Background: Determinants of balance have not been well studied in women with osteoporosis yet falls are the major cause of fracture in this population. Objective: To describe the associations among knee extension strength, medication history, medical history, physical activity and both static and dynamic balance in women diagnosed with osteoporosis. Methods: We assessed health history, current medication and quality of life by questionnaire in 97 community-dwelling women with osteoporosis. Static balance was measured by computerized dynamic posturography (Equitest), dynamic balance by timed figure-eight run, and knee extension strength by dynamometry. Results: The 97 participants (mean (SD) age 69 (3.2) years) had a mean lumbar spine BMD of T = –3.3 (0.7) and total hip BMD of –2.9 (0.4). In stepwise linear regression, the significant determinants of static balance that explained 18% of total variance were knee extension strength (10%, p < 0.001), age (5%, p < 0.01) and tobacco use (3%, p < 0.05). The significant predictors of dynamic balance were knee extension strength (26%, p < 0.001), medications (6%, p < 0.05), age (4%, p < 0.05), height (4%, p < 0.001), as well as years of estrogen use (2%), tobacco use (2%) and weight (2%) (all p < 0.05). Knee extension strength was also associated with quality of life (r² = 0.12, p < 0.001). Based on these models, a 1 kg/cm (∼3%) increase in mean knee extension strength was associated with 1.2, 2.4 and 3.4% greater static balance, dynamic balance and quality of life, respectively. Conclusions: Knee extension strength is a significant determinant of performance on static and dynamic balance tests in 65- to 75-year-old women with osteoporosis. In this cross-sectional study, knee extension strength explained a greater proportion of the variance in balance tests than did age. Investigation into the effect of intervention to improve knee extension strength in older women with osteoporosis is warranted.

Results-The outcome in 79 participants (39 exercise, 40 control) who were available for measurement 10 weeks after baseline measurement is reported. After confounding factors had been controlled for, the exercise group did not make significant gains compared with their control counterparts, although there were consistent trends toward greater improvement in all three primary outcome measures. Relative to the change in control subjects, the exercise group improved by 2.3% in static balance, 1.9% in dynamic balance, and 13.9% in knee extension strength. Conclusions-A 10 week community based physical activity intervention did not significantly reduce fall risk factors in women with osteoporosis. However, trends toward improvement in key independent risk factors for falling suggest that a study with greater power may show that these variables can be improved to a level that reaches statistical significance. (Br J Sports Med 2001;35:348-351)

The Dynamic Illegible E (DIE) test measures visual acuity with head held still while reading a specially designed visual acuity chart of E's. The head is then moved passively and the change in visual acuity is recorded. The DIE test has previously been shown to be very useful for assessing patients with aminoglycoside ototoxicity. In the present study, statistical analysis using multiple regression showed that the degree of abnormality in the DIE test during horizontal and vertical head movement was correlated with the degree of caloric reduction. Ridit analysis allows comparison between a number of naturally ordered categories. The ridit analysis showed significant differences between groups of patients with varying degrees of caloric reduction. There was also a significant difference in DIE test scores between a group of normals with no history of otoneurological complaint and an age- and sex-matched population of dizzy patients with normal caloric results. As none of our 110 normal patients had more than a one row drop while reading the DIE test with head moving, we feel that it is safe to regard a drop of more than two rows with head moving as abnormal. Perhaps even a mild caloric reduction represents relatively severe vestibular damage and the DIE test has the potential to delineate some patients who have no caloric reduction.

To determine whether the presence of back pain and its related disabilities are determinants of balance and functional mobility in a group of women with osteoporosis, we carried out a cross-sectional analysis of 93 community-dwelling women with osteoporosis between the ages of 65 and 75 years old. We assessed health history, anthropometrics, self-report of current physical activity level and self-report of back pain (intensity and pain-related disabilities). Balance was measured by computerized dynamic posturography and functional mobility was assessed by timed figure-of-eight test. The prevalence of back pain was high (75%) in this cohort of older women with osteoporosis. Age was the major determinant of both balance and functional mobility and accounted for 9% and 14% of the variance, respectively. After accounting for age, back pain explained an additional 9% of the variance in balance and 13% of the variance in functional mobility. The high prevalence of back pain demonstrates the importance of pain management in the treatment of osteoporosis. Furthermore, the finding of self-reported back pain as a determinant of both balance and functional mobility suggests that this measure may deserve attention when screening women with osteoporosis for fracture risk. Prospective studies are needed to determine whether pain management will improve balance and functional mobility.

"Migraine associated vertigo" is emerging as a popular diagnosis for patients with recurrent vertigo. However, in view of our current understanding of both migraine and vertigo, "migraine associated vertigo," in contrast to basilar artery migraine, is neither clinically nor biologically plausible as a migraine variant.

The tandem Romberg and tandem walking tests, despite being in widespread clinical use as office screening tests, may not be effective at determining the presence of newly developed vestibular disease.

Although aminoglycoside antibiotics have been successful in controlling infections, the side effects of these drugs include vestibulotoxicity that can be irreversible. In a patient with intact visual and proprioceptive systems, the effects can be compensated for, but in a patient with impairment of one of these systems, loss of vestibular function can be devastating. There is little if any agreement in the literature about how to monitor patients undergoing therapy with these drugs. A reading test is described. It uses the ability of the vestibulo-ocular reflex to stabilize an image during head movement. The test is quantified using change in visual acuity with head movement to monitor damage to the vestibular system. Patients with loss of vestibular function are incapable of performing the test. Some evidence points to the test being more sensitive than standard caloric irrigations. We propose that it be used to monitor patients receiving aminoglycoside antibiotics.

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