An epidemiological study to investigate the relationship between Meniere's disease and migraine.

OBJECTIVES: A relationship between Meniere's disease and migraine has been postulated previously. This study investigates this relationship further and determines the most influential factors for developing Meniere's disease. DESIGN: Epidemiological study. SETTING: Two tertiary referral Neuro-Otological centres in Sheffield and Sydney. PARTICIPANTS: Adult patients referred to the Neuro-Otology clinic between 2003 and 2010. MAIN OUTCOME MEASURES: Past history and family history of Meniere's disease and migraine. Logistic regression analysis to determine the most influential factors for Meniere's disease. RESULTS: One hundred and eighty-one patients were included in the study, 102 with Meniere's disease and 79 with other balance disorders. Three significant findings were demonstrated. Firstly, a family history of Meniere's disease (33.3% versus 6.3%) or migraine (21.6% versus 9%) is more common in the Meniere's disease group than in the other balance disorders group. Secondly, a history of migrainous headaches is more common in the Meniere's disease group than in the other balance disorders group (45.1% versus 9%). Thirdly, patients with a past history or a family history of Meniere's disease or migraine have a higher likelihood of suffering from Meniere's disease. CONCLUSIONS: There is an overall relationship between Meniere's disease and migraine. A family history of Meniere's disease or migraine is more common in Meniere's disease. A history of migrainous headache is more common in Meniere's disease. Patients with a past history or family history of Meniere's disease or migraine have a higher likelihood of suffering from Meniere's disease.

Sensitivity of the cochlear nerve to acoustic and electrical stimulation months after a vestibular labyrinthectomy in guinea pigs.

Single-sided deafness patients are now being considered candidates to receive a cochlear implant. With this, many people who have undergone a unilateral vestibular labyrinthectomy for the treatment of chronic vertigo are now being considered for cochlear implantation. There is still some concern regarding the potential efficacy of cochlear implants in these patients, where factors such as cochlear fibrosis or nerve degeneration following unilateral vestibular labyrinthectomy may preclude their use. Here, we have performed a unilateral vestibular labyrinthectomy in normally hearing guinea pigs, and allowed them to recover for either 6 weeks, or 10 months, before assessing morphological and functional changes related to cochlear implantation. Light sheet fluorescence microscopy was used to assess gross morphology throughout the entire ear. Whole nerve responses to acoustic, vibrational, or electrical stimuli were used as functional measures. Mild cellular infiltration was observed at 6 weeks, and to a lesser extent at 10 months after labyrinthectomy. Following labyrinthectomy, cochlear sensitivity to high-frequency acoustic tone-bursts was reduced by 16 ± 4 dB, vestibular sensitivity was almost entirely abolished, and electrical sensitivity was only mildly reduced. These results support recent clinical findings that patients who have received a vestibular labyrinthectomy may still benefit from a cochlear implant.

Polarity order of biphasic square pulse electric current stimulation of human cochlear nerve: observations with transtympanic electrodes.

Eighteen totally deaf human cochleae were stimulated with biphasic square pulses of current through transtympanic needle electrodes. The thresholds of the 2 polarity orders, + - and - +, were compared for various pulse durations. For a pulse duration of 500 microseconds the polarity order - + had the lower threshold. For pulse durations of 2 ms and longer, the polarity order + - had the lower threshold. A discussion is given of the significance of the results for finding out the site of cochlear nerve excitation by the stimuli.

Meniere's disease: the incidence of hydrops in the contralateral asymptomatic ear.

OBJECTIVE: This study analyzes the incidence of endolymphatic hydrops in the asymptomatic contralateral ear of patients with classic Meniere's disease. STUDY DESIGN: A retrospective study of 3000 subjects who underwent electrocochleography (ECOG) from 1988 to 1998. METHODS: The presence of endolymphatic hydrops was determined by use of ECOG recordings, which were made through a transtympanic recording needle situated in the round window niche. Analysis was made of the 1-kHz toneburst summation potential (SP), and comparison was made between asymptomatic contralateral "Meniere's ears" (n = 144) and asymptomatic normal "control ears" (n = 114). RESULTS: Results demonstrated that more than 10% of the contralateral asymptomatic Meniere's ears have an ECOG recording that is highly suggestive of the presence of endolymphatic hydrops. In contrast, less than 2% of the control population demonstrate abnormal ECOG recordings. Furthermore, 15% of the population of contralateral Meniere's ears lie above the 95th percentile of the control population for 1-kHz tone-burst (100 dB) SP negativity. CONCLUSIONS: This study suggests that a high percentage of patients who have what appears to be unilateral Meniere's disease have evidence of endolymphatic hydrops in the contralateral asymptomatic ear. This finding has important clinical relevance for the management of patients in whom destructive surgery is planned and further highlights the importance of electrocochleography in the diagnosis and management of this disease process.

Diagnostic significance of transtympanic electrocochleography in Menière's disease.

Transtympanic electrocochleography (ECoG) was performed on 32 normal ears, 40 ears affected by hair cell damage without any evidence of endolymphatic hydrops (sensory damage) and 44 ears affected by established Menière's disease. The amplitude of the summating potential (SP) and the amplitude of the action potential (AP) were measured at a click stimulus intensity level of 100 dB HL. The SP amplitude was expressed as a percentage of the AP amplitude. In normal ears, the mean SP/AP ratio was 25% (range 10%-63%). In sensory damage, the SP/AP ratio was 13% (range 0%-29%), and in Menière's ears, the SP/AP ratio was 51% (range 29%-89%). In this series, an SP/AP ratio of 29% provided a diagnostic dividing mark between the sensory damage and Menière's-affected ears. Although this precise division was probably fortuitous, it does suggest that ECoG is a useful tool in the differential diagnosis of these two types of cochlear disorders.

Transtympanic electrocochleography in patients with syphilis and hearing loss.

Transtympanic electrocochleography was carried out on 18 syphilitic patients (30 ears were tested) most of whom were suffering from the late onset congenital form of the disease. A diphasic action potential with a large negative summating potential on the descending limb was found in 77.7% of ears; the cochlear microphonic potential was always of small amplitude. While these findings are not pathognomonic of syphilis, they are characteristic and may be explained on pathological grounds.

Pathophysiologic theories in the etiology of Meniere's disease.

The etiology of the attacks of vertigo that occur in Meniere's disease is discussed in this article. None of the current theories remain tenable in view of recent findings concerning the physiology and pathophysiology of the cochlea and endolymphatic sac. A new theory suggests that a narrowed duct becomes obstructed by debris that is cleared by a combination of the secretion of hydrophillic proteins within the sac and a hormone, saccin, that increases the volume of endolymph within the cochlea. It is proposed that the sudden restoration of longitudinal flow initiates the attacks of vertigo.

Electrocochleography in the diagnosis of Meniere's disease.

This study prospectively analyses electrocochleography (ECoG) recordings obtained from ears demonstrating symptoms highly suggestive of Meniere's disease. Comparison is made with ECoG recording from ears in which the diagnosis of Meniere's is considered unlikely (control ears). Electrocochleograph recordings were made through a transtympanic recording needle, situated in the round window niche. Analysis was made of the 1 kHz tone burst summation potential (SP) and the summation potential:action potential (SP/AP) ratio response to a 90 dB click. All patients were prospectively awarded a Meniere's score based on a 10-point scale, and comparison was made between ears awarded a score of 7 or greater (Meniere's ears; n > 500), and ears awarded a score 3 or less (control ears; n > 900). Results demonstrate a significant difference in the 1 kHz SP response, and the SP/AP ratio, between "control" and "Meniere's" ears. Furthermore, we show that SP negativity is proportional to the amplitude of the AP click response, and in patients producing an AP click amplitude exceeding 10 V, sensitivity of the tone burst test approaches 85%. This study provides further evidence suggesting the useful role of electrocochleography in determining a diagnosis of endolymphatic hydrops. and demonstrates improved sensitivity of the 1 kHz SP response, compared with SP/AP click ratio, in the diagnosis of Meniere's disease.

Racial considerations in acoustic neuroma removal with hearing preservation via the retrosigmoid approach.

Racial differences in the size, shape and structure of the cranium exist. This paper evaluates the importance of race in influencing the required sizes of craniotomies for gaining access to the lateral end of the internal auditory meatus without breaching the labyrinth via the retrosigmoid approach. Fine-cut CT scans of the temporal bones (axial cuts) of 34 Chinese and 34 Europeans were studied. The relevant distances and angles of the posterior cranial fossa and temporal bone were measured and statistically significant differences between the two races were found. This led us to the conclusion that a larger craniotomy is required in Europeans than in Chinese. In recommending an optimal size for a retrosigmoid craniotomy to remove acoustic neuromas completely and preserve hearing, the racial factor must be considered.

Transtympanic electrocochleography during glycerol dehydration.

Thirteen patients with Meniere's disorder were tested using transtympanic electrocochleography during glycerol dehydration. The most common finding was a decrease in the negative summating potential and this appeared to be a more sensitive indicator of changes occurring in the cochlea than pure tone audiometry and speech discrimination. A pathophysiological explanation for this observation is offered and the possibility of using this decrease in the negative summating potential as a pointer to the prognosis of endolymphatic sac surgery is discussed.

Surgical technique for inserting the cochlear multielectrode array into ears with total neo-ossification.

A method of inserting a multielectrode cochlear implant into a cochlea that has become totally ossified following meningitis is described. The method, called the inlay technique, involves drilling a cleft so that the electrode array can be inserted along the position of the basal coil. First, the technique involves drilling along the scala tympani. Second, by drilling out the scala vestibuli, space is created to follow the basal turn of the cochlea without removing the overlying promontory. Five children have had this surgery, and between 12 and 15 electrodes were inserted. Two of the children have developed some open-set listening ability, with open-set sentence recognition scores of over 10%. One child has obtained open-set listening scores of over 50%.

The effect of surgical removal of the extraosseous portion of the endolymphatic sac in patients suffering from Menière's disease.

Between April 1990 and June 1996, the extraosseous portion of endolymphatic sac has been removed from the affected ear in 77 patients suffering from Menière's disease. Removal of the extraosseous part of the endolymphatic sac without any drainage procedure did not increase the frequency or severity of the attacks of vertigo in any patient. The results of 43 patients with unilateral disease who had a follow-up period of two years are presented. Only eight of the patients had more than two recurrent attacks of vertigo lasting over two minutes within the two years after the surgery, and in three of these patients the severity of the attacks was greatly reduced. In 56 per cent of the operated ears, the hearing deteriorated at least 10 dBHL across five audiometric frequencies (250 Hz, 500 Hz, 1 kHz, 2 kHz and 3 kHz). To the author, endolymphatic sac removal appeared to provide better relief from vertigo than a simple drainage procedure with less tendency for recurrence several months or years after the initial surgery. At present, the statistical analysis of the results shows no significant difference between removal of the extraosseous portion of the endolymphatic sac and the "so called' endolymphatic sac drainage procedures.

Positioning of the receiver-stimulator for the CI-24M cochlear implant in infants.

A new cochlear implant (CI-24M) has recently been released by Cochlear Ltd. The shape and size of the receiver-stimulator differs from that of the CI-22M. Infants as young as one year of age are now receiving cochlear implants. We have examined the likely effect of skull growth following the implantation of a CI-24M cochlear implant in an infant of this age.

Further experience with a straight, vertical incision for placement of cochlear implants.

Experience with a straight, vertical incision for cochlear implantation in 168 patients of all ages is reported and comparison made with previous experience using a 'C' shaped incision in 173 patients with regard to complications encountered. With the straight incision the only complication was a wound infection which settled in one week; this is in contrast to the 'C' shaped incision, which was associated with a number of serious complications. The straight incision also compared favourably with the other incisions commonly used for cochlear implantation and appears to offer advantages over them.

Hearing loss associated with large internal auditory meatus: a report of five paediatric cases.

This paper describes the abnormality of a large internal auditory meatus (LIAM). Computed tomography (CT) scans show the otic capsule to be affected by a widened, bulbar internal auditory meatus with loss of or reduction of the bony wall dividing the lateral fundus of the meatus from the cochlea. The vestibule is abnormally dilated. We report five cases of children with LIAM and profound hearing loss. Three of these children are girls and two children were boys. Three had congenital progressive hearing loss, one of these had an accompanying large vestibular aqueduct and dysplasia of the cochlea. Two patients had had meningitis resulting in profound loss.

Immediate effects of intravenous tobramycin and gentamicin on human cochlear function.

Immediate electrocochleographic changes have been studied in a series of patients following intravenous infusion of either tobramycin or gentamicin. In patients receiving tobramycin, as soon as peak serum levels of antibiotic were reached, a dramatic decrease occurred in the magnitude of the compound VIII nerve action potential (AP), and of the cochlear microphonic (CM). The shape of the AP also changed. The N1 component of the waveform became very small, and N2 increased in size; this is the dissociated pattern of basal coil cochlear damage. The speed of onset of these electrical changes and their apparent reversibility suggests a temporary metabolic block caused by tobramycin. No such changes were observed following infusion of gentamicin.

A new incision for placement of cochlear implants.

A straight, vertical post-aural incision for the 'Cochlear' multichannel cochlear implant has been evaluated in 52 patients (20 adults and 32 children). Nineteen of the children were under three years of age and five of these were under two years of age. The 7 cm long incision is placed approximately 3 mm behind the post-auricular crease and runs from the tip of the mastoid to a point 3 cm above the superior attachment of the pinna. The incision heals within several days. Because the incision is straight interruption of the blood supply to the flaps raised is the least possible. This also minimizes the possibility of scalp necrosis and implant extrusion. The likelihood of infection is reduced by the small size of the incision, minimal soft tissue dissection and small amount of dead space. Rapid healing has occurred in all cases despite infection in one.

Surviving cochlear function in the presence of auditory nerve agenesis.

This case reports electrophysiological evidence for cochlear function in a child with radiological evidence of bilateral auditory nerve agenesis or severe hypoplasia. The diagnosis of auditory nerve agenesis was supported by a bilateral atresia of internal auditory canals on computed tomography (CT) scan and magnetic resonance imaging (MRI) absent auditory brainstem responses and absent behavioural responses to sound. Despite the apparent absence of an auditory nerve or spiral ganglion, electrocochleography revealed surviving cochlear function at 70-80 db HL and an abnormal electrocochleographic waveform. This case demonstrates that cochlear function may develop without afferent, or efferent innervation. It also emphasizes that cochlear function may occur in the presence of profound deafness.

Cochlear implant extrusion in a young child--a preventive procedure.

A Cochlear Mini System 22 Channel cochlear implant extruded through the skin of a young girl. The implant was saved by use of a transposition flap. Extrusion appeared to be due to pressure necrosis from the implant on the overlying tissues. It is believed that this problem can be prevented by angulation of the implant before insertion so that it conforms to the curvature of the skull, so avoiding pressure on the tissues. The method of angulation is described.

Anaesthesia of the tympanic membrane using iontophoresis.

Experience is described of the use of iontophoresis of 2% lignocaine to achieve effective tympanic membrane anaesthesia. The main uses are for outpatient myringotomy and transtympanic electrocochleography. Complete anaesthesia of the drum has been obtained in all cases, and those patients who had previously had these procedures carried out without anaesthetic, or with surface 'anaesthesia' only, all stated a marked preference for iontophoresis. No complications have occurred.