Long-term outcome of patients with Ménière's disease following cochlear implantation: a comprehensive outcome study with validated assessment tools.

PURPOSE: Patients suffering from Ménière's disease (MD) experience vertigo, and impairments in hearing and quality of life (QoL). This study aims to investigate the impact of cochlear implantation (CI) on various aspects affecting patients with MD. METHODS: A single tertiary centre's CI database for CI recipients with MD between 2014 and 2022 was screened retrospectively. Hearing, vertigo, tinnitus symptoms, and hearing-related QoL were assessed. Pre- and postoperative hearing tests in conjunction with subjective outcome measures by visual analogue scale (VAS) and validated tools such as the Dizziness Handicap Inventory (DHI), Tinnitus Handicap Inventory (THI) and Nijmegen Cochlear Implant Questionnaire (NCIQ), as well as the assessment of the pre- and postoperative Functional Level Scale (FLS) were examined. RESULTS: Eleven ears were included (median age: 59 years at implantation). Following implantation, there was a significant enhancement in Word Recognition Scores at sound levels of 65 dB and 80 dB compared to before treatment (preop vs. 12 months postop: p = 0.012). However, no significant enhancement was observed for 50 dB. MD-related impairments improved significantly postoperatively, as measured by the VAS (vertigo: p = 0.017; tinnitus: p = 0.042), DHI (p = 0.043), THI (p = 0.043) and NCIQ (p < 0.001). The FLS improved significantly (p = 0.020). CONCLUSION: CI has positive effects on all areas examined in our cohort. However, discrimination of speech at low sound pressure levels remained problematic postoperatively. In patients suffering from MD, the prioritized treatment goals include not only improved hearing but also the rehabilitation of vertigo and tinnitus, as well as the enhancement of QoL. Validated instruments are useful screening tools.

[How much digitization do ENT curricula need? : Opportunities and limits from the perspective of students and teachers]. / Wieviel Digitalisierung braucht die HNO-Lehre? : Chancen und Grenzen aus Sicht von Studierenden und Lehrenden.

BACKGROUND: Digitalization has long been an integral part of students' everyday lives and increasingly also of their medical training. It seems to be an unwritten law that "digital natives" want as much digitalization as possible. This study aims to shed more light on how students in the clinical phase of medical studies perceive the increasing digitalization of teaching and what they need for good education. MATERIALS AND METHODS: This study analyzed two surveys that were conducted using an online questionnaire. On the one hand, students in the 5th-9th semesters of the medical faculty at the University of Hamburg (n = 282) were surveyed (survey 1). Another survey addressed all employees of ENT clinics in Germany (n = 175; survey 2). RESULTS: A total of 76 students took part in survey 1 and 123 lecturers in survey 2. The results show that both students and lecturers do not want face-to-face teaching to be completely replaced by digital formats. A total of 72.7% of students reject the possibility of teaching practical skills through digital formats. The majority of students surveyed stated that offline formats improve their concentration (61.1%), participation probability (63.9%), and motivation to learn (76.6%). In contrast, 40.2% of lecturers see digitalization as a way to reduce the workload without any relevant loss in teaching quality. CONCLUSION: Digital teaching formats have a negative impact on the medical education of the students surveyed. Interaction and physical presence are needed to increase the motivation to learn. This leads to the first conclusion that students are critical of the increasing digitalization of medical studies.

Cholesteatoma Severely Impacts the Integrity and Bone Material Quality of the Incus.

Cholesteatoma can lead to progressive destruction of the auditory ossicles along with conductive hearing loss but precise data on the microstructural, cellular, and compositional aspects of affected ossicles are not available. Here, we obtained incus specimens from patients who had cholesteatoma with conductive hearing loss. Incudes were evaluated by micro-computed tomography, histomorphometry on undecalcified sections, quantitative backscattered electron imaging, and nanoindentation. Results were compared with two control groups taken from patients with chronic otitis media as well as from skeletally intact donors at autopsy. The porosity of incus specimens was higher in cholesteatoma than in chronic otitis media, along with a higher osteoclast surface per bone surface. Histomorphometric assessment revealed higher osteoid levels and osteocyte numbers in cholesteatoma incudes. Incudes affected by cholesteatoma also showed lower matrix mineralization compared with specimens from healthy controls and chronic otitis media. Furthermore, the modulus-to-hardness ratio was higher in cholesteatoma specimens compared with controls. Taken together, we demonstrated increased porosity along with increased osteoclast indices, impaired matrix mineralization, and altered biomechanical properties as distinct features of the incus in cholesteatoma. Based on our findings, a possible impact of impaired bone quality on conductive hearing loss should be further explored.

[Validity of the German Menière's Disease Patient-Oriented Symptom Severity Index]. / Validierung des deutschsprachigen Menière's Disease Patient-Oriented Symptom Severity Index.

BACKGROUND: The MD POSI is a disease-specific questionnaire to determine the health-related quality of life (HRQoL) of patients with Menière's disease (MD). OBJECTIVES: Validity and reliability of the German translation of the MD POSI. MATERIAL AND METHODS: Prospective data analysis of a patient group with vertigo (n = 162), which was treated in the otorhinolaryngology of a University Hospital from 2005-2019. A clinical selection was made according to the new Bárány classification in a "definite" and "probable" Menière's disease. HRQoL was assessed using the German translation of the MD POSI, the Vertigo Symptom Score (VSS) and the Short Form (SF-36). Reliability was measured by Cronbach's α and test-retesting after 12 months and again 2 weeks later. Content and agreement validity were examined. RESULTS: Cronbach α values greater than 0.9 indicated good internal consistency. There was no statistically significant difference from baseline to 12 months, except for the subscore "during the attack". There were significant positive correlations between the VSS overall/VER/AA and the overall index of the MD POSI and negative significant correlations with the SF-36 domains physical functioning, physical role functioning, social functioning, emotional role functioning, mental well-being. There were low SRM (standardized response mean) values below 0.5. CONCLUSIONS: The German translation of the MD POSI is a valid and reliable instrument to evaluate the impact of MD on patients' disease-specific quality of life.

Cross-cultural adaptation and validation of the 22-item sinonasal outcome test (SNOT-22) in German-speaking patients: a prospective, multicenter cohort study.

PURPOSE: Chronic rhinosinusitis (CRS) is a common condition associated with a significant reduction of the health-related quality of life. One of the most widely used assessment tools in CRS is the disease-specific, health-related questionnaire SNOT-22. The aim of this study was to translate and validate the SNOT-22 into the German language. METHODS: The questionnaire was translated using the forward-backward translation technique. After the translation its reliability, validity, and sensitivity were evaluated. For this purpose, the questionnaire was completed by patients diagnosed with CRS before, 3 months and 1 year after endoscopic sinus surgery and by healthy individuals as controls at three university hospitals in Germany. The individual scores of the questionnaire before surgery was correlated with the Lund-Mackay score as well as a global disease-specific question. RESULTS: A total of 139 CRS patients and 31 healthy individuals participated in the study. Internal consistency at all timepoints was very good, with Cronbach's alpha scores of 0.897, 0.941, and 0.945. The questionnaire was able to discriminate between CRS patients and control subjects (p < 0.0001) and scores improved significantly 3 month and 1 year after sinus surgery (p < 0.0001), indicating a good test-retest reliability, validity, and responsiveness. A significant correlation to the single global disease-specific question could be found (p < 0.0001), but no correlation with the Lund-Mackay score. CONCLUSION: The German Version of the SNOT-22 is a reliable, valid, and sensitive instrument for measuring health-related quality of life in patients with CRS. It can be recommended for clinical practice and outcome research for German-speaking patients.

Prospective study on health-related quality of life in patients before and after cochlear implantation.

PURPOSE: Assessing cochlear implant (CI)-associated patient outcomes is a focus of implant research. Most studies have analyzed outcomes retrospectively with low patient numbers and few measurement time points. In addition, standardized CI-specific health-related quality of life (HRQoL) instruments have not been used. To address this, we prospectively assessed HRQoL in patients before and after implantation. METHODS: We assessed HRQoL using the Nijmegen Cochlear Implant Questionnaire (NCIQ), Abbreviated Profile of Hearing Aid Benefit (APHAB), Hearing Participation Scale (HPS), and the Visual Analogue Scale (VAS) in 100 deaf or severely hearing-impaired patients (57 unilaterally deaf and 43 bilaterally deaf) before and 3, 6, and 12 months after cochlear implantation. We compared the results of unilaterally and bilaterally hearing-impaired patients and patients with or without a hearing aid. Principal component (PCA) and exploratory factor analyses (EFA) were also conducted. RESULTS: The NCIQ measured improvements in all 6 domains after CI and correlated well with other QoL instruments. The PCA revealed that the NCIQ can be better explained by physical, physical advanced, and socio-psychological components. The APHAB score ameliorated over time, except for the background noise domain. The overall HPS score improved over time, but the hearing handicap subscore significantly decreased. Sociodemographic influences on the questionnaire scores were relatively weak. CONCLUSION: Assessing HRQoL is essential for quantifying the patient outcome after CI. NCIQ scores in our patient cohort showed improved HRQoL in all domains and we recommend that the NCIQ be used as a first-line questionnaire for assessing QoL in hearing-impaired patients after CI.

[Validity and reliability of the Nijmegen Cochlear Implant Questionnaire in German]. / Validierung und Reliabilitätsprüfung des Nijmegen Cochlear Implant Questionnaire in deutscher Sprache.

BACKGROUND: The Nijmegen Cochlear Implant Questionnaire (NCIQ) is a disease-specific questionnaire to determine the health-related quality of life (HRQoL) of patients before and after cochlear implantation. OBJECTIVE: This study aimed to assess the validity and reliability of the German translation of the NCIQ. MATERIALS AND METHODS: A prospective study was performed in 100 postlingually deaf or severely hearing-impaired patients. HRQoL was assessed using the NCIQ, the Abbreviated Profile of Hearing Aid Benefit (APHAB), and the Hearing Participation Scale (HPS) before as well as 3 and 6 months after cochlear implantation. An untreated group of postlingually deaf or severely hearing-impaired patients (n = 54) served as a control. Cronbach's α and test-retest reliability were measured. The content, discrimination, and agreement validity were tested. The evaluation of construct validity was based on recently published data. Sensitivity and receiver operating curve (ROC) analysis, including consideration of the area under the curve (AUC), were used as quality criteria. RESULTS: The test-retest analysis showed stable NCIQ values 3 and 6 months postoperatively. The Cronbach's α values indicated good internal consistency. The NCIQ validly discriminated between treated and untreated patient groups. There were statistically significant albeit weak correlations between the NCIQ and the APHAB (r = -0.22; p = 0.04) and the HPS (r = 0.30; p = 0.01). Sensitivity and ROC analyses showed good measurement quality of the German-speaking NCIQ. CONCLUSION: The German translation of the NCIQ reliably and validly measures HRQoL before and after cochlear implantation and can be used for clinical monitoring after treatment with cochlear implants.

Living with otosclerosis: disease-specific health-related quality-of-life measurement in patients undergoing stapes surgery.

INTRODUCTION: Otosclerosis is associated with hearing disability, leading to communication deficits and social and psychological restrictions. The objective of our study was to analyze disease-specific health-related quality of life (HRQOL) after stapes surgery and compare the outcome of HRQOL with audiometric parameters. SUBJECTS AND METHODS: Our clinical case study was conducted at two tertiary referral centers. All the 37 patients who had undergone stapes surgery were analyzed clinically and by audiometric testing (pure tone and speech audiometry) in the pre- and postoperative settings. Disease-specific HRQOL was assessed by the validated Stapesplasty Outcome Test 25 (SPOT-25) pre- and postoperatively. The subjective hearing disability was evaluated by the hearing handicap inventory for adults (HHIA). The postinterventional benefit was measured by the Glasgow Benefit Inventory (GBI). RESULTS: Disease-specific HRQOL improved significantly after stapes surgery in all scales of the SPOT-25. Postoperatively, the total score and the subscore "hearing function" correlated well with the audiometric data. The subscores "tinnitus", "social restrictions", and "mental condition" did not show significant association with audiometric parameters. The comparison of pre- and postoperative HHIA offered a significant improvement in the hearing disability. The scores of the HHIA correlated very well with the audiometric data. The GBI showed a postoperative benefit for each individual patient. CONCLUSION: Stapes surgery leads to a significant improvement in the hearing handicap and of disease-specific HRQOL. The audiometric parameters were shown as not being a sufficient indicator of social and mental well-being. HRQOL outcome measuring instruments should be used routinely in clinical practice to provide an individualized postoperative assessment.

Cochlear NMDA receptors as a therapeutic target of noise-induced tinnitus.

BACKGROUND: Accumulating evidence suggests that tinnitus may occur despite normal auditory sensitivity, probably linked to partial degeneration of the cochlear nerve and damage of the inner hair cell (IHC) synapse. Damage to the IHC synapses and deafferentation may occur even after moderate noise exposure. For both salicylate- and noise-induced tinnitus, aberrant N-methyl-d-aspartate (NMDA) receptor activation and related auditory nerve excitation have been suggested as origin of cochlear tinnitus. Accordingly, NMDA receptor inhibition has been proposed as a pharmacologic approach for treatment of synaptopathic tinnitus. METHODS: Round-window application of the NMDA receptor antagonist AM-101 (Esketamine hydrochloride gel; Auris Medical AG, Basel, Switzerland) was tested in an animal model of tinnitus induced by acute traumatic noise. The study included the quantification of IHC ribbon synapses as a correlate for deafferentation as well as the measurement of the auditory brainstem response (ABR) to close-threshold sensation level stimuli as an indication of sound-induced auditory nerve activity. RESULTS: We have shown that AM-101 reduced the trauma-induced loss of IHC ribbons and counteracted the decline of ABR wave I amplitude generated in the cochlea/auditory nerve. CONCLUSION: Local round-window application of AM-101 may be a promising therapeutic intervention for the treatment of synaptopathic tinnitus.

Face, Content, and Construct Validity of a Virtual Reality Otoscopy Simulator and Applicability to Medical Training.

OBJECTIVE: Otologic diseases are common in all age groups and can significantly impair the function of this important sensory organ. To make a correct diagnosis, the correct handling of the otoscope and a correctly performed examination are essential. A virtual reality simulator could make it easier to teach this difficult-to-teach skill. The aim of this study was to assess the face, content, and construct validity of the novel virtual reality otoscopy simulator and the applicability to otologic training. STUDY DESIGN: Face and content validity was assessed with a questionnaire. Construct validity was assessed in a prospectively designed controlled trial. SETTING: Training for medical students at a tertiary referral center. METHOD: The questionnaire used a 6-point Likert scale. The otoscopy was rated with a modified Objective Structured Assessment of Technical Skills. Time to complete the task and the percentage of the assessed eardrum surface were recorded. RESULTS: The realism of the simulator and the applicability to medical training were assessed across several items. The ratings suggested good face and content validity as well as usefulness and functionality of the simulator. The otolaryngologists significantly outperformed the student group in all categories measured (P < .0001), suggesting construct validity of the simulator. CONCLUSION: In this study, we could demonstrate face, content, and construct validity for a novel high-fidelity virtual reality otoscopy simulator. The results encourage the use of the otoscopy simulator as a complementary tool to traditional teaching methods in a curriculum for medical students.

Decalcification method for nondestructive exposure of human inner ear specimens using ultrasonic EDTA scrubbing.

Owing to the density of the surrounding bone, preparation for histological preparation of the delicate inner ear is difficult and time-consuming; long preparation time increases the risk of deterioration. We present an EDTA decalcification method using an ultrasonic bath and microscopic removal of tissue along defined anatomical landmarks. Our method is rapid and enables preservation of delicate inner ear structures while minimizing the bony capsule. The reduction in volume made possible by our method creates ideal conditions for further processing with digital imaging techniques, in which the resolution is increased with reduced volume.

A direct comparison of voice pitch processing in acoustic and electric hearing.

In single-sided deafness patients fitted with a cochlear implant (CI) in the affected ear and preserved normal hearing in the other ear, acoustic and electric hearing can be directly compared without the need for an external control group. Although poor pitch perception is a crucial limitation when listening through CIs, it remains unclear how exactly the cortical processing of pitch information differs between acoustic and electric hearing. Hence, we separately presented both ears of 20 of these patients with vowel sequences in which the pitch contours were either repetitive or variable, while simultaneously recording functional near-infrared spectroscopy (fNIRS) and EEG data. Overall, the results showed smaller and delayed auditory cortex activity in electric hearing, particularly for the P2 event-related potential component, which appears to reflect the processing of voice pitch information. Both the fNIRS data and EEG source reconstructions furthermore showed that vowel sequences with variable pitch contours evoked additional activity in posterior right auditory cortex in electric but not acoustic hearing. This surprising discrepancy demonstrates, firstly, that the acoustic detail transmitted by CIs is sufficient to distinguish between speech sounds that only vary regarding their pitch information. Secondly, the absence of a condition difference when stimulating the normal-hearing ears suggests a saturation of cortical activity levels following unilateral deafness. Taken together, these results provide strong evidence in favour of using CIs in this patient group.

General and disease-specific quality of life in patients with chronic suppurative otitis media--a prospective study.

BACKGROUND: Chronic suppurative otitis media (CSOM) is frequently associated with symptoms of inflammation like discharge from the ear or pain. In many cases, patients suffer from hearing loss causing communication problems and social withdrawal. The objective of this work was to collect prospective audiological data and data on general and disease-specific quality of life with validated quality of life measurement instruments to assess the impact of the disease on health-related quality of life (HR-QOL). METHODS: 121 patients were included in the study. Patients were clinically examined in the hospital before and 6 months after surgery including audiological testing. They filled in the quality of life questionnaires SF-36 and Chronic Otitis Media Outcome Test 15 (COMOT-15) pre-operatively and 6 and 12 months post-operatively, respectively. RESULTS: Complete data records from 90 patients were available for statistical analysis. Disease-specific HR-QOL in patients with CSOM improved after tympanoplasty in all the scales of the COMOT-15. There was no difference in HR-QOL assessment between patients with mesotympanic respectively epitympanic CSOM. However, we did find the outcome to be worse in patients who received revision surgery compared with those receiving primary surgery. Audiometric findings correlated very well with the subscale hearing function from the COMOT-15 questionnaire. General HR-QOL measured with the SF-36 was not significantly changed by tympanoplasty. CONCLUSIONS: Tympanoplasty did lead to a significant improvement of disease-specific HR-QOL in patients with CSOM while general HR-QOL did not change. Very well correlations were found between the subscale hearing function from the COMOT-15 questionnaire and audiological findings. Revision surgery seems to be a predictor for a worse outcome.

Conductive Hearing Loss in the Hyp Mouse Model of X-Linked Hypophosphatemia Is Accompanied by Hypomineralization of the Auditory Ossicles.

X-linked hypophosphatemia (XLH) is a hereditary musculoskeletal disorder caused by loss-of-function mutations in the PHEX gene. In XLH, increased circulating fibroblast growth factor 23 (FGF23) levels cause renal phosphate wasting and low concentrations of 1,25-dihydroxyvitamin D, leading to an early clinical manifestation of rickets. Importantly, hearing loss is commonly observed in XLH patients. We present here data from two XLH patients with marked conductive hearing loss. To decipher the underlying pathophysiology of hearing loss in XLH, we utilized the Hyp mouse model of XLH and measured auditory brain stem responses (ABRs) and distortion product otoacoustic emissions (DPOAEs) to functionally assess hearing. As evidenced by the increased ABR/DPOAE threshold shifts in the mid-frequency range, these measurements indicated a predominantly conductive hearing loss in Hyp mice compared to wild-type (WT) mice. Therefore, we carried out an in-depth histomorphometric and scanning electron microscopic analysis of the auditory ossicles. Quantitative backscattered electron imaging (qBEI) indicated a severe hypomineralization of the ossicles in Hyp mice, evidenced by lower calcium content (CaMean) and higher void volume (ie, porosity) compared to WT mice. Histologically, voids correlated with unmineralized bone (ie, osteoid), and the osteoid volume per bone volume (OV/BV) was markedly higher in Hyp mice than WT mice. The density of osteocyte lacunae was lower in Hyp mice than in WT mice, whereas osteocyte lacunae were enlarged. Taken together, our findings highlight the importance of ossicular mineralization for hearing conduction and point toward the potential benefit of improving mineralization to prevent hearing loss in XLH. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Hearing Preservation Following Repeated Adenovector Delivery.

Factors influencing the damage to the inner ear can include the surgical approach used for vector delivery, the volume of vector used, the buffer that the vector is suspended in as well as the host response to the vector capsid and vector genes that are transferred. We evaluated the effect of Ad5 capsid adenovectors on hearing function after delivery to the perilymph of adult C57Bl/6 mice. Hearing was evaluated before surgery and 3 days post-surgery by auditory brain stem response (ABR) and distortion product otoacoustic emissions (DPOAE). A second group of mice underwent repeated delivery of adenovector two times to determine if a preliminary exposure to an Ad vector could induce an inflammatory response leading to further loss. The first adenovector (Ad.11D.LacZ) was delivered to the posterior semicircular canal or via round window. In the second surgery, a second adenovector (Ad.11D.gfp) was delivered to the horizontal semicircular canal. The functional outcome was tested prior, 7 days post first vector delivery, and 3 days post second vector delivery via ABR and DPOAE. Dual delivery via the semicircular canals resulted in preservation of hearing suggesting that pre-exposure to Ad5 capsid does not predispose to hearing loss. Delivery to the round window resulted in hearing loss that was worsened after the second vector delivery, suggesting that delivery route and prior injury to the inner ear rather than the repetition of delivery predisposes to further hearing loss. Anat Rec, 303:600-607, 2020. © 2019 American Association for Anatomy.

Bcl-2 gene therapy prevents aminoglycoside-induced degeneration of auditory and vestibular hair cells.

To evaluate the protective effects of bcl-2, we have developed an in vivo model of gentamicin ototoxicity in C57BL/6 mice using intratympanic delivery of gentamicin. Hair cell survival was evaluated using myosin VIIa immunohistochemistry, cytocochleogram and auditory brainstem response (ABR) testing. At 10 days after gentamicin application, a consistent loss of outer hair cells was seen. Mice were pretreated with an adenovector expressing human bcl-2 (Ad.11D.bcl-2) or a control vector (Ad.11D). Seventy-two hours after vector delivery mice were treated with intratympanic gentamicin and evaluated at 10 days after ototoxin delivery. Pretreatment with Ad.11D.bcl-2 resulted in morphologic protection of hair cells and preservation of hearing thresholds measured by ABR.

Efficient transfer of embryonic stem cells into the cochlea via a non-invasive vestibular route.

CONCLUSION: Cell transplantation into the utriculus provides an efficient and non-invasive route to introduce embryonic stem (ES) cells into the vestibular and cochlear portions of the inner ear. OBJECTIVE: The transfer of stem cells into the inner ear for therapeutic purposes is an important approach to cure damage to the cochlea and vestibulum. A key issue is to provide an entry point for cell transplants into the inner ear that does not affect its physiologic functions. The aim of this study was to examine the feasibility of transferring ES cells into the inner ear via the utriculus. MATERIALS AND METHODS: ES cells were injected via utriculostomy into the mouse inner ear. The distribution of the injected cells was determined using a beta-galactosidase marker gene expressed by the ES cells. RESULTS: Injected ES cells were found within the perilymph of the scala tympani and vestibuli. Moreover, ES cells were detected close to the cochlear sensory epithelium and spiral limbus.

Decompression illness reported in a survey of 429 recreational divers.

BACKGROUND: The purpose of this study was to investigate the influence of diving experience and diving techniques on the lifetime incidence of decompression illness (DCI). METHODS: Attendants of three diving medical symposia voluntarily answered a questionnaire about their age, gender, medical history, diving experience, diving habits, diving certification levels, and diving associated incidents (cross-sectional survey). RESULTS: Out of 650 divers, 429 completed the questionnaire. The study population consisted of experienced divers with an average of 670 dives. The majority of the divers were certified diving instructors (43%). There were 37 participants (8.7%) who were classified as technical divers with an average of 1193 logged dives. There was an overall lifetime incidence of DCI of 1 per 5463 dives. The complete study group showed an increased lifetime incidence of DCI with decreased diving experience (1.97-fold to 8.17-fold higher). Of the divers, 27% reported severe DCI with neurological symptoms. The lifetime incidence for severe DCI was 1 in 20,291 dives. Again, lifetime incidence for severe DCI was increased with decreased diving certification level (1.1-fold to 13.7-fold higher). Technical divers showed a DCI lifetime incidence of 1 to 8591 dives compared to the non-technical divers with a lifetime incidence of 1 to 5077 dives (not significant). CONCLUSION: In our study population, the lifetime incidence of DCI was increased in divers with less diving experience. If further studies confirm this finding, diving federations should be encouraged to intensify their efforts of educating divers and should limit diving time and depth in inexperienced divers.