Detection of Reduced Diameter of the Cochlear Nerve in Long-term Deaf Patients Quantified With Semiautomatic Measurement of Nerve Cross-sectional Area Using 3T MRI Data.

Hypothesis: High-resolution parallel transmit T2 sampling perfection with application optimized contrast using different flip angle evolution sequence with improved edge discrimination and semiautomatic determination of nerve cross-sectional area (CSA) can be used to evaluate nerve degeneration in the inner auditory canal (IAC) in long-term deaf patients. Background: In patients with hearing loss, temporal bone MRI is routinely acquired to evaluate the morphology of the nerves within the IAC. Earlier studies have shown that the diameter of the cochlear nerve can be used as prognostic marker for the auditory performance after cochlear implantation in postlingually deaf patients. Methods: Eighty-two consecutive MRI scans were analyzed using a semiautomatic tool to measure CSA of cranial nerves in the IAC. Results were correlated with patient history and audiology testing as well as with age and gender. Results: There was a significant reduced CSA of the cochlear nerve in ears with moderate-to-profound hearing loss and deafness compared with ears with normal hearing, but no significant difference in ears with mild-to-moderate hearing loss compared with normal hearing. In detail, normal hearing ears had a CSA of 1.23 ± 0.11 mm2, whereas ears with pantonal hearing loss of more than 40 dB had 1.02 ± 0.05 mm2 (P = 0.026). Maximal CSA of the facial nerve was not different among all groups (average, 1.04 mm2 ± 0.03; linear regression, P = 0.001) and stable with age. However, vestibular nerve CSA decreased significantly with age (average, 1.78 ± 0.05 mm2; linear regression, P = 0.128). Conclusions: In long-term deaf patients, smaller the diameter of cochlear nerve is the more severe the hearing loss is. The new semiautomatic tool can primarily be used to assess nerve diameter and possibly determine ears with nerve degeneration.

Role of prior intratympanic gentamicin and corticosteroids therapy on speech understanding in patients with Menière's disease after cochlear implantation.

AIM: Intratympanic injection of corticosteroids (ITC) and gentamicin therapy (ITG) are widely used treatments for vertigo in Meniere's disease (MD). Even though studies show good results after cochlea implantation (CI) in MD patients when compared to non-MD groups, there is no indication on the effect of ITC and ITG prior to CI on hearing after CI. This study compares the post-operative hearing of CI patients with and without MD and patients who have received ITG or ITC prior to CI. METHODS: In a retrospective case control study, adult patients with MD who received CI from 2002 till 2021 were compared to a matched control group of CI patients without MD. Patients with prior ITC/ITG were extracted from MD group. Pre-operative audiological results were measured and trends across post-operative monosyllabic word recognition score at 65 decibels (WRS65CI) at switch-on, 3-6 months, 1 year and last yearly value were analyzed across all groups. RESULTS: 28 MD ears were compared with 33 control ears. From MD ears 9 had received ITG and 6 ITC prior to CI. WRS65CI increased significantly with time within MD and control groups, but no difference in WRS65CI was found between these 2 groups. ITG ears showed fluctuating WRS65CI after CI with no change across time, while ITC ears showed significant increase in trend of WRS65CI values across time. CONCLUSION: MD and non-MD patients showed comparable hearing results after CI. Prior ITC might positively influence hearing preservation after CI in MD patients whereas ITG group showed fluctuating hearing.

Auditory capacity of the better-hearing ear in asymmetric hearing loss.

PURPOSE: Our aim was to investigate the course of the hearing capacity of the better-hearing ear in single-sided deafness (SSD) and asymmetric hearing loss (AHL) over time, in a multicenter study. METHODS: We included 2086 pure-tone audiograms from 323 patients with SSD and AHL from four hospitals and 156 private practice otorhinolaryngologists. We collected: age, gender, etiology, duration of deafness, treatment with CI, number and monosyllabic speech recognition, numerical rating scale (NRS) of tinnitus intensity, and the tinnitus questionnaire according to Goebel and Hiller. We compared the pure tone audiogram of the better-hearing ear in patients with SSD with age- and gender-controlled hearing thresholds from ISO 7029:2017. RESULTS: First, individuals with SSD showed a significantly higher hearing threshold from 0.125 to 8 kHz in the better-hearing ear compared to the ISO 7029:2017. The duration of deafness of the poorer-hearing ear showed no relationship with the hearing threshold of the better-hearing ear. The hearing threshold was significantly higher in typically bilaterally presenting etiologies (chronic otitis media, otosclerosis, and congenital hearing loss), except for Menière's disease. Second, subjects that developed AHL did so in 5.19 ± 5.91 years and showed significant reduction in monosyllabic word and number recognition. CONCLUSIONS: Individuals with SSD show significantly poorer hearing in the better-hearing ear than individuals with NH from the ISO 7029:2017. In clinical practice, we should, therefore, inform our SSD patients that their disease is accompanied by a reduced hearing capacity on the contralateral side, especially in certain etiologies.

Flat panel CT versus multidetector CT in skull base imaging: are there differences in image quality?

BACKGROUND: Purpose of this study was to compare image quality of the skull base in standard 20s protocol flat panel computed tomography (FPCT) with the new time and dose improved 10s protocol as well as with 128 slice multidetector computed tomography (MDCT). METHODS: 10 whole skull preparations were scanned with either 128 slice MDCT(SOMATOM Definition AS+, Siemens, Erlangen) or FPCT (AXIOM-Artis, Siemens, Erlangen) using 10s or 20s protocol. RESULTS: FPCT provides significantly better image quality and improved delimitation of clinically relevant structures in the anterior, temporal and posterior skull base compared to 128 slice MDCT. The 20s FPCT protocol yielded best delimitability of evaluated skull base structures. However, the shorter, dose saving 10s FPCT protocol was still significantly superior to 128 slice MDCT regarding delimitability of skull base structures and additionally showed no significant inferiority compared with the 20s FPCT protocol. CONCLUSIONS: The 10s FPCT protocol yields a significantly better image quality at a comparable radiation dose exposure in imaging skull base structures compared to MDCT. TRIAL REGISTRATION: 371/2017BO2.

Distribution of ciliary adaptor proteins tubby and TULP3 in the organ of Corti.

Tubby-like proteins are membrane-associated adaptors that mediate directional trafficking into primary cilia. In inner ear sensory epithelia, cilia-including the hair cell's kinocilium-play important roles as organizers of polarity, tissue architecture and cellular function. However, auditory dysfunction in tubby mutant mice was recently found to be related to a non-ciliary function of tubby, the organization of a protein complex in sensory hair bundles of auditory outer hair cells (OHCs). Targeting of signaling components into cilia in the cochlea might therefore rather rely on closely related tubby-like proteins (TULPs). In this study, we compared cellular and subcellular localization of tubby and TULP3 in the mouse inner ear sensory organs. Immunofluorescence microscopy confirmed the previously reported highly selective localization of tubby in the stereocilia tips of OHCs and revealed a previously unnoticed transient localization to kinocilia during early postnatal development. TULP3 was detected in the organ of Corti and vestibular sensory epithelium, where it displayed a complex spatiotemporal pattern. TULP3 localized to kinocilia of cochlear and vestibular hair cells in early postnatal development but disappeared subsequently before the onset of hearing. This pattern suggested a role in targeting ciliary components into kinocilia, possibly related to the developmental processes that shape the sensory epithelia. Concurrent with loss from kinocilia, pronounced TULP3 immunolabeling progressively appeared at microtubule bundles in non-sensory Pillar (PCs) and Deiters cells (DC). This subcellular localization may indicate a novel function of TULP proteins associated with the formation or regulation of microtubule-based cellular structures.

Role of cochlear reserve in adults with cochlear implants following post-lingual hearing loss.

INTRODUCTION: Pre-operative assessments before cochlear implantation (CI) includes the examination of both tone hearing, and the level of the cochlear reserve indicated by speech understanding. The goal of this study was to explore the predictive influence of tone hearing and cochlear reserve in CI. METHODS: We did a retrospective cohort study, which included adult patients who had undergone CI between January 2012 and December 2019 in a tertiary care center. The pre-operative tone hearing, unaided maximum monosyllabic word recognition score (WRSmax), aided hearing gain, aided monosyllabic word recognition score at 65 dB (WRS65(HA)), and speech perception gap (SPG) were measured. The duration of unaided hearing loss (UHL) was also assessed. These variables were compared with post-operative monosyllabic word recognition score after CI at 65 dB (WRS65(CI)). RESULTS: 103 patients and 128 ears were included in this study. Regardless of tone hearing, patients with better pre-operative WRSmax and WRS65(HA) performed better post-operatively. WRSmax was found to be the most important factor that was statistically significantly associated with WRS65(CI). SPG was statistically significantly associated with WRSmax and SPG ≥ 20% group performed better post-operatively. Any duration of unaided hearing loss was statistically significantly inversely associated with WRSmax above 0%. CONCLUSION: Cochlear reserve represented by WRSmax may play the most important role as a predictive factor in outcomes after CI. SPG should be considered for indicating CI in patients, when WRS65(HA) does not reach WRSmax. Early rehabilitation with hearing aids and duration of hearing aid usage might play an important role in preserving cochlear reserve in adults.

[Follow-up II of newborn hearing screening : Evaluation of a follow-up II facility after implementation of newborn hearing screening in Germany]. / Follow-up-II des Neugeborenen-Hörscreenings : Evaluation der Ergebnisqualität einer Follow-up-II-Einrichtung nach Einführung des Neugeborenen-Hörscreenings in Deutschland.

BACKGROUND: With the implementation of newborn hearing screening, evaluation in terms of quality and goal achievement was required. The present study evaluates a follow-up II facility from 2009 to 2016. METHODS: Data of 2705 newborns were retrospectively evaluated. The annual number of patients was analyzed, as well as the median age at first presentation, at diagnosis, and at treatment, each according to the reason for presentation and the diagnosis. RESULTS: From 2009 to 2016, the number of presented newborns increased by 91.4%. Newborns with abnormal initial screening or risk factors were presented significantly later than those for initial screening (median 5.3 and 8.0 vs. 4.6 weeks, respectively; p < 0.001). Permanently or transiently hearing-impaired patients were presented and diagnosed significantly later than those with normal hearing (age at initial presentation 6.1 and 7.6 vs. 5.4 weeks, p < 0.01 and p < 0.001, respectively; age at diagnosis 11.4 and 23.1 vs. 5.9 weeks, respectively; p < 0.001). Permanent hearing loss was treated at the age of 14.1 weeks. From 2009 to 2014, the age at first presentation and at diagnosis increased and subsequently mostly decreased until 2016. CONCLUSION: The age at first presentation and at diagnosis depends on the reason for presentation and on the diagnosis. Despite increasing patient numbers, the Joint Federal Committee (Gemeinsame Bundesausschuss, G­BA) targets were met due to effective and efficient organizational structuring of the follow-up II facility. However, early admission to a follow-up II facility is a prerequisite for the success of newborn hearing screening.

Hearing rehabilitation after subtotal cochleoectomy using a new, perimodiolar malleable cochlear implant electrode array: a preliminary report.

PURPOSE: We here report about the first surgical experience and audiological outcome using a new, perimodiolar malleable cochlear implant electrode array for hearing rehabilitation after subtotal cochleoectomy for intralabyrinthine schwannoma (ILS). METHOD: Based on a cochlear implant with MRI compatibility of the magnet in the receiver coil up to 3 T, a cochlear implant electrode array was developed that is malleable and can be placed perimodiolar after tumor removal from the cochlea via subtotal cochleoectomy. Malleability was reached by incorporating a nitinol wire into the silicone of the electrode array lateral to the electrode contacts. The custom-made device was implanted in four patients with intracochlear, intravestibulocochlear or transmodiolar schwannomas. Outcome was assessed by evaluating the feasibility of the surgical procedure and by measuring sound field thresholds and word recognition scores. RESULTS: After complete or partial tumor removal via subtotal cochleoectomy with or without labyrinthectomy, the new, perimodiolar malleable electrode array could successfully be implanted in all four patients. Six months after surgery, the averaged sound field thresholds to pulsed narrowband noise in the four patients were 36, 28, 41, and 35 dB HL, and the word recognitions scores for monosyllables at 65 dB SPL were 65, 80, 70, and 25% (one patient non-German speaking). CONCLUSION: The surgical evaluation demonstrated the feasibility of cochlear implantation with the new, perimodiolar malleable electrode array after subtotal cochleoectomy. The audiological results were comparable to those achieved with another commercially available type of perimodiolar electrode array from a different manufacturer applied in patients with ILS.

Guanylyl Cyclase A/cGMP Signaling Slows Hidden, Age- and Acoustic Trauma-Induced Hearing Loss.

In the inner ear, cyclic guanosine monophosphate (cGMP) signaling has been described as facilitating otoprotection, which was previously observed through elevated cGMP levels achieved by phosphodiesterase 5 inhibition. However, to date, the upstream guanylyl cyclase (GC) subtype eliciting cGMP production is unknown. Here, we show that mice with a genetic disruption of the gene encoding the cGMP generator GC-A, the receptor for atrial and B-type natriuretic peptides, display a greater vulnerability of hair cells to hidden hearing loss and noise- and age-dependent hearing loss. This vulnerability was associated with GC-A expression in spiral ganglia and outer hair cells (OHCs) but not in inner hair cells (IHCs). GC-A knockout mice exhibited elevated hearing thresholds, most pronounced for the detection of high-frequency tones. Deficits in OHC input-output functions in high-frequency regions were already present in young GC-A-deficient mice, with no signs of an accelerated progression of age-related hearing loss or higher vulnerability to acoustic trauma. OHCs in these frequency regions in young GC-A knockout mice exhibited diminished levels of KCNQ4 expression, which is the dominant K+ channel in OHCs, and decreased activation of poly (ADP-ribose) polymerase-1, an enzyme involved in DNA repair. Further, GC-A knockout mice had IHC synapse impairments and reduced amplitudes of auditory brainstem responses that progressed with age and with acoustic trauma, in contrast to OHCs, when compared to GC-A wild-type littermates. We conclude that GC-A/cGMP-dependent signaling pathways have otoprotective functions and GC-A gene disruption differentially contributes to hair-cell damage in a healthy, aged, or injured system. Thus, augmentation of natriuretic peptide GC-A signaling likely has potential to overcome hidden and noise-induced hearing loss, as well as presbycusis.

Correction to: Safety of the "Saxophone®" electrode in parotid surgery for continuous intraoperative neuromonitoring of the facial nerve: results of a pro- and retrospective cohort study.

In the original publication of the article, first name and last names of all authors were swapped.

Safety of the "Saxophone®" electrode in parotid surgery for continuous intraoperative neuromonitoring of the facial nerve: results of a pro- and retrospective cohort study.

PURPOSE: Early facial nerve palsy (eFNP) is the most frequent complication of the parotidectomy. Intraoperative neuromonitoring (IONM) in parotid surgery, which aims at reducing eFNP, has not evolved any further than the mere differentiation between the nerve and the surrounding tissue. Continuous IONM (cIONM), used in thyroid and posterior fossa surgery, has developed over the past years and has proved beneficial in reducing the rate of paresis in cases where a pattern of impending nerve injury is identified. In this study, we aim to demonstrate the safety of using the stimulating electrode (Saxophone®) for cIONM in parotid surgery. METHODS: From 2016 to 2018, 40 patients who were referred for primary parotidectomy under cIONM according to our study protocol (registered at the German Clinical Trials Register, DRKS-ID: DRKS00011051, http://www.drks.de; http://apps.who.int/trialsearch) were included in this study. All patients with a normal preoperative facial nerve function [House-Brackman (HB)-Index 1] underwent surgery using continuous facial nerve stimulation with the Saxophone® electrode (system AVALANCHE XT, Dr. Langer Medical, Waldkirch, Germany). A control group which underwent parotidectomies with only intermittent IONM was recruited from our records. RESULTS: Half of the patients in our study group suffered from eFNP. All except one regained normal facial nerve function within 6 months of surgery. There was no significant difference regarding eFNP when compared to the control group without cIONM (p = 0.11). No statistically significant correlation between the stimulation threshold (p = 0.74) or the duration of nerve stimulation and eFNP was found (p = 0.51). CONCLUSION: We have demonstrated the safety of using the Saxophone®-electrode for cIONM of the facial nerve in parotid surgery. Future development of this method could enable the recognition of impending nerve injury and thus reduce eFNP.

Image quality of flat-panel computed tomography using 2 different acquisition times versus multidetector computed tomography in whole-head temporal bone specimen.

PURPOSE: Imaging of temporal bone and skull base acquire high resolution due to the small anatomic structures with high clinical relevance. The purpose of this study was to compare image quality of the temporal bone in standard 20 s protocol flat-panel computed tomography (FPCT) with the new time- and dose improved 10 s protocol as well as with 128 slice multidetector computed tomography (MDCT). The aim was to evaluate the new time- and dose improved 10 s protocol. METHODS: 10 whole-skull preparations-20 temporal bones-were scanned with either 128 slice MDCT CT (SOMATOM Definition AS + , Siemens, Erlangen) or FPCT (AXIOM-Artis, Siemens, Erlangen) using 10 s or 20 s protocol. RESULTS: We show here that overall FPCT provides significantly better image quality and improved delimitation of clinically relevant structures in the temporal bone compared to 128 slice MDCT. Especially the shorter, dose saving 10 s protocol of the FPCT is still superior to 128 slice MDCT. The 20 s FPCT protocol was only significantly superior in identification of the cochlear apical turn and can thereby be used specifically in clinical cases with pathologies in this area. CONCLUSIONS: The 10 s FPCT protocol yields a significantly better image quality than MDCT in imaging finer structures of the temporal bone.

Implantability of endaurally insertable active vibratory middle-ear implants - an anatomical study.

Background: Hearing loss is often treated with an acoustic hearing aid. However, distortion and insufficient gain may cause problems. Active non-acoustic vibratory middle-ear implants (AMEI) may contribute to solve this problem. We recently developed an AMEI which is to be implanted completely through the patient's external auditory canal. The device uses a light-emitting diode (LED) in the external auditory canal that stimulates a photovoltaic sensor, placed in the middle ear, through the intact tympanic membrane. This results in activation of a vibratory miniaturized piezoelectric displacement transducer (MDT) (actuator) coupled to the auditory organ. Aims/objectives: The aim of this study was to evaluate the anatomical implantability of the novel AMEI using an exclusively endaural approach. Materials and methods: The internal components of our AMEI were implanted into 39 human temporal bones. The surgical procedure and the optimal size and anatomical fitting were systematically evaluated. Results: We can show here that implantation of all components of this novel AMEI into anatomical specimens proves to be a quick and easy procedure, performed using an endaural approach. Conclusions and significance: The anatomical data of this study establish the basis for further technical development of our AMEI and other future implantable hearing systems.

Positioning a Novel Transcutaneous Bone Conduction Hearing Implant: a Systematic Anatomical and Radiological Study to Standardize the Retrosigmoid Approach, Correlating Navigation-guided, and Landmark-based Surgery.

HYPOTHESIS: Anatomical and radiological evaluation improves safety and accuracy of the retrosigmoid approach for positioning a transcutaneous bone conduction implant and provides anatomical reference data for standardized, landmark-based implantation at this alternative site. BACKGROUND: The primary implantation site for the floating mass transducer of a novel bone conduction hearing implant is the mastoid. However, anatomical limitations or previous mastoid surgery may prevent mastoid implantation. Therefore, the retrosigmoid approach has been introduced as an alternative. METHODS: Mastoid and retrosigmoid implantation sites were radiologically identified and evaluated in preoperative computed tomography scans of anatomical head specimens. Navigation-guided implantation was then performed in the retrosigmoid site (n = 20). The optimal retrosigmoid position was determined in relation to both the asterion and the mastoid notch as surgical landmarks in an anatomical coordinate system. RESULTS: Preoperative radiological analysis revealed spatial limitations in the mastoid in 45% of the specimens. Navigation-guided retrosigmoid implantation was possible without affecting the sigmoid sinus in all the specimens. The optimal implantation site was located 1.9 ±â€Š0.1 cm posterior/1.7 ±â€Š0.1 cm inferior to the asterion and 3.3 ±â€Š0.2 cm posterior/2.1 ±â€Š0.1 cm superior to the mastoid notch.Retrosigmoid skull thickness was 6.6 ±â€Š0.4 mm, measured anatomically, 7.0 ±â€Š0.4 mm, measured radiologically and 6.7 ±â€Š0.5 mm, measured with the navigation software. CONCLUSION: The navigation-guided retrosigmoid approach seemed to be a reliable procedure in all the specimens. Measurements of bone thickness revealed the need for spacers in 95% of the specimens. Reference coordinates of the optimal implantation site are provided and can confirm image-guided surgery or facilitate orientation if a navigation system is not available.

NO-Sensitive Guanylate Cyclase Isoforms NO-GC1 and NO-GC2 Contribute to Noise-Induced Inner Hair Cell Synaptopathy.

Nitric oxide (NO) activates the NO-sensitive soluble guanylate cyclase (NO-GC, sGC) and triggers intracellular signaling pathways involving cGMP. For survival of cochlear hair cells and preservation of hearing, NO-mediated cascades have both protective and detrimental potential. Here we examine the cochlear function of mice lacking one of the two NO-sensitive guanylate cyclase isoforms [NO-GC1 knockout (KO) or NO-GC2 KO]. The deletion of NO-GC1 or NO-GC2 did not influence electromechanical outer hair cell (OHC) properties, as measured by distortion product otoacoustic emissions, neither before nor after noise exposure, nor were click- or noise-burst-evoked auditory brainstem response thresholds different from controls. Yet inner hair cell (IHC) ribbons and auditory nerve responses showed significantly less deterioration in NO-GC1 KO and NO-GC2 KO mice after noise exposure. Consistent with a selective role of NO-GC in IHCs, NO-GC ß1 mRNA was found in isolated IHCs but not in OHCs. Using transgenic mice expressing the fluorescence resonance energy transfer-based cGMP biosensor cGi500, NO-induced elevation of cGMP was detected in real-time in IHCs but not in OHCs. Pharmacologic long-term treatment with a NO-GC stimulator altered auditory nerve responses but did not affect OHC function and hearing thresholds. Interestingly, NO-GC stimulation exacerbated the loss of auditory nerve response in aged animals but attenuated the loss in younger animals. We propose NO-GC2 and, to some degree, NO-GC1 as targets for early pharmacologic prevention of auditory fiber loss (synaptopathy). Both isoforms provide selective benefits for hearing function by maintaining the functional integrity of auditory nerve fibers in early life rather than at old age.

Ryanodine-induced vasoconstriction of the gerbil spiral modiolar artery depends on the Ca2+ sensitivity but not on Ca2+ sparks or BK channels.

BACKGROUND: In many vascular smooth muscle cells (SMCs), ryanodine receptor-mediated Ca2+ sparks activate large-conductance Ca2+-activated K+ (BK) channels leading to lowered SMC [Ca2+]i and vasodilation. Here we investigated whether Ca2+ sparks regulate SMC global [Ca2+]i and diameter in the spiral modiolar artery (SMA) by activating BK channels. METHODS: SMAs were isolated from adult female gerbils, loaded with the Ca2+-sensitive flourescent dye fluo-4 and pressurized using a concentric double-pipette system. Ca2+ signals and vascular diameter changes were recorded using a laser-scanning confocal imaging system. Effects of various pharmacological agents on Ca2+ signals and vascular diameter were analyzed. RESULTS: Ca2+ sparks and waves were observed in pressurized SMAs. Inhibition of Ca2+ sparks with ryanodine increased global Ca2+ and constricted SMA at 40 cmH2O but inhibition of Ca2+ sparks with tetracaine or inhibition of BK channels with iberiotoxin at 40 cmH2O did not produce a similar effect. The ryanodine-induced vasoconstriction observed at 40 cmH2O was abolished at 60 cmH2O, consistent with a greater Ca2+-sensitivity of constriction at 40 cmH2O than at 60 cmH2O. When the Ca2+-sensitivity of the SMA was increased by prior application of 1 nM endothelin-1, ryanodine induced a robust vasoconstriction at 60 cmH2O. CONCLUSIONS: The results suggest that Ca2+ sparks, while present, do not regulate vascular diameter in the SMA by activating BK channels and that the regulation of vascular diameter in the SMA is determined by the Ca2+-sensitivity of constriction.

Parallel-transmit-accelerated 2D Selective RF Excitation MR of the Temporal Bone: Enhanced Resolution of Labyrinthine and IAC Structures.

RATIONALE AND OBJECTIVES: The purpose of this study was to compare a standard T2 SPACE sequence (standard-SPACE) used in temporal bone imaging at 3 T with a new parallel-transmit-accelerated 2D-selective radio frequency excitation technique for SPACE which was either time-improved or resolution-improved. MATERIALS AND METHODS: Thirty-two consecutive patients were examined in this IRB-approved study using a standard T2 SPACE sequence, and then a time-improved zoomed SPACE sequence (short z-SPACE) with identical resolution but accelerated image acquisition and a resolution-improved zoomed SPACE sequence (high-resolution z-SPACE) with identical acquisition time but higher resolution at a 3-T magnetic resonance imaging system. Signal-to-noise ratio (SNR) was measured within selected regions of interest. Image quality of anatomic temporal bone structures was determined by two independent readers using a four-point visual scale. RESULTS: Significant image quality improvement (p < 0.05) was observed in short z-SPACE and high-resolution z-SPACE, especially in structures of the cochlea and also regarding the delineation of the cranial nerves within the internal auditory canal. SNR measurements showed a lower SNR in the short z-SPACE and high-resolution z-SPACE sequences compared with standard-SPACE. CONCLUSION: At 3 T parallel transmission using the zoomed SPACE sequences improves the delineation of small anatomical structures within the temporal bone significantly. It is especially helpful in depicting cochlear and internal auditory canal anatomy and can therefore improve imaging in patients with temporal bone pathologies.

Diffusion restriction of the optic nerve in patients with acute visual deficit.

PURPOSE: Diffusion magnetic resonance imaging (MRI) is commonly used in acute stroke, but not considered diagnostic in ischemic optic neuropathy. This study evaluates the presence of diffusion restriction in patients with acute visual loss by analyzing diffusion-weighted images (DWI). MATERIALS AND METHODS: A retrospective study of all patients who clinically presented with acute visual loss and who underwent MRI with DWI between January 2011 and May 2012 were evaluated. Patients with suspected brainstem ischemia were used as a control group. Two neuroradiologists evaluated the DWI for the presence of diffusion restriction within the optic nerve. RESULTS: In all, 34 patients with acute visual deficit and 32 controls were evaluated. In all five cases of acute optic ischemia, diffusion restriction with reduced apparent diffusion coefficient was present. In 2/25 patients with clinically defined optic neuritis, a diffusion restriction was present. No diffusion restriction was seen in the control cases or in cases with other causes for an acute visual deficit. CONCLUSION: DWI can identify ischemic lesions of the optic nerve. As in acute multiple sclerosis lesions, optic neuritis can also present in rare circumstances with diffusion restriction and can therefore not be ruled out solely by DWI MRI.

NOS inhibition enhances myogenic tone by increasing rho-kinase mediated Ca2+ sensitivity in the male but not the female gerbil spiral modiolar artery.

Cochlear blood flow regulation is important to prevent hearing loss caused by ischemia and oxidative stress. Cochlear blood supply is provided by the spiral modiolar artery (SMA). The myogenic tone of the SMA is enhanced by the nitric oxide synthase (NOS) blocker L-N(G)-nitro-arginine (LNNA) in males, but not in females. Here, we investigated whether this gender difference is based on differences in the cytosolic Ca(2+) concentration and/or the Ca(2+) sensitivity of the myofilaments. Vascular diameter, myogenic tone, cytosolic Ca(2+), and Ca(2+) sensitivity were evaluated in pressurized SMA segments isolated from male and female gerbils using laser-scanning microscopy and microfluorometry. The gender difference of the LNNA-induced tone was compared, in the same vessel segments, to tone induced by 150 mM K(+) and endothelin-1, neither of which showed an apparent gender-difference. Interestingly, LNNA-induced tone in male SMAs was observed in protocols that included changes in intramural pressure, but not when the intramural pressure was held constant. LNNA in male SMAs did not increase the global Ca(2+) concentration in smooth muscle cells but increased the Ca(2+) sensitivity. This increase in the Ca(2+) sensitivity was abolished in the presence of the guanylyl cyclase inhibitor ODQ or by extrinsic application of either the nitric oxide (NO)-donor DEA-NONOate or the cGMP analog 8-pCPT-cGMP. The rho-kinase blocker Y27632 decreased the basal Ca(2+) sensitivity and abolished the LNNA-induced increase in Ca(2+) sensitivity in male SMAs. Neither LNNA nor Y27632 changed the Ca(2+) sensitivity in female SMAs. The data suggest that the gender difference in LNNA-induced tone is based on a gender difference in the regulation of rho-kinase mediated Ca(2+) sensitivity. Rho-kinase and NO thus emerge as critical factors in the regulation of cochlear blood flow. The larger role of NO-dependent mechanisms in male SMAs predicts greater restrictions on cochlear blood flow under conditions of impaired endothelial cell function.