Acta Otolaryngol. 2013 Apr;133(4):361-7. doi: 10.3109/00016489.2012.739731. Epub 2013 Jan 14.
The measurement of the energy consumption (EC) of the body’s center of pressure (COP) to maintain the upright stance position was higher in elderly patients with bilateral vestibular hypofunction (BVH) compared with a control group and may be a valid parameter in the assessment of balance disorders.
The aim of the study was to evaluate the energy consumption of the COP in elderly patients with BVH.
The COP was recorded on a force platform (FP) for eight elderly patients with BVH related to aging and eight normal control group subjects. The EC of the COP was calculated using the discrete wavelet transform. The two groups were tested in standing position on the FP in three sensory conditions:1, eyes open; 2, eyes closed; and 3, standing on a foam pad placed on the force platform. Wilcoxon’s rank test and multi-factor analysis of variance were used, with the level of significance set at 0.05.
BVH patients showed higher values of EC of the COP signal measured in arbitrary units compared with the control group (conditions 1 and 2). None of the BVH patients could perform the test in condition 3. BVH patients had increased EC in the frequency band between 0.1 and 0.78 Hz when the visual information was canceled (condition 2).
Clin Interv Aging. 2013;8:257-63. doi: 10.2147/CIA.S41453. Epub 2013 Feb 28.
Duque G1, Boersma D, Loza-Diaz G, Hassan S, Suarez H, Geisinger D, Suriyaarachchi P, Sharma A, Demontiero O.
Poor balance is considered a challenging risk factor for falls in older adults. Therefore, innovative interventions for balance improvement in this population are greatly needed. The aim of this study was to evaluate the effect of a new virtual-reality system (the Balance Rehabilitation Unit [BRU]) on balance, falls, and fear of falling in a population of community-dwelling older subjects with a known history of falls. In this study, 60 community-dwelling older subjects were recruited after being diagnosed with poor balance at the Falls and Fractures Clinic, Nepean Hospital (Penrith, NSW, Australia). Subjects were randomly assigned to either the BRU-training or control groups. Both groups received the usual falls prevention care. The BRU-training group attended balance training (two sessions/week for 6 weeks) using an established protocol. Change in balance parameters was assessed in the BRU-training group at the end of their 6-week training program. Both groups were assessed 9 months after their initial assessment (month 0). Adherence to the BRU-training program was 97%. Balance parameters were significantly improved in the BRU-training group (P < 0.01). This effect was also associated with a significant reduction in falls and lower levels of fear of falling (P < 0.01). Some components of balance that were improved by BRU training showed a decline after 9 months post-training. In conclusion, BRU training is an effective and well-accepted intervention to improve balance, increase confidence, and prevent falls in the elderly.
balance; elderly; falls; postural instability; virtual reality
Acta Otolaryngol. 2015 Apr;135(4):348-53. doi: 10.3109/00016489.2014.974287. Epub 2015 Mar 7.
Suarez H, Ferreira E, Arocena S, Bagalciague F, San Roman C, Sotta G, Geisinger D, Suarez A.
The head tilt response (HTR) test performed in a group of patients with chronic dizziness after acoustic neuroma surgery showed alterations in the gravitational vertical perception (GV).
The assessment of the accuracy in the GV through the HTR test in patients with long-term balance disorders after acoustic neuroma surgery.
The HTR was performed in two groups of patients that had undergone acoustic neuroma surgery: six uncompensated patients (UPs) who maintained vestibular symptoms 1 year after surgery and two compensated patients (CPs) without vestibular symptoms. Twelve healthy control adults were also tested (control group, CG). Three parameters were measured in the HTR test: steady-state error (SSE), rise time (TRS), and mean energy of the error signal per step (MEE).
The UP group showed higher values for the TRS and MEE parameters compared with the CG (p < 0.05) when performing the HTR test to the side of the lesion and to the contralateral side, while the SSE only showed significant higher values when the patient estimated the GV towards the side of the lesion. The two patients in the CP group did not have differences in the three parameters assessed when compared with the CG.
Head tilt response test; chronic dizziness; vestibular symptoms
ACTA OTO-LARYNGOLOGICA, 2016 http://dx.doi.org/10.1080/00016489.2016.1247496
Hamlet Suarez, Rafael Alonso, Sofia Arocena, Enrique Ferreira, Cecilia San
Roman, Alejo Suarez & Valeria Lapilover
Conclusions: The results suggest that auditory input is not neutral in motor skills and the complex interaction between them is generated in the earlier stages of childhood development.
Objective: The assessment of gait performance in pre-lingual deaf children with cochlear implant (CI).
Methods: Gait velocity (GV), using a 10-meter test, was measured by means of three inertial sensors in 10 pre-lingual cochlear implant users (CIU) (10–16 years old) in three sensory conditions: (1) cochlear implant turned on with environmental noise (EN), (2) cochlear implant turned on with EN and with cognitive dual task (DT), and (3) CI turned off (CI-OFF). GV with EN and DT was assessed in a normal hearing control group (CG) (n = 14). Mann-Whitney and Wilcoxon Signed ranked test were used for significance validation.
Results: (1) GV in CG was lower in DT than with EN (p= 0.019). (2) GV was faster in CG with EN compared with the three conditions in CIU (EN, p= 0.006; DT, p= 0.0001; CI-OFF, p= 0.03). (3) CIU had slower GV walking with EN (p=0.037) and with DT (p=0.022). (4) Dividing the CIU sample by age, the acoustic information generates a slower gait for those implanted after 3 years old.
Acta Otolaryngol. 2016 Apr;136(4):344-50.
Suarez H1, Ferreira E2, Alonso R3, Arocena S1, San Roman C1, Herrera T1, Lapilover V1.
Conclusions The assessment of postural responses (PR) based in a feedback control system model shows selective gains in different bands of frequencies adaptable with child development. Objective PR characterization of pre-lingual cochlear implant users (CIU) in different sensory conditions. Methods Total energy consumption of the body’s center of pressure signal (ECCOP) and its distribution in three bands of frequencies: band 1 (0-0.1 Hz), band 2 (0.1-0.7 Hz), and band 3 (0.7-20 Hz) was measured in a sample of 18 CIU (8-16 years old) and in a control group (CG) (8-15 years old). They were assessed in a standing position on a force platform in two sensory conditions: 1 = Eyes open. 2 = Eyes closed and standing on foam. Results In condition 1, total ECCOP of PR and its proportion of energy consumption in the three bands of frequencies were similar between CIU and CG (p > 0.05). In condition 2, CIU have significantly higher ECCOP, mainly in high frequencies (bands 2 and 3) (p < 0.05). ECCOP values decreased with age also, mainly in bands 2 and 3. This behavior is interpreted in the control system model proposed as an adaptation process related with child development.
Posture; cochlear implant; postural control model
Lai, T.T., Svirsky, M.A., Meyer, T.A., Kaiser, A.R., Basalo, S, Silveira, A., Suárez, H., Simmons, P.M. & Miyamoto, R.T. (1999). Eastern Society for Pediatric Research. Journal of Investigative Medicine, 47 (2) Feb. 1999. Atlantic City, NJ.
Despite advances in implant technology, cochlear implant (CI) users demonstrate a wide range of the ability to perceive speech in the absence of visual cues. To explain speech perception with a CI, Svirsky & Meyer (1997) developed a psychophysically-based mathematical model [Multidimensional Phoneme Identification (MPI)]. The model provides a full description of how listeners encode, represent and combine the sensory information elicited by vowel sounds. The model generates predicted confusion matrices, given a listener’s performance on various psychophysical tasks. The model predicts, for any given listener, how well s/he perceives vowels, as well as which pairs of vowels are and are not confused by the listener. A three-dimensional model has successfully predicted vowel identification for a group of experienced CI users. In this study, we were interested in using the MPI model to predict long-term vowel perception for an individual CI user based on performance on a psychophysical (pitch ranking) task at the time of initial stimulation. Vowel perception improves with continued CI use. Is this improvement due to increases in the listener’s ability to discriminate between sounds or to label vowel sounds according to a learned pattern? We measured vowel identification and pitch ranking at the time of initial stimulation and several months later. Vowel identification was obtained using ten to fifteen repetitions of each Spanish vowel (I,E,A,O,U) presented in a /hVd/-like context. In the pitch ranking task, the subject heard stimuli sent to adjacent pairs of intra-cochlear electrodes and had to indicate which stimulus was higher pitched. A software version of the MPI model was implemented to obtain predicted vowel confusion matrices based on the patient’s pitch ranking capabilities. The subject’s ability to accurately rank the pitch of different intracochlear electrodes did not vary much between initial stimulation and 6 months of use. Vowel identification, however, increased from approximately chance performance (24%) at initial stimulation to 86% correct identification by 4 months of implant use. Based on the subject’s pitch ranking ability at initial stimulation, the model generated a reasonably accurate prediction of her vowel identification performance 4 months post-implant. The results suggest that the MPI model is an appropriate tool for predicting vowel perception in individual CI users, and that improvements in vowel identification are related to changes in vowel labeling rather than to changes in pitch ranking abilities.
D. Boersma, O. Demontiero, Z. Mohtasham Amiri, S. Hassan, H. Suarez, D. Geisinger, P. Suriyaarachchi, A. Sharma and Gustavo Duque
THE JOURNAL OF NUTRITION, HEALTH & AGING
Postural instability (PI) is an important risk factor for falls, especially in the frail older population. In this study, we investigated the impact of vitamin D deficiency on PI in a sample of community dwelling older subjects. Our objective was to determine the potential association between vitamin D deficiency and PI in older fallers.
Falls and Fractures Clinic, Department of Geriatric Medicine, Nepean Hospital, Penrith, Australia.
One hundred and forty-five adults aged 65 years and older who have had at least one episode of a fall within the six months prior to assessment at the Falls and Fractures Clinic.
Serum 25(OH) vitamin D3 [25(OH)D3] and parathyroid hormone concentrations were determined at baseline. Subjects were separated into 3 groups based on serum 25(OH)D3 levels with the following cut-off values: < 30 nmol/L (deficient), 30–50 nmol/L (insufficient) and > 50 nmol/L (normal). Other baseline measurements included body mass index, mini-nutritional assessment, grip strength, serum calcium concentration and creatinine clearance, which were used as covariables. PI was assessed using a computerized virtual reality system (Medicaa, Uruguay). Measured parameters included limits of stability (LOS) and centre of pressure (COP) under eyes closed on foam (ECF) and visio-vestibular stimulation. The estimated swaying area, computed from the ellipse of confidence under eyes closed standing on foam (ECF), was also used as a PI parameter. Gait velocity (GV) was measured using a GaitRITE walkway system.
Posture was impaired in vitamin D deficiency (<30 nmol/L) as indicated by lower LOS (90 +/- 18), higher ECF (25 +/- 10) and slower GV (55 +/- 7) as compared with the insufficient and normal groups. After adjustment for demographic, biochemical and anthropometric variables, vitamin D deficiency significantly correlated with low LOS and high COP under ECF.
Low levels of vitamin D were associated with PI. This association could also have an effect on slow GV and increased risk of falls. In conclusion, using an objective method to measure balance in older fallers we have identified a novel role of vitamin D in balance control. Prospective studies are required to confirm the effect of vitamin D on PI and elucidate the mechanisms of this association.
Suarez H, Geisinger D, Ferreira E, Suarez A, San Román C, Sotta G.
Acta Otolaryngol. 2011 Nov 10.
Abstract Conclusions: Rise time in the estimation of the gravitational vertical in the head tilt response (HTR) test is increased in patients with peripheral vestibular lesions and residual chronic dizziness. Objective: Assessment of the perception of the gravitational vertical in patients with peripheral vestibular lesions through the HTR. Methods: HTR was studied in 12 patients with peripheral vestibular lesion, 8 clinically with chronic dizziness and 4 without it; 23 normal subjects were studied as control group. Two parameters of the HTR were assessed, rise time and steady-state error to characterize a dynamical system step response. The Kolmogorov-Smirnov test (alpha = 5%) was used to verify normal distribution (steady-state error, p = 0.53; rise time, p = 0.88). The three sigma ellipse was calculated for the control group. ROC curves were used to measure the sensitivity and specificity of these parameters. Results: Rise time showed increased values in peripheral vestibular lesion patients with chronic dizziness. Two-dimensional analysis (rise time vs steady-state error) allows a better discrimination between patients with peripheral vestibular hypofunction with chronic dizziness and the rest of the studied population.
Suárez H, Cibils D, Caffa. C, Silveira A, Basalo S, Svirsky M. Acta Otolaryngol.(Stock) 1997 117:208-210.
Six profoundly deaf patients were studied with mapping evoked potentials (MEP) using an acoustic signal passed through the vibrotactile prosthesis. This stimulus produced an activation of the central sulcus brain cortex. When the prothesis was placed in the presternal area it showed Nl PI potentials with higher voltage and a more defined cortical dipole inversion than when the prosthesis was placed in the arm or abdomen: thus the presternal stimulation is considered an adequate place for the use of vibrotactile stimulation. The MEP were recorded in 2 patients after a period of audiological training and they showed new earlier potentials. These suggest plastic changes in the processing of an acoustic signal sent from the presternal skin by the somatosensory pathway after training and involving learning procedures.
Suarez H, Alonso R, Arocena M., Suarez A., Geisinger D.
Conclusion: This study showed that a population with benign paroxysmal positional vertigo related to mild head trauma (BPPVAT) was younger and more frequently presented with bilateral canalithiasis than another population with idiopathic etiology (IBPPV). In both groups, females presented a higher risk of BPPV. Objective: To compare the clinical features of a population with BPPVAT and another with IBBPV. Methods: We carried out statistical analysis of a population of 51 subjects with BPPVAT and another of 325 subjects with IBPPV, comparing age, gender, recurrence of symptoms, associated chronic dizziness (CD), and clinical presentation. Kolmogorov Smirnov test, Student’s t test, Mann–Whitney test, 95% binomial confidence interval for proportions, chi-squared, and Fisher’s test were used as statistical tools. A significance level of p < 0.05 was considered in all cases. Results: The population affected with BPPVAT was younger and bilateral canalithiasis was also more frequent. No differences were found in gender distribution, semicircular canals involved in the symptoms, recurrence after repositioning maneuvers, or associated CD.
BPPV, chronic dizziness, symptom recurrence