Perilymphatic enhancement and endolymphatic hydrops: MRI findings and clinical associations.

Objective: In this study, we aimed to summarize magnetic resonance imaging (MRI) findings of perilymphatic enhancement (PE) and endolymphatic hydrops (EH) of the inner ear, which are associated with vestibular and cochlear symptoms. Methods: We analyzed data on ears with definite Meniere's disease (MD), sensorineural hearing loss (SNHL), vertigo, and listening difficulties (LiD) from 508 ears of 254 patients who underwent contrast-enhanced 3-Tesla MRI between April 2021 and March 2023. We evaluated the degree of endolymphatic hydrops (EH), signal intensity ratios (SIRs) between the basal turns of the cochlea and cerebellum, and hearing levels for all ears. Ears with definite MD were also assessed for changes in vestibular and cochlear symptoms within 6 months. Results: Ears with definite MD exhibited significantly higher percentages of EH in both the vestibule and cochlea compared with ears with other diseases. Furthermore, ears with MD or sensorineural hearing loss (SNHL) had significantly higher SIRs of PE compared with ears with other diseases or asymptomatic ears. Among patients with definite MD, those experiencing hearing fluctuations or vertigo attacks within the last 6 months had significantly higher SIRs of PE compared with those who did not experience any symptoms. Conclusion: Significant EH in the vestibule and cochlea was a major finding for the imaging diagnosis of definite MD. A high SIR of PE was a good indicator for assessing MD activity, reflecting vestibular and cochlear symptoms and fluctuations.Level of Evidence: 4.

Factors influencing auditory brainstem response changes in infants.

BACKGROUND: To elucidate the factors influencing auditory brainstem response (ABR) threshold improvement in infants. METHODS: This retrospective study included 626 infants who underwent ABR at the our Health and Medical Center between 2016 and 2020. Preliminary assessment indicated that 352 infants had an ABR threshold ≥40 dBnHL in both ears. A second ABR examination was conducted 5 months after delivery. The participants were divided into the improved (improvement ≥20 dBnHL) and unchanged (improvement <20 dBnHL) groups. The associations between risk factors were evaluated. Furthermore, we measured and compared the latencies of waves I, III, and V between participants with normal hearing and those in the improved and unchanged groups. RESULTS: The improved and unchanged groups consisted of 185 and 167 participants, respectively. ABR deterioration occurred in one infant with unilateral congenital cytomegalovirus-associated hearing loss. Binary logistic regression analysis revealed that the presence of otitis media with effusion and Down syndrome were factors contributing to ABR threshold improvement. In the ABR waveform analysis, patients in the improved group who had otitis media with effusion exhibited prolonged latencies of waves I, III, and V. Conversely, patients in the unchanged group who had Down syndrome showed shortened I-V interval. CONCLUSIONS: Half of the infants tested the second time showed improvement in ABR threshold. Children with congenital syndromes (such as Down syndrome) or otitis media with effusion should undergo a second ABR examination or other auditory assessments to ensure an accurate diagnosis of hearing loss.

Correlation of Endolysmphatic Duct Signal Intensity With Clinical Features in Otological Diseases.

OBJECTIVE: Bilateral high signal intensity (SI) in the endolymphatic duct (ED) on magnetic resonance imaging (MRI) has been reported as a common characteristic in ears with large vestibular aqueduct syndrome (LVAS). However, the significance of bilateral high SI in the ED remains unknown. The present study aimed to compare the correlation between SI in the ED and the clinical manifestations in various otological disorders and consider the significance of the MRI findings. STUDY DESIGN: Retrospective study. SETTING: University hospital. PATIENTS: The study included 2,450 ears from 1,225 patients with various otological disorders. INTERVENTION: All ears underwent 3T enhanced MRI and were evaluated for the degree of endolymphatic hydrops (EH) and the SI ratios (SIRs; i.e., the calculation between SIs in the ED and those in the cerebellum). MAIN OUTCOME MEASURE: The imaging findings were compared with their clinical symptoms. RESULTS: Ears with bilateral high SIRs in the ED tended to have considerably less occurrence of EH in both the cochlea and vestibule than those with bilateral low SIRs. Ears with SIR ≥8 showed significantly elevated hearing thresholds at lower frequencies on pure-tone audiometry, although they exhibited a markedly lower incidence of cochlear EH than those with SIR <8. Moreover, ears with vertigo exhibited notably higher SIRs than those without vertigo. CONCLUSION: Bilateral high SI in the ED on MRI may reflect pathophysiology underlying sensorineural hearing loss and vestibular symptoms, which are not associated with EH formation.

Efficacy of 100 hz sound stimulation on saccular dysfunction in meniere's disease.

BACKGROUND: Although various medical remedies have been attempted to alleviate the symptoms of Meniere's disease (MD), the risk-benefit ratios of these various treatments remain debatable. OBJECTIVE: We investigated the efficacy of sound stimulation of 100 Hz for treating vestibular dysfunction in patients with Meniere's disease (MD). MATERIALS AND METHODS: Patients with definitive MD with intractable vestibular symptoms and endolymphatic hydrops (EH) in the inner ear were evaluated. The experimental group received sound stimulation of 75 dB at a frequency of 100 Hz for 5 min, and the control group received sound stimulation of 75 dB at a frequency of 250 Hz for 5 min. Cervical vestibular-evoked myogenic potentials (cVEMPs) were measured before and after each sound stimulation, and the results of the clinical tests were compared between the two patient groups. RESULTS: Significant increases in cVEMP amplitudes were observed after sound stimulation of 100 Hz in ears with vestibular endolymphatic hydrops, although no such improvement was observed in the control group. CONCLUSION: Sound stimulation of 75 dB at a frequency of 100 Hz leads to improvement in cVEMP amplitude in patients with definitive MD. Adequate sound stimulation might be a new method for treating vestibular dysfunction associated with MD.

Lifestyle habits and examination findings before and during the COVID-19 pandemic: From health checkups in a rural area in Japan.

Aim: Few health checkup studies have reported lifestyle habits and examination results before and during the COVID-19 pandemic. We compared lifestyle habits and examination results surveyed before and during the COVID-19 pandemic. Methods: Five hundred and ten and 396 participants attended the health checkup in 2019 and 2022, respectively. The median age of females was 65 in 2019 and 2022, and that of males was 68 in 2019 and 69 in 2022. We investigated dietary and exercise habits, alcohol consumption, sleeping situation, and examination results, including body mass index (BMI), smell function, and blood examination results before and during the COVID-19 pandemic in a rural area in Japan. Results: An ordinal logistic regression analysis revealed that the intake frequency of vegetables and marine products was significantly less in 2022 than in 2019 after adjusting age and sex; green leafy vegetables (p = .016), fish (p = .002), and other marine products, including squid, shrimp, crabs, and octopus (p = .008). Alcohol consumption amount increased significantly in 2022 than in 2019 in men who drank beer (p = .007) and chuhai (p = .040). Albumin, hematocrit, cholesterols, and uric acid decreased, but serum calcium increased significantly in 2022 than in 2019 after adjusting age and sex. BMI and hemoglobin A1c were not significantly different between 2019 and 2022. A decrease in subjective smell feeling and smell test results was associated with decreased intake frequency of vegetables. Conclusion: Both dietary habits and blood examination results changed significantly during the COVID-19 pandemic in a rural area in Japan.

Direct Visualization of Tracer Permeation into the Endolymph in Human Patients Using MR Imaging.

PURPOSE: The endolymph of the inner ear, vital for balance and hearing, has long been considered impermeable to intravenously administered gadolinium-based contrast agents (GBCAs) due to the tight blood-endolymph barrier. However, anecdotal observations suggested potential GBCA entry in delayed heavily T2-weighted 3D-real inversion recovery (IR) MRI scans. This study systematically investigated GBCA distribution in the endolymph using this 3D-real IR sequence. METHODS: Forty-one patients suspected of endolymphatic hydrops (EHs) underwent pre-contrast, 4-h, and 24-h post-contrast 3D-real IR imaging. Signal intensity in cerebrospinal fluid (CSF), perilymph, and endolymph was measured and analyzed for temporal dynamics of GBCA uptake, correlations between compartments, and the influence of age and presence of EH. RESULTS: Endolymph showed a delayed peak GBCA uptake at 24h, contrasting with peaks in perilymph and CSF at 4h. Weak to moderate positive correlations between endolymph and CSF contrast effect were observed at both 4 (r = 0.483) and 24h (r = 0.585), suggesting possible inter-compartmental interactions. Neither the presence of EH nor age significantly influenced endolymph enhancement. However, both perilymph and CSF contrast effects significantly correlated with age at both time points. CONCLUSION: This study provides the first in vivo systematic confirmation of GBCA entering the endolymph following intravenous administration. Notably, endolymph uptake peaked at 24h, significantly later than perilymph and CSF. The lack of a link between endolymph contrast and both perilymph and age suggests distinct uptake mechanisms. These findings shed light on inner ear fluid dynamics and their potential implications in Ménière's disease and other inner ear disorders.

Imaging evaluation and volumetric measurement of the space surrounding the diploic veins.

PURPOSE: The diploic veins have been suggested to be involved in the excretion of cerebrospinal fluid and intracranial waste products; however, to date, there have been no reports evaluating the space surrounding the diploic veins. Therefore, we aimed to visualize the distribution of gadolinium-based contrast agent (GBCA) in the space surrounding the diploic veins and to evaluate the spatial characteristics. MATERIALS AND METHODS: Ninety-eight participants (aged 14-84 years) were scanned 4 h after intravenous GBCA injection at Nagoya University Hospital between April 2021 and December 2022. The volume of the space surrounding the diploic veins where the GBCA was distributed was measured using contrast-enhanced T1-weighted images with the application of three-axis motion-sensitized driven equilibrium. The parasagittal dura (PSD) volume adjacent to the superior sagittal sinus was also measured using the same images. Both volumes were corrected for intracranial volume. The correlation between age and the corrected volume was examined using Spearman's rank correlation coefficient; the relationship between the corrected volume and sex was assessed using the Mann-Whitney U test. RESULTS: A significant weak negative correlation was observed between the volume of the space surrounding the diploic veins and age (r = -0.330, p < 0.001). Furthermore, there was a significant weak positive correlation between the PSD volume and age (r = 0.385, p < 0.001). Both volumes were significantly greater in men than in women. There was no correlation between the volume of the space surrounding the diploic veins and the volume of the PSD. CONCLUSION: The volume of the space surrounding the diploic veins was measurable and, in contrast to the volume of the PSD, was greater in younger participants. This space may be related to intracranial excretory mechanisms and immune responses during youth, requiring further research.

Clinical significance of posterior expansion of the utricular endolymphatic space.

BACKGROUND: Posterior expansion of the utricular endolymphatic space (ES) is a finding occasionally observed, and often occurs in bilateral ears. The clinical significance of posterior expansion of the utricular ES is not clear. OBJECTIVES: To investigate the clinical significance of posterior expansion of the utricular ES detected on magnetic resonance imaging (MRI). MATERIALS AND METHODS: Among 957 patients who underwent contrast-enhanced MRI to investigate the presence of endolymphatic hydrops (EH), clinical findings in cases with posterior expansion of the utricular ES were evaluated and the significance of their existence is considered. RESULTS: Posterior expansion of the utricular ES was detected in 30 ears from 20 cases (7 males, 13 females; mean age 48.7 years). The ears with posterior expansion had a significantly lower incidence of vestibular EH than those without, and this tendency was more prominent in cases in bilateral ears. Some cases with posterior expansion had vestibular symptoms and were diagnosed with Ménière's disease, although EH was not detected in their vestibules. CONCLUSION AND SIGNIFICANCE: Posterior expansion of the utricular ES was associated with Ménière's disease without vestibular EH. Posterior expansion of the utricular ES might not be associated with the formation of EH but may occur independently.

Improvement of vertigo symptoms and acoustic power absorbance in cases with endolymphatic hydrops.

Objective: The pathophysiology and symptoms underlying Meniere's disease (MD) manifest as endolymphatic hydrops (EH), potentially impacting acoustic power absorbance in vestibular EH. The longitudinal effects of middle ear pressure therapy (MEPT) and conservative therapies for EH by magnetic resonance imaging (MRI) and on acoustic power absorbance on wideband acoustic immittance (WAI) were evaluated, and their changes were compared with clinical symptoms. Methods: Eleven patients with definite MD or delayed endolymphatic hydrops (DEH), resistant to conservative therapies and who continued MEPT for 1 year, were included. Vertigo scores, hearing levels, acoustic power absorbance on WAI, and degrees of EH on 3-T MRI were evaluated and compared before and after the treatments. Results: One year after the start of MEPT, all cases showed symptomatic improvement in vertigo score; however, the degrees of EH showed no improvements except in one case. In the affected ears with EH, their absorbances on WAI improved, particularly at 1580-1905 or 2400-2953 Hz (p < .05). Conclusion: Alleviation of vestibular symptoms with the therapy of MD was not necessarily associated with improved EH. Vestibular symptoms could be related to the change in the impedance of inner ear pressure, which was proven by the normalization of acoustic power absorbance. Assessments of acoustic power absorbance may provide useful information for physiological conditions and causative factors of vertigo in ears with EH. Level of evidence: 4.

Association between the Putative Meningeal Lymphatics at the Posterior Wall of the Sigmoid Sinus and Delayed Contrast-agent Elimination from the Cerebrospinal Fluid.

PURPOSE: To investigate the characteristics of the putative meningeal lymphatics located at the posterior wall of the sigmoid sinus (PML-PSS) in human subjects imaged before and after intravenous administration (IV) of a gadolinium-based contrast agent (GBCA). The appearance of the PML-PSS and the enhancement of the perivascular space of the basal ganglia (PVS-BG) were analyzed for an association with gender, age, and clearance of the GBCA from the cerebrospinal fluid (CSF). METHODS: Forty-two patients with suspected endolymphatic hydrops were included. Heavily T2-weighted 3D-fluid attenuated inversion recovery (hT2w-3D-FLAIR) and 3D-real inversion recovery (IR) images were obtained at pre-administration, immediately post-administration, and at 4 and 24 hours after IV-GBCA. The appearance of the PML-PSS and the presence of enhancement in the PVS-BG were analyzed for a relationship with age, gender, contrast enhancement of the CSF at 4 hours after IV-GBCA, and the washout ratio of the GBCA in the CSF from 4 to 24 hours after IV-GBCA. RESULTS: The PML-PSS and PVS-BG were seen in 23 of 42 and 21 of 42 cases, respectively, at 4 hours after IV-GBCA. In all PML-PSS positive cases, hT2w-3D-FLAIR signal enhancement was highest at 4 hours after IV-GBCA. A multivariate analysis between gender, age, CSF signal elevation at 4 hours, and washout ratio indicated that only the washout ratio was independently associated with the enhancement of the PML-PSS or PVS-BG. The odds ratios (95% CIs; P value) were 4.09 × 10-5 (2.39 × 10-8 - 0.07; 0.0078) for the PML-PSS and 1.7 × 10-4 (1.66 × 10-7 - 0.174; 0.014) for the PVS-BG. CONCLUSION: The PML-PSS had the highest signal enhancement at 4 hours after IV-GBCA. When the PML-PSS was seen, there was also often enhancement of the PVS-BG at 4 hours after IV-GBCA. Both observed enhancements were associated with delayed GBCA excretion from the CSF.

Association between Locomotive Syndrome and Hearing Loss in Community-Dwelling Adults.

The relationship between hearing and motor function as a function of aging is unclear. Therefore, we aimed to clarify the relationship between age-related hearing loss and locomotive syndrome. In total, 240 participants aged ≥40 years, whose hearing acuity and motor function had been measured, were included in this study. Patients with a hearing acuity of <35 dB and ≥35 dB were categorized into normal and low hearing acuity groups, respectively. Motor function was compared according to sex between the groups. Among men, those in the low hearing acuity group (51/100) were older, had a significantly slower walking speed, and had a higher prevalence of locomotive syndrome than those in the normal group. Among women, those in the low hearing group (14/140) were older and had a significantly slower gait speed than those in the normal group. The multivariate analysis showed that, in the low hearing acuity group, age and gait speed were risk factors in men, while age was the only risk factor in women. In conclusion, hearing loss was associated with walking speed. The association between hearing loss and locomotive syndrome was observed only in men. In the multivariate analysis, hearing loss was associated with walking speed only in men.

Evaluation of the Listening Environment of Bilateral Cochlear Implant Users through Data Logging: A Comparison of Bilateral Simultaneous and Sequential Implantation.

OBJECTIVE: To evaluate the listening conditions of bilateral cochlear implant (CI) users in their daily living environment. STUDY DESIGN: Retrospective study. SETTING: University hospital. PATIENTS: Thirty-one adult CI users 16 years or older; 18 underwent sequential surgery, and 13 underwent simultaneous surgery. Inclusion criteria included the availability of CI data logging features and a minimum duration of binaural use of 6 months. INTERVENTION: Retrospective analysis of data obtained from the automatic scene classifier data logging system. MAIN OUTCOME MEASURE: Comparison of data logging and maximum speech discrimination scores of the two surgery groups (sequential vs. simultaneous) to investigate the potential influence of these factors on the listening conditions of CI users. RESULTS: The maximum speech discrimination score of the second CI in the sequential group was significantly worse than that of any other CI in the sequential and simultaneous CI groups. Additionally, the longer the interval between surgeries, the more significant the difference in "time on air" between the first and the second CIs. The second CI in sequential CI surgery had a shorter "time on air" than the first or the bilateral simultaneous CIs; the second CI was also used more frequently in noisy and speech with background noise environments. CONCLUSIONS: A second CI may be more frequently used in challenging listening environments because of its binaural auditory effect, despite its lower speech discrimination performance. The timing of sequential implantation and the potential impact of binaural hearing should be considered when developing rehabilitation strategies for individuals with bilateral CIs.

Comparative Analysis of Cartilage Conduction Hearing Aid Users and Non-Users: An Investigative Study.

Clinical findings on cartilage conduction hearing aids (CCHAs) have gradually become clear; however, few reports include a large number of cases. This study included 91 ears from 69 patients who underwent CCHA fitting in our hospital. Their ears were divided into six groups (i.e., bilateral aural atresia or severe canal stenosis, unilateral aural atresia or severe canal stenosis, chronic otitis media or chronic otitis externa with otorrhea, sensorineural hearing loss, mixed hearing loss, and conductive hearing loss) according to their clinical diagnosis and type of hearing loss. Most clinical diagnoses were aural atresia or meatal stenosis (bilateral, 21.8%; unilateral, 39.6%). The purchase rate of CCHAs was higher in the closed-ear group (bilateral, 77.3%; unilateral, 62.5%). In the bilateral closed-ear group, air conduction thresholds at 1000, 2000, and 4000 Hz and aided thresholds with CCHAs at 4000 Hz were significantly lower in the purchase group than the non-purchase group. No significant difference was observed between the purchase and non-purchase groups in the unilateral closed-ear group. In the bilateral closed-ear group, air conduction thresholds and aided thresholds were associated with the purchase rate of CCHAs. In the unilateral closed-ear group, factors other than hearing might have affected the purchase rate of CCHAs.

Significance of an augmented response on cervical vestibular evoked myogenic potential testing in Meniere's disease.

The potential mechanism of augmented response on cervical vestibular evoked myogenic potential (cVEMP) testing and its decrease following treatment in a patient with Meniere's disease (MD) are discussed. Changes of static posturography and cVEMP testing before and after a glycerol drip in a 69-year-old man with unilateral MD, in which significant endolymphatic hydrops (EH) was confirmed on magnetic resonance imaging (MRI) on the diseased side, were evaluated. Values of total locus lengths, areas of postural sway, and their Romberg ratios were decreased after the glycerol drip. On cVEMP testing, the diseased ear demonstrated a 375% larger amplitude than the contralateral ear before treatment, but both ears showed almost the same responses after treatment. An augmented response on cVEMP testing and a decrease following treatment for MD reflect the diversity of clinical findings in MD. Responses on cVEMP testing may relate not only to the degree of EH, but also be due to abnormal acoustic energy absorbance transmitted into the saccule.

Relationship between tinnitus and olfactory dysfunction: audiovisual, olfactory, and medical examinations.

Introduction: Sensory dysfunctions and cognitive impairments are related to each other. Although a relationship between tinnitus and subjective olfactory dysfunction has been reported, there have been no reports investigating the relationship between tinnitus and olfactory test results. Methods: To investigate the relationship between tinnitus and olfactory test results, we conducted sensory tests, including hearing and visual examinations. The subjects included 510 community-dwelling individuals (295 women and 215 men) who attended a health checkup in Yakumo, Japan. The age of the subjects ranged from 40 to 91 years (mean ± standard deviation, 63.8 ± 9.9 years). The participants completed a self-reported questionnaire on subjective tinnitus, olfactory function, and hearing function, as well as their lifestyle. The health checkup included smell, hearing, vision, and blood examinations. Results: After adjusting for age and sex, the presence of tinnitus was significantly associated with subjective olfactory dysfunction, poor olfactory test results, hearing deterioration, vertigo, and headache. Additionally, high serum calcium levels and a low albumin/globulin ratio were significantly associated with low physical activity and nutrition. Women scored higher than men in olfactory and hearing examinations, but there was no gender difference in vision examinations. Conclusion: Subjective smell dysfunction and poor smell test results were significantly associated with tinnitus complaints. Hearing and vision were associated even after adjusting for age and sex. These findings suggest that evaluating the mutual relationships among sensory organs is important when evaluating the influence of sensory dysfunctions on cognitive function.

Pathophysiological analysis of idiopathic sudden sensorineural hearing loss by magnetic resonance imaging: A mini scoping review.

Objective: To summarize the pathophysiological analysis of idiopathic sudden sensorineural hearing loss (ISSNHL) by magnetic resonance imaging (MRI), focusing on the findings of high signal or endolymphatic hydrops (EH) in the inner ear. Methods: We summarize the published studies of our research group regarding the pathophysiological analysis of ISSNHL on MRI and review related clinical articles that have reported significantly high signal or the existence of EH in ears with ISSNHL. Results: Pre-contrast high signal on MRI may indicate minor hemorrhage or increased permeability of surrounding vessels to the perilymph, whereas post-contrast high signal indicates breakdown of the blood-labyrinth barrier, in which irreversible changes would lead to poor prognosis. In some cases of ISSNHL, primary EH could be pre-existing and may be a risk factor for the onset of ISSNHL. Conclusion: Analysis of ISSNHL by cutting-edge MRI evaluation could provide useful information for elucidating its pathophysiology and for predicting prognosis in this disease.

Presence of endolymphatic hydrops on listening difficulties in patients with normal hearing level.

BACKGROUND: Listening difficulties (LiD) present difficulties in listening and paying attention to spoken information despite normal pure tone audiometry. Endolymphatic hydrops (EH) is a common inner ear condition associated with Ménière's disease but may also be present in the asymptomatic ear. OBJECTIVES: Using magnetic resonance imaging, we investigated EH in patients with LiD and assessed whether the severity of EH was related to the results of auditory processing tests (APTs). MATERIALS AND METHODS: 111 patients with no abnormalities on pure tone audiometry, but displaying difficulties in listening, underwent evaluation through APTs and questionnaires. Upon obtaining informed consent, the inner ears of 20 consenting patients were evaluated utilizing a 3-Tesla magnetic resonance imaging. RESULTS: A higher percentage of patients diagnosed with LiD by APTs had significant EH in the cochlea and vestibule than in previously reported control cases. The percentage of correct answers in the speech-in-noise test was significantly lower in patients with than in those without significant EH. CONCLUSION AND SIGNIFICANCE: In this study, significant EH of the cochlea was associated with poor listening to noise. The presence of EH affects the functioning of the auditory processing system, even in ears that test normally on standard audiometric tests.

Surgical Strategy for Squamous Cell Carcinoma of the External Auditory Canal: Management of Locally Advanced Cases with Skull Base Involvement.

Objective Surgical indications for advanced-stage squamous cell carcinoma (SCC) of the external auditory canal (EAC) are highly dependent on the skull base surgery team. The aim of this study was to evaluate the surgical outcomes in patients with SCC of the EAC and to clarify the surgical indication of far advanced cases using the T4 subclassification. Methods Patients with SCC of the EAC who underwent curative treatment from 2002 to 2021 at our hospital were retrospectively reviewed. Clinical and surgical results, including operative data, overall survival (OS), and disease-specific survival (DSS), were analyzed. To clarify the surgical indication for advanced-stage tumors, we proposed the T4 subclassification. Results In the 46 patients included in the study, 8 patients had T1 tumors, 10 had T2 tumor, 5 had T3 tumors, and 23 had T4 tumors. The 5-year DSS with T1, T2, T3, and T4 tumors were 100, 85.7, 100, and 61.7%, respectively. No prognostic impacts for margin status were found between the 5-year OS and DSS ( p = 0.23 and 0.13, respectively). Patients with far-advanced-stage (T4b) tumors were significantly associated with shorter DSS than those with early-stage (T1/T2) and advanced-stage (T3/T4a) tumors ( p = 0.007 and 0.03, respectively). Conclusion The present study focused on patients with SCC of the EAC at a university hospital over a period of 20 years, especially with skull base involvement, and a T4 subclassification was proposed. Complete tumor resection in an en bloc fashion could help achieve a good survival rate even in patients with locally advanced tumors.