Sensory Phenotypes for Balance Dysfunction After Mild Traumatic Brain Injury.

BACKGROUND AND OBJECTIVES: Recent team-based models of care use symptom subtypes to guide treatments for individuals with chronic effects of mild traumatic brain injury (mTBI). However, these subtypes, or phenotypes, may be too broad, particularly for balance (e.g., 'vestibular subtype'). To gain insight into mTBI-related imbalance we 1) explored whether a dominant sensory phenotype (e.g., vestibular impaired) exists in the chronic mTBI population, 2) determined the clinical characteristics, symptomatic clusters, functional measures, and injury mechanisms that associate with sensory phenotypes for balance control in this population, and 3) compared the presentations of sensory phenotypes between individuals with and without previous mTBI. METHODS: A secondary analysis was conducted on the Long-Term Impact of Military-Relevant Brain Injury Consortium - Chronic Effects of Neurotrauma Consortium. Sensory ratios were calculated from the Sensory Organization Test, and individuals were categorized into one of eight possible sensory phenotypes. Demographic, clinical, and injury characteristics were compared across phenotypes. Symptoms, cognition, and physical function were compared across phenotypes, groups, and their interaction. RESULTS: Data from 758 Service Members and Veterans with mTBI and 172 with no lifetime history of mTBI were included. Abnormal visual, vestibular, and proprioception ratios were observed in 29%, 36%, and 38% of people with mTBI, respectively, with 32% exhibiting more than one abnormal sensory ratio. Within the mTBI group, global outcomes (p<0.001), self-reported symptom severity (p<0.027), and nearly all physical and cognitive functioning tests (p<0.027) differed across sensory phenotypes. Individuals with mTBI generally reported worse symptoms than their non-mTBI counterparts within the same phenotype (p=0.026), but participants with mTBI in the Vestibular-Deficient phenotype reported lower symptom burdens than their non-mTBI counterparts [e.g., mean(SD) Dizziness Handicap Inventory = 4.9(8.1) for mTBI vs. 12.8(12.4) for non-mTBI, group*phenotype interaction p<0.001]. Physical and cognitive functioning did not differ between groups after accounting for phenotype. DISCUSSION: Individuals with mTBI exhibit a variety of chronic balance deficits involving heterogeneous sensory integration problems. While imbalance when relying on vestibular information is common, it is inaccurate to label all mTBI-related balance dysfunction under the 'vestibular' umbrella. Future work should consider specific classification of balance deficits, including specific sensory phenotypes for balance control.

Eccentric exercise versus usual-care with older cancer survivors: the impact on muscle and mobility--an exploratory pilot study.

BACKGROUND: Resistance exercise programs with high compliance are needed to counter impaired muscle and mobility in older cancer survivors. To date outcomes have focused on older prostate cancer survivors, though more heterogeneous groups of older survivors are in-need. The purpose of this exploratory pilot study is to examine whether resistance exercise via negative eccentrically-induced work (RENEW) improves muscle and mobility in a diverse sample of older cancer survivors. METHODS: A total of 40 individuals (25 female, 15 male) with a mean age of 74 (± 6) years who have survived (8.4 ± 8 years) since their cancer diagnosis (breast, prostate, colorectal and lymphoma) were assigned to a RENEW group or a non-exercise Usual-care group. RENEW was performed for 12 weeks and measures of muscle size, strength, power and mobility were made pre and post training. RESULTS: RENEW induced increases in quadriceps lean tissue average cross sectional area (Pre: 43.2 ± 10.8 cm2; Post: 44.9 ± 10.9 cm2), knee extension peak strength (Pre: 248.3 ± 10.8 N; Post: 275.4 ± 10.9 N), leg extension muscle power (Pre: 198.2 ± 74.7 W; Post 255.5 ± 87.3 W), six minute walk distance (Pre: 417.2 ± 127.1 m; Post 466.9 ± 125.1 m) and a decrease on the time to safely descend stairs (Pre: 6.8 ± 4.5 s; Post 5.4 ± 2.5 s). A significant (P < 0.05) group x time interaction was noted for the muscle size and mobility improvements. CONCLUSIONS: This exploration of RENEW in a heterogeneous cohort of older cancer survivors demonstrates increases in muscle size, strength and power along with improved mobility. The efficacy of a high-force, low perceived exertion exercise suggests RENEW may be suited to older individuals who are survivors of cancer.

Predicting falls in individuals with Parkinson disease: a reconsideration of clinical balance measures.

BACKGROUND AND PURPOSE: Postural control problems, falls, and fall-related injuries are a common source of morbidity in elderly individuals, especially those with Parkinson disease (PD). Clinical balance tests such as the Berg balance scale and the functional reach have been reported to be useful in assessing fall risk in elderly individuals. However, the utility of commonly used clinical balance tests as accurate screens for fall risk has not been sufficiently examined in persons with PD. The purposes of this study were to identify which commonly used clinical balance tests of persons with PD were predictive of falls, to re-examine the cutoff scores for these tests with the goal of maximizing sensitivity as well as minimizing the negative likelihood ratio, and to determine which of the clinical balance tests had the most value in predicting falls. PARTICIPANTS: Forty-five persons with a diagnosis of idiopathic PD, aged 39-90 years (mean [sd] =69.94 [11.28]; mean [sd] Hoehn and Yahr level = 2.60 [.66]) participated. METHODS: Upon initial contact with participants, demographics and fall history were gathered and baseline physical examinations were performed. Each individual underwent balance testing with the functional reach test, the Berg balance scale, the dynamic gait index, timed up and go, and the cognitive timed up and go. Fallers and nonfallers were divided based on fall history and groups were compared on balance test performance. Sensitivity, specificity, likelihood ratios, and receiver operator characteristic curves were calculated for all balance tests. RESULTS: Twenty-five (55%) participants had a history of falls. Using cut-off scores reported in previous studies, the sensitivity of all tests was low (less than 0.60) and the specificity was high (greater than 0.85). Reconsideration of the cut-off scores resulted in increased sensitivity for all tests (greater than 0.75) and low negative likelihood ratios (less then .30). DISCUSSION AND CONCLUSION: Given the large financial, psychological, and physical complications that are associated with a fall and relatively little harmful effects of fall prevention interventions, we propose consideration of cut-off scores that maximize sensitivity for individuals with PD. Regardless of the performance on any individual clinical balance test, the multifactorial nature of postural instability in PD may necessitate a battery of tests to provide the most accurate identification of fall risk.