BACKGROUND Chemotherapy-induced peripheral neuropathy (CIPN) is a dose-limiting toxicity of several commonly used chemotherapy drugs including taxanes, vinca alkaloids, and platinum compounds. Development of CIPN is highly variable, both in self-reported symptoms and functional consequences, and can be severe enough to alter dose intensity. PURPOSE To describe the natural histories of both patient-reported symptoms of chemotherapy-induced peripheral neuropathy (CIPN) and functional impairments in breast cancer patients undergoing taxane-based chemotherapy. METHODS Thirty-three breast cancer patients (32 female/1 male; 47.8 ± 11.2 years; n=17 stage II/n=16 stage III) were enrolled. Patients completed self-reports of symptoms and function (e.g., EORTC QLQ-CIPN20) and objective measures of physical function (i.e., balance and gait testing) in an outpatient oncology clinic at five timepoints: (1) baseline - prior to starting chemotherapy, (2–4) before starting subsequent chemotherapy cycles, and (5) 1–3 months after receiving their last taxane infusion. RESULTS Significant negative changes in both patient-reported outcomes and objective functional measures were observed. Decreased balance was observed after the first chemotherapy cycle (28% increase in medial-lateral excursion of the center of pressure, p=0.016) and progressed with cumulative exposure (43% increase, p<0.001). Patients also demonstrated slower walking speeds (5% decrease, p=0.003) as they progressed through treatment. These functional deficits were mirrored with increased patient-reported symptom severity for all EORTC QLQ-CIPN20 subscales (all p<0.05). CONCLUSION This study longitudinally assessed patient-reported outcomes concurrently with balance and gait testing in patients undergoing taxane therapy. Taxane treatment was associated with the development of clinically-relevant problems in both CIPN symptoms and patient function.

Background: Identifying athletes at an increased risk of injury is a promising approach to improve the effect of injury prevention interventions; however, it requires first identifying the potential athlete-specific risk factors. Cognitive ability was recently shown to correlate with noncontact anterior cruciate ligament injury rates and lower extremity mechanics, marking an underexplored area. A better understanding of how individuals’ cognitive ability is associated with neuromuscular control during sport-specific tasks may improve injury prevention. Hypothesis: Athletes with lower cognitive performance on a standardized cognitive assessment would demonstrate greater increases in knee valgus angle and moment when performing a sidestep cut with soccer ball dribbling versus without. Visual-spatial memory was expected to demonstrate stronger relationships than reaction time or processing speed. Study Design: Descriptive laboratory study. Methods: Fifteen male collegiate club soccer players participated (mean ± SD: 20.7 ± 2.0 years, 1.78 ± 0.07 m, 76.5 ± 8.9 kg). Participants performed anticipated 45° run-to-cut trials with and without a dual task of dribbling a soccer ball. Peak early-stance knee valgus angle and moment for the plant limb were calculated. Participants also completed a cognitive assessment to evaluate visual memory, verbal memory, reaction time, and processing speed. These composite scores were entered as candidate predictors for a stepwise regression analysis on the dual-task change scores in lower extremity biomechanical parameters (ie, ball handling – non–ball handling). Results: Visual memory composite score (a measure of visual-spatial memory) was the only cognitive outcome significantly associated with the change in biomechanical parameters. Each unit decrease in the visual memory composite score was associated with an increase of 0.21°± 0.05° in peak knee valgus angle during the ball-handling task as compared with the non–ball handling task ( R2 = 52%, P = .003). Conclusion: Visual-spatial memory was associated with neuromuscular control during a sidestep cutting task during soccer ball dribbling, with deficits in this cognitive domain being associated with increased peak knee valgus angle. Clinical Relevance: Assessing visual-spatial memory ability may provide useful information to better understand conditions associated with impaired neuromuscular control and to potentially identify athletes at an elevated risk for musculoskeletal injury.

Over 230,000 new cases of breast cancer are expected to be diagnosed in the United States in 2015. Taxane-based chemotherapy is often an effective treatment, but can also cause adverse symptoms in patients due to neurotoxicity. These side effects can impair postural control in patients; however, this instability has scarcely been quantified. The purpose of this pilot study was to gain insight into the natural history of postural instability in breast cancer patients being treated with taxane-based chemotherapy. Thirty-two breast cancer patients (31 female/ 1 male; 47.6 ± 11.2 yr; 16 stage II/ 16 stage III) completed eyes open and eyes closed quiet standing trials in the oncology clinic where they were being treated. These trials were collected at five timepoints throughout their chemotherapy treatment: (1) before initiating chemotherapy to provide a baseline, (2–4) before starting subsequent chemotherapy cycles, and (5) 1–3 months after receiving their last taxane infusion. After the first chemotherapy cycle, patients demonstrated increases in 95% confidence ellipse area of center of pressure (CoP) [45.2%, p=0.01] and root mean squared CoP excursion [18%, p=0.006] compared to baseline values for the eyes closed condition. These balance deficiencies progressed with cumulative taxane exposure. Postural instability persisted 1–3 months after completing chemotherapy with increases in 95% CoP ellipse area [86.8%, p=0.002], root mean squared CoP excursion [32.6%, p=0.001], and mean CoP velocity [30.4%, p=0.024]. The balance impairments demonstrated by patients in this study appear to be clinically relevant when compared to balance impairments previously reported in other patient populations.

Postural control provides insight into health concerns such as fall risk but remains relatively untapped as a vital sign of health. One understudied aspect of postural control involves transient responses within center of pressure (CoP) data to events such as vision occlusion. Such responses are masked by common whole-trial analyses. We hypothesized that the transient behavior of postural control would yield unique and clinically-relevant information for quiet stance compared to traditionally calculated whole-trial CoP estimates. Three experiments were conducted to test different aspects of this central hypothesis. To test whether transient, epoch-based characteristics of CoP estimates provide different information than traditional whole-trial estimates, we investigated correlations between these estimates for a population of young adults performing three 60-second trials of quiet stance with eyes closed. Next, to test if transient behavior is a result of sensory reweighting after eye closure, we compared transient characteristics between eyes closed and eyes open conditions. Finally, to test if there was an effect of age on transient behavior, we compared transient characteristics during eyes closed stance between populations of young and older adults. Negligible correlations were found between transient characteristics and whole-trial estimates (p>0.08), demonstrating limited overlap in information between them. Additionally, transient behavior was exaggerated during eyes closed stance relative to eyes open (p<0.044). Lastly, we found that transient characteristics were able to distinguish between younger and older adults, supporting their clinical relevance (p<0.029). An epoch-based approach captured unique and potentially clinically-relevant postural control information compared to whole-trial estimates. While longer trials may improve the reliability of wholetrial estimates, including a complementary assessment of the initial transient characteristics may provide a more comprehensive characterization of postural control.

Individuals diagnosed with chemotherapy-induced peripheral neuropathy (CIPN) demonstrate impaired balance and carry an increased risk of falling. However, prior investigations of postural instability have only compared these individuals against healthy controls, limiting the understanding of impairments associated with CIPN. Therefore, the purpose of this study was to better isolate postural control impairments that are associated with CIPN. Twenty cancer survivors previously diagnosed with breast or colorectal cancer participated. Participants were separated into 3 groups: no prior chemotherapy exposure (CON, n = 6), and recent treatment with taxane-or oxaliplatin-based chemotherapy with no/mild symptoms of CIPN (−CIPN, n = 8) or moderate/severe symptoms of CIPN (+CIPN, n = 6). Postural control was assessed by measuring center of pressure during standing balance conditions that systematically interfered with somatosensory, visual, and/or vestibular information. The presence of CIPN sensory symptoms was associated with impaired postural control, particularly during eyes-closed balance conditions (P < .05). Additionally, medial-lateral postural instability was more pronounced in the +CIPN group compared with the −CIPN group and CON participants (P < .05). Greater postural instability during eyes-closed balance in individuals with CIPN is consistent with impaired peripheral sensation. Balance impairments in cancer survivors with CIPN demonstrate the unique challenges in this population and motivate the need for targeted efforts to mitigate postural control deficits that have previously been associated with fall risk.