Federico Dagna

Modifications of perineuronal nets and remodelling of excitatory and inhibitory afferents during vestibular compensation in the adult mouse

Perineuronal nets (PNNs) are aggregates of extracellular matrix molecules surrounding several types of neurons in the adult CNS, which contribute to stabilising neuronal connections. Interestingly, a reduction of PNN number and staining intensity has been observed in conditions associated with plasticity in the adult brain. However, it is not known whether spontaneous PNN changes are functional to plasticity and repair after injury. To address this issue, we investigated PNN expression in the vestibular nuclei of the adult mouse during vestibular compensation, namely the resolution of motor deficits resulting from a unilateral peripheral vestibular lesion. After unilateral labyrinthectomy, we found that PNN number and staining intensity were strongly attenuated in the lateral vestibular nucleus on both sides, in parallel with remodelling of excitatory and inhibitory afferents. Moreover, PNNs were completely restored when vestibular deficits of the mice were abated. Interestingly, in mice with genetically reduced PNNs, vestibular compensation was accelerated. Overall, these results strongly suggest that temporal tuning of PNN expression may be crucial for vestibular compensation.

Nestin expression and reactive phenomena in the mouse cochlea after kanamycin ototoxicity

Following injury to the adult mammalian cochlea, hair cells cannot be spontaneously replaced. Nonetheless, the postnatal cochlea contains progenitor cells, distinguished by the expression of nestin, which are able to proliferate and form neurospheres in vitro. Such resident progenitors might be endowed with reparative potential. However, to date little is known about their behaviour in situ following hair cell injury. Using adult mice and ex vivo cochlear cultures, we sought to determine whether: (i) resident cochlear progenitors respond to kanamycin ototoxicity and compensate for it; and (ii) the reparative potential of cochlear progenitors can be stimulated by the addition of growth factors. Morphological changes of cochlear tissue, expression of nestin mRNA and protein and cell proliferation were investigated in these models. Our observations show that ototoxic injury has modest effects on nestin expression and cell proliferation. On the other hand, the addition of growth factors to the injured cochlear explants induced the appearance of nestin‐positive cells in the supporting cell area of the organ of Corti. The vast majority of nestin‐expressing cells, however, were not proliferating. Growth factors also had a robust stimulatory effect on axonal sprouting and the proliferative response, which was more pronounced in injured cochleae. On the whole, our findings indicate that nestin expression after kanamycin ototoxicity is related to tissue reactivity rather than activation of resident progenitors attempting to replace the lost receptors. In addition, administration of growth factors significantly enhances tissue remodelling, suggesting that cochlear repair may be promoted by the exogenous application of regeneration‐promoting substances.

Equine versus Bovine Pericardium in Transmeatal Underlay Myringoplasty

Objectives: Many different grafting materials have been proposed in myringoplasty. The aim of this study was to evaluate the results obtained in transmeatal underlay myringoplasty using bovine and equine pericardium. The results were compared with those obtained by using autologous temporalis fascia. Methods: The study group consisted of 52 patients with tympanic perforation. Twenty-nine patients were randomly selected for treatment with bovine pericardium and 23 for equine pericardium. A group of 14 patients was treated with autologous temporalis fascia. Results: Closure of the perforation was achieved in 19 of 29 patients (66%) treated with bovine pericardium, in 19 of 23 (83%) treated with equine pericardium, and in 13 of 14 (93%) treated with autologous fascia. The best functional results in patients who gained closure of the perforation were obtained by means of equine pericardium. Conclusions: The overall long-term tympanic closure rate demonstrates that equine pericardium has a greater take rate than bovine pericardium. The results obtained are inferior to those obtained with autologous fascia, but this technique is less aggressive. The higher success rate with equine pericardium may be due to the fact that it is thinner and easier to handle and model than bovine pericardium.

Myeloid sarcoma of submandibular salivary gland

Objective: To report a rare case of a myeloid sarcoma of submandibular salivary gland. Methods: A 65-year-old woman with a history of successfully treated myelodysplastic syndrome, presenting with periodic painful swelling of her right submandibular area. Results: Physical evaluation, ultrasound and CT scan revealed the presence of a 3-cm mass contiguous to the submandibular salivary gland. A core needle biopsy confirmed the diagnosis of myeloid sarcoma. Bone marrow biopsy was still showing complete remission and the submandibular gland was the only extramedullary site involved. The patient was submitted to chemotherapy. Conclusion: Myeloid sarcoma is a rare extramedullary neoplasm. It can virtually involve any anatomic site, but it usually involves lymph nodes, paranasal sinuses, skin, soft tissue and periostium. Myeloid sarcomas of salivary glands are very rare and ENTs should be aware of this disease in order to include it in the differential diagnosis of a solitary neck mass.

Monaural or binaural sound deprivation in postlingual hearing loss: Cochlear implant in the worse ear.

To determine whether speech recognition scores (SRS) differ between adults with long‐term auditory deprivation in the implanted ear and adults who received cochlear implant (CI) in the nonsound‐deprived ear, either for hearing aid–assisted or due to rapidly deteriorating hearing loss.

Relationship between hearing threshold at the affected and unaffected ear in unilateral Meniere’s disease

Hearing loss in Menière’s disease has been described to affect above all low frequencies (upward curve) with a tendency to become irreversible and non-fluctuating at the higher frequencies (peaked curve) over time. The aim of the study was to determine the effects of MD on hearing function on the basis of differences existing between the affected and the unaffected ear in a group of patients affected by definite unilateral MD and whose contralateral ear was not affected by any disease other than age-related hearing loss (ARHL). Following this procedure we have also evaluated the possible effects of age and disease duration on hearing loss in MD. The study group consisted of 86 subjects affected by definite unilateral MD. In our sample a peaked audiometric curve characterized the affected ears; however, the result after subtracting the normal ear hearing threshold was an upward sloping curve, which highlighted the greater suffering at the lower frequencies. On the basis of differences existing between affected and unaffected ear, our data suggest that threshold evolution is more related to disease duration rather than to age.

Ossicular Chain Lesions in Tympanic Perforations and Chronic Otitis Media without Cholesteatoma

OBJECTIVE The first aim was to determine the prevalence, kind, and functional effects on hearing of ossicular chain suffering (OCS) in chronic otitis without cholesteatoma (NCOM) and tympanic perforations (TP). The second aim was to correlate the findings with clinical parameters and hearing level. MATERIALS AND METHODS The study group comprised 250 consecutive patients affected by NCOM and who were subjected to tympanoplasty and never operated on before. Each patient underwent preoperative pure tone audiometry. Ossicles were evaluated during surgery. The incidence of OCS in NCOM was reported in 15-62% of the patients. RESULTS Ossicular chain suffering was found in 26 out of the 250 patients included in the overall sample (10%). It was found in 7% of the patients affected by TP without otorrhea and in 19% of the patients affected by chronic ear discharge with drum perforation. OCS was found most frequently in posterior eardrum perforations and in patients with bilateral disease. The incus was the ossicle most frequently interested by resorption (92% of the patients). The air conduction threshold and air bone gap were more impaired in NCOM than in TP. CONCLUSION Ossicular chain damages in patients with non-cholesteatomatous middle ear pathologies are not frequent and are present in no more than 10% of the patients, but lesions found were similar to those reported in patients with cholesteatoma. Otorrhea, posterior perforation, and bilateral disease can be considered as good predictors of OCS.

The role of the efferent auditory system in developmental dyslexia

OBJECTIVE To assess the role of the efferent auditory system by inhibition of contralateral otoacoustic emission in dyslexic children with auditory processing disorders. METHODS The study sample was 34 children: 17 with dyslexia and 17 age-matched controls. Sensitive speech tests (low-pass filtered, time-compressed, distorted and dichotic) were performed to assess coexisting auditory processing disorder. Distortion-product otoacoustic emission (DPOAE) values were measured in basal condition and with contralateral broadband noise signal delivered via an earphone transducer at 60 dB SPL. RESULTS The lower scores at sensitive speech testing confirmed the association of an auditory processing disorder in the dyslexic children. DPOAE values were significantly attenuated by contralateral inhibition only in the control group (p=0.001; dyslexics, p=0.19); attenuation was not significant at any frequency in the dyslexic group. CONCLUSIONS The differences in DPOAE attenuation between the groups, although not statistically significant, suggest alterations in the auditory efferent system in the dyslexic population. These alterations may affect language perception. If confirmed in further studies with larger samples, these results could provide insight into a possible pathophysiological background of dyslexia.

Tone burst stimulus for auditory brainstem responses: prediction of hearing threshold at 1kHz.

OBJECTIVE To assess differences in hearing threshold estimation of four different ABR tone-bursts at 1kHz. METHODS Twenty-one (21) ears from 11 subjects were tested with pure-tone audiometry (PTA): 5 ears (24%) were normal hearing, 5 (24%) affected by mild hearing loss, 7 (33%) showed moderate hearing loss and 4 (19%) severe hearing loss. After PTA each subject underwent tone-burst ABR test at 1kHz using a linear gated (L_ABR) or Blackman windowed (B_ABR) stimuli with (nn_ABR) and without ipsilateral notched noise. Stimulation rate and filters settings were unchanged. RESULTS Overall correlation between PTA and all ABRs thresholds was high, ranging from 0.84 to 0.94. In normal hearing ears none of the differences was significant, except for those measured with B_nn_ABR, which showed a mean 16dB overestimation of the pure-tone threshold (p<0.05). In mild hearing loss group none of the differences between thresholds were significant. In moderate and severe hearing loss groups significant differences were measured with L_nn_ABR (p<0.05) with a mean 7.5dB underestimation of PTA. CONCLUSIONS Although very similar, some significant differences were found when considering specific group of patients with different degrees of hearing loss.

Prevention and management of hearing loss in syndromic craniosynostosis: A case series

OBJECTIVE To assess the audiological profile in a cohort of children affected by syndromic craniosynostosis. METHODS Eleven children with Apert syndrome (n=4), Saethre-Chotzen syndrome (n=3), Muenke syndrome (n=2), Crouzon syndrome (n=1) and Pfeiffer syndrome type 1 (n=1) were submitted to a complete audiologic evaluation including otoscopy, pure-tone audiometry, tympanometry and acoustic reflex testing, ABR, otoacustic emissions, temporal bone High Resolution CT (HRCT) scan. The main outcome measures were prevalence, type and severity of hearing loss, prevalence of chronic otitis media, correlation with the time of first surgical correction. RESULTS Seven of 11 patients (64%) presented hearing loss (HL), conductive in 3/7 patients (43%) and mixed in 4/7 (57%). No patients showed a purely sensorineural HL. All hearing impaired patients displayed middle ear disorders: the patients with conductive HL had otitis media with effusion (OME) and 3/4 patients with mixed HL showed tympanic alterations or cholesteatoma. A bilateral vestibular aqueduct enlargement was detected by HRCT scan in one normal hearing patient. The ABRs resulted normal in all cases. CONCLUSION Our study confirms the high prevalence of otologic diseases in such patients. In contrast with previous studies, middle ear disorders were responsible for the hearing impairment also in patients with mixed HL due to secondary inner ear damage. These findings restate the necessity of a close audiologic follow-up. We did not detect the specific ABR abnormalities previously reported, possibly because of an early correction of the cranial vault malformations.