Reuven Kohen-Raz

Postural control in children with autism

Postural control was evaluated in samples of autistic, normal, and mentally retarded children in this pilot study using a recently developed, computerized posturographic procedure. A battery of postural positions was administered including postures involving some degree of “stress” (e.g., occluded vision or standing on pads). The postural patterns of children with autism differed from those observed in normal children, in mentally retarded children, and in adults with vestibular disorders. In comparison to normal children the autistic subjects were less likely to exhibit age-related changes in postural performance and postures were more variable and less stable with more lateral sway. Autistic subjects also exhibited a “paradoxical” response of greater stability with more “stressful” postures, putting excessive weight on one foot, one toe, or one heel. The implications for neuroanatomical models of autism are discussed.

APPLICATION OF TETRA-ATAXIAMETRIC POSTUROGRAPHY IN CLINICAL AND DEVELOPMENTAL DIAGNOSIS " '

Tetra-ataxiametric posturography is based on the measurement and computerized elaboration of electronic signals emitted by four footplates, one for each heel and toe, respectively. These are sensitive to vertical pressure produced by a subject standing straight but in various positions (feet parallel, in tandem, eyes closed, on pads, etc.). The method yields additional parameters not obtained by the traditional monoplate stabilometers, namely, weight-distribution patterns and correlations among six combinations of paired outputs from the two heels, two toes, heel/toe of each foot, and the two diagonals (tetra-ataxiametric synchronisations). Comparing age-matched learning disabled, mentally retarded, autistic, and hearing impaired (with and without labyrinthine hypofunction) with normal children, significant and clinically meaningful differences were detected between the tetra-ataxiametric measures of stability, interaction between Fourier Spectral Power Ranges of body sway, weight distributions, and synchronisations of toe parts. The same parameters correlated significantly with cognitive school readiness in normal populations. While the stability and spectral quotients show significant developmental changes, weight distribution and toe synchronisations are stable from 5 years onwards. The method is suitable for young subjects and attractive to children who may ordinarily be reluctant to cooperate, such as the autistic ones. The equipment is portable and tests can be conveniently carried out in a childs familiar educational setting.

An Initial Evaluation of Work Fatigue and Circadian Changes as Assessed by Multiplate Posturography

The sensitivity of postural responses to the effects of work fatigue and circadian changes was explored in a pilot study using a specific method of multiplate posturography based on the differential assessment of vertical pressure on four separate platforms for each heel and set of toes of each foot, respectively. 8 normal subjects, M.D.s, were given six posturographic examinations immediately before and after three 8-hr. work shifts in the emergency room of a major hospital in Tel-Aviv. 3 posturographic measures (stability, spectral power of postural sway at low frequency of 0.1–0.25 Hz, and unilateral weakening of heel-toe synchronisation) were significantly affected by work fatigue whilst also showing interaction with circadian rhythm. 2 additional measures (power of sway at high frequency of 1.00–3.00 Hz and dysharmonic distribution of weight over the four platforms) were not related to workload but showed significant circadian changes. These effects appeared only on positions involving restricted visual and somatosensory feedback causing vestibular stress. Results justify the application of multiplate posturography as an ancillary tool in measuring objectively the effects of fatigue and circadian changes as well as the interaction between endogenous chronobiological processes and their external conditioning factors (Zeitgebers). Pragmatic implications of the findings in the context of industrial medicine and interdisciplinary efforts to prevent road and air accidents are discussed.

Brief posturographic test as an indicator of fatigue

Abstract  The purpose of the present paper was to analyze the efficiency of an abbreviated, albeit objective posturographic test as an indicator of fatigue. Posturography was measured in 10 healthy adults (age 18–33 years, male/female 7/3). Baseline posturographic measurements were taken for each subject. Later, a shorter (3‐min) posturographic test was administered 12 times during 25 h of sleep deprivation. This was correlated with subjective assessment of fatigue using a questionnaire and cognitive performance assessed with a reaction time test (Psychomotor Vigilance Test). Although showing significant individual differences, the score of the abbreviated posturographic examination, normalized to each subject’s baseline performance (‘fatigue index’) had a pronounced circadian pattern with a peak of instability in the early morning hours. Fatigue index was highly correlated with the cognitive test (r = 0.80–0.90). A substantial, albeit weaker correlation was found between the fatigue index and the subjective fatigue scores (r = 0.59–0.75). Fourier spectral analysis showed that low median sway (0.10–0.50 Hz), considered to be an expression of vestibular control, was most affected by fatigue. The study demonstrates that cognitive deterioration caused by fatigue can be objectively predicted by an abbreviated postural test of ≤3 min. This test is promising to be valid, reliable, and practicable, while being significantly correlated with physiological markers and validated cognitive measures of fatigue obtained by substantially more time‐consuming and less convenient methods.

Association between maternal bleeding during gestation and congenital anomalies in the offspring

The incidence of maternal bleeding complicating the pregnancies of 326 children examined at the Jerusalem Community Center for Child and Family Development is surveyed. A history of bleeding during pregnancy was more frequent in children with congenital anomalies of the central nervous system (and/or psychomotor retardation) (33 per cent) and in children with congenital anomalies of other systems (29 per cent) than in control children (12 per cent). The implications of these findings are discussed in relation to placental pathophysiology and the pathogenesis of threatened abortion.

Postural control in subjects with visual impairment.

Purpose TO investigate the effect of long-term, not experimentally induced visual impairment on balance, and to clarify which means are used to compensate for this sensory deficit. Methods Posturography was examined in 50 visually impaired subjects (11 with congenital blindness and 39 with acquired visual impairment) and 50 healthy controls. Examination was performed in 4 testing conditions: while standing on firm surface or foam pads (which decreases the somatosensory input) and with open or closed eyes (manipulating visual input). Results Subjects with acquired visual impairment were significantly less stable than controls when tested with open eyes, especially when standing on foam pads, but equal to controls when eyes were closed. Congenitally blind subjects performed equally to normal controls in all test conditions when tested with eyes open, and performed significantly better than controls with eyes closed. In comparison to subjects with acquired visual impairment, the congenitally blind were significantly more stable in all test conditions. Fourier analysis revealed that the visually impaired subjects showed decreased intensity values within the lowest frequency range of 0.1 Hz and below, a range believed to be sensitive to the function of the visual system. Conclusions We have found that vision impairment influenced postural control, especially if acquired and not congenital. The somatosensory and vestibular systems serve as compensatory mechanisms, which is utilized most effectively by the congenitally blind.

Some Observations on Tetra-Ataxiametric Patterns of Static Balance and Their Relation to Mental and Scholastic Achievements

Recent experiences and observations gathered in the context of six independent studies in California, France, and Israel with a new method of tetra-ataxiametry based on the use of four footplates, are presented. Two independent postural parameters assessed by this method (fluctuations and anterio-posterior weight displacement) have been shown to be reliable over time and to correlate with scholastic progress at the lower elementary grades (ages 5 to 9 yr.). They also seem to be sensitive to minimal neurological dysfunction and to postural characteristics of deaf children. Results of one study indicate that diagonal balancing movements (between heel and contra-lateral toe) reflected by the tetra-ataxiametric measure of synchrony may play an important role in postural organization. Findings offer new perspectives on problems of posrural laterality and on the relationship between static balance, cognition, and scholastic aptitudes at the lower grades of elementary education.

Posturography Characteristics of Obese Children with and without Associated Disorders

A group of 59 obese children ages 6–12 years were interviewed for current medical diagnoses (e.g., Attention Deficit Hyperactivity Disorder- ADHD, and clumsiness) and later were examined posturographically for balance and stability. General stability of all the obese children deviated significantly from norms. 32.2% of the obese children had a pattern of balance that could indicate orthopedic problems. Obese children with ADHD or perceived clumsiness had significantly worse balance and postural performance compared to other obese children. Balance and posture among obese children without suspicion of problems were similar to non-obese controls. In conclusion, obese children with associated disorders (such as ADHD and perceived clumsiness) manifested disturbance in balance control. Thus, physical activity interventions for these children should include safety measures to decrease the chances of falling and subsequent injury.

RELATIONS OF BASIC ARITHMETIC AND MOTOR SKILLS IN DEAF ELEMENTARY SCHOOL CHILDREN

3 segregated groups of Arab and Jewish deaf children of CA 10;9 (n = 28) were compared with a group of hearing Arab first graders (CA = 6;10, n = 32) on tests of basic arithmetic, static balance control, and the ability to suppress synkinetic finger movements. The hearing-impaired performed as well on arithmetic tasks and on the tests of synkinetic control as their normal peers who were four years younger, while on static balance they were even inferior to the latter. Significant correlations were found between the basic airthmetic and motor skills, within the hearing as well as within the hearing-impaired groups; these remained significant even within the small subgroups of the latter. As these results cannot be accounted for by low intelligence and neurological disturbances, or by direct or indirect effects of deficient language development, the assumption is supported that some type of neurological immaturity, unrelated to hearing loss, interferes with the acquisition of numerical skills in deaf children.

A post-residential-treatment follow-up of socially and emotionally deviant adolescents in Israel.

Fifty-five emotionally and socially deviant but normally intelligent adolescents who had spent 2–7 years in a childrens and apprentice home in Israel were followed up 5–9 years after they had left the institution. Their postresidential social and vocational careers were evaluated by means of personal interviews, home visits, and reports from employers, and it was found that good adjustment was substantially related to family background variables (having lived with biological parents prior to residential placement, mutual positive relationship between parent and child, being first born) as well as to satisfactory behavior and performance in peer group, school, and workshop during residence. Level of intelligence, unrelated to overall adjustment, correlated positively with vocational status and income at followup. On the other hand, length of stay in the apprentice home had no impact on postresidential adaptation to work and society. Fewer than 10% of exinmates expressed retrospectively a negative attitude toward their stay in the institution. The importance of paying more attention to the eventual long-term and enduring impact of family relationship on the residential and postresidential behavior of adolescents is discussed, suggesting a shift of emphasis in evaluating factors involved in institutional treatment. Findings also indicate that later social and vocational success may be fairly predicted from observation of behavior during the stay in the institution.