Publications

In the 1990s and early 2000s, the common definition for sarcopenia was age-related loss of skeletal muscle, and low levels of muscle mass were central to sarcopenia diagnosis. In more recent consensus definitions, however, low muscle strength displaces low muscle mass as a defining feature of sarcopenia. The change stems from growing evidence that muscle weakness is a better predictor of adverse health outcomes (eg, mobility limitations) than muscle mass. This evidence accompanies an emerging recognition that central neural mechanisms are critical determinants of age-related changes in strength and mobility that can occur independently of variations in muscle mass. However, strikingly little practical attention is typically given to the potential role of the central nervous system in the etiology or remediation of sarcopenia (ie, low muscle function). In this article, we provide an overview of some mechanisms that mediate neural regulation of muscle contraction and control, and highlight the specific contributions of neural hypoexcitability, dopaminergic dysfunction, and degradation of functional and structural brain connectivity in relation to sarcopenia. We aim to enhance the lines of communication between the domains of sarcopenia and neuroscience. We believe that appreciation of the neural regulation of muscle contraction and control is fundamental to understanding sarcopenia and to developing targeted therapeutic strategies for its treatment.

Every second of every day, an older adult suffers a fall in the United States (>30 million older adults fall each year). More than 20% of these falls cause serious injury (e.g., broken bones, head injury) and result in 800,000 hospitalizations and 30,000 deaths annually. Bhasin and colleagues recently reported results from a pragmatic, cluster-randomized trial designed to evaluate the effectiveness of a multifactorial intervention to prevent fall injuries. The intervention did not result in a significantly lower rate of a first adjudicated serious fall injury among older adults at increased risk for fall injuries as compared with enhanced usual care. In this commentary we briefly review and highlight these recent findings. Additionally, we argue that the findings should not be discounted just because of the lack of statistical significance. The approximately 10% reduction compared to enhanced usual care is, arguably, meaningful at both the individual and public health level, especially when one considers that the control group had better outcomes than expected based on prior work. Moreover, we encourage future research as well as practitioners to give strong consideration to the nuances of the exercise interventions for reducing falls and fall-related injuries particularly as it relates to exercise programming specifics, namely intensity and volume, to enhance neuromuscular function and also to neurorehabilitation approaches to enhance motor function (e.g., balance, motor planning, and coordination).

Mal de Debarquement syndrome (MdDS), also known as disembarkment syndrome, is a benign neurological condition characterized by a feeling of rocking, bobbing, or swaying, usually presenting after an individual has been exposed to passive motion as from being on a cruise, long drive, turbulent air travel, or train. Clinical awareness about this condition is limited, as is research; thus, many patients go undiagnosed. In this case report, the authors describe a case of a severe headache as a major presenting symptom of MdDS in a 46-year-old woman who eventually attained full resolution of symptoms. This report aims to highlight this unique presentation and make practitioners more aware of the cardinal clinical features, to assist in prompt diagnosis of this disorder.

Mal de Debarquement syndrome (MdDS) is composed of constant phantom sensations of motion, which are frequently accompanied by increased sensitivity to light, inability to walk on a patterned floor, the sensation of ear fullness, head pressure, anxiety, and depression. This disabling condition generally occurs in premenopausal women within 2 days after prolonged passive motion (e.g., travel on a cruise ship, plane, or in a car). It has been previously hypothesized that MdDS is the result of maladaptive changes in the polysynaptic vestibulo-ocular reflex (VOR) pathway called velocity storage. Past research indicates that full-field optokinetic stimulation is an optimal way to activate velocity storage. Unfortunately, such devices are typically bulky and not commonly available. We questioned whether virtual reality (VR) goggles with a restricted visual field could effectively simulate a laboratory environment for MdDS treatment. A stripes program for optokinetic stimulation was implemented using Google Daydream Viewer. Five female patients (42 +/- 10 years; range 26-50), whose average MdDS symptom duration was 2 months, participated in this study. Four patients had symptoms triggered by prolonged passive motion, and in one, symptoms spontaneously occurred. Symptom severity was self-scored by patients on a scale of 0-10, where 0 is no symptoms at all and 10 is the strongest symptoms that the patient could imagine. Static posturography was obtained to determine objective changes in body motion. The treatment was considered effective if the patient's subjective score improved by at least 50%. All five patients reported immediate improvement. On 2-month follow-ups, symptoms returned only in one patient. These data provide proof of concept for the limited-visual-field goggles potentially having clinical utility as a substitute for full-field optokinetic stimulation in treating patients with MdDS in clinics or via telemedicine.

BACKGROUND: Approximately 35% of individuals > 70 years have mobility limitations. Historically, it was posited lean mass and muscle strength were major contributors to mobility limitations, but recent findings indicate lean mass and muscle strength only moderately explain mobility limitations. One likely reason is that lean mass and muscle strength do not necessarily incorporate measures globally reflective of motor function (defined as the ability to learn, or to demonstrate, the skillful and efficient assumption, maintenance, modification, and control of voluntary postures and movement patterns). In this study we determined the relative contribution of lean mass, muscle strength, and the four square step test, as an index of lower extremity motor function, in explaining between-participant variance in mobility tasks. METHODS: In community-dwelling older adults (N = 89; 67% women; mean 74.9 +/- 6.7 years), we quantified grip and leg extension strength, total and regional lean mass, and time to complete the four square step test. Mobility was assessed via 6-min walk gait speed, stair climb power, 5x-chair rise time, and time to complete a complex functional task. Multifactorial linear regression modeling was used to determine the relative contribution (via semi-partial r(2)) for indices of lean mass, indices of muscle strength, and the four square step test. RESULTS: When aggregated by sex, the four square step test explained 17-34% of the variance for all mobility tasks (p 0.01). Muscle strength explained   12% and   7% of the variance in 6-min walk gait speed and 5x-chair rise time, respectively (p 0.02). Lean mass explained 32% and   4% of the variance in stair climb power and complex functional task time, respectively (p 0.02). When disaggregated by sex, lean mass was a stronger predictor of mobility in men. CONCLUSION: The four square step test is uniquely associated with multiple measures of mobility in older adults, suggesting lower extremity motor function is an important factor for mobility performance. TRIAL REGISTRATION: NCT02505529 -2015/07/22.

IMPORTANCE: Low back pain (LBP) is one of the most common reasons for seeking medical care. Manual therapy is a common treatment of LBP, yet few studies have directly compared the effectiveness of thrust (spinal manipulation) vs nonthrust (spinal mobilization) techniques. OBJECTIVE: To evaluate the comparative effectiveness of spinal manipulation and spinal mobilization at reducing pain and disability compared with a placebo control group (sham cold laser) in a cohort of young adults with chronic LBP. DESIGN, SETTING, AND PARTICIPANTS: This single-blinded (investigator-blinded), placebo-controlled randomized clinical trial with 3 treatment groups was conducted at the Ohio Musculoskeletal and Neurological Institute at Ohio University from June 1, 2013, to August 31, 2017. Of 4903 adult patients assessed for eligibility, 4741 did not meet inclusion criteria, and 162 patients with chronic LBP qualified for randomization to 1 of 3 treatment groups. Recruitment began on June 1, 2013, and the primary completion date was August 31, 2017. Data were analyzed from September 1, 2017, to January 20, 2020. INTERVENTIONS: Participants received 6 treatment sessions of (1) spinal manipulation, (2) spinal mobilization, or (3) sham cold laser therapy (placebo) during a 3-week period. MAIN OUTCOMES AND MEASURES: Coprimary outcome measures were the change from baseline in Numerical Pain Rating Scale (NPRS) score over the last 7 days and the change in disability assessed with the Roland-Morris Disability Questionnaire (scores range from 0 to 24, with higher scores indicating greater disability) 48 to 72 hours after completion of the 6 treatments. RESULTS: A total of 162 participants (mean [SD] age, 25.0 [6.2] years; 92 women [57%]) with chronic LBP (mean [SD] NPRS score, 4.3 [2.6] on a 1-10 scale, with higher scores indicating greater pain) were randomized. Fifty-four participants were randomized to the spinal manipulation group, 54 to the spinal mobilization group, and 54 to the placebo group. There were no significant group differences for sex, age, body mass index, duration of LBP symptoms, depression, fear avoidance, current pain, average pain over the last 7 days, and self-reported disability. At the primary end point, there was no significant difference in change in pain scores between spinal manipulation and spinal mobilization (0.24 [95% CI, -0.38 to 0.86]; P = .45), spinal manipulation and placebo (-0.03 [95% CI, -0.65 to 0.59]; P = .92), or spinal mobilization and placebo (-0.26 [95% CI, -0.38 to 0.85]; P = .39). There was no significant difference in change in self-reported disability scores between spinal manipulation and spinal mobilization (-1.00 [95% CI, -2.27 to 0.36]; P = .14), spinal manipulation and placebo (-0.07 [95% CI, -1.43 to 1.29]; P = .92) or spinal mobilization and placebo (0.93 [95% CI, -0.41 to 2.29]; P = .17). CONCLUSIONS AND RELEVANCE: In this randomized clinical trial, neither spinal manipulation nor spinal mobilization appeared to be effective treatments for mild to moderate chronic LBP. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01854892.