Acetazolamide improves neurotological abnormalities in a family with episodic ataxia type 2 (EA-2).
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Acetazolamide↗
Biomedical subjects
Heikki Aalto
Publications and source records attributed to Heikki Aalto.
Influence of lossy compression on eye movement signals.
Eye movements considered in our research are physiological signals that are measured in otoneurological balance tests. They are also investigated in other areas of medicine and in psychology. When great amounts of signals are measured in clinical and research work, signal compression is of great use in storing measurements for later investigations. In this research we assessed the influence of lossy compression on medically interesting parameter values that are computed from eye movement signals. We found that high compression ratios with bit rates lower than 1.5 bits per sample on signals with an original resolution of 13 bits per sample produced results without significant changes to the medical parameters values.
Data Compression↗
Nystagmus measured with video-oculography: methodological aspects and normative data.
Detailed analysis of eye movements is essential in order to understand the pathophysiology underlying vestibular disturbances. We applied a commercial video-oculography (VOG) to measure spontaneous and provoked nystagmus in 20 healthy subjects. The slow-phase velocity (SPV) of the nystagmus was calculated. We also simultaneously recorded the eye movements on a standard VHS videotape to be able to confirm the results derived from the VOG paper charts. The nystagmus results derived from the VOG charts and the simultaneous videotaping agreed well. Nystagmus was found in 17 subjects. Spontaneous nystagmus was seen in 20%, positional nystagmus in 55%, and head-shaking nystagmus in 35% of the participants. Although nystagmus was frequent (85%), the mean SPV for nystagmus was low (1.7 degrees /s). The VOG is a modern and sensitive method to record eye movements, but visual inspection of the videotape may be needed in selected cases to confirm occurrence of nystagmus.
Adolescent↗
Development of virtual reality stimuli for force platform posturography.
People relying much on vision in the control of posture are known to have an elevated risk of falling. Dependence on visual control is an important parameter in the diagnosis of balance disorders. We have previously shown that virtual reality (VR) methods can be used to produce visual stimuli that affect balance, but suitable stimuli need to be found. In this study, the effect of six different VR stimuli on the balance of 22 healthy test subjects was evaluated using force platform posturography. We report in more detail and expand the results published earlier. According to the tests two of the stimuli have a significant destabilizing effect on balance. In addition a significant displacement effect on the subject's center of pressure (COP) was found. Thus it is shown that the design of VR stimuli to cause different effects on the control of balance is possible.
Adult↗
Virtual reality stimuli for force platform posturography.
People relying much on vision in the control of posture are known to have an elevated risk of falling. Dependence on visual control is an important parameter in the diagnosis of balance disorders. We have previously shown that virtual reality methods can be used to produce visual stimuli that affect balance, but suitable stimuli need to be found. In this study the effect of six different virtual reality stimuli on the balance of 22 healthy test subjects was evaluated using force platform posturography. According to the tests two of the stimuli have a significant effect on balance.
Adult↗
Postural control measured by visual feedback posturography.
The objective was to study the applicability and repeatability of visual feedback posturography (VFP) in assessing postural control of 23 healthy subjects. The subjects had to move their center of gravity (COG) marker on a computer screen to chosen targets by leaning their body on the platform, and the accuracy, velocity, and side difference of these movements were measured. The intraclass correlation coefficients for all parameters during repeated tests were significant (r = 0.93 - 0.96; p < 0.01). Hold percentage within the targets and COG marker velocity to the targets did not change significantly during repeated tests. Balance index and hit delay were significantly smaller during the 4th and 5th than during the 1st test session (p < 0.05), but they did not change significantly between the other test sessions. The normative limit for side difference in postural control was 22%. VFP can be used to follow active postural control due to its high test-retest repeatability. However, learning effects in some parameters must be taken into account when applying VFP repeatedly in different patient populations to assess the progress in postural control.
Adolescent↗