Cochlear, auditory brainstem responses in Type 1 diabetes: relationship with metabolic variables and diabetic complications

AIMS

Few studies have analysed the presence of hearing abnormalities in diabetes. We assessed the presence of subclinical auditory alterations and their possible association with early vascular and neurological dysfunction in young adults with Type 1 diabetes of long duration.

METHODS

Thirty-one patients with Type 1 diabetes (mean age 33 ± 2.3 years, disease duration 25.7 ± 4.2 years) and 10 healthy controls underwent pure tone audiometry (PTA), distortion product otoacoustic emission (DPOAE) and auditory brainstem response (ABR) analyses. Associations with metabolic variables and chronic complications were explored.

RESULTS

Compared with healthy controls, patients with diabetes had significantly higher mean hearing thresholds, although still within the normoacusic range. DPOAE intensities at medium frequencies (2.8-4 kHz) were significantly lower in patients with diabetes. In ABR, in addition to waves I, III and V, we observed the appearance of a visible wave IV in patients with diabetes compared with controls (prevalence 61% vs. 10%, P < 0.05), and its appearance was related to a prolonged I-V interval (4.40 ± 0.62 ms vs. 4.19 ± 0.58 ms, P < 0.05). Diastolic blood pressure was higher in people with abnormal DPOAE (P < 0.05), whereas systolic blood pressure correlated with wave V and interpeak I-V interval latencies. A trend towards an association between evidence of wave IV and the presence of somatic neuropathy or abnormal cardiovascular autonomic tests was observed.

CONCLUSIONS

Young adults with long-term Type 1 diabetes have subclinical abnormalities in qualitative auditory perception, despite normal hearing thresholds, which might reflect neuropathic and/or vascular alterations.

Age at diagnosis of deaf babies: a retrospective analysis highlighting the advantage of newborn hearing screening

OBJECTIVE

Aim of the study was to assess the mean age at diagnosis of bilateral congenital hearing loss in the Audiology and Phoniatry Centre of the University of Turin, pointing out, by North-West Italy experience, the role of the newborn hearing screening in anticipating the age of diagnosis.

METHODS

This was a retrospective study. Forty-six congenital deaf babies were reviewed and age at diagnosis was assessed for each, taking in consideration the role of hearing loss risk factors. Eighteen babies (39%) were sent by the centres that participate to the newborn hearing screening program while 28 (61%) came for parental or pediatrician suspicion of hearing loss and for general language delay. Sixteen babies (35%) presented risk factors for hearing loss.

RESULTS

The mean age of identification of severe to profound hearing loss was 20.5 months (S.D.=15.3) in the whole group; considering the group of 28 babies not screened the mean age was 29.3 months (S.D.=13.4). This value decreased to 6.8 months (S.D.=3.6) in the group which underwent screening programme. This difference was statistically significant at Student's t-test (p<0.001). The average ages of diagnosis for healthy versus high risk children were significantly different only in the group of screened babies (p<0.05).

CONCLUSIONS

Childhood hearing impairment is one of the most common of congenital disorders, and even though there is a general trend of early identification, in reality age of diagnosis is as yet still too late even in developed countries. Our results show that newborn hearing screening could reduce the age at which infants with hearing loss are diagnosed and treated; this would improve speech, language, auditory outcome and the quality of parents and infant life.

Auditory-evoked potentials in general anesthesia monitoring: baseline study of availability in relation to hearing function in awake status

BACKGROUND

It has been confirmed that middle latency auditory-evoked potentials are good indicators of the hypnotic level in patients undergoing general anesthesia. The focal point for the evocation of auditory-evoked potentials is the presence of a serviceable hearing function. The aim of the study was to evaluate the limit of hearing loss above which the test could not be applied.

METHODS

To determine the limit of applicability of the technique, 100 subjects were studied. Twenty of them were normally hearing and 80 were affected by sensorineural hearing loss of various degrees. Each subject was submitted to pure tone audiometry, to determine hearing threshold, and then, in awake status, to auditory-evoked potentials recording using acoustic stimuli of 85 dB HL.

RESULTS

All the 20 normally hearing subjects showed a reliable auditory-evoked potentials. Among the 80 subjects affected by hearing loss, only five had no potentials. These five subjects presented a pure tone audiometry threshold greater than 85 dB HL.

CONCLUSION

The study demonstrated that middle latency auditory-evoked potentials recorded using an A-Line (software version 1.4) AEP monitor (Danmeter, Odense, Denmark) can be carried out even in presence of hearing loss if the pure tone threshold is less than 85 dB HL.

[Equilibrium and orthognathodontic surgery: correlations in a group of patients undergoing treatment]

BACKGROUND

The aim of this study was to evaluate the main parameters provided by the static stabilometric test (mean X, mean Y, mean velocity, length of tracing, standard deviation of velocity, ellipse area) in the follow-up of patients suffering from skeletal occlusive pathology undergoing orthognathodontic surgery to confirm the re-establishment of postural equilibrium.

METHODS

Fifteen patients with skeletal dysgnathia were correlated with a group of 10 healthy subjects. The same parameters were analysed in the dysgnathic subjects at 6 and 12 months after surgical correction. The patients enrolled in this study underwent surgery at the Division of Maxillofacial surgery of Turin University. Student's "t"-test and multivariate statistical analysis (Cox regression) were used for the statistical analysis of results.

RESULTS

A significant variability was noted in some of the main parameters analysed (mean X, mean Y, tracing length) between the two populations (healthy and dysgnathic) compared to visual signs (eyes opened-closed). The change in stabilometric values within the group of dysgnathic patients was highly significant 6 and 12 months after surgery, not only in terms of visual signs but also the cervical component (retroflexion of the head), above all the value of mean Y (p = 0.001).

CONCLUSIONS

An analysis of these results shows that static stabilometry can be a valuable aid both during the preoperative evaluation and during the follow-up in patients undergoing jaw surgery since it can quantify the improvement of body balance.

[Tinnitus during headache: clinical-instrumental evaluation]

During the five years running from December 1993 to January 1998, 112 patients who had come to our University Clinic suffering from headache were examined. From this group 71 complaining of tinnitus during headache were recruited for the study: 19 patients suffered from migraine without aura, 8 migraine with aura, 15 tension headache, 21 mixed headache, 3 basic migraine and 5 cluster headache. The purpose of this work was to determine the incidence and to identify the frequency of the various types of tinnitus in the study sample. Once cardiovascular and metabolic pathologies, previous cranial or cervical traumas, barotrauma, chronic on-the-job noise exposure, cervical arthritis, ATM malocclusion, use of drugs that damage the hearing apparatus, morbose processes of the external and middle ear, otosclerosis, jugular tympanum paraganglioma, Meniere's disease, acoustic neurinoma were all ruled out, the patients underwent the following battery of instrumental tests: tonal audiometry, impedance measurement, vestibular examination, electronystagmography, ABR, simplified tinnitometry. Only those patients with normal hearing underwent the tinnitometry and, therefore, the type of tinnitus was established only for this group of 53 patients. Tinnitometry showed that 37% of these subjects had tinnitus at the higher frequency tones, 11% at the middle frequencies, 29% complained of tinnitus at the lower frequencies while 23% complained that the bothersome buzzing was a compound noise. In addition, the subjective intensity of the tinnitus was analyzed. The authors devised a tinnitus irritation scale covering a range from 0 (not irritating) to 10 (intolerable). The tinnitus was bilateral in 66% of the cases while it was limited to only one ear in the remaining 34%. In 15% of the cases tinnitus was present even when there was no headache. In the literature, the etiopathogenesis of tinnitus associated with migraine headache has been attributed to vascular and neuropeptide mechanisms. Even the psychological component appears to play a role in triggering the event. These hypotheses deserve more in depth study.

[Myringoplasty in children: a comparison with an adult population]

The indications for myringoplasty in children has always been a controversial subject since many authors feel the high frequency of the phlogistic auricular processes in children constitute an unfavorable prognostic factor to success of the procedure. The authors present the results obtained in 23 patients under 17 years of age who had undergone myringoplasty for simple perforation of the tympanum. In cases of posterior and inferior perforations, surgery was performed using the underlay technique and a transmeatal approach; in all other cases the overlay technique was used with a retroauricular approach. An average 30 month follow-up (range 12-55 months) revealed new perforations in only 2 cases (9%). From the functional point of view the average air/bone conduction gap was reduced to 10 dB. As a control, the results were compared to those obtained in 150 patients over 16 years of age, again affected by simple perforation of the tympanic membrane and treated by myringoplasty using the same methods. In the adults, 22 new perforations were found (15%) while the functional results were analogous to those obtained in the children group. In this light, it can be asserted that myringoplasty can be considered a safe procedure to be used in children and it does not appear essential to wait until they have finished growing before performing this procedure.

Impedance measurement as a noninvasive technique for the monitoring of intracranial pressure variations

In previous reports it has been demonstrated that jugular compression causes a modification of middle ear acoustic impedance; this phenomenon has been named the jugulotympanic reflex (JTR). The aim of the present study was to contribute to the understanding of the origin of this reflex. We have analyzed the middle-ear impedance modifications induced by unilateral and bilateral jugular compression in 12 normal subjects, in 12 patients afflicted with otosclerosis, in 3 patients with Menière's disease and in 6 patients demonstrating intracranial hypertension. In the latter group, the cerebrospinal fluid (CSF) pressure was simultaneously recorded. The JTR was elicited in each normal subject and in each patient affected by Menière's disease and intracranial hypertension, while it was usually absent or modified in otosclerotic patients. The absence of the JTR in otosclerotic patients and, above all, the correspondence between CSF pressure and the middle-ear impedance modification induced by jugular compression suggest that it is due to the transmission of pressure changes from the CSF to the perilymph through the cochlear aqueduct.

[Modification of vestibular function after radiation therapy for head and neck tumors]

The effect of radiation on the vestibular apparatus of animals and man have not been widely investigate. Referred symptoms are disequilibrium and spontaneous nystagmus in animals while histological features are intralabyrinthic haemorrhage, edema of the endolymphatic spaces and alterations of sensory hair cells. A group of 20 patients with head and neck cancer located in different sites (nasal cavity, oropharynx, oral cavity, parotid gland) underwent to vestibular investigations before and 3-6 months after radiation therapy. Ten patients (50%) showed an alteration of the vestibular function of peripheral origin after radiation treatment. Complications appeared from a few weeks up to several months following termination of radiotherapy. The slow development of the lesion permitted central compensation. Few patients had symptoms and vestibular symptomatology was always of secondary importance with respect to the initial pathology.

[Identification of the waveform of cortical auditory evoked potentials]

Slow vertex response (SVR) audiometry is presently one of the methods of choice in objective auditory threshold assessment. The aim of this study, carried out on twenty subjects with various degrees and types of hearing loss, was to evaluate the difficulties found in N1P2 complex identification. Tracings, presented as single averages and super-imposed averages, were examined separately by two Authors who had not been received any information concerning the audiometric thresholds of the subjects under investigation. Results showed that erroneous identification of SVR waveforms occurred frequently, especially near threshold level. The rate of false negatives (i.e. a waveform present but not identified) was higher than the rate of false positives (i.e. erroneous identification of a non-existing N1P2 complex). High intra- and interindividual discrepancies were also found. Our results appear to indicate that the SVR waveform is not easily identifiable and thus that SVR audiometry cannot, therefore, be considered a truly objective audiometric test since analysis of the tracings may be influenced by the high degree of variability in individual interpretation.

[Relations between pure-tone audiometry and cortical evoked auditory potentials]

Slow vertex response (SVR) audiometry is presently one of the methods of choice in objective auditory threshold assessment. The aim of this study was to evaluate, as objectively possible, the relationship existing between the thresholds of SVR and or pure tone audiometry (PTA). The study was carried out on twenty subjects with hearing losses of various degrees and types. While mean differences between SVR and PTA thresholds ranged between 6 to 13 dB, in some cases values over 30 dB were found. No statistically significant intra- and interindividual discrepancies were found, even though in some cases the thresholds were given different in evaluations by different examiners. No statistically significant difference in SVR versus PTA thresholds was found in patients with sensory-neural and conductive hearing loss, while in subjects with normal hearing the difference between the thresholds was greater. Our results suggest that SVR is a reliable technique in objective threshold evaluation but that in single cases its threshold cannot be directly compared to that of pure tone audiometry.

[Modified Semont's maneuver in the treatment of benign paroxysmal positional vertigo]

Benign paroxysmal positional vertigo (BPPV) is one of the most frequent causes of vertigo. It is characterized by a peripheral balance impairment which occurs during specific movements or positions of the head. The etiology of BPPV is not clear although recent studies by Harada have given more weight to the otolithic theory. The present author has found frequent otoconia attached to the dark cell area around the crista of the semicircular canals. The treatment of BPPV is based on functional re-education of the patient (Semont maneuvers, the Brandt Daroff technique, Norre's V.H.T). The present study involves 62 patients affected by BPPV. The Hallpike maneuver was employed to define the affected side and then the modified Semont maneuver was performed. Recovery was obtained in all patients. The cure rate proved to be 82% after the first examination. The modified Semont maneuver is easier to perform than the traditional maneuver and has given excellent therapeutic results.

Hearing loss and desferrioxamine in homozygous beta-thalassemia

The authors present the results obtained during an audiometric screening of 153 children aged 5-18 years, affected by beta-thalassemia and treated with regular blood transfusions and iron overload chelation by means of desferrioxamine. Thirty-eight percent of the patients showed a significant sensorineural hearing loss at high frequencies with recruitment. Younger patients had a greater hearing loss, indicating that cochlear damage was not due to the disease itself. Furthermore, hearing loss appeared to be correlated with the mean and peak desferrioxamine doses administered and was higher in subjects with lower iron load. Thus, the ototoxic effect seems to have been higher when a good iron chelation had been obtained. Among our patients, conductive hearing loss was not more frequent than in patients without beta thalassemia.