11/54. Tympanic electrocochleography: normal and abnormal patterns of response. Electrocochleography has been widely used in human and animal studies of endolymphatic hydrops. A variety of response patterns have been reported in normal and hydropic ears. Recent clinical studies have focused almost exclusively on the amplitude ratio of the summating potential (SP) and action potential (AP) derived from alternating polarity click responses. In this report normal response patterns are described with a tympanic membrane electrode employing condensation, rarefaction and alternating polarity clicks and tone burst stimulation. A variety of response abnormalities are described in patients with suspected endolymphatic hydrops. The exclusive use of alternating polarity clicks is not adequate to reveal the nature of these abnormalities. ( info) |
12/54. A case of tympanogenic labyrinthitis complicated by acute otitis media. Widespread use of antimicrobial drugs in the management of otitis media has significantly reduced the incidence of labyrinthitis nowadays. Cases of tympanogenic labyrinthitis following acute otitis media have rarely been reported in recent literature on otolaryngology. We report an unusual case of tympanogenic labyrinthitis that presented with sudden sensorineural hearing loss (SNHL) following acute otitis media in an adult who had no previous otological complaints. An audiogram revealed SNHL with pure tone threshold of 43.7 dB in the left ear. MRI was helpful to identify the inflammatory change of the membranous labyrinth. The patient's hearing returned to normal after treatment. The definite diagnosis of serous labyrinthitis was established retrospectively. ( info) |
| A 9-year old boy with perinatal hiv infection developed meningitis due to nontypeable haemophilus influenzae. His course was complicated by progressive hearing loss due to labyrinthitis ossificans. Placement of cochlear implant improved hearing thresholds. Nontypeable H. influenzae meningitis and use of cochlear implants have not previously been in hiv-infected children. ( info) |
14/54. Early bilateral eighth nerve involvement in meningococcal meningitis. A male Navy recruit had hearing loss and bilateral otitis media. Meningeal signs, not initially present, developed approximately 48 hours after admission to the hospital. Type Y meningococcus was isolated from blood cultures drawn after two days of ampicillin administered orally. Permanent, bilateral, vestibular and auditory loss resulted, in spite of adequate doses of penicillin. This unusual presentation of bilateral eighth nerve involvement was thought to be due to a localized, bilateral meningococcal labyrinthitis. ( info) |
15/54. Multichannel cochlear implant and electrically evoked auditory brainstem responses in a child with labyrinthitis ossificans. Ossification of the cochlea following meningitis presents a surgical challenge. Electrode mapping, especially in the young child, is difficult given the uncertainty of electrode contact with viable neural elements. This paper reviews surgical technique and the use of auditory brainstem responses to map the electrodes. A 4-year-old child deafened by meningitis at age 20 months had bilateral cochlear ossification by computed tomography. At surgery, a canal wall-down mastoidectomy and closure of the ear canal were performed. A trough around the modiolus was drilled, and the electrode array was placed in it. Post-operatively, the patient gave aversive or no responses to electrode stimulation. To assess electrode function, auditory brainstem responses to individual electrode activation were obtained under general anesthesia. Functioning electrodes could thus be selected for mapping. The patient now responds well to sound. ( info) |
16/54. Contrast enhancement of the labyrinth on MR scans in patients with sudden hearing loss and vertigo: evidence of labyrinthine disease. The sudden onset of hearing loss and vertigo presents a difficult diagnostic problem. We describe the finding of labyrinthine enhancement on MR images in five patients with sudden unilateral hearing loss or vertigo or both and correlate the MR findings with audiologic and electronystagmographic studies. All patients were studied with T2-weighted axial images through the whole brain, contrast-enhanced 3-mm axial T1-weighted images through the temporal bone, and enhanced T1-weighted sagittal images through the whole brain. Cochlear enhancement, on the side of hearing loss only, was found in all five patients. The presence of associated vestibular enhancement correlates with objective measures of vestibular function on the electronystagmogram. In two patients, the resolution of symptoms 4-6 months later correlated with resolution of the enhancement on gadopentetate dimeglumine-enhanced MR images. Two patients had luetic labyrinthitis. No labyrinthine enhancement was seen in a series of 30 control subjects studied with gadopentetate dimeglumine-enhanced MR using the same protocol. Labyrinthine enhancement in patients with auditory and vestibular symptoms is a new finding and is indicative of labyrinthine disease. While abnormalities on electronystagmograms and audiograms are nonspecific and indicate only a sensorineural problem, gadopentetate dimeglumine-enhanced MR may separate patients with retrocochlear lesions, such as acoustic neuromas, from those in whom the abnormal process is in the labyrinth or is intraaxial. This group of patients underscores the importance of identifying and commenting on the structures of the membranous labyrinth when evaluating MR studies of the internal auditory canal and the cerebellopontine angle in individuals with hearing loss. ( info) |
| A premature male infant, who died 22 days after birth with hyaline membrane disease, was found to have had cytomegalic inclusion disease at autopsy. Histopathologic examination of the temporal bones showed cytomegalovirus (CMV) infection of the entire endolabyrinth without involvement of the neural and sensory structures. These findings support the thesis that late gestational or perinatal fetal CMV infection results in an endolymphatic labyrinthitis. We hypothesize that blood-borne virus passes from the stria vascularis into the endolymphatic spaces and infects the nonneurosensory epithelium. This pattern of infection differs from the perilabyrinthitis of human varicellazoster and experimentally produced mouse CMV. ( info) |
18/54. Delayed endolymphatic hydrops and its relationship to Meniere's disease. Delayed endolymphatic hydrops (EH) can be characterized as having ipsilateral and contralateral types. They are similar in that both have early and late phases of otologic symptoms and that the early phase is a profound hearing loss in one ear. The late phases differ, however, in that the ipsilateral type develops the symptoms of EH (episodic vertigo) in the deaf ear and the contralateral type develops the symptoms of EH (fluctuating hearing loss and/or episodic vertigo) in the hearing ear. In more than half the cases of both types of delayed EH, the profound hearing losses in the early phase are simply discovered to be present in early childhood without a known time of onset. The temporal bones of two patients with contralateral delayed EH show pathologic changes in the deaf ears that are similar to those known to occur in mumps and measles labyrinthitis, whereas the pathologic changes in the hearing ears are similar to those known to occur in Meniere's disease. These observations support the proposition that Meniere's disease may occur as a delayed sequela of inner ear damage sustained during an attack of subclinical viral labyrinthitis occurring in childhood. ( info) |
19/54. Idiopathic sudden sensorineural hearing loss and postnatal viral labyrinthitis: a statistical comparison of temporal bone findings. Although the cause of idiopathic sudden sensorineural hearing loss remains uncertain, a viral origin has been suggested in many cases on the basis of anamnestic microbiologic and pathologic data. Twenty-two temporal bone specimens from 18 patients who during life suffered a sudden partial or complete sensorineural hearing loss were studied. On the basis of clinical data, these cases were assigned to one of three diagnostic categories, and the temporal bones were studied by light microscopy and serial section analysis. The implications of the histopathologic findings for the pathogenesis of idiopathic sudden sensorineural hearing loss are discussed. ( info) |
20/54. Histopathology of sudden hearing loss. Eleven temporal bones from eight patients who had clinical histories of sudden hearing loss (SHL) were studied to assess the possible etiopathogenesis. The origin of SHL in seven ears from five patients was obscure, but appeared to be due to multiple causes. Common histopathologic changes in the cochlea, although complex, included atrophy of the organ of corti and loss of cochlear neurons. Loss of cochlear neurons was the main finding in ears of viral infection. Labyrinthine fibrosis and formation of new bone were seen in two ears associated with vascular insult and in two ears of autoimmune disease. Different histopathologic findings causing SHL were observed even in cases with the same etiology. A case of SHL showing endolymphatic hydrops as the main histopathologic finding is described. ( info) |