Skull Vibration-Induced Nystagmus in Superior Semicircular Canal Dehiscence: A New Insight into Vestibular Exploration-A Review.

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.

Balance control impairments in Fabry disease.

Background: Fabry disease (FD) is a rare inherited lysosomal storage disorder caused by the deficiency of the enzyme alpha-galactosidase A. This deficiency leads to an accumulation of glycosphingolipids leading to progressive and multisystemic disease, including renal, cardiac, and neurological damages. FD may also have neuro-otological and visual impairments, which can generate postural control alterations, inner ear, and vision being involved in this function. This study aimed to evaluate the impact of FD on postural control. Methods: In total, fourteen adult patients (8 men/6 women, mean age = 37.6 ± 11.4 years) and two children (mean age = 11 years) with FD and 19 healthy adults (12 men/7 women, mean age = 36.5 ± 16.9 years) and two healthy children (mean age = 10.5 years) took part in this study. Postural control was evaluated by a sensory organization test combining three visual situations (eyes open, eyes closed, and sway referenced visual surround motion) with two platform situations (stable platform and sway referenced platform motion), aiming to calculate a composite equilibrium score (CES), a high score being representative of good postural control. Somatosensory (RSOM), visual (RVIS), and vestibular (RVEST) contributions to postural control were calculated, a low score reflecting a poor use of the indicated sensory input. Results: The CES was lower in adult patients with FD compared with the healthy subjects (p < 0.001). RVIS (p = 0.001) and RVEST (p = 0.003) were lower in patients with FD compared with the control group, whereas no difference in RSOM was observed. Conclusion: Inner ear and visual pathologies associated with the central nervous system impairments are factors of postural control impairments. Physical activities, which can also be rehabilitative, by maintaining or increasing the weight of proprioception, may help diminish dependency on altered sensorial inputs.

Postural Control in Lyric Singers.

BACKGROUND: Singers are unique musicians because they use their whole body as a musical instrument. Posture and proprioception are key components for a robust and healthy voice. OBJECTIVE: This study aimed to analyze the postural control of lyric singers in different sensorimotor conditions. METHODS: Seventeen lyric singers were compared to a control group of 12 participants in static postural control test in eyes open (C1) and eyes closed (C2) conditions. Postural control of singers was also assessed in four specific singing conditions: singing posture eyes open (C3) and eyes closed (C4), vocalization (C5) and free aria (C6), low values being representative of good postural control. Singers also completed the Singing Voice Handicap Index (SVHI) French version, low scores reflecting a good SVHI result. RESULTS: No significant difference was observed between the two groups in C1 and C2. Postural control of singers was more accurate in C3 than in C1. Increased values in all postural parameters were seen in the singing conditions. Scores obtained at the SVHI were correlated to the area covered by the center of foot pressure in C5, low scores at the SVHI being correlated with low area values in this postural condition. CONCLUSIONS: Singing is a multitask situation which involves several movements including breathing, and management of factors such as stress. This can affect balance and so rigorous work on posture and proprioception is required as soon as a singer begins to perform in order to take care of the voice.

Relation of arterial stiffness with postural control in older people.

PURPOSE: Arterial stiffness generates vascular alterations that may cause balance disorders and falls. This study aimed to investigate the possible link between arterial stiffness and postural control under different sensorial conditions in patients over 65 years. METHODS: Carotid-femoral pulse wave velocity (PWV) was measured in 47 participants aged over 65 years to evaluate their arterial stiffness (high PWV). Twenty-seven participants (mean age = 70.52 ± 4.02 years, 22 females) had a normal PWV (< 10 m s-1) and 20 participants (mean age = 75.93 ± 6.11 years; 15 females) had a high PWV (≥ 10 m s-1). Postural control was evaluated using a force platform in four postural conditions: eyes open (EO) 1, eyes closed (EC), eyes open with a dual task (DT) and eyes open again (EO2). Using sway path traveled and surface covered by the center of foot pressure, we calculate the length function of surface (LFS). This ratio provides information about the precision (surface) of postural control and the effort made (length) by the subjects. RESULTS: After an age-adjustment, LFS was lower in EO than in EC and DT in both groups (p ≤ 0.001). LFS was higher in participants with high PWV both in eyes open and eyes closed conditions (p < 0.05). LFS increased when PWV increased in EO (p < 0.01) and EC conditions (p < 0.001) but not when a dual task was performed. CONCLUSION: Difficulties in maintaining equilibrium under a dual-task condition are more pronounced in people with increased arterial stiffness. These data suggest that understanding of the influence of the arterial stiffness level on specific balance control parameters could contribute to propose better balance-oriented rehabilitation programs in older adults in an attempt to prevent fall.

No significant improvement in neuromuscular proprioception and increased reliance on visual compensation 6 months after ACL reconstruction.

PURPOSE: To determine the contributions of proprioceptive and visual feedbacks for postural control at 6 months following ACLR, and to determine their associations with knee laxity, isokinetic tests and clinical scores. STUDY DESIGN: Level IV, Case series. METHODS: Fifty volunteers who received ACLR between May 2015 and January 2017 were prospectively enrolled, and at 6 months following ACLR, postural stability was assessed. Somatosensory ratios (somatic proprioception), and visual ratios (visual compensation), were calculated to evaluate the use of sensory inputs for postural control. Univariable regression analyses were performed to determine associations of somatosensory and visual ratios with knee laxity, isokinetic tests and clinical scores. RESULTS: At 6 months following ACLR, the somatosensory ratio did not change, while the visual ratio decreased significantly from 5.73 ± 4.13 to 3.07 ± 1.96 (p = 0.002), indicating greater reliance on visual cues to maintain balance. Univariable analyses revealed that the somatosensory ratio was significantly lower for patients who performed aquatic therapy (ß = -0.50; p = 0.045), but was not associated with knee laxity, muscle strength or clinical scores. An increased visual ratio was associated with patients who received hamstrings tendon autografts (ß = 1.32; p = 0.049), but was not associated with knee laxity, muscle strength or clinical scores. CONCLUSION: At 6 months following ACLR, visual ratios decreased significantly, while somatosensory ratios did not change. This may suggest that there is little or no improvement in neuromuscular proprioception and therefore greater reliance on visual cues to maintain balance. The clinical relevance of this study is that posturography can provide useful information to help research following ACLR and to predict successful return to play.

Comparison of high-frequency intensive balneotherapy with low-frequency balneotherapy combined with land-based exercise on postural control in symptomatic knee osteoarthritis: a randomized clinical trial.

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.

Characteristics of phantom upper limb mobility encourage phantom-mobility-based prosthesis control.

There is an increasing need to extend the control possibilities of upper limb amputees over their prosthetics, especially given the development of devices with numerous active joints. One way of feeding pattern recognition myoelectric control is to rely on the myoelectric activities of the residual limb associated with phantom limb movements (PLM). This study aimed to describe the types, characteristics, potential influencing factors and trainability of upper limb PLM. Seventy-six below- and above-elbow amputees with major amputation underwent a semi-directed interview about their phantom limb. Amputation level, elapsed time since amputation, chronic pain and use of prostheses of upper limb PLM were extracted from the interviews. Thirteen different PLM were found involving the hand, wrist and elbow. Seventy-six percent of the patients were able to produce at least one type of PLM; most of them could execute several. Amputation level, elapsed time since amputation, chronic pain and use of myoelectric prostheses were not found to influence PLM. Five above-elbow amputees participated in a PLM training program and consequently increased both endurance and speed of their PLM. These results clearly encourage further research on PLM-associated muscle activation patterns for future PLM-based modes of prostheses control.

Defining Clinical-Posturographic and Intra-Posturographic Discordances: What Do These Two Concepts Mean?

The European Society for Clinical Evaluation of Balance Disorders - ESCEBD - Executive Committee meets yearly to identify and address clinical equilibrium problems that are not yet well understood. This particular discussion addressed "discordances" (defined as "lack of agreement") in clinical assessment. Sometimes there is disagreement between a clinical assessment and measured abnormality (ies); sometimes the results within the assessment do not agree. This is sometimes thought of as "malingering" or an attempt to exaggerate what is wrong, but this is not always the case. The Committee discussed the clinical significance of unexpected findings in a patient's assessment. For example intraposturographic discordances sometimes exhibit findings (eg performance on more difficult trials may sometimes be better than on simpler trials). This can be suggestive of malingering, but in some situations can be a legitimate finding. The extreme malingerer and the genuine patient are at opposite ends of a spectrum but there are many variations along this spectrum and clinicians need to be cautious, as a posturography assessment may or may not be diagnostically helpful. Sometimes there is poor correlation between symptom severity and test results. Interpretation of posturography performance can at times be difficult and a patient's results must be correlated with clinical findings without stereotyping the patient. It is only in this situation that assessment in a diagnostic setting can be carried out in an accurate and unbiased manner.

Comparison of an Innovative Rehabilitation, Combining Reduced Conventional Rehabilitation with Balneotherapy, and a Conventional Rehabilitation after Anterior Cruciate Ligament Reconstruction in Athletes.

BACKGROUND: Instability of the knee, related to anterior cruciate ligament injury, is treated by surgical reconstruction. During recovery, a loss of proprioceptive input can have a significant impact. Few studies have evaluated the benefits of rehabilitation of the knee in aquatic environment on functional outcomes. OBJECTIVE: This study aimed to compare an innovative rehabilitation protocol combining reduced conventional rehabilitation with aquatic rehabilitation, with a conventional rehabilitation, according to the National French Health Authority, in terms of kinetics, development of proprioceptive skills, and functional improvement of the knee. METHODS: 67 patients, who were amateur or professional athletes, were randomized into two groups: 35 patients followed the conventional rehabilitation protocol (Gr1) and 32 patients followed the innovative rehabilitation protocol (Gr2). Patients were evaluated before surgery, and at 2 weeks, 1, 2, and 6 months after surgery using posturography, and evaluation of muscular strength, walking performance and proprioception. This study is multicenter, prospective, randomized, and controlled with a group of patients following conventional rehabilitation (level of evidence I). RESULTS: For the same quality of postural control, Gr2 relied more on somesthesia than Gr1 at 6 months. The affected side had an impact on postural control and in particular on the preoperative lateralization, at 2 weeks and at 1 month. Lateralization depended on the affected knee, with less important lateralization in Gr2 preoperatively and at 1 month. The quadriceps muscular strength was higher in Gr2 than in Gr1 at 2 and 6 months and muscle strength of the external hamstring was greater in Gr2 than in Gr1 at 6 months. The isokinetic test showed a greater quadriceps muscular strength in Gr2. Gr2 showed a greater walking distance than Gr1 at one month. Gr2 showed an improvement in the proprioceptive capacities of the operated limb in flexion for the first 2 months. CONCLUSION: The effectiveness of the innovative rehabilitation program permits faster recovery, allowing for an earlier return to social, sporting, and professional activities. Faster retrieval of knee function following aquatic rehabilitation would prevent both short-term risk of lesions of the contralateral limb due to overcompensation and long-term risk of surgery due to osteoarthritis. REGISTRATION OF CLINICAL TRIALS: NCT02225613.