Yohan Song

Prestin Regulation and Function in Residual Outer Hair Cells after Noise-Induced Hearing Loss

The outer hair cell (OHC) motor protein prestin is necessary for electromotility, which drives cochlear amplification and produces exquisitely sharp frequency tuning. TectaC1509G transgenic mice have hearing loss, and surprisingly have increased OHC prestin levels. We hypothesized, therefore, that prestin up-regulation may represent a generalized response to compensate for a state of hearing loss. In the present study, we sought to determine the effects of noise-induced hearing loss on prestin expression. After noise exposure, we performed cytocochleograms and observed OHC loss only in the basal region of the cochlea. Next, we patch clamped OHCs from the apical turn (9–12 kHz region), where no OHCs were lost, in noise-exposed and age-matched control mice. The non-linear capacitance was significantly higher in noise-exposed mice, consistent with higher functional prestin levels. We then measured prestin protein and mRNA levels in whole-cochlea specimens. Both Western blot and qPCR studies demonstrated increased prestin expression after noise exposure. Finally, we examined the effect of the prestin increase in vivo following noise damage. Immediately after noise exposure, ABR and DPOAE thresholds were elevated by 30–40 dB. While most of the temporary threshold shifts recovered within 3 days, there were additional improvements over the next month. However, DPOAE magnitudes, basilar membrane vibration, and CAP tuning curve measurements from the 9–12 kHz cochlear region demonstrated no differences between noise-exposed mice and control mice. Taken together, these data indicate that prestin is up-regulated by 32–58% in residual OHCs after noise exposure and that the prestin is functional. These findings are consistent with the notion that prestin increases in an attempt to partially compensate for reduced force production because of missing OHCs. However, in regions where there is no OHC loss, the cochlea is able to compensate for the excess prestin in order to maintain stable auditory thresholds and frequency discrimination.

Suture-Button Suspensionplasty for Thumb Carpometacarpal Arthritis: A Minimum 2-Year Follow-Up

PURPOSE To retrospectively review the results at a minimum of 2 years of suture-button plasty with partial or full trapeziectomy and suture-button suspensionplasty. METHODS We evaluated 21 patients who received suture-button suspensionplasty at least 2 years after surgery. We measured postoperative pinch strength, grip strength, range of motion, and metacarpal height. All patients also completed the Quick Disabilities of the Arm, Shoulder, and Hand questionnaire. RESULTS At an average follow-up of 2.8 ± 0.7 years, the mean Quick Disabilities of the Arm, Shoulder, and Hand score was 10 ± 9. Pinch and grip strengths were 86% and 89% of the contralateral limb, respectively. Average first trapezial height was 74% of the contralateral trapezial height. There were no major complications. CONCLUSIONS The favorable results of the suture-button suspensionplasty procedure confirm its usefulness in treating thumb carpometacarpal arthritis with minimal risk of complications, ineffective fixation, or loss of function. Subjective and objective outcomes measures are similar to previously described techniques. The benefit of this technique results from the implanted nature of the suspensionplasty elements that require no time to heal, so rehabilitation is begun as early as 10 days postoperatively. TYPE OF STUDY/LEVEL OF EVIDENCE Therapeutic IV.

Outcomes of Ulnar Shortening Osteotomy Fixed With a Dynamic Compression System

PURPOSE To evaluate the outcomes of patients with ulnar impaction syndrome treated with a jig-facilitated, oblique, diaphyseal ulnar shortening osteotomy and fixed with a TriMed (Santa Clarita, CA) ulnar osteotomy compression plate. METHODS A retrospective chart review of patients with ulnar impaction syndrome identified 38 patients who had had ulnar shortening osteotomy and fixation with the TriMed dynamic compression system. The following clinical data were obtained: patient age, sex, follow-up range of motion, grip strength, and complications. After a minimum of 2 years after surgery, patients reported complications and completed a Disabilities of the Arm, Shoulder, and Hand questionnaire. RESULTS Eight patients were lost to follow-up. Compared to the opposite limb at an average of 8 months after surgery, the remaining 30 patients attained 92% to 97% of wrist and forearm motion and 71% of grip strength. The average Disabilities of the Arm, Shoulder, and Hand score was 12 after a minimum of 2 years after surgery. Four patients required plate removal due to irritation. Two patients reported persistent ulnar-sided pain, and 2 other patients developed atrophic nonunions and required autologous bone grafting. There were no infections. CONCLUSIONS Ulnar shortening osteotomy using the TriMed system yielded good clinical outcomes that are comparable to those previously documented using other systems. TYPE OF STUDY/LEVEL OF EVIDENCE Therapeutic IV.

A potentially hazardous complication during central venous catheterization: lost guidewire retained in the patient

Guidewires are routinely used in the Seldinger technique during central venous catheter placement. A case in which a guidewire was unsuspectingly released and retained in a patient during the catheterization of the internal jugular vein is presented. Physicians from multiple services subsequently failed to detect the retained guidewire on several chest radiographs; however, the guidewire was incidentally discovered after a computed tomographic scan was obtained.

Consultation via telemedicine and access to operative care for patients with head and neck cancer in a Veterans Health Administration population.

The purpose of this study was to evaluate a telemedicine model that utilizes an audiovisual teleconference as a preoperative visit.

Activity-dependent regulation of prestin expression in mouse outer hair cells

Prestin is a membrane protein necessary for outer hair cell (OHC) electromotility and normal hearing. Its regulatory mechanisms are unknown. Several mouse models of hearing loss demonstrate increased prestin, inspiring us to investigate how hearing loss might feedback onto OHCs. To test whether centrally mediated feedback regulates prestin, we developed a novel model of inner hair cell loss. Injection of diphtheria toxin (DT) into adult CBA mice produced significant loss of inner hair cells without affecting OHCs. Thus, DT-injected mice were deaf because they had no afferent auditory input despite OHCs continuing to receive normal auditory mechanical stimulation and having normal function. Patch-clamp experiments demonstrated no change in OHC prestin, indicating that loss of information transfer centrally did not alter prestin expression. To test whether local mechanical feedback regulates prestin, we used Tecta(C1509G) mice, where the tectorial membrane is malformed and only some OHCs are stimulated. OHCs connected to the tectorial membrane had normal prestin levels, whereas OHCs not connected to the tectorial membrane had elevated prestin levels, supporting an activity-dependent model. To test whether the endocochlear potential was necessary for prestin regulation, we studied Tecta(C1509G) mice at different developmental ages. OHCs not connected to the tectorial membrane had lower than normal prestin levels before the onset of the endocochlear potential and higher than normal prestin levels after the onset of the endocochlear potential. Taken together, these data indicate that OHC prestin levels are regulated through local feedback that requires mechanoelectrical transduction currents. This adaptation may serve to compensate for variations in the local mechanical environment.

Trapezial Metastasis as the First Indication of Primary Non–small Cell Carcinoma of the Lung

Metastasis to the bones of the hand and wrist is not common, and its discovery may reveal an advanced primary tumor located centrally. Clinically, hand metastasis is hard to differentiate from other more common hand pathologies. Its rarity, coupled with a lack of unique clinical manifestations, makes hand and wrist metastasis difficult to diagnose. However, its diagnosis is critical to initiate an appropriate course of treatment. We present a patient in whom lung carcinoma metastasis to the trapezium was definitively diagnosed upon surgical management of symptoms that were consistent with thumb carpometacarpal arthritis.

Retrograde Parotidectomy and facial nerve outcomes: A case series of 44 patients

PURPOSE The most common surgical method to remove benign parotid tumors remains the prograde approach. We examined if a retrograde surgical technique offers better outcomes than historical prograde controls. MATERIALS AND METHODS A retrospective chart review at Stanford Hospital was conducted to identify retrograde parotidectomies between February 2012 and October 2014 that were staffed by the senior author (DS) with resident involvement. Facial nerve (FN) outcomes and other post-surgical parameters were recorded. RESULTS We identified 44 consecutive cases and found that 18.2% (n=8) of patients experienced temporary paresis and 2.3% (n=1) experienced minor (HB 2) permanent paresis limited to one branch. The average hospital length of stay was 0.64 days and complication rate was 6.8%. CONCLUSION The retrograde technique has complication rates comparable to historical rates for the prograde technique and is amenable to minimally invasive outpatient superficial parotidectomy.

Anterolateral approach to the upper cervical spine: Case report and operative technique

Transcervical approaches to the upper cervical spine are challenging because several upper anterior neurovascular structures need to be displaced to provide access. Although various techniques have been described, the anterolateral approach is one of the safest and most effective methods available to access the anterior C2–C3 disc space. Despite the approachs efficacy, however, it can cause postoperative complications because of, at least partly, the inter‐surgeon differences in the methods by which the larynx and hypopharynx are displaced medially.

Suture-Button Suspensionplasty for the Treatment of Thumb Carpometacarpal Joint Arthritis

Despite the numerous techniques available to treat thumb carpometacarpal arthritis, studies show no long-term differences in outcomes among these techniques. However, simple trapeziectomy has been gaining popularity because of its low propensity for complications and relatively short intraoperative procedural time. Current approaches to trapeziectomy use Kirschner wire fixation to prevent subsidence. Unfortunately, this fixation method requires at least 4 weeks of immobilization of the thumb. We describe a novel technique involving suture-button (SB) suspensionplasty (Mini TightRope, Arthrex, Naples, FL) that allows for earlier mobilization of the thumb and faster overall recovery. This method uses a SB device that suspends the thumb ray after arthroscopic hemitrapeziectomy or full trapeziectomy. Preliminary results are promising, but further studies must be conducted to confirm the safety and efficacy of this SB suspensionplasty technique.