Resonance Frequency Analysis Identifies Implant- and Host-Related Factors Associated With Bone-Anchored Hearing Implant Stability.

HYPOTHESIS: Resonance frequency analysis (RFA) is a reliable, noninvasive method to assess the stability of bone-anchored hearing implants (BAHIs), although surgical-, implant-, and host-related factors can affect its outcome. BACKGROUND: BAHI plays an important role in restoring hearing function. However, implant- and host-related factors contribute to premature implant extrusion. To mitigate this, noninvasive methods to assess implant stability, along with a better understanding of factors contributing to BAHI failure, are needed. METHODS: We evaluated the utility of RFA to quantify implant stability in sawbone (bone mimicking material), 29 human cadaveric samples, and a prospective cohort of 29 pediatric and 27 adult participants, and identified factors associated with implant stability. To validate the use of RFA in BAHI, we compared RFA-derived implant stability quotient (ISQ) estimates to peak loads obtained from mechanical push-out testing. RESULTS: ISQ and peak loads were significantly correlated (Spearman rho = 0.48, p = 0.0088), and ISQ reliably predicted peak load up to 1 kN. We then showed that in cadaveric samples, abutment length, internal table bone volume, and donor age were significantly associated with implant stability. We validated findings in our prospective patient cohort and showed that minimally invasive Ponto surgery (MIPS; versus linear incision), longer implantation durations (>16 wk), older age (>25 yr), and shorter abutment lengths (≤10 mm) were associated with better implant stability. Finally, we characterized the short-term reproducibility of ISQ measurements in sawbone and patient implants. CONCLUSIONS: Together, our findings support the use of ISQ as a measure of implant stability and emphasize important considerations that impact implant stability, including surgical method, implant duration, age, and abutment lengths.

Otologic safety of intratympanic N-acetylcysteine in an animal model.

OBJECTIVE: N-acetylcysteine (NAC) is an anti-oxidant and mucolytic effective against bacterial biofilms, making it useful in the treatment of chronically discharging ears that are unresponsive to traditional treatment methods. The objective of this study was to evaluate the otologic safety of intratympanic NAC combined with Ciprodex® in an animal model. METHODS: Baseline distortion product otoacoustic emissions (DPOAE) and auditory brainstem response (ABR) measurements were performed for both ears on thirteen guinea pigs from the animal care research facilities of the McGill University Health Center. This was followed by intratympanic administration of control solution (Ciprofloxacin 0.3%/Dexamethasone 0.1%) to the left ear and experimental solution (1.25% NAC/Ciprofloxacin 0.3%/Dexamethasone 0.1%) to the right ear. Three additional intratympanic injections were performed over the next fourteen days. DPOAE and ABR measurements were repeated 3-4 weeks after the initial procedure. Outcome measures included differences in DPOAE and ABR thresholds after intervention, clinical evidence of vestibular dysfunction and histological evidence of ototoxicity. RESULTS: There were no significant differences in the ABR thresholds and DPOAE results of the control and experimental ears at baseline and after intervention. There was neither clinical manifestation of vestibular dysfunction nor histological evidence of ototoxicity. CONCLUSION: Our study suggests that intratympanic 1.25% NAC with ciprofloxacin and dexamethasone is safe in guinea pigs and support its potential use in the treatment of chronically discharging ears. Further studies in humans are required to analyze its efficacy relative to conventional treatments. LEVEL OF EVIDENCE: Animal Research.

Percutaneous Bone-Anchored Hearing Implant Surgery: Do Syndromic Children Have More Adverse Perioperative Outcomes?

OBJECTIVE: To evaluate and compare perioperative outcomes of percutaneous bone-anchored hearing implant (BAHI) surgery in syndromic and nonsyndromic pediatric patients. STUDY DESIGN: Retrospective cohort study. SETTING: McGill University Health Centre in Montreal, Quebec, Canada. PATIENTS: Forty-one pediatric patients (22 syndromic, 19 nonsyndromic) who underwent percutaneous BAHI surgery between March 2008 and April 2021. INTERVENTION: Percutaneous BAHI surgery. MAIN OUTCOME MEASURES: Patient demographics (age at surgery, gender, implant laterality), operative information (American Society of Anesthesia [ASA] score, anesthesia type, surgical technique, implant/abutment characteristics), and postoperative outcomes (implant stability, soft tissue integrity, surgical revisions, implant failure). RESULTS: The most frequent syndromes among implanted patients were Treacher Collins (27.3%), Goldenhar (13.6%), Trisomy 21 (13.6%), and Nager (9.1%). Syndromic patients were more frequently given higher ASA scores: 2 ( p = 0.003) and 3 ( p = 0.014). All cases of implant extrusion were in syndromic patients: two posttraumatic and two failures to osseointegrate. Nine (40.9%) syndromic patients experienced a Holgers Grade 4 skin reaction at one of their postoperative follow-up visits as compared to 0% of nonsyndromic patients ( p < 0.001). Implant stability was similar between cohorts at all postoperative time-points, except for significantly greater nonsyndromic implant stability quotient scores at 16 weeks ( p = 0.027) and 31+ weeks ( p = 0.016). CONCLUSIONS: Percutaneous BAHI surgery is a successful rehabilitation option in syndromic patients. However, it presents a relatively higher incidence of implant extrusion and severe postoperative skin reactions as compared to nonsyndromic patients. In light of these findings, syndromic patients may be great candidates for novel transcutaneous bone conduction implants.

Prioritization of head and neck cancer patient care during the COVID-19 pandemic: a retrospective cohort study.

BACKGROUND: The COVID-19 pandemic placed considerable strain on the healthcare system, leading to the re-allocation of resources and implementation of new practice guidelines. The objective of this study is to assess the impact of COVID-19 guideline modifications on head and neck cancer (HNC) care at two tertiary care centers in Canada. METHODS: A retrospective cohort study was conducted. HNC patients seen at two tertiary care centers before and after the onset of the COVID-19 pandemic (pre-pandemic: July 1st, 2019, to February 29th, 2020; pandemic: March 1st, 2020, to October 31st, 2020) were included. The pre-pandemic and pandemic cohorts were compared according to patient and tumor characteristics, duration of HNC workup, and treatment type and duration. Mean differences in cancer care wait times, including time to diagnosis, tumor board, and treatment as well as total treatment package time and postoperative hospital stay were compared between cohorts. Univariate and multivariate analyses were used to compare characteristics and outcomes between cohorts. RESULTS: Pre-pandemic (n = 132) and pandemic (n = 133) patients did not differ significantly in sex, age, habits, or tumor characteristics. The percentage of patients who received surgery only, chemo/radiotherapy (CXRT) only, and surgery plus adjuvant CXRT did not differ significantly between cohorts. Pandemic patients experienced a significant time reduction compared to pre-pandemic patients with regards to the date first seen by a HNC service until start of treatment ([Formula: see text] = 48.7 and 76.6 days respectively; p = .0001), the date first seen by a HNC service until first presentation at tumor board ([Formula: see text] = 25.1 and 38 days respectively; p = .001), mean total package time for patients who received surgery only ([Formula: see text] = 3.7 and 9.0 days respectively; p = .017), and mean total package time for patients who received surgery plus adjuvant CXRT ([Formula: see text] = 80.2 and 112.7 days respectively; p = .035). CONCLUSION: The time to treatment was significantly reduced during the COVID-19 pandemic as compared to pre-pandemic. This transparent model of patient-centered operative-room prioritization can serve as a model for improving resource allocation and efficiency of HNC care during emergency and non-emergency scenarios.

The scheduling of adolescence with Netrin-1 and UNC5C.

Dopamine axons are the only axons known to grow during adolescence. Here, using rodent models, we examined how two proteins, Netrin-1 and its receptor, UNC5C, guide dopamine axons towards the prefrontal cortex and shape behaviour. We demonstrate in mice ( Mus musculus ) that dopamine axons reach the cortex through a transient gradient of Netrin-1 expressing cells - disrupting this gradient reroutes axons away from their target. Using a seasonal model (Siberian hamsters; Phodopus sungorus ) we find that mesocortical dopamine development can be regulated by a natural environmental cue (daylength) in a sexually dimorphic manner - delayed in males, but advanced in females. The timings of dopamine axon growth and UNC5C expression are always phase-locked. Adolescence is an ill-defined, transitional period; we pinpoint neurodevelopmental markers underlying this period.

The Minimally Invasive Star-Shaped Incision Technique and the Linear Incision Technique With Tissue Preservation for Percutaneous Bone Conduction Devices: A Retrospective Cohort Study.

Purpose: To compare intra- and postoperative outcomes between the standard linear incision technique with tissue preservation (LITT-P) and the minimally invasive star-shaped incision (SSI). Study Design: A retrospective cohort study. Methods: Primary outcomes evaluated operative time, implant survival, and intra-operative complications. A secondary outcome evaluated soft tissue tolerability assessed by the Holger's classification. Results: A total of 38 implants were placed (19 LITT-P; 19 SSI). The median and mean surgical duration for the LITT-P group was statistically shorter than the SSI group (p = 0.0001). No intra-operative complications were reported for both surgical approaches. Five implants were lost during postoperative follow-up: one in the LITT-P and four in the SSI cohort. Both cohorts showed favorable soft tissue tolerability. Less Holgers 1 and 2 and more Holgers 3 soft tissue reactions were observed after the LITT-P compared to the SSI. Conclusion: The novel SSI approach could be an alternative option based on the theoretical benefits and found favorable (and similar) soft tissue outcomes. Implant loss and surgical time are aspects to investigate regarding long-term durability and warrant further research.

Surgical Outcomes of Thyroid Nodules Positive for Gene Expression Alterations Using ThyroSeq V3 Genomic Classifier.

ThyroSeq V3 (TsV3) tests for various genetic alterations, including gene expression alterations (GEAs), to improve diagnostic accuracy and clinical decision-making for indeterminate thyroid nodules. This study aimed to clarify the clinico-pathological features and outcomes of GEA-positive thyroid nodules, which have not yet been well-described in the literature. A retrospective chart review was performed whereby patients were included if they underwent thyroid surgery between January 2018 and May 2022 at two McGill University teaching hospitals and their surgery was preceded by pre-operative molecular TsV3 testing. In total, 75 of the 328 patients with thyroid nodules (22.9%) who underwent molecular testing and surgery were GEA-positive. On surgical pathology, GEA-positive nodules showed a significantly higher malignancy rate compared to their GEA-negative counterparts (90.7% vs. 77.7%, respectively, p = 0.011). Among those that were malignant, 48.5% had at least one aggressive pathological feature, including histological subtype, extra-thyroidal extension, or lymph node metastasis. BRAF V600E mutation had a significantly greater association with aggressive malignant GEA-positive nodules compared to non-aggressive ones (p < 0.001). This study demonstrates that GEA may be an effective diagnostic and prognostic tool for thyroid nodule management. However, further investigation is needed to characterize the clinico-pathological features of GEA in isolation and in association with other gene alterations.

Sonic hedgehog accelerates DNA replication to cause replication stress promoting cancer initiation in medulloblastoma.

The mechanisms generating cancer-initiating mutations are not well understood. Sonic hedgehog (SHH) pathway activation is frequent in medulloblastoma (MB), with PTCH1 mutations being a common initiating event. Here we investigated the role of the developmental mitogen SHH in initiating carcinogenesis in the cells of origin: granule cell progenitors (GCPs). We delineate a molecular mechanism for tumor initiation in MB. Exposure of GCPs to Shh causes a distinct form of DNA replication stress, increasing both origin firing and fork velocity. Shh promotes DNA helicase loading and activation, with increased Cdc7-dependent origin firing. The S-phase duration is reduced and hyper-recombination occurs, causing copy number neutral loss of heterozygosity-a frequent event at the PTCH1/ptch1 locus. Moreover, Cdc7 inhibition to attenuate origin firing reduces recombination and preneoplastic tumor formation in mice. Therefore, tissue-specific replication stress induced by Shh promotes loss of heterozygosity, which in tumor-prone Ptch1+/- GCPs results in loss of this tumor suppressor-an early cancer-initiating event.

An optimized immunohistochemistry protocol for detecting the guidance cue Netrin-1 in neural tissue.

Netrin-1, an axon guidance protein, is difficult to detect using immunohistochemistry. We performed a multi-step, blinded, and controlled protocol optimization procedure to establish an efficient and effective fluorescent immunohistochemistry protocol for characterizing Netrin-1 expression. Coronal mouse brain sections were used to test numerous antigen retrieval methods and combinations thereof in order to optimize the stain quality of a commercially available Netrin-1 antibody. Stain quality was evaluated by experienced neuroanatomists for two criteria: signal intensity and signal-to-noise ratio. After five rounds of testing protocol variants, we established a modified immunohistochemistry protocol that produced a Netrin-1 signal with good signal intensity and a high signal-to-noise ratio. The key protocol modifications are as follows: •Use phosphate buffer (PB) as the blocking solution solvent.•Use 1% sodium dodecyl sulfate (SDS) treatment for antigen retrieval. The original protocol was optimized for use with the Netrin-1 antibody produced by Novus Biologicals. However, we subsequently further modified the protocol to work with the antibody produced by Abcam. The Abcam protocol uses PBS as the blocking solution solvent and adds a citrate buffer antigen retrieval step.