significantly from cochlear implantation. These patients have all been native speakers of Western languages. A 3-year-old Mandarin-speaking boy was referred to our center because of speech delay. After a series of audiological surveys, retro-cochlear lesion was impressed. During the 2-year period of rehabilitation, poor speech discrimination out of proportion to aided hearing thresholds led to the diagnosis of auditory neuropathy. Because of the limited benefit from amplification, he received a cochlear implant. Significant improvement of speech perception skills assessed by a Mandarin auditory perception test was noted shortly after implantation. The post-implantation performance in this Mandarin-speaking child was consistent with that of reports for implantees speaking Western languages. For Mandarin-speaking children with AN who fail to benefit from conventional treatment, cochlear implantation may be a good alternative choice. ( info) |
16/54. Central deafness associated with a midbrain lesion. Central deafness has been linked historically to bihemispheric involvement of the temporal lobe, with more recent findings suggesting that compromise of other cortical and subcortical structures can also result in this disorder. The present investigation extends our understanding of the potential anatomical correlates to central deafness by demonstrating that bilateral involvement of an auditory structure within the midbrain can additionally result in this condition. Our subject was a 21-year-old male with a subarachnoid bleed affecting both inferior colliculi. Significant auditory deficits were noted for the middle and late auditory evoked potentials, while electrophysiologic measures of the periphery indicated normal function. The patient was enrolled in a rehabilitation program for approximately 14 weeks. Although initially unresponsive to sounds, the patient regained most of his auditory abilities during the 10 months he was followed. This case documents the range of auditory deficits that may be associated with damage to the inferior colliculi, and it profiles a hierarchical recovery of auditory function consistent with test findings. ( info) |
| The extent to which the auditory system, like the visual system, processes spatial stimulus characteristics such as location and motion in separate specialized neuronal modules or in one homogeneously distributed network is unresolved. Here we present a patient with a selective deficit for the perception and discrimination of auditory motion following resection of the right anterior temporal lobe and the right posterior superior temporal gyrus (STG). Analysis of stimulus identity and location within the auditory scene remained intact. In addition, intracranial auditory evoked potentials, recorded preoperatively, revealed motion-specific responses selectively over the resected right posterior STG, and electrical cortical stimulation of this region was experienced by the patient as incoming moving sounds. Collectively, these data present a patient with cortical motion deafness, providing evidence that cortical processing of auditory motion is performed in a specialized module within the posterior STG. ( info) |
18/54. Auditory neuropathy/auditory dys-synchrony detected by universal newborn hearing screening. The implementation of neonatal hearing screening has enabled early detection and intervention in hearing loss. The use of otoacoustic emissions (OAE) and auditory brainstem response testing in universal screening has led to the recognition of this recently described disorder called auditory neuropathy/auditory dys-synchrony (AN/AD). This diagnosis indicates that the infant has significant hearing loss despite having normal outer hair cells in the cochlea. We reviewed the characteristics and natural history of nine infants detected to have AN/AD from universal newborn hearing screening in a national pediatric hospital. Fifty-two cases of hearing loss were detected from 14,807 consecutively screened cases. Of the 52 cases, 9 had electrophysiological test results consistent with AN/AD. They include both premature infants who had major neonatal complications and term infants with no perinatal complications. Six cases had bilateral and three cases had unilateral findings. We suggest that AN/AD can occur in low-risk infants and hence screening of high-risk cases alone is insufficient. Our findings are discussed with reference to the current literature. ( info) |
19/54. 'So-called' cortical deafness. Clinical, neurophysiological and radiological observations. Two patients with severe, persistent hearing loss caused by bilateral cerebral lesions are described. To determine the location of lesions responsible for the severe hearing loss, we examined magnetic resonance images and compared the lesions in these 2 patients with those in another with only mild hearing loss following extensive bilateral temporoparietal lesions. The extent of bilateral damage to the white matter adjacent to the posterior half of the putamen proved crucial in determining the severity of the hearing loss. hearing loss was more severe when the white matter immediately ventral and lateral to the posterior half of the putamen was involved bilaterally. Based on this observation and from a review of the literature, we infer that the auditory radiations in humans course in a dense tract from the medial geniculate body up to the sublenticular region, and disperse from there to the primary auditory cortex as well as to the other auditory-related areas, partly by coursing through the white matter immediately ventral to the posterior half of the putamen, and partly by penetrating the ventral and lateral portions of the posterior half of the putamen. Accordingly, bilateral lesions in the white matter ventral and lateral to the posterior half of the putamen appear to interrupt all the projection fibres from the medial geniculate bodies to the auditory-related areas, resulting in severe, persistent hearing loss. ( info) |
20/54. The separability of central auditory and cognitive deficits: implications for the elderly. After viral encephalitis a 40-year-old man showed both central auditory deficit and severe cognitive deficits. The asymmetric central auditory deficit was revealed by speech audiometry. The effect could be explained neither by peripheral sensitivity loss nor by cognitive status. Results highlight the separability of central auditory and cognitive deficits. Implications for the elderly are discussed. ( info) |