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Biomedical subjects

H S Cohen

Publications and source records attributed to H S Cohen.

At least 19 recordsLinked to original sources

Variable practice with lenses improves visuo-motor plasticity.

Novel sensorimotor situations present a unique challenge to an individual's adaptive ability. Using the simple and easily measured paradigm of visual-motor rearrangement created by the use of visual displacement lenses, we sought to determine whether an individual's ability to adapt to visuo-motor discordance could be improved through training. Subjects threw small balls at a stationary target during a 3-week practice regimen involving repeated exposure to one set of lenses in block practice (x 2.0 magnifying lenses), multiple sets of lenses in variable practice (x 2.0 magnifying, x 0.5 minifying and up-down reversing lenses) or sham lenses. At the end of training, adaptation to a novel visuo-motor situation (20-degree right shift lenses) was tested. We found that (1) training with variable practice can increase adaptability to a novel visuo-motor situation, (2) increased adaptability is retained for at least 1 month and is transferable to further novel visuo-motor permutations and (3) variable practice improves performance of a simple motor task even in the undisturbed state. These results have implications for the design of clinical rehabilitation programs and countermeasures to enhance astronaut adaptability, facilitating adaptive transitions between gravitational environments.

Adaptation, Physiological↗

Development of the vestibular disorders activities of daily living scale.

BACKGROUND: Existing scales of self-perceived disablement in patients with vestibular impairment either are too broad to detect the subtle deficits in this population or omit some important daily life tasks. OBJECTIVES: To develop a scale to assess self-perceived disablement in patients with vestibular impairment and to describe the development and initial testing of this new assessment tool. DESIGN: A list of items was developed, sent to a panel of expert therapists for review, and then revised to yield the preliminary 31-item, 10-point scale that was administered to subjects. The scale was revised again, yielding the final 28-item scale, which was administered to a new group of subjects. SETTING: Data were collected from patients in an outpatient clinic of a tertiary care center. PARTICIPANTS: Patients diagnosed as having benign paroxysmal positional vertigo and patients diagnosed as having chronic vestibulopathy, excluding Ménière disease, postsurgical vertigo, and postconcussion vertigo. RESULTS: The final scale has 3 subscales: functional, ambulation, and instrumental. It has good face validity, high internal consistency (alpha> or =.90), and high test-retest reliability (r(c)> or =0.87). Scale ratings ranged from 1 (independent) to 10 (ceasing to participate in the activity), but median scores for most subjects were 4 or less. From 41% (39/94) to 44% (41/94) of subjects considered themselves to be independent on those tasks. CONCLUSIONS: This scale has good face validity, high internal consistency, and high test-retest reliability. It may be useful for evaluating functional limitation and perceived handicap or disability before and after intervention and for helping patients become more realistic in understanding their own capabilities.

Activities of Daily Living↗

Long-term vestibulo-ocular reflex changes in patients with vestibular ablation.

Long-term changes in the parameters of the vestibulo-ocular reflex (VOR) were evaluated using recently developed multilevel statistical modelling techniques in a group of patients who had undergone ablative inner ear procedures. Data from 84 patients were available for study. The most dramatic recovery in the VOR occurred during the first 60 postoperative days, however, slow changes continued, levelling off at about 120 days. While frequency was a highly significant predictor of outcomes in all parameters, age showed significant predictive value only to phase measures (p = 0.006) and gender had no effect. Sum gain at the lowest frequency tested remained below the 5th percentile and at the higher frequencies remained below the 50th percentile for normal subjects. Phase decreased exponentially, but remained above the 95th percentile for normal subjects, except at the highest frequency where it remained above the 50th percentile. DC bias decreased exponentially, dropping to the 50th percentile by day 146. Asymmetry stayed between the 50th and 95th percentile, except at the highest frequency, where it was at the 50th percentile by day 125.

Female↗

Application of the vestibular disorders activities of daily living scale.

OBJECTIVE: Existing scales of functional performance are either insufficiently sensitive or omit some important daily life tasks. This paper demonstrates that a new scale of self-perceived disablement in the vestibularly impaired population-the Vestibular Disorders Activities of Daily Living Scale (VADL)-differentiates between disabled and healthy persons and evaluates the associations of this assessment with other measures of vestibular disorders. STUDY DESIGN: Prospective. METHODS: Subjects were 1) asymptomatic, healthy adults, 2) patients with benign paroxysmal positional vertigo, 3) patients with chronic vestibulopathy excluding Meniere's disease, postsurgical vertigo, and postconcussion vertigo, and 4) family members. Patient were assessed on the VADL, the Dizziness Handicap Inventory, level of vertigo, and computerized dynamic posturography. Healthy subjects and family members completed the VADL. RESULTS: The VADL differentiates healthy persons from patients but does not differentiate between patient groups. Patients perceived themselves as more independent than their spouses perceived them to be. Scores are weakly correlated with vertigo frequency and posturography scores for conditions with unreliable kinesthesia and absent or unreliable vision. The VADL is more responsive to higher levels of impairment than the Dizziness Handicap Inventory. CONCLUSIONS: This well-normed, self-administered scale of self-perceived disablement is useful for evaluating the functional status of patients with peripheral vestibular disorders. Perceptions of patients and significant others vary, but scores are moderately correlated with some standard measures of vestibular function. As it assesses a different domain of function than do standard diagnostic tests, the VADL will augment these tests during initial evaluation and may be useful for assessing posttreatment change.

Activities of Daily Living↗

Vestibular disorders and impaired path integration along a linear trajectory.

The goal of this study was to determine if people use vestibular information to keep track of their positions while walking through a simple course. Subjects were normals and patients with chronic peripheral vestibulopathies-- each of whom were tested once--and patients with acoustic neuromas tested pre-operatively and one and three weeks post-operatively. Subjects walked over a straight course, 7.62 m, with their eyes open and then with their eyes closed. The time needed for task performance, the forward distance subjects walked before veering, and the lateral distance subjects veered from the straight ahead were recorded. The angle of veering was then calculated. Normals were able to perform this task easily with eyes open or closed. With eyes closed pre-operative acoustic neuroma subjects walked significantly shorter distances before veering than normals but did not veer significantly more than normals or take longer than normals to perform the task. Chronic vestibulopathy subjects, by contrast, were significantly impaired compared to normals on all measures. With eyes open within a week after acoustic neuroma resection subjects could perform the task as well as normals. With eyes closed, however, post-operative subjects were impaired compared to their own pre- operative levels, but they had returned to their pre-operative levels at the second post-operative test. Ataxia was only weakly correlated to any measures and tumor size was not related to performance. These findings support the hypothesis that vestibular input is used for spatial orientation during active motion.

Adult↗

Effects of adaptation of vestibulo-ocular reflex function on manual target localization.

The goal of the present study was to determine if adaptive modulation of vestibulo-ocular reflex (VOR) function is associated with commensurate alterations in manual target localization. To measure the effects of adapted VOR on manual responses we developed the Vestibular-Contingent Pointing Test (VCP). In the VCP test, subjects pointed to a remembered target following passive whole body rotation in the dark. In the first experiment, subjects performed VCP before and after wearing 0.5X minifying lenses that adaptively attenuate horizontal VOR gain. Results showed that adaptive reduction in horizontal VOR gain was accompanied by a commensurate change in VCP performance. In the second experiment, bilaterally labyrinthine deficient (LD) subjects were tested to confirm that vestibular cues were central to the spatial coding of both eye and hand movements during VCP. LD subjects performed significantly worse than normal subjects. These results demonstrate that adaptive change in VOR can lead to alterations in manual target localization.

Adaptation, Physiological↗

Efficacy of treatments for posterior canal benign paroxysmal positional vertigo.

OBJECTIVE: This study was performed to determine the relative effectiveness of several passive head maneuvers for treating benign paroxysmal positional vertigo. STUDY DESIGN: This prospective study used 87 subjects diagnosed by their physicians with unilateral benign paroxysmal positional vertigo of the posterior semicircular canal. METHODS: Subjects were randomly assigned to three treatment groups: modified Epley maneuver, modified Epley maneuver with augmented head rotations, and modified Semont maneuver. They were interviewed 1 week after receiving one maneuver. If subjects desired further treatment, they were treated again with the same maneuver, a methodology repeated until subjects desired no further treatment; they were telephoned 3 and 6 months after the last treatment. RESULTS: The groups did not differ significantly, but subjects decreased significantly on vertigo intensity and frequency and improved significantly on independence in activities of daily living. Before treatment, tasks requiring pitch rotations of the head induced vertigo; common comorbid conditions were osteoporosis, cervical spine problems, and head trauma. CONCLUSIONS: These data suggest that augmented head rotations are unnecessary and that the modified Epley and Semont maneuvers are equally effective in the remediation of vertigo in this population.

Adult↗

Dynamic visual acuity while walking in normals and labyrinthine-deficient patients.

We describe a new, objective, easily administered test of dynamic visual acuity (DVA) while walking. Ten normal subjects and five patients with histories of severe bilateral vestibular dysfunction participated in this study. Subjects viewed a visual display of numerals of different font sizes presented on a laptop computer while they stood still and while they walked on a motorized treadmill. Treadmill speed was adapted for 4 of 5 patients. Subjects were asked to identify the numerals as they appeared on the computer screen. Test results were reasonably repeatable in normals. The percent correct responses at each font size dropped slightly while walking in normals and dropped significantly more in patients. Patients performed significantly worse than normals while standing still and while walking. This task may be useful for evaluating post-flight astronauts and vestibularly impaired patients.

Adult↗

A task for assessing vertigo elicited by repetitive head movements.

OBJECTIVE: We developed a simple, inexpensive test for assessing vertigo in persons with peripheral vestibular disorders. METHOD: The test was administered to 16 asymptomatic adults and 16 patients with chronic vertigo caused by peripheral vestibular disorders. Participants sat in a chair and as rapidly as possible transferred 25 beanbags one at a time from a basket placed on the floor to a basket held .91 m up in the air. The task was timed, and the participants rated the level of vertigo elicited on a 10-point scale. RESULTS: Patients took significantly more time to perform the task and reported significantly greater levels of vertigo than did the asymptomatic adults. Test scores did not differ significantly across test sessions or raters. CONCLUSION: Performance on this task reliably differentiated patients with vestibular disorders from asymptomatic adults. The test is inexpensive, takes less than 1 min to perform, and has minimal technical requirements, making it suitable for a variety of facilities and levels of staff expertise.

Adolescent↗

Prevalence of dental caries among Ethiopian emmigrants.

Studies have documented the prevalence of caries in developing countries. The current study adds to this body of knowledge. Of the total Ethiopian Jewish population who emmigrated to Israel in 1991, a sample of over 800 individuals was randomly selected representing all age groups. DMF-T and DMF-S scores were recorded, as well as percentages of caries free individuals. Results indicated that almost no fillings or crowns had been provided to the study population. The Missing 'M' component was low as was the Decay 'D' component, although this increased with increasing age, ranging from 0.33 D-T at the 0-12 age group to 2.46 at the 51+ age group. In the permanent dentition 88.4 per cent of those 0-12 years of age were caries free and 74.5 per cent were caries free in both the primary and permanent dentition. Almost 59 per cent of the 13-20 years olds were caries free and 32.8 per cent of those 21-50 years old. Only 16.7 per cent were caries free at age 51+ years old. The data indicate a relatively low prevalence of both coronal and root caries, and an effort has to be made to keep these figures low for years to come mainly by diet and dental health education.

Adolescent↗

Dental anxiety and oral health in young Israeli male adults.

Dental anxiety may be a serious limiting factor in providing adequate dental treatment. The present study sought to define the prevalence of dental anxiety in a cross-section of young Israeli adults (389 male Israeli army recruits) to correlate anxiety scores with their oral health status and to compare the findings with existing data. The main stimuli triggering anxiety were found to be in the following descending order: seeing the needle, feeling the drill, and feeling pain despite local anaesthesia. A positive correlation was found between the degree of anxiety and the dental status; the highest percentage of untreated patients was found in the high anxiety group. It is concluded that young adult Israeli males manifest dental anxiety in a manner similar to that reported in the United States and Sweden. Dental anxiety may be an important factor in the avoidance of seeking dental care.

Adolescent↗

Incidence and neurodevelopmental outcome of periventricular hemorrhage and hydrocephalus in a regional population of very low birth weight infants.

During the years 1984 to 1987, 459 very low birth weight (VLBW) infants were admitted to a state-designated Level III Neonatal Intensive Care Unit. Cerebral sonography performed in a standardized sequence and graded with the Papile scale diagnosed 97 (21.1%) children with periventricular hemorrhage (PVH). The incidence of PVH declined from a peak of 26.6% in 1985 to 16.4% in 1987, associated with an increase in the incidence of inborn admissions (including maternal transport) from 62.0% in 1984 to 80.4% in 1987. During initial hospitalization, the occurrence of both low-grade (Grades I and II) and high-grade PVH was associated with a significantly higher incidence of perinatal risk factors compared with a concurrent population of VLBW infants without PVH. Developmental follow-up was achieved in 93.3% of VLBW infants without PVH and 95.7% of VLBW infants with PVH who survived their initial hospitalization. The incidence of abnormal outcome ranged from 7 of 37 infants with Grade I PVH to 7 of 8 VLBW infants with Grade IV PVH. Only 1 of 16 VLBW infants with high-grade PVH demonstrated normal motor and cognitive development. Active hydrocephalus developed in 12 infants; 11 sustained a high-grade PVH. Appropriate treatment of intracranial hypertension did not modify the neurodevelopmental outcome. In conclusion, this regional population of VLBW infants demonstrated a decline in the incidence of PVH during the years 1984 to 1987 associated with an increase in the incidence of inborn admissions. The risk of abnormal neurodevelopmental outcome was elevated for all grades of PVH. A 12.0% incidence of hydrocephalus was associated with high-grade PVH, and appropriate treatment did not alter the poor prognosis.

Cerebral Hemorrhage↗

Breastfeeding and return to ovulation in Bangkok.

Twenty-seven breastfeeding mothers and nine non-breastfeeding postpartum comparison mothers in Bangkok, Thailand were followed longitudinally until ovulation resumed. A simple set of guidelines is described involving three obvious milestones for the breastfeeding mother to safely use the natural contraceptive benefit of breastfeeding. Those milestones are the first menses, the initiation of supplementation and the child's monthly birthday. In the absence of menses and supplementation, 93% of breastfeeding mothers remained anovular for 3 months postpartum and 88-89% for up to 6 months. Further, the work of other investigators suggests that the proportion ovulatory provides an overestimate of those at risk of pregnancy. The guidelines suggest a way to estimate the period of lactational infertility and may be most useful on a programmatic level.

Adult↗

Tabasco throat.

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Condiments↗