Influence of diabetes and other risk factors on in-hospital mortality following kidney transplantation: an analysis of the Spanish National Hospital Discharge Database from 2016 to 2020.

INTRODUCTION: To assess time trends in incidence, clinical characteristics, complications, and hospital outcomes among patients with type 1 diabetes (T1D), with type 2 diabetes (T2D), and patients without diabetes who underwent kidney transplant (KT); to identify variables associated with in-hospital mortality (IHM); and to determine the impact of the COVID-19 pandemic. RESEARCH DESIGN AND METHODS: We used a nationwide discharge database to select KT recipients admitted to Spanish hospitals from 2016 to 2020. We stratified patients according to diabetes status. We used multivariable logistic regression to identify the variables associated with IHM. RESULTS: A total of 14 594 KTs were performed in Spain (T2D, 22.28%; T1D, 3.72%). The number of KTs rose between 2016 and 2019 and and decreased from 2019 to 2020 in all groups. In patients with T2D, the frequency of KT complications increased from 21.08% in 2016 to 34.17% in 2020 (p<0.001). Patients with T2D had significantly more comorbidity than patients with T1D and patients without diabetes (p<0.001). Patients with T1D experienced KT rejection significantly more frequently (8.09%) than patients with T2D (5.57%).COVID-19 was recorded in 26 out of the 2444 KTs performed in 2020, being found in 6 of the 39 patients deceased that year (15.38%) and in 0.83% of the survivors.The variables associated with IHM were comorbidity and complications of KT. The presence of T1D was associated with IHM (OR 2.6; 95% CI 1.36 to 5.16) when patients without diabetes were the reference category. However, T2D was not associated with a higher IHM (OR 0.86; 95% CI 0.61 to 1.2). CONCLUSIONS: The COVID-19 pandemic led to a decrease in the number of transplants. Patients with T1D have more rejection of the transplanted organ than patients with T2D. Fewer women with T2D undergo KT. The presence of T1D is a risk factor for IHM.

Association between Asthma and Lower Levels of Physical Activity: Results of a Population-Based Case-Control Study in Spain.

(1) Background: Our aim was to determine changes in the prevalence of physical activity (PA) in adults with asthma between 2014 and 2020 in Spain, investigate sex differences and the effect of other variables on adherence to PA, and compare the prevalence of PA between individuals with and without asthma. (2) Methods: This study was a cross-sectional, population-based, matched, case-control study using European Health Interview Surveys for Spain (EHISS) for 2014 and 2020. (3) Results: We identified 1262 and 1103 patients with asthma in the 2014 and 2020 EHISS, respectively. The prevalence of PA remained stable (57.2% vs. 55.7%, respectively), while the percentage of persons who reported walking continuously for at least 2 days a week increased from 73.9% to 82.2% (p < 0.001). Male sex, younger age, better self-rated health, and lower body mass index (BMI) were significantly associated with greater PA. From 2014 to 2020, the number of walking days ≥2 increased by 64% (OR1.64 95%CI 1.34-2.00). Asthma was associated with less PA (OR0.87 95%CI 0.47-0.72) and a lower number of walking days ≥2 (OR0.84 95%0.72-0.97). (4) Conclusions: Walking frequency improved over time among people with asthma. Differences in PA were detected by age, sex, self-rated health status, and BMI. Asthma was associated with less LTPA and a lower number of walking days ≥2.

Trends in Anaphylaxis Hospitalizations among Adults in Spain and Their Relationship with Asthma-Analysis of Hospital Discharge data from 2016 to 2021.

(1) Background: Anaphylaxis is a rapid-onset, life-threatening hypersensitivity reaction. This study explores the epidemiological trends and clinical outcomes of adult patients with and without asthma hospitalized for anaphylaxis in Spain from 2016 to 2021. (2) Methods: Data from the Spanish National Hospital Discharge Database (RAE-CMBD) were analyzed. We stratified patients with anaphylaxis based on their asthma diagnosis and evaluated various comorbidities and clinical outcomes. Propensity score matching was used to match confounders. (3) Results: The total number of hospitalizations for anaphylaxis remained stable, with a decrease in 2020 probably due to the COVID-19 pandemic. Drug-induced anaphylaxis increased, in addition to being the main triggering factor. Asthma prevalence among those admitted for anaphylaxis emerged from 7.63% to 10.69%, with a higher frequency of respiratory failure and need for mechanical ventilation in this group; despite this, ICU admissions and in-hospital mortality did not differ significantly between asthmatics and non-asthmatics. Asthma was also not a risk factor for severe anaphylaxis. Multivariable analysis identified advanced age, ischemic heart disease, acute respiratory failure, and invasive mechanical ventilation as factors associated with severe anaphylaxis. (4) Conclusions: This study provides valuable information on the complexity of anaphylaxis, its relationship with asthma, and factors influencing its severity. Overall, clinical outcomes did not differ significantly in asthmatic patients compared to non-asthmatic patients, although asthmatic patients had more respiratory complications. Further research is necessary to delve deeper into the multifactorial nature of anaphylaxis and its implications in clinical practice.

Observational Study of the Association between Atrial Fibrillation and In-Hospital Mortality during Hospitalization for Solid Organ Transplants in Spain from 2004 to 2021.

(1) Background: We analyzed the association between atrial fibrillation or atrial flutter (AF) and in-hospital mortality (IHM) among patients who underwent solid organ transplants in Spain from 2004 to 2021. (2) Methods: We gathered information from all hospital admissions for lung, liver, kidney, and heart transplants. (3) Results: A total of 71,827 transplants were analyzed (4598 lung transplants; 18,127 liver transplants; 45,262 kidney transplants; and 4734 heart transplants). One third of these were for women. Overall, the prevalence of AF was 6.8% and increased from 5.3% in 2004-2009 to 8.6% in 2016-2021. The highest prevalence of AF was found for heart transplants (24.0%), followed by lung transplants (14.7%). The rates for kidney and liver transplants were 5.3% and 4.1%, respectively. The AF code increased over time for all of the transplants analyzed (p < 0.001). The patients' IHM decreased significantly from 2004-2009 to 2016-2021 for all types of transplants. AF was associated with a higher IHM for all of the types of transplants analyzed, except for heart transplants. (4) Conclusions: The prevalence of AF among patients admitted for solid organ transplants was highest for those who underwent heart transplants. The mortality rate during the patients' admission for lung, liver, kidney, or heart transplants decreased over time. AF was independently associated with a higher risk of dying in the hospital for those who underwent lung, liver, or kidney transplants.

Asthma Is Associated with Back Pain and Migraine-Results of Population-Based Case-Control Study.

(1) Background: Worldwide, asthma, back pain, and migraine are major public health problems due to their high prevalence, effect on the quality of life, and huge economic costs. The association of asthma with an increased risk of these types of pain has been suggested; however, no conclusive results have been obtained to date. The aims of our study were (1) to describe and compare the prevalence of three types of pain localization, namely migraine or frequent headaches (MFH), chronic neck pain (CNP), and chronic low back pain (CLBP), in adults with and without asthma in Spain during the years 2014 and 2020 and (2) to identify which variables were associated with the presence of these types of pain in adults with asthma. (2) Methods: A cross-sectional study and a case-control study were conducted. The 2014 and 2020 European Health Interview Surveys for Spain were used as the data source. (3) Results: A total of 2463 individuals were interviewed and had self-reported asthma. In this group, the prevalence of pain was high, with CLBP (30.9%) being the most common, followed by CNP (26.7%) and MFH (13.3%). All types of pain remained stable from 2014 to 2020. In both surveys, the women with asthma reported a remarkably higher prevalence of all the types of pain analyzed than the men with asthma. After matching by age and sex, the prevalence of all pain types was significantly higher in the patients with asthma than in the matched individuals without asthma. Multivariable adjustment showed that asthma increased the likelihood of CNP by 1.45 times (OR 1.45; 95% CI 1.19-1.76), that of CLBP by 1.37 times (OR 1.37; 95% CI 1.11-1.64), and that of MFH by 1.19 times (OR 1.19; 95% CI 1.02-1.51). The three types of pain analyzed were associated with the female sex and worse self-rated health. (4) Conclusions: Among the men and women with asthma, the prevalence of all the pain types was high and remained stable over time. The prevalence was higher and the severity was greater among the women with asthma than among the men with asthma. The prevalence of any pain was significantly higher in people with asthma than in the sex-age-matched individuals without asthma. Multivariable analysis showed that the variables associated with the reporting of the three types of pain in people with asthma were female sex, worse self-reported health, and self-reported mental illness.

Comparison Between two Surgical Techniques for Increasing Vocal Pitch by Endoscopic Shortening of the Vocal Folds.

OBJECTIVE: To compare two surgical techniques, the Wendler glottoplasty (GP) and its modification, the vocal fold shortening, and retrodisplacement of the anterior commissure (VFSRAC) associated with laser assisted voice adjustment (LAVA) cordotomy, used to feminize the voice of transgender women by increasing the fundamental frequency (F0). METHODS: A retrospective study of 22 trans-women (20-62 years-old) was carried out. 12 of them were treated with GP and 10 with the VFSRAC+LAVA technique. They were evaluated before surgery and 6 months after surgery and the postoperative speech therapy. Laryngostroboscopy examination, F0 measurements, Transgender Woman Voice Questionnaire (TWVQ) assessment and the perceptual assessment using a visual analog scale (PA-VAS) were obtained from all patients. RESULTS: Laryngostroboscopic findings showed normal vocal folds before surgery and a shortening of the vocal folds, due to the anterior glottic synechia, after surgery. Significant increases of F0 were found in both groups but they were higher in the VFSRAC+LAVA group (47.75Hz in GP group vs 69.70Hz in VFSRAC+LAVA group). TWVQ scores showed a significant decrease in both groups although the difference was greater in the VFSRAC+LAVA group. Similarly, PA-VAS scores lowered significantly in both groups but VFSRAC+LAVA group presented the biggest decreases. CONCLUSION: Both surgical techniques produce the shortening of the vocal folds through an endoscopic approach and result in voices with higher vocal pitch. Of the two techniques presented, the VFSRAC+LAVA produces better results although when compared with previous studies it seems that the LAVA technique may not significantly contribute to the postoperative results. So, the VFSRAC technique followed by postoperative speech therapy could be recommended for trans-women who wish to feminize their voice.

Effect of Intravenous Lidocaine on Inflammatory and Apoptotic Response of Ischemia-Reperfusion Injury in Pigs Undergoing Lung Resection Surgery.

BACKGROUND: Ischemia-reperfusion injury is one of the most critical phenomena in lung transplantation and causes primary graft failure. Its pathophysiology remains incompletely understood, although the inflammatory response and apoptosis play key roles. Lidocaine has anti-inflammatory properties. The aim of this research is to evaluate the effect of intravenous lidocaine on the inflammatory and apoptotic responses in lung ischemia-reperfusion injury. METHODS: We studied the histological and immunohistochemical changes in an experimental model of lung transplantation in pigs. Twelve pigs underwent left pneumonectomy, cranial lobectomy, caudal lobe reimplantation, and 60 minutes of graft reperfusion. Six of the pigs made up the control group, while six other pigs received 1.5 mg/kg of intravenous lidocaine after induction and a 1.5 mg/kg/h intravenous lidocaine infusion during surgery. In addition, six more pigs underwent simulated surgery. Lung biopsies were collected from the left caudal lobe 60 minutes after reperfusion. We conducted a double study on these biopsies and assessed the degree of inflammation, predominant cell type (monocyte-macrophage, lymphocytes, or polymorphous), the degree of congestion, and tissue edema by hematoxylin and eosin stain. We also conducted an immunohistochemical analysis with antibodies against CD68 antigens, monocyte chemoattractant protein-1 (MCP-1), Bcl-2, and caspase-9. RESULTS: The lungs subjected to ischemia-reperfusion injury exhibited a higher degree of inflammatory infiltration. The predominant cell type was monocyte-macrophage cells. Both findings were mitigated by intravenous lidocaine administration. Immunohistochemical detection of anti-CD68 and anti-MCP-1 showed higher infiltration in the lungs subjected to ischemia-reperfusion injury, while intravenous lidocaine decreased the expression. Ischemia-reperfusion induced apoptotic changes and decreased Bcl-2 expression. The group treated with lidocaine showed an increased number of Bcl-2-positive cells. No differences were observed in caspase-9 expression. CONCLUSIONS: In our animal model, intravenous lidocaine was associated with an attenuation of the histological markers of lung damage in the early stages of reperfusion.

The Cochlear Spiral Ganglion Neurons: The Auditory Portion of the VIII Nerve.

The VIII nerve is formed by sensory neurons that innervate the inner ear, i.e., the vestibular and the auditory receptors. Neurons of the auditory portion, the cochlear afferent fibers that innervate the sensory hair cells of the organ of Corti, have their somas in the cochlear spiral ganglion where two types of neurons can be distinguished. Afferent Type-I neurons are the 95% of the total population. Bipolar and myelinated fibers, each one innervates only one cochlear inner hair cell (IHC). In contrast, afferent Type-II neurons are only the 5% of the spiral ganglion population. They are pseudounipolar and unmyelinated fibers and innervate the cochlear outer hair cells (OHC) so that one afferent Type-II fiber contacts with multiple OHCs, but each OHC only receives one contact from one Type-II neuron. Both types of VIII nerve fibers are glutamatergic, but these asymmetric innervations of the cochlear sensory cells could suggest that the IHC codifies the truly auditory message but the OHC only informs about mechanical aspects of the state of the organ of Corti. In fact, the central nervous system (CNS) has control over the information transmitted by the Type-I neuron by means of axons from the superior olivary complex that innervate them to modulate, filter and/or inhibit the entry of auditory message to CNS. The aim of this paper is to review the current knowledge about the anatomy and physiology of the auditory portion of the VIII nerve. Anat Rec, 302:463-471, 2019. © 2018 Wiley Periodicals, Inc.

Electrophysiological monitoring of hearing function during cochlear perilymphatic perfusions.

CONCLUSION: The cochlear perilymphatic perfusion produces, by itself, significant effects in the cochlear physiology that could be associated with the surgical procedure. These effects need to be well characterized to allow a reliable quantification of the effects of the experimental agent being tested. OBJECTIVES: The study focused on the accurate description of the electrophysiological effects on the cochlear potential recordings of perilymphatic perfusions. METHODS: Two successive cochlear perilymphatic perfusions were carried out. The first used artificial perilymph. The second used artificial perilymph alone or a kainic acid (KA) solution in artificial perilymph. The compound action potential of the auditory nerve (CAP-AN) was recorded: (1) before the first perfusion, (2) after the first perfusion and (3) after the second perfusion, and compared between groups. RESULTS: The first intracochlear perfusion with artificial perilymph produced significant effects in the CAP-AN that could be related to the surgical procedure. These effects were analysed separately from the effects produced by the KA. In particular, the KA administered intracochlearly produced a significant increase in the latency and a decrease in the amplitude of the CAP-AN N1 wave compared with the controls that were perfused twice with artificial perilymph.

Pharyngo-cutaneous fistula: an old problem revisited.

CONCLUSION: Pharyngo-cutaneous fistula is the most common complication after total laryngectomy (TL), with many factors linked to its emergence. However, it has rarely been associated with the type of pharyngeal suture. We conclude that the technique of surgical closure of the pharynx and care in the tightness of the suture seem to be fundamental factors for pharyngo-cutaneous fistula development. OBJECTIVE: The aim of present work was to determine whether the type of pharyngeal suture can be considered as a major risk factor for developing a pharyngo-cutaneous fistula following TL. METHODS: We carried out a series of 157 consecutive TLs. In the first 90 procedures, we performed a pharyngeal closure technique with T-shaped interrupted stitches reinforced with constrictors. In the other 67 cases, a doubled continuous suture technique with reinforcement with the cutaneous flap was developed. RESULTS: In all, 25.5% of the cases sutured with the interrupted stitches developed a fistula while only 2.9% of the patients that underwent continuous suture developed a fistula.

The impact of comorbidity on the survival of patients with laryngeal squamous cell carcinoma.

UNLABELLED: Abstract Conclusions: In survival analysis, the combined Charlson comorbidity index (CCI) can be considered as a prognostic factor independent of the tumor node metastasis (TNM) classification, tumor stage, and tumor location. Severe comorbidity was the factor that had the greatest impact on prognosis in cases of initial tumor. OBJECTIVE: To study the influence of comorbidity on the survival of patients undergoing surgery for larynx cancer. METHODS: This was a retrospective study of the survival of 231 patients with laryngeal cancer who underwent surgery between 1995 and 2002. The CCI was used to assess comorbidity, the Kaplan-Meier method was used for survival analysis, and the Cox proportional risk regression model was used to identify independent prognostic factors. RESULTS: The multivariate analysis of specific mortality showed that patients classified as having severe comorbidity (CCI) were more likely to die (adjusted hazard ratio (adjHR) 1.85, 95% confidence interval (CI) 1.07-3.17). This difference was more important in patients with early tumor stages than in those with advanced stages.

In vitro long-term development of cultured inner ear stem cells of newborn rat.

The adult mammalian auditory receptor lacks any ability to repair and/or regenerate after injury. However, the late developing cochlea still contains some stem-cell-like elements that might be used to regenerate damaged neurons and/or cells of the organ of Corti. Before their use in any application, stem cell numbers need to be amplified because they are usually rare in late developing and adult tissues. The numerous re-explant cultures required for the progressive amplification process can result in a spontaneous differentiation process. This aspect has been implicated in the tumorigenicity of stem cells when transplanted into a tissue. The aim of this study has been to determine whether cochlear stem cells can proliferate and differentiate spontaneously in long-term cultures without the addition of any factor that might influence these processes. Cochlear stem cells, which express nestin protein, were cultured in monolayers and fed with DMEM containing 5% FBS. They quickly organized themselves into typical spheres exhibiting a high proliferation rate, self-renewal property, and differentiation ability. Secondary cultures of these stem cell spheres spontaneously differentiated into neuroectodermal-like cells. The expression of nestin, glial-fibrillary-acidic protein, vimentin, and neurofilaments was evaluated to identify early differentiation. Nestin expression appeared in primary and secondary cultures. Other markers were also identified in differentiating cells. Further research might demonstrate the spontaneous differentiation of cochlear stem cells and their teratogenic probability when they are used for transplantation.

Cellular and molecular bases of neuroplasticity: brainstem effects after cochlear damage.

After a cochlear lesion or auditory nerve damage, afferent connections from auditory ganglia can be highly altered. This results in a clear reduction of auditory input and an alteration of connectivity of terminals on cochlear nuclei neurons. Such a process could stimulate the reorganization of the neural circuits and neuroplasticity. Cochlea removal has been demonstrated to be a good model in which to analyse brainstem neuroplasticity, particularly with regard to the cochlear nuclei. After cochlea removal three main periods of degeneration and regeneration were observed. Early effects, during the first week post lesion, involved acute degeneration with nerve ending oedema and degeneration. During the second and, probably, the third post lesion weeks, degeneration was still present, even though a limited and diffuse expression of GAP-43 started. Around 1 month post lesion, degeneration at the cochlear nuclei progressively disappeared and a relevant GAP-43 expression was found. We conclude that neuroplasticity leads neurons to modify their activity and/or their synaptic tree as a consequence of animal adaptation to learning and memory. For the human being neuroplasticity is involved in language learning and comprehension, particularly the acquisition of a second language. Neuroplasticity is important for therapeutic strategies, such as hearing aids and cochlear implants.

Immunocytochemical detection of synaptophysin in C57BL/6 mice cochlea during aging process.

Aged mammals frequently exhibit a bilateral, progressive, and symmetric deafness related to the degeneration of auditory receptor. However, little is still known about aging effects on synapses in this receptor. Synaptophysin (Syp) is a 38 kDa Ca2+ binding glycoprotein widely found in presynaptic membrane and vesicles. The Syp has been found in presynaptic buttons of efferent auditory fibers, within the developing and adult auditory receptor. The detection of Syp in aged cochleae could provide relevant information about synaptic changes and receptor degeneration process observed in old animals. This paper focuses on aging linked changes related to the presence of Syp in cochleae of C57BL/6J mice (from 1 to 24 months old). Results showed that during the first months of age, no significant changes were observed in the Syp distribution under the basal pole of inner (IHCs) neither the outer (OHCs) hair cells. At six months of age, a significant decrease of Syp immunocytochemical detection appeared in fibers under the most external row of OHCs, but restricted to the cochlear basal coil. Only a very scarce reduction of Syp was noted under the IHC and the other OHC rows, also at the basal coil. From mice 9 months old on, a progressive decrease of the presence of Syp was found under IHC and all OHC rows starting at the basal coil and reaching the apical coil in the oldest mice. All these data could indicate that the cochlea aging process early affects to presynaptic membrane proteins of efferent endings fibers. This early alteration of cochleae efferent synapses could be involved in the whole degeneration of the Corti's organ.

Cochlear microphonic audiometry: a new hearing test for objective diagnosis of deafness.

CONCLUSIONS: Objective audiometric tests could constitute a valuable tool for detection of deafness. This could be especially useful in children (universal newborn hearing screening) and non-collaborative patients, who are especially difficult candidates for classic audiometry. The cochlear microphonic audiometry (CMA) technique offers the possibility of obtaining objective audiometric profiles, highly correlated with those obtained by pure tone audiometry (PTA). Therefore, CMA could be used as an alternative test to obtain the audiometric profile of these patients. OBJECTIVE: The main purpose of the present study was to demonstrate that CMA provides objective audiometric profiles by avoiding active participation by the patient. Subjects and methods. CMA specific equipment, improved for non-invasive recording of cochlear microphonic potentials, was used. This tool plots the recordings obtained as the classic audiogram. Verification of the method was carried out in adult patients by comparing the PTA with the CMA audiometric profiles obtained for each patient. RESULTS: Our findings showed that audiometric profiles obtained from CMA are highly correlated, without statistical differences, to those obtained with PTA. More than 81% of patients explored (91.67% at 250 Hz) exhibited differences below 10 dB(HL) between tests at all exploration frequencies, while a low number of cases showed differences over 20 dB(HL).

Biochemical evidence for the presence of serotonin transporters in the rat cochlea.

Cochlear serotonergic innervation is constituted by efferent fibers projecting both to the area below the inner and the outer hair cells. Previous detection of serotonin (5-HT) metabolites and 5-HT receptor mRNAs suggests the existence of serotonergic synaptic activity in the cochlea. The present study explores this possibility through the effect of 6-nitroquipazine (6-NQ), a 5-HT selective reuptake inhibitor, on the basal turnover of 5-HT. The concentrations of 5-HT and its metabolite 5-hydroxyindole-3-acetic acid (5-HIAA) were quantified by high performance liquid chromatography with electrochemical detection in blood-free cochleae of rats treated with 6-NQ or saline and kept under silent conditions. Treatment with 6-NQ induced a significant increase of the cochlear concentration of 5-HT and a significant reduction of 5-HIAA concentration with respect to saline treatment. These findings could indicate that 6-NQ induced the blockade of the 5-HT selective reuptake to the cochlear serotonergic fibers. This suggests that plasma membrane 5-HT transporters are present in cochlear serotonergic fibers. Even though the role of serotonergic innervation on cochlear physiology remains unknown, the existence of cochlear serotonergic synaptic activity is strongly supported by present contributions.

Simultaneous HPLC quantification of monoamines and metabolites in the blood-free rat cochlea.

Monoamine quantification in peripheral sensory receptors, such as the cochlea, is of major interest since monoamines could play a role in neurotransmission. A three-step biochemical protocol was developed to analyze monoamine content within the cochlea. Removal of the blood by aortic perfusion was carried out with an anticoagulant solution prior to the dissection of the cochlea from the temporal bone. The cochlear monoamines and some of their metabolites were then quantified, from homogenated cochlear tissue, by a new application of high performance liquid chromatography coupled to electrochemical detection. This method demonstrated enough sensitivity to detect norepinephrine (NE), dopamine (DA), serotonin (5-HT) and some of their metabolites (3,4-dihydroxyphenylacetic acid, DOPAC; homovanillic acid, HVA; and 5-hydroxyindole-3-acetic acid, 5-HIAA). Furthermore, it enabled the demonstration of noise-induced changes in the cochlear concentrations of NE, DA, DOPAC and HVA. In addition, the aortic perfusion allowed removal of the blood-borne 5-HT from the cochlea without inducing systemic alterations or monoamine degradation, as shown by the absence of effects on NE, DA, DOPAC, HVA or 5-HIAA concentrations. The present methodology may constitute a useful strategy to analyze monoamine turnover in the cochlea and other peripheral sensory receptors.

Effects of aging on C57BL/6J mice: an electrophysiological and morphological study.

Presbycusis is a progressive hearing loss associated with aging that manifests as deafness linked to cochlear morphological degeneration. The effects of aging on the auditory system were studied in C57BL/6J mice using electrophysiological (brainstem auditory evoked potentials; BAEP) and morphological techniques. Cochleae of animals aged 1, 6, 9, 12, 15, 18, 21, or 24 months old were used for that purpose. The BAEP showed a progressive increase in latency and a reduction in amplitude. Morphological studies demonstrated total degeneration of the organ of Corti, which was replaced by a single epithelial layer. An affinity histochemistry study demonstrated minor modifications of glycoconjugates in the organ of Corti during the aging process.