Laetitia Peultier-Celli

The third window syndrome, often associated with the Tullio phenomenon, is currently most often observed in patients with a superior semicircular-canal dehiscence (SCD) but is not specific to this pathology. Clinical and vestibular tests suggestive of this pathology are not always concomitantly observed and have been recently complemented by the skull-vibration-induced nystagmus test, which constitutes a bone-conducted Tullio phenomenon (BCTP). The aim of this work was to collect from the literature the insights given by this bedside test performed with bone-conducted stimulations in SCD. The PRISMA guidelines were used, and 10 publications were included and analyzed. Skull vibration-induced nystagmus (SVIN), as observed in 55 to 100% of SCD patients, usually signals SCD with greater sensitivity than the air-conducted Tullio phenomenon (ACTP) or the Hennebert sign. The SVIN direction when the test is performed on the vertex location at 100 Hz is most often ipsilaterally beating in 82% of cases for the horizontal and torsional components and down-beating for the vertical component. Vertex stimulations are more efficient than mastoid stimulations at 100 Hz but are equivalent at higher frequencies. SVIN efficiency may depend on stimulus location, order, and duration. In SCD, SVIN frequency sensitivity is extended toward high frequencies, with around 400 Hz being optimal. SVIN direction may depend in 25% on stimulus frequency and in 50% on stimulus location. Mastoid stimulations show frequently diverging results following the side of stimulation. An after-nystagmus observed in 25% of cases can be interpreted in light of recent physiological data showing two modes of activation: (1) cycle-by-cycle phase-locked activation of action potentials in SCC afferents with irregular resting discharge; (2) cupula deflection by fluid streaming caused by the travelling waves of fluid displacement initiated by sound or vibration at the point of the dehiscence. The SVIN direction and intensity may result from these two mechanisms’ competition. This instability explains the SVIN variability following stimulus location and frequency observed in some patients but also discrepancies between investigators. SVIN is a recent useful insight among other bedside examination tests for the diagnosis of SCD in clinical practice.

Knee osteoarthritis (KOA) can generate postural control impairments which can increase fall risk. Land-based exercise (LBE) and balneotherapy are two modalities currently prescribed, but the impact of the latter on balance control has not been studied. This study aimed to compare two programs of balneotherapy with or without LBE to improve postural control, looking at frequency and duration of treatment. A total of 236 KOA patients (mean age = 64 years) were included in this prospective and randomized study: 122 patients went through 3 weeks of standardized continuous balneotherapy (high frequency/short duration) program (Gr1) and 114 went through 3 weeks of discontinuous (low frequency) balneotherapy program followed by 3 weeks of LBE (Gr2). The total number of treatment sessions was the same for both groups. Posturography was carried out before balneotherapy (W0) and at 3 (W3), 6 (W6), and 12 (W12) weeks after the beginning of treatment. Postural control increased in Gr1 from W0 to W3 and from W0 to W12 and in Gr2 from W0 to W6 and from W3 to W6. The improvement was greater in Gr1 from W0 to W3 and from W6 to W12 and in Gr2 from W3 to W6. High-frequency intensive balneotherapy improved posture control at 3 weeks, while low-frequency balneotherapy did not. This improvement persisted over a 12-week assessment period at the same level. LBE generated an improvement that did not persist over time. Sustained improvement of postural control requires high-frequency repetition of consecutive balneotherapy sessions.