[Maturation aspects of the auditory apparatus].
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Aging↗
Biomedical subjects
W Di Nardo
Publications and source records attributed to W Di Nardo.
Auditory brainstem and cochlear implants: functional results obtained after one year of rehabilitation.
Very little information has been published on the clinical outcome of auditory brainstem implants (ABI). The present paper evaluates results obtained in a patient affected by a bilateral acoustic neuroma in type II neurofibromatosis who received an implant during removal of the residual tumor. One year later surgical revision of the ABI was necessary because no auditory sensation was obtained after ABI activation. Twelve months after the surgical revision, 12 electrodes out of 15 evoked auditory sensation. The results of rehabilitation were compared with those obtained in a group of eight postlingually deaf patients with cochlear implants (CI). Twelve months postoperatively the CI patients identified 97.7 +/- 5.1% of bisyllabic words in a closed set while the ABI patient identified 86%. CI patients recognized 87.1 +/- 11.3% of sentences and 81.3 +/- 14.8% of words with contextual cues while the ABI patient recognized 75% and 65% respectively. Speech recognition improved more slowly in the ABI patient than in the CI patients and his scores for open-set words and sentences without lip reading and contextual cues were poorer. Although the results obtained in the ABI patient were not as good as those obtained in the CI patients, the ABI patient said his quality of life was improved.
Adult↗
SPET monitoring of auditory cortex activation by electric stimulation in a patient with auditory brainstem implant.
Auditory cortex activation following multifrequency acoustic stimulation has been evaluated by means of single photon emission tomography (SPET) in one patient before and after an auditory brainstem implant (ABI). No activation could be observed after acoustic stimulation before ABI. After ABI stimulation in the coronal and axial slices, the activation within the temporal cortex contralateral to the stimulated ear was twice (43.76%) that of normal controls (23.94 +/- 2.74%). This marked difference was not present in other selected cortical auditory areas (homolateral temporal, homolateral and contralateral parietal cortices). The temporal cortex was also examined with six consecutive sagittal slices from 18.75 mm up to 56.25 mm lateral to the midline. A very strong activation (51.20%) compared with that of normal controls (9.94 +/- 7.45%) was detected in the 25.26-mm sagittal slice of the temporal cortex contralateral to the stimulated side. The remaining sagittal slices showed an almost normal post-stimulatory activation. As the 25.26-mm sagittal slice corresponds to the medial part of the auditory temporal cortex, its activation suggests that electrode stimulation is concentrated on the region of the cochlear nucleus in which the neurons that transduce high frequencies are located. SPET can be considered useful, in combination with electric auditory-evoked potentials, to obtain information on ABI placement and function, effectiveness of acoustic stimulation, degree of cortical stimulation and tonotopic spatial distribution of auditory cortex activation.
Adult↗
The role of cholinergic transmission in outer hair cell functioning evaluated by distortion product otoacoustic emissions in myasthenic patients.
Outer hair cells (OHCs) are the source of otoacoustic emissions, following a tropomyosin-miosin-dependent contraction, which are regulated by the olivocochlear bundle via the release of acetylcholine (ACh). ACh acts on ACh receptors (AChR) located on the OHC post-synaptic membrane. In myasthenia gravis (M.G.) neuromuscular transmission is reduced due to the action of AChR autoantibodies. It has previously been shown that M.G. induces a reduction in transient evoked otoacoustic emissions (TEOAEs), which is reversed after administration of a cholinesterase (AChE) inhibitor. Distortion product otoacoustic emissions (DPOAEs) were recorded before and 60 min after oral administration of 60 mg pyridostigmine bromide in 25 patients with normal hearing affected by M.G. The results were compared with those from 25 age-matched normal controls. Mean values of DPOAE amplitude in myasthenic patients were significantly (p < 0.05) lower at all frequencies before drug administration. All patients showed an overall significant (p < 0.05) increase in DPOAE amplitude after drug administration, although without reaching the control values. Such a recovery was more evident and highly significant (p < 0.01) for middle and high frequencies and could be explained by a higher concentration of ACh receptors in the basal and middle cochlear turns. These data seem to confirm the role of ACh in the neurotransmission of the auditory efferent system and may represent a new in vivo model for the investigation of the physiology of this system.
Acetylcholine↗
Vestibulo-ocular reflex modification after virtual environment exposure.
Immersion in an illusory world is possible by means of virtual reality (VR), where environmental perception is modified by artificial sensorial stimulation. The application of VR for the assessment and rehabilitation of pathologies affecting the vestibular system, in terms of both diagnosis and care, could represent an interesting new line of research. Our perception of reality is in fact based on static and dynamic spatial information perceived by our senses. During head movements in a virtual environment the images on the display and the labyrinthine information relative to the head angular accelerations differ and therefore a visuo-vestibular conflict is present. It is known that mismatches between visual and labyrinthine information may modify the vestibulo-oculomotor reflex (VOR) gain. We studied the post-immersion modifications in 20 healthy subjects (mean age 25 years) exposed to a virtual environment for 20 min by wearing a head-mounted display. VOR gain and phase were measured by means of harmonic sinusoidal stimulation in the dark before, at the end of and 30 min after VR exposure. A VOR gain reduction was observed in all subjects at the end of VR exposure which disappeared after 30 min. Our data show that exposure to a virtual environment can induce a temporary modification of the VOR gain. This finding can be employed to enable an artificial, instrumental modification of the VOR gain and therefore opens up new perspectives in the assessment and rehabilitation of vestibular diseases.
Adult↗
Postural control and glycerol test in Ménière's disease.
Ménière's disease is a clinical disorder, characterized by fluctuating hearing loss, recurrent spontaneous episodic vertigo, tinnitus and aural fullness, which may be defined as the idiopathic syndrome of endolymphatic hydrops. The most important test for diagnosis of Ménière's disease is the glycerol test. This is a simple and rapid method and several authors have confirmed its efficiency for identifying endolymphatic hydrops. This test provides information on the cochlear response to the osmotic changes produced by glycerol in the inner ear, whereas modifications in the vestibular labyrinth are usually not evaluated. The aim of this study was to evaluate the effects of glycerol on postural control during attacks of Ménière's disease, and to correlate this data with data on cochlear function. After the glycerol test, an improvement in postural control was recorded in 70% of patients, with all patients reporting a recovery of vertigo. The impairment of postural control during endolymphatic hydrops could be related to a pressure increase in the labyrinth, which interferes with the normal dynamics of the endolymph, and a rapid functional recovery could occur during an osmotic depletion. Dynamic posturography improves the sensitivity of the glycerol test and may therefore be useful in the diagnosis and staging of Ménière's disease.
Adult↗
Postural control in horizontal benign paroxysmal positional vertigo.
Sixteen patients affected by benign paroxysmal positional vertigo of the horizontal semicircular canal (BPPV-HSC) were investigated by means of dynamic posturography (DP) and during bithermal caloric stimulation. Data were compared to data from 40 patients with benign paroxysmal positional vertigo of the posterior semicircular canal (BPPV-PSC) and 20 healthy controls. No postural deficit was observed before or after a liberative Lempert's manoeuvre when patients were compared to control subjects. BPPV-PSC postural scores were significantly impaired compared to scores from the BPPV-HSC group. A residual significant postural impairment was also observed after a successful liberative manoeuvre in the BPPV-PSC group. Electronystagmographic recordings before recovery revealed significant hypoexcitability of the affected ear in 8/16 patients of the BPPV-HSC group. After the liberative manoeuvre, a symmetric bilateral response to caloric stimulation was recorded in all patients. Three main conclusions can be drawn from the present data. First, disorders of the horizontal semicircular canal do not change postural control. Second, dynamic posturography can detect the postural imbalance due to posterior semicircular canal dysfunction even after resolution of paroxysmal vertigo attacks. Third, utricular dysfunction can be ruled out as a cause of the residual postural deficit observed in BPPV-PSC patients. Therefore the recovery delay observed even 1 month after the liberative manoeuvre in the BPPV-PSC-group might be due to the persistence of small amounts of residual debris in the canal, to paralysis of ampullar receptors, or to the time needed for central vestibular re-adaptation.
Caloric Tests↗
The role of ocular oscillations upon visually dependent postural stabilization in patients affected by congenital nystagmus.
Visually dependent postural stabilization decreases as a consequence of a long-standing reduction of visual cues in patients affected by congenital nystagmus. The aim of the present study was to verify whether the changes in postural control in this group of patients are due to ocular oscillations or to reduced visual acuity. Therefore, postural control was evaluated when the nystagmus was blocked by the blocking position or by prisms and compared with the postural score observed in a group of normal controls whose visual acuity had been artificially reduced to the same level as that of the patients using Bangerter's filters. The results show a statistically significant improvement of visually dependent postural stabilization when ocular oscillations are inhibited either by the gaze blocking position or by prisms. They also show that postural control in normal subjects with Bangerter's filters is reduced, but is still significantly better than that observed when ocular oscillations are inhibited in patients affected by congenital nystagmus. Our data strongly support the role of ocular oscillations in visually dependent postural control, since postural impairment recovered under any condition in which ocular oscillations were abolished, despite differences in visual acuity. Our data also show that reduced visual acuity decreases visually dependent postural control to a lesser degree than ocular oscillations. This could be due to the fact that ocular oscillations are a disturbing input, usually inhibited centrally, in order to avoid oscillopsia. This mechanism is probably responsible for the reduced role of visual cues in the postural control in this group of patients. The reduction of visual acuity, by comparison, merely causes a decrease in visual cues, depending on the degree of visual loss. It can be concluded that the impaired postural control in patients affected by congenital nystagmus is mainly due to ocular oscillations, with reduced visual acuity creating a secondary effect.
Adult↗
An unusual complication of cochlear implant: benign paroxysmal positional vertigo.
Three days after the initial fitting of the cochlear device a 40-year-old woman complained of severe rotational vertigo following head movements associated with neurovegetative symptoms. Otoneurological evaluation revealed a horizontal paroxysmal positional nystagmus beating towards the lowermost ear, induced by rolling the patient's head from supine both to the right or to the left lateral position suggesting the diagnosis of benign paroxysmal positional vertigo of the left horizontal semicircular canal. The nystagmus characteristics were the same whether the cochlear device was switched on or off. The hypothesis of an otolith dislodging due to the electrical stimulation during the initial fitting is discussed.
Adult↗
The role of vision on postural strategy evaluated in patients affected by congenital nystagmus as an experimental model.
The role of vision in postural control is crucial and is strictly related to the characteristics of the visual stimulus and to the performance of the visual system. The purpose of this investigation was to evaluate the effects of chronically reduced visual cues upon postural control in patients affected by Congenital Nystagmus (CN). These patients have developed since birth a postural strategy mainly based on vestibular and somatosensorial cues. Fifteen patients affected by CN and 15 normal controls (NC) were enrolled in the study and evaluated by means of dynamic posturography. The overall postural control in CN patients was impaired as demonstrated by the equilibrium score and by the changes of the postural strategy. This impairment was even more enhanced in CN than in NC group when somatosensorial cues were experimentally reduced. An aspecific pattern of visual impairment and a pathological composite score were also present. Our data outline that in patients affected by CN an impairment of the postural balance is present especially when the postural control relies mainly on visual cues. Moreover, a decrease in accuracy of the somatosensory cues has a proportionally greater effect on balance than it has on normal subjects.
Adult↗
Postural control in benign paroxysmal positional vertigo before and after recovery.
Thirty-two patients affected by idiopathic benign paroxysmal positional vertigo (BPPV) of the posterior semicircular canal were studied before, 3 days and I month after a resolutive Semont manoeuvre by means of dynamic posturography. The overall postural control in BPPV patients was shown to be impaired, as demonstrated by the pathological equilibrium scores. Data obtained before treatment showed a specific pattern of vestibular involvement and a pathological composite score. After the liberatory manoeuvre the Sensory Organization Test indicated a significant improvement in the pathological composite and vestibular scores. However, significant differences from controls were still detected 3 days and 1 month after clinical recovery from BPPV. The results clearly show that, in BPPV patients, there is an impairment of the vestibular system, which seems unable to maintain a normal postural balance. This deficit can be particularly detected when dynamic posturography evaluates the vestibular cues. After the liberatory manoeuvre a consistent improvement in the overall postural control has been observed but the residual differences from controls seem to suggest that damage to the otoconial maculae influences postural control, even when there is significant improvement in the clinical signs.
Analysis of Variance↗
Distortion-product otoacoustic emissions and selective sensorineural loss in IDDM.
OBJECTIVE: To provide information about possible subclinical damage of the cochlear outer hair cells (OHCs) by means of transiently evoked otoacoustic emissions (TEOAEs) and distortion-product otoacoustic emissions (DPOAEs) in subjects with IDDM. RESEARCH DESIGN AND METHODS: TEOAEs and DPOAEs were recorded in 47 IDDM patients with normal hearing and in age- and sex-matched nondiabetic subjects. Peripheral neuropathy was diagnosed by nerve conduction velocity (NCV) at the peroneal and surral nerves. RESULTS: A subclinical peripheral neuropathy was found in 15 diabetic patients. Mean TEOAE amplitude was found to be significantly reduced in diabetic patients with a reduced NCV (7.6 +/- 3.2 dB; Scheffé's test: P = 0.03), but not in those without neuropathy (9.5 +/- 4.3 dB), with respect to control subjects (11 +/- 3.1 dB). Neuropathic patients also showed mean reduced DPOAE amplitude values in the region of middle and high frequencies from 1,306 to 5,200 Hz (P < 0.05), whereas no difference was found at the lowest-frequency amplitudes. A frequency-selective reduction of DPOAEs was also found in non-neuropathic patients (P < 0.05) in the region of higher frequencies at 3,284, 4,126, and 5,200 Hz compared with control subjects. No correlations were found among duration of diabetes, HbA1c values, TEOAEs and DPOAEs. CONCLUSIONS: Our results suggest that IDDM patients show an early abnormality of the micromechanical properties of the OHCs. In IDDM patients without a subclinical peripheral neuropathy, damage is limited to the higher frequencies and can be detected only by DPOAEs, whereas in IDDM patients with neuropathy, damage also involves the middle range of frequencies and can be detected by TEOAEs and DPOAEs. Therefore, DPOAEs seem to be able to detect the earliest cochlear selective-frequency dysfunction in IDDM patients without peripheral neuropathy. DPOAEs appear to be of greater clinical interest than TEOAEs; the former seem to be frequency specific and can be recorded at any chosen frequency, including high frequencies.
Acoustic Stimulation↗
Cochlear dysfunction in IDDM patients with subclinical peripheral neuropathy.
OBJECTIVE: To investigate the function of the auditory pathway from the cochlea to the auditory cortex in subjects with IDDM. RESEARCH DESIGN AND METHODS: Brain stem, middle-, and long-latency auditory-evoked responses and evoked otoacoustic emissions were measured in 48 normally hearing IDDM patients and in age- and sex-matched nondiabetic subjects. Peripheral neuropathy was diagnosed by nerve conduction velocity (NCV) at the peroneal and sural nerves. Auditory brain stem responses (ABRs) reflect auditory pathway function within the brain stem; middle-latency responses (MLRs) and long-latency responses (LLRs) originate from the auditory cortex; and evoked otoacoustic emissions (EOAEs) give objective information about preneural, mechanical elements of the cochlear function. RESULTS: A subclinical peripheral neuropathy was found in 12 diabetic patients. We found higher latencies of waves I (t = 4.4, P < 0.0001), III (t = 3.7, P = 0.0004), and V (t = 2.7, P = 0.008) of ABRs in diabetic patients (I: 1.7 +/- 0.13 ms; III: 3.9 +/- 0.17 ms; V: 5.7 +/- 0.24 ms), compared with those of the control group (I: 1.6 +/- 0.13 ms; III: 3.7 +/- 0.18 ms; V: 5.6 +/- 0.17 ms). However, neither central transmission time (i.e., the wave interpeak I-V) nor MLRs and LLRs were found to be significantly different in diabetic and control subjects. Mean EOAE amplitude was found to be significantly reduced (F = 4.2, P = 0.02) in diabetic patients with a reduced NCV (7.6 +/- 3.9 dB; Scheffé test: P = 0.03), but not in those without neuropathy (9.1 +/- 4.2 dB), compared with the control group (10.8 +/- 3.1 dB). No correlations were found between duration of diabetes and EOAEs or between sural NCV and peroneal NCV and metabolic control. EOAEs were not correlated with peroneal and sural NCVs. CONCLUSIONS: Our results indicate that the early preneural dysfunction of cochlear receptors causes a prolonged activation of the peripheral portion of the auditory pathway, while signal conduction along the central auditory pathway was shown to be normal in diabetes.
Adult↗
[An oropharyngeal-esophageal scintigraphic study of deglutition].
The aim of the present work was to evaluate whether oro-pharyngeal-esophageal scintigraphy could be used in the dynamic study of the various phases of deglutition and to determine whether it could be applied in otorhinolaryngological practice along with videofluoroscopy and videoendoscopy. The patients were divided into four different groups according to clinical features and the scintigraphic data were analyzed on this basis. Emphasis is placed on the ease of this technique, its tolerability and the low level of radiation. It is pointed out that scintigraphy is quite useful in determinating the exact percentage of the bolus inhaled into the trachealbronchial branch and in measuring the transit time of the various phases of deglutition in detail. In patients affected by upper airway-digestive tract neoplasms it is, therefore, possible to make a semiquantitative evaluation of the results of surgery. Moreover, with this method the results of any rehabilitation can be measured as well as the onset of compensation mechanisms.
Aged↗
Brain SPET and auditory cortex perfusion. Technical notes and preliminary results.
Auditory cortex stimulation was studied by 99Tcm-hexamethylpropyleneamine oxime (HMPAO) single photon emission tomography (SPET) in 11 patients with normal vestibular and auditory tests, as well as computed tomography. Markedly increased temporal and parietal blood flows were found in left brain cortex, contralateral to the stimulus. The right auditory areas showed moderate hyperactivity. The method might be useful for tonotopic mapping of auditory cortex, using various pure tonal stimuli.
Acoustic Stimulation↗
Functional study of the eustachian tube with sequential scintigraphy.
The authors investigated the tubal function by means of sequential scintigraphy in 16 patients affected by chronic otitis media and in 3 patients with posttraumatic perforation of the tympanic membrane. Evaluated parameters were: appearance time (AT), radioactivity peak time, rise time in the tympanic cavity, eustachian tube and rhinopharynx, and radioactivity percent values passed in the rhinopharynx. The tubal pressure-equilibrating function was determined by means of the manometer pump section of the impedance meter. A significant relationship between the pressure-equilibrating function and the tubal scintigraphy parameters has been detected. The variability of the AT in the tube and the almost constant time needed by the radioactive tracer to go through the tube and reach the rhinopharynx could indicate that a major role in the tympanic cavity drainage is played by the tympanic ostium and the surrounding mucosa.
Chronic Disease↗
Left ventricular aneurysm secondary to Behçet's disease.
A 16-year-old boy with Behçet's disease who was seen with thrombophlebitis of the leg was found to have coronary artery occlusion with postinfarction left ventricular aneurysm. Recurrent femoral artery aneurysms and orogenital ulceration developed in him. The diagnostic features together with successful treatment of this patient and a discussion of Behçet's syndrome are presented.
Adolescent↗
Giant left atrium and mitral valve replacement: risk factor analysis.
Giant left atrium (GLA) associated with mitral valve disease (MVD) has been reported as a significant risk factor in mitral valve surgery with mortality ranging from 8%-32%. Plication of the left atrium has been suggested to reduce postoperative left ventricular failure, respiratory failure and mortality. The 203 consecutive patients with MVD operated upon between 1980 and 1986 were reviewed and divided in two groups: group A without GLA (165 patients) and group B with GLA (38 patients = 19%). The pertinent preoperative and intraoperative notes and the early and late postoperative course were reviewed and correlated. The hospital mortality was 2.4% in group A and 2.6% in group B. Late mortality, at a mean follow-up of 54 months was 4.3% in group A and 5.4% in group B. In this series, GLA was not a significant risk factor in MVR and did not affect early and late results as compared with cases without GLA. Plication may not be required in absence of extracardiac signs of compression.
Cardiomegaly↗