Changes in the vestibulo-ocular reflex: a study of elderly day hospital patients.

The vestibulo-ocular reflex (VOR) of 50 elderly day hospital patients (mean age of 82 years) was studied with the head autorotation test. Amplitude gain, phase and the highest frequency band reached were determined in the five frequency bands of 1, 2, 3, 4, and 5 Hz. Of the 50 patients, 81% had abnormal results. The gain of the elderly was significantly increased to 1.06-1.24 in the frequency bands of 3, 4, and 5 Hz in comparison with that of a control group. The elderly showed constantly a phase lead of 8-19 degrees in the frequency range of 1-4 hz and in this range differed significantly from the control group. The percentage of the elderly who reached high frequencies of head movements was reduced to 55% in the frequency band of 3 Hz and to 30% in the frequency band of 4 Hz. These findings may lead to oscillopsia and explain the high prevalence of dizziness and falls among the elderly.

Changes in vestibulo-ocular reflex of elderly people.

Dizziness is a common symptom in elderly people. Head autorotation test (HART) has earlier shown no significant vestibulo-ocular reflex (VOR) disturbances in healthy elderly subjects. We used our recently developed HART to determine VOR in 14 elderly volunteers without otoneurological diseases and sedative medications. Gain and phase were determined in 5 frequency bands from 0.5 to 5 Hz. The gain of the elderly was significantly increased to 1.11-1.27 in the frequency range of 3-5 Hz compared with the controls. The phase lead of 7-8 degrees in the frequency bands of 2 and 4 Hz differed significantly from normative values of the controls. The percentage of the elderly to reach high-frequency head movements was diminished to 50% in the frequency band of 3 Hz and to 36% in the frequency band of 4 Hz (controls 100% and 95%, respectively). The individual HART results were abnormal in 86% of the elderly. The high-frequency VOR of the elderly was inaccurate in magnitude and timing. More than half of aged subjects were not able to generate voluntary fast head movements. These findings may explain the high prevalence of dizziness and falls in elderly subjects.

Vitamin D treatment and bone mineral density in the aged.

The purpose of this study was to investigate whether long-term vitamin D treatment increased bone mineral density in the aged. The bone mineral density in the distal forearm and femoral neck did not differ between nine residents (mean age 81.0 years) of an old peoples' home who had received an annual injection of 150,000 IU ergocalciferol during the foregoing 2-7 years (mean 5.1 years) and nine age-, weight- and height-matched control subjects who had subnormal 25 hydroxyvitamin D level. The alkaline phosphatase and parathyroid hormone levels were clearly higher when the 25 hydroxyvitamin D level was below 10 nmol/1. The authors suggest that the ability of vitamin D treatment to diminish fracture incidence may derive from improved bone quality, not measurable by the standard dual energy X-ray absorptiometry, and/or improved nervous and muscular control of movements to counter the tendency to fall.

Prognosis of falls among elderly nursing home residents.

The survival rate of 207 nursing home residents who fell during a two-month study period was followed for 12 months and compared with that of 94 residents of the same nursing home who did not fall during the same period. One year after the fall, 74 fallers and 13 controls had died. In the group of fallers, the main factors associated with mortality were male gender, dementia, Parkinsonism, the use of antidepressants, diuretics and vasodilators. Among the controls, the main factors associated with mortality were Parkinsonism, diabetes and the use of diuretics. Thirty-eight fallers (33 women and 5 men) and one (female) control suffered a fracture; 32 of them required hospital attention, and 15 (47%) died during the same hospital stay. These results indicate that falls are an ominous sign, particularly if the subject has dementia, depression or Parkinsonism, or uses diuretics. The male subjects in this study had a lower injury rate than females, but their mortality rate was higher. In terms of prevention, the major concern should be the effective treatment of depression and Parkinsonism. Withdrawal of diuretics, when possible, may have an effect on mortality. Physical training and other stimulating activities should be beneficial, but subjects with severe dementia seem to be beyond this kind of prevention.

Influence of sensory manipulation on postural control in Parkinson's disease.

Postural control was assessed on a tilting platform system in 20 patients with idiopathic Parkinson's disease and 20 age-matched controls. The amount of information provided by vision and lower limb proprioception was varied during the experiment to investigate the influence of changes in sensory cues on postural control. The patient group with clinical evidence of impaired postural control (Hoehn and Yahr III) had significantly higher sway scores over all sensory conditions than either the Hoehn and Yahr II group or controls. The pattern of sway scores indicated that no obvious deficit in the quality, or processing, of sensory information was responsible for the postural instability observed in this group. The patients in both Hoehn and Yahr groups were also able to respond appropriately to potentially destabilising sensory conflict situations and significantly improved their sway scores when provided with visual feedback of body sway. The results indicate that in Parkinson's disease, the main site of dysfunction in postural control is likely to be at a central motor level.

Falls among elderly nursing home residents.

The purpose of this study was to measure the rate of falls and to identify the causes, consequences and opportunities for preventing falls among 796 permanent residents of a nursing home. Altogether 377 falls were reported among 207 residents during the study period. The most important association discovered was that between impaired visual acuity and falls. In addition, 49% of the fallers suffered from severe and 19% from mild dementia. In the group of demented subjects it was impossible to assess visual acuity in 30% of the fallers as the subjects were unable to fixate at request. This finding may be one explanation for the increased incidence of falls in demented subjects. We conclude that the high number of subjects suffering from dementia among institutionalized elderly limits the possibility of training in prevention. The main emphasis in prevention of falls in institutions should be in proper design of the environment, including the visual environment.

Orthostatic reactions in the 85-year olds.

Testing of the orthostatic reaction is recommended in the examination of elderly fallers. This test usually includes blood pressure and instantaneous heart rate measurement but is difficult to perform in very elderly people according to the guidelines suggested for younger subjects. One reason for this is that old people often stand up slowly. The use of a tilt table, which enables a rapid change in posture from recumbent to erect position, is tempting as it could provide a method for a better standardized test. To study the usefulness of the tilt table as well as the degree of orthostatic reaction in the very elderly, we examined a sample of 85-year olds who did not suffer from falls. All were tested both with the tilt table and with active rising. The drop in blood pressure was equal in the two test types, but the increase in heart rate was significantly larger in active rising. Many test subjects were afraid of the tilt table, and two developed cardiac arrhythmia, i.e., atrial fibrillation, during the test. In our opinion, active rising is the method of choice in old persons. While the test subjects were in unusually good health for their age and thus could provide a suitable reference group for this test, the systolic blood pressure dropped considerably in several during the test. Criteria and indexes developed for younger subjects are not useful, and different evaluation criteria should be developed for the very elderly.

Postural control in elderly subjects.

The postural stability of 23 subjects aged 85 years or over was studied with a force platform. The sensory function of the lower limbs was disturbed with small vibrators placed on both calf muscles and/or by placing the subjects on a platform covered with foam plastic. When compared with a group (n = 100) of 50-60-year-old subjects, the elderly subjects had significantly higher sway velocities even during nonperturbed conditions. The perturbation of muscle spindles with vibration and/or pressoreceptor function with foam plastic did not increase the postural instability of the elderly subjects. Visual deprivation had a significant effect on postural stability, and the visual influx contributed about 50% of the postural stability. Postural control is reduced as a result of loss of sensory cues of pressoreceptors and also deterioration in function of stretch reflexes initiated from muscle spindles. The very elderly seem to rely on visual control of posture; this is slow, which can be one reason for susceptibility to falls.