Benign paroxysmal positional vertigo and asymmetric hearing loss: is the worst hearing ear likely to suffer from otoconial displacement?

PURPOSE: Benign paroxysmal positional vertigo (BPPV) may be found in patients complaining of hearing disorders. The aim of our investigation was to describe audiological findings in BPPV patients, focusing on subjects with asymmetric hearing loss (AHL), to better understand whether otoconial displacement may occur preferentially in the worst hearing ear. METHODS: A prospective study was performed on 112 BPPV patients. We divided the sample into subjects who suffered from AHL (G1) and patients with did not (G2). Data regarding vestibular symptoms, tinnitus, migraine, antivertigo drug therapy, and vascular risk factors were collected. RESULTS: Out of 30 AHL subjects, 83.33% of them were affected by sensorineural hearing loss (SNHL) in at least one ear, with a significant difference in the distribution of hearing loss type between groups (p = 0.0006). In 70% of cases, the ear affected by BPPV was the one with the worst hearing threshold (p = 0.02); threshold asymmetry predicted BPPV in the worst hearing ear (p = 0.03). The predictability depended neither on the hearing threshold gap between ears nor the severity of the hearing threshold in the worst ear (p > 0.05). No differences in vascular risk factors between groups were observed (p > 0.05). We evidenced a moderate correlation between age and hearing threshold (ρ = 0.43). Age did not result a predictive factor for residual dizziness or BPPV in the worst ear (p > 0.05). CONCLUSIONS: Our study supports the likelihood of an otoconial displacement in the worse hearing ear in BPPV patients. Clinicians should start testing the worst hearing ear when managing AHL patients with suspected BPPV.

Frequency shift algorithm: Design of a baseband phase locked loop for frequency-domain multiplexing readout of x-ray transition-edge sensor microcalorimeters.

The Transition-Edge Sensor (TES) is an extremely sensitive device, which is used to measure the energy of individual x-ray photons. For astronomical spectrometry applications, SRON develops a frequency domain multiplexing readout system for kilopixel arrays of such TESs. Each TES is voltage biased at a specific frequency in the range of 1-5 MHz. Isolation between the individual pixels is obtained through very narrow-band (high-Q) lithographic LC resonators. To prevent energy resolution degradation due to intermodulation line noise, the bias frequencies are distributed on a regular grid. The requirements on the accuracy of the LC resonance frequency are very high. The deviation of the resonance frequencies due to production tolerances is significant with respect to the bandwidth, and a controller is necessary to compensate for the LC series impedance. We present two such controllers: a simple orthogonal proportional-integral controller and a more complex impedance estimator. Both controllers operate in baseband and try to make the TES current in-phase with the bias voltage, effectively operating as phase-locked loops. They allow off-LC-resonance operation of the TES pixels while preserving the TES thermal response and energy resolution. Extensive experimental results-published in a companion paper recently-with the proposed methods show that these controllers allow the preservation of single pixel energy resolution in multiplexed operation.