[Clinical features of vestibular syncope associated with tumarkin attacks in delayed endolymphatic hydrops].

Objective: To analyze the clinical characteristics of vestibular syncope (VS) associated with drop attacks (DA) in delayed endolymphatic hydrops (DEH). Methods: DEH cases with complete data were retrospectively analyzed, including three DEH cases with DA and VS (VS group), and six DEH cases without DA or VS (control group). The clinical profile, the results of neurotological examinations [such as pure tone audiometry, electrocochleography (EcochG), caloric test, vestibular evoked myogenic potentials (VEMP), and video head impulse test (vHIT)] and treatment outcomes were analyzed. Results: (1) In the VS group, there were three cases of ipsilateral DEH; in the control group, there were six cases of ipsilateral type. One case in each group had a history of migraine. (2) The prevalence of abnormal results in caloric test, vHIT, cervical VEMP, and ocular VEMP in the VS group was 3/3, 1/3, 2/2, and 2/2, respectively, and in the control group was 3/6, 0/3, 1/6, and 4/6, respectively. Two cases in each group underwent EcochG, and no identifiable waveform was elicited on the affected side, and-SP/AP ratio of unaffected side was less than 0.4. (3) Patients in both groups were initially treated with conservative medication. Two cases in the VS group subsequently received intratympanic injections of dexamethasone. No DA or VS occurred during a follow-up period lasting over one year. All patients achieved good control of vertigo during the follow-up period. Conclusions: VS may occur in the patients with DEH. The differential diagnosis of syncope in patients with otogenic vertiginous disease can help improve clinical diagnosis and treatment.

Unusual magnetization process and magnetocaloric effect in α-CoV2O6driven by pulsed magnetic fields.

In low-dimensional Ising spin systems, an interesting observation is the presence of step magnetization at low temperatures. Here we combine both DC and pulsed magnetic fields to study the 1/3 magnetization plateau and multiple steps in the Ising spin-chain material α-CoV2O6. Magnetization in pulsed fields is quite different from that in DC fields, showing multiple steps in an intermediate range of 4.2-6 K, inverted hysteresis below 4.2 K and asymmetric magnetization in negative fields below 11 K. We demonstrate that these unusual behaviors in magnetization are caused by the spin dynamics and the anomalous magnetocaloric effect (MCE) in α-CoV2O6, i.e., abrupt changes of sample temperature in adiabatic conditions. We successfully separate the influence between the intrinsic slow spin dynamics and the quasi-extrinsic temperature change. From the MCE, we find that some irreversible behavior is originated from the slow spin dynamics. Two different slow dynamics associated with the metastable steps are observed: one is sensitive to the slow field sweep rate at the order of ∼mT s-1and weakly depends on temperature, while the other responds to the rapid field sweep rate of ∼kT s-1and dominates at lowest temperature. We also distinguish that the metastable transition atH4is the first order and crucial for the ferrimagnetic to ferromagnetic transition. This study is useful to the understanding of multistep magnetization in α-CoV2O6and sheds light on recent experimental findings of related compounds.