Post-implantation clinical cost analysis between transcutaneous and percutaneous bone conduction devices.

INTRODUCTION: Bone conduction devices (BCD) are effective for hearing rehabilitation in patients with conductive and mixed hearing loss or single-sided deafness. Transcutaneous bone conduction devices (tBCD) seem to lead to fewer soft tissue complications than percutaneous BCDs (pBCD) but have other drawbacks such as MRI incompatibility and higher costs. Previous cost analyses have shown a cost advantage of tBCDs. The purpose of this study is to compare long-term post-implantations costs between percutaneous and transcutaneous BCDs. MATERIALS AND METHODS: Retrospective data from 77 patients implanted in a tertiary referral centre with a pBCD (n = 34), tBCD (n = 43; passive (tpasBCD; n = 34) and active (tactBCD; n = 9) and a reference group who underwent cochlear implantation (CI; n = 34), were included in a clinical cost analysis. Post-implantation costs were determined as the sum of consultation (medical and audiological) and additional (all post-operative care) costs. Median (cumulative) costs per device incurred for the different cohorts were compared at 1, 3 and 5 years after implantation. RESULTS: After 5 years, the total post-implantation costs of the pBCD vs tpasBCD were not significantly different (€1550.7 [IQR 1174.6-2797.4] vs €2266.9 [IQR 1314.1-3535.3], p = 0.185), nor was there a significant difference between pBCD vs tactBCD (€1550.7 [1174.6-2797.4] vs €1428.8 [1277.3-1760.4], p = 0.550). Additional post-implantation costs were significantly highest in the tpasBCD cohort at all moments of follow-up. CONCLUSION: Total costs related to post-operative rehabilitation and treatments are comparable between percutaneous and transcutaneous BCDs up to 5 years after implantation. Complications related to passive transcutaneous bone conduction devices appeared significantly more expensive after implantation due to more frequent explantations.

Subjective Fatigue in Children With Unaided and Aided Unilateral Hearing Loss.

OBJECTIVES: Fatigue is frequently observed in children with chronic diseases and can affect the quality of life (QoL). However, research in children with unilateral hearing loss (UHL) is scarce. Subsequently, no studies investigated the effects of hearing aids on fatigue in children. This study investigates subjective fatigue and hearing-related QoL in children with UHL. Furthermore, it evaluates the influence of hearing aids, subject-specific factors, and respondent-type on subjective fatigue. STUDY DESIGN: A cross-sectional study was conducted from June 2020 until September 2020 at the department of otorhinolaryngology in a tertiary referral center. METHODS: The primary outcome was the difference in subjective fatigue and hearing-related QoL between children with unaided UHL, aided UHL, and normal hearing. Subjective fatigue and hearing-related QoL were measured using the Pediatric Quality of Life Inventory™ Multidimensional Fatigue Scale (PedsQL™-MFS) and Hearing Environments and Reflection on Quality of Life (HEAR-QL™) questionnaires. RESULTS: Along with 36 aided children with UHL, 34 unaided and 36 normal-hearing children were included. Child reports revealed significantly more cognitive fatigue in children with aided UHL than children with normal hearing (median difference 12.5, P = .013). Parents reported more fatigue in children with UHL compared to normal-hearing siblings. Especially children with aided UHL seemed at increased risk for fatigue. Children with UHL scored lower on hearing-related QoL than children with normal hearing. No apparent differences were found in fatigue and QoL between children with unaided and aided UHL. CONCLUSION: Children with unaided and even aided UHL seem to experience more subjective fatigue and lower hearing-related QoL than children with normal hearing. Prospective longitudinal studies are required to investigate the influence of hearing aids on fatigue and QoL in individual patients. LEVEL OF EVIDENCE: 3 Laryngoscope, 2021 Laryngoscope, 133:189-198, 2023.

Unexplained Variation in Benefit of Treatment of Congenital Unilateral Aural Atresia: A Review of the Literature.

OBJECTIVE: A review of published data regarding binaural hearing after treatment of congenital unilateral conductive hearing loss (UCHL) due to aural atresia. Treatment options concern atresia surgery (reconstructive surgery), application of a bone conduction device (BCD), or application of a middle ear implant (MEI). DATA SOURCES: Database PubMed was searched for articles published in English and German between January 1, 1994, and January 1, 2019. STUDY SELECTION: The initial search identified 52 studies, of which 9 met the inclusion criteria. DATA SYNTHESIS: Comparison of studies was based on a structured review. Meta-analysis was not feasible because of the heterogeneity of outcome measures, the limited number of relevant papers (9), and diverse types of treatment (5). CONCLUSIONS: Treatment of UCHL results in bilateral hearing instead of binaural hearing. The large intersubject variability in benefit of treatment is unexplained with a clear improvement in the minority of listeners and a limited improvement or binaural interference in most listeners after atresia repair or amplification with a BCD or MEI.

Assessment of the equivalent dipole layer source model in the reconstruction of cardiac activation times on the basis of BSPMs produced by an anisotropic model of the heart.

Promising results have been reported in noninvasive estimation of cardiac activation times (AT) using the equivalent dipole layer (EDL) source model in combination with the boundary element method (BEM). However, the assumption of equal anisotropy ratios in the heart that underlies the EDL model does not reflect reality. In the present study, we quantify the errors of the nonlinear AT imaging based on the EDL approximation. Nine different excitation patterns (sinus rhythm and eight ectopic beats) were simulated with the monodomain model. Based on the bidomain theory, the body surface potential maps (BSPMs) were calculated for a realistic finite element volume conductor with an anisotropic heart model. For the forward calculations, three cases of bidomain conductivity tensors in the heart were considered: isotropic, equal, and unequal anisotropy ratios in the intra- and extracellular spaces. In all inverse reconstructions, the EDL model with BEM was employed: AT were estimated by solving the nonlinear optimization problem with the initial guess provided by the fastest route algorithm. Expectedly, the case of unequal anisotropy ratios resulted in larger localization errors for almost all considered activation patterns. For the sinus rhythm, all sites of early activation were correctly estimated with an optimal regularization parameter being used. For the ectopic beats, all but one foci were correctly classified to have either endo- or epicardial origin with an average localization error of 20.4 mm for unequal anisotropy ratio. The obtained results confirm validation studies and suggest that cardiac anisotropy might be neglected in clinical applications of the considered EDL-based inverse procedure.

Cerebellar theta burst stimulation does not improve freezing of gait in patients with Parkinson's disease.

Freezing of gait (FOG) in Parkinson's disease (PD) likely results from dysfunction within a complex neural gait circuitry involving multiple brain regions. Herein, cerebellar activity is increased in patients compared to healthy subjects. This cerebellar involvement has been proposed to be compensatory. We hypothesized that patients with FOG would have a reduced ability to recruit the cerebellum to compensate for dysfunction in other brain areas. In this study cerebellar activity was modified unilaterally by either excitatory or inhibitory theta burst stimulation (TBS), applied during two separate sessions. The ipsilateral cerebellar hemisphere, corresponding to the body side most affected by PD, was stimulated. Seventeen patients with PD showing 'off' state FOG participated. The presence of FOG was verified objectively upon inclusion. We monitored gait and bimanual rhythmic upper limb movements before and directly after TBS. Gait was evaluated with a FOG-provoking protocol, including rapid 360° turns and a 10-m walking test with small fast steps. Upper limb movement performance was evaluated with a repetitive finger flexion-extension task. TBS did not affect the amount of freezing during walking or finger tapping. However, TBS did increase gait speed when walking with small steps, and decreased gait speed when walking as fast as possible with a normal step size. The changes in gait speed were not accompanied by changes in corticospinal excitability of M1. Unilateral cerebellar TBS did not improve FOG. However, changes in gait speed were found which suggests a role of the cerebellum in PD.

Identifying freezing of gait in Parkinson's disease during freezing provoking tasks using waist-mounted accelerometry.

BACKGROUND: Freezing of gait (FOG) is a common and debilitating phenomenon in Parkinson's disease (PD). Wearable accelerometers might help to assess FOG in the research setting. Here, we evaluate whether accelerometry can detect FOG while executing rapid full turns and while walking with rapid short steps (the two most common provoking circumstances for FOG). METHODS: We included 23 PD patients, who all had objective FOG. Participants performed several walking tasks, including walking rapidly with short steps and rapid full turns in both directions with a triaxial linear waist-mounted accelerometer. Two independent experts identified FOG episodes using off-line video-analysis (gold standard). A validated algorithm [ratio between pathological freezing (3-8 Hz)-and normal locomotor frequencies (0.5-3 Hz)] was applied on the accelerometer data to detect FOG episodes. RESULTS: Clinically, FOG was most often observed during full rapid turns (81% of all episodes), followed by walking with short rapid steps (12% of all episodes). During full rapid turns, accelerometry yielded a sensitivity of 78% and specificity of 59%. A sensitivity of 64% and specificity of 69% was observed during walking rapidly with small steps. Combining all tasks rendered a sensitivity of 75% and specificity of 76%. CONCLUSION: Our results suggest that FOG can be detected from a single lumbar accelerometer during several walking tasks, including full rapid turns and walking with short steps rapidly, with reasonable sensitivity and specificity. This approach holds promise for possible implementation as complementary objective outcome in a research setting, but more work remains needed to improve the sensitivity and specificity.

The coil orientation dependency of the electric field induced by TMS for M1 and other brain areas.

BACKGROUND: The effectiveness of transcranial magnetic stimulation (TMS) depends highly on the coil orientation relative to the subject's head. This implies that the direction of the induced electric field has a large effect on the efficiency of TMS. To improve future protocols, knowledge about the relationship between the coil orientation and the direction of the induced electric field on the one hand, and the head and brain anatomy on the other hand, seems crucial. Therefore, the induced electric field in the cortex as a function of the coil orientation has been examined in this study. METHODS: The effect of changing the coil orientation on the induced electric field was evaluated for fourteen cortical targets. We used a finite element model to calculate the induced electric fields for thirty-six coil orientations (10 degrees resolution) per target location. The effects on the electric field due to coil rotation, in combination with target site anatomy, have been quantified. RESULTS: The results confirm that the electric field perpendicular to the anterior sulcal wall of the central sulcus is highly susceptible to coil orientation changes and has to be maximized for an optimal stimulation effect of the motor cortex. In order to obtain maximum stimulation effect in areas other than the motor cortex, the electric field perpendicular to the cortical surface in those areas has to be maximized as well. Small orientation changes (10 degrees) do not alter the induced electric field drastically. CONCLUSIONS: The results suggest that for all cortical targets, maximizing the strength of the electric field perpendicular to the targeted cortical surface area (and inward directed) optimizes the effect of TMS. Orienting the TMS coil based on anatomical information (anatomical magnetic resonance imaging data) about the targeted brain area can improve future results. The standard coil orientations, used in cognitive and clinical neuroscience, induce (near) optimal electric fields in the subject-specific head model in most cases.

Alterations in red blood cell deformability during storage: a microfluidic approach.

Red blood cells (RBCs) undergo extensive deformation when travelling through the microcapillaries. Deformability, the combined result of properties of the membrane-cytoskeleton complex, the surface area-to-volume ratio, and the hemoglobin content, is a critical determinant of capillary blood flow. During blood bank storage and in many pathophysiological conditions, RBC morphology changes, which has been suggested to be associated with decreased deformability and removal of RBC. While various techniques provide information on the rheological properties of stored RBCs, their clinical significance is controversial. We developed a microfluidic approach for evaluating RBC deformability in a physiologically meaningful and clinically significant manner. Unlike other techniques, our method enables a high-throughput determination of changes in deformation capacity to provide statistically significant data, while providing morphological information at the single-cell level. Our data show that, under conditions that closely mimic capillary dimensions and flow, the capacity to deform and the capacity to relax are not affected during storage in the blood bank. Our data also show that altered cell morphology by itself does not necessarily affect deformability.

The effect of local anatomy on the electric field induced by TMS: evaluation at 14 different target sites.

Many human cortical regions are targeted with transcranial magnetic stimulation (TMS). The stimulus intensity used for a certain region is generally based on the motor threshold stimulation intensity determined over the motor cortex (M1). However, it is well known that differences exist in coil-target distance and target site anatomy between cortical regions. These differences may well make the stimulation intensity derived from M1 sub-optimal for other regions. Our goal was to determine in what way the induced electric fields differ between cortical target regions. We used finite element method modeling to calculate the induced electric field for multiple target sites in a realistic head model. The effects on the electric field due to coil-target distance and target site anatomy have been quantified. The results show that a correction based on the distance alone does not correctly adjust the induced electric field for regions other than M1. In addition, a correction based solely on the TMS-induced electric field (primary field) does not suffice. A precise adjustment should include coil-target distance, the secondary field caused by charge accumulation at conductivity discontinuities and the direction of the field relative to the local cerebrospinal fluid-grey matter boundary.

Short rapid steps to provoke freezing of gait in Parkinson's disease.

Freezing of gait (FOG) is both common and debilitating in patients with Parkinson's disease. Due to its episodic nature, it is a challenge to provoke FOG in clinical practice and in the research setting. Turning is most sensitive to provoke FOG, particularly when performed as rapidly as possible. Walking with short steps is an alternative approach to provoke FOG. Here, we assessed a modified version of this test, consisting of the instruction to make short steps as rapidly as possible. We evaluated what the diagnostic value of this new test is compared to rapid turning. 28 patients with Parkinson's disease participated, who all had objective FOG. Patients performed the following tasks two times: (1) normal walking, (2) walking as rapidly as possible, (3) walking with short steps, (4) walking with short steps as rapidly as possible and (5) making full rapid turns in both directions. FOG was provoked in 20 subjects (71 %). The most effective test to provoke FOG was rapid full turns (64 % of subjects). FOG occurred more often when patients walked with rapid short steps (50 %) compared to walking with short steps at normal speed (18 %). The combination of 'full rapid turns' and 'walking with short steps rapidly' yielded the highest sensitivity of provoking FOG (0.71, CI 0.51-0.86). The most sensitive way to provoke FOG is by asking patients to make full rapid turns, but if negative, walking with short steps as rapidly as possible can identify further subjects with FOG.

Simulating transcranial direct current stimulation with a detailed anisotropic human head model.

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique able to induce long-lasting changes in cortical excitability that can benefit cognitive functioning and clinical treatment. In order to both better understand the mechanisms behind tDCS and possibly improve the technique, finite element models are used to simulate tDCS of the human brain. With the detailed anisotropic head model presented in this study, we provide accurate predictions of tDCS in the human brain for six of the practically most-used setups in clinical and cognitive research, targeting the primary motor cortex, dorsolateral prefrontal cortex, inferior frontal gyrus, occipital cortex, and cerebellum. We present the resulting electric field strengths in the complete brain and introduce new methods to evaluate the effectivity in the target area specifically, where we have analyzed both the strength and direction of the field. For all cerebral targets studied, the currently accepted configurations produced sub-optimal field strengths. The configuration for cerebellum stimulation produced relatively high field strengths in its target area, but it needs higher input currents than cerebral stimulation does. This study suggests that improvements in the effects of transcranial direct current stimulation are achievable.