Spinal Cord Injury and Osteoporosis: Causes, Mechanisms, and Rehabilitation Strategies

Spinal cord injury (SCI) has a huge impact on the individual, society and the economy. Though advances in acute care resulted in greatly reduced co-morbidities, there has been much less progress preventing long-term sequelae of SCI. Among the long-term consequences of SCI is bone loss (osteoporosis) due to the mechanical unloading of the paralyzed limbs and vascular dysfunction below the level of injury. Though osteoporosis may be partially prevented via pharmacologic interventions during the acute post-injury phase, there are no clinical guidelines to treat osteoporosis during the chronic phase. Thus there is need for scientific advances to improve the rehabilitative approaches to SCI-related osteoporosis. Recent advances in application of a new technology, functional electrical stimulation, provide a new and exciting opportunity to improve bone metabolism and to provide mechanical strain to the paralyzed lower limbs sufficient to stimulate new bone formation in individuals with SCI. The purpose of this minireview is to delineate our current understanding of SCI-related osteoporosis and to highlight recent literature towards its prevention and treatment

Study adherence in a tDCS longitudinal clinical trial with people with spinal cord injury

Study design Secondary analysis of a clinical trial.Objectives To analyze adherence to 1-year transcranial Direct Current Stimulation (tDCS) clinical trial in people with chronic pain due to spinal cord injury (SCI). We also explore the association between dropout and several baseline variables such as age, depression levels, pain severity, number of days with pain in the last 7 days, walking ability, sleep, work, relationship with others, and enjoyment with life.Setting Boston, USA.Methods Forty-six participants were enrolled in this trial, and 33 participants were randomized to receive either active or sham tDCS.Results Using the full intention-to-treat (ITT) criteria, only 8 participants (24%) finished the study. The median time to dropout was seven (IQR:6,19) sessions (i.e., immediately after the first follow-up), regardless of the type of stimulation that participants received (active vs. sham tDCS) (chi(2) = 0.025, p = 0.875). An exploratory analysis suggested that only the number of days with pain in the last 7 days was moderately associated with dropout, with people experiencing less pain being more prone to dropout from the study.Conclusions Despite all the measures to improve study adherence (such as providing parking, flexibility to schedule sessions, follow-up with participants by phone), it seems that long follow-up periods may increase the likelihood of dropout. Given the need to understand long-term effects of interventions, longitudinal trials need to consider alternative designs or methods of treatment (for instance home treatment or home assessment) to decrease attrition rate.This project was supported by the National Institute on Disability, Independent Living, and Rehabilitation Research (NIDILRR grant numbers H133N110010 and 90SI5021-01-00). SC and JL are supported by the Portuguese Foundation for Science and Technology PTDC/MHC-PCN/3950/2014; SC is also funded by the following FCT grant IF/00091/2015

Feasibility of remotely-supervised tDCS in a person with neuropathic pain due to spinal cord injury

[Excerpt] Nearly 40% of people with spinal cord injury (SCI) report neuropathic pain that is often refractory to medications.1,2 Substantial research has shown that anodal transcranial direct current stimulation (tDCS) over the motor cortex can induce clinically significant pain relief in chronic pain.3–6 However, these clinical trials often require multiple study visits per trial and are associated to poor adherence to the study protocol. For instance, in our recent tDCS study in SCI, only 7 participants from the initial 46 that were enrolled completed the study.7 In fact, despite all attempts to improve adherence, such as flexibility to schedule sessions, free parking and follow-ups by the phone, most participants ended up dropping out from the study. Since many people with SCI have limited mobility, alternatives for home-based care are needed. Here we report the feasibility of supervised home-based tDCS application in a 57-year old woman with tetraplegia and sublesional neuropathic pain secondary to SCI since 2012. At time of enrollment, she self-reported pain as being 9 out of 10 in a visual analogue scale. [...]This project was supported by the National Institute on Disability, Independent Living, and Rehabilitation Research (NIDILRR grant numbers 90DP0035 and H133N110010)

Concurrent muscle and bone deterioration in a murine model of cancer cachexia

Cachexia is defined as an excessive, involuntary loss of fat and lean tissue. We tested the validity of the Lewis lung carcinoma (LLC) as a model of cancer cachexia and examined its effect on the two major lean tissue components, skeletal muscle and bone. LLC cells (0.75 × 106) were injected into the left thigh of C57BL/6 mice. Control mice received an equal volume injection of growth media. Tumors were observed in all LLC-injected animals 21 and 25 days post inoculation. LLC-injected animals showed significant reductions in fat and lean mass despite having the same average daily caloric intake as media-treated mice. Global bone mineral density (BMD) had fallen by 5% and 6% in the LLC animals at 21 and 25 days, respectively, compared to a BMD increase of 5% in the 25-day media-treated animals. Extensor digitorum longus (EDL) muscles (isolated from the noninjected hindlimb) showed earlier and quantitatively greater losses in mass, physiological cross-sectional area (pCSA), and tetanic force compared to soleus muscles from the same hindlimb. By the 25th day post-LLC inoculation, EDL force/pCSA was reduced by 19% versus media treatment. This loss in specific force was not trivial as it accounted for about one-third of the reduction in EDL absolute force at this time point. Muscle strips dissected from the diaphragm of LLC mice also exhibited significant reductions in force/pCSA at day 25. We conclude that LLC is a valid model of cachexia that induces rapid losses in global BMD and in limb and respiratory muscle function

Reliability and Validity of S3 Pressure Sensation as an Alternative to Deep Anal Pressure in Neurologic Classification of Persons With Spinal Cord Injury.

OBJECTIVE: To determine whether pressure sensation at the S3 dermatome (a new test) could be used in place of deep anal pressure (DAP) to determine completeness of injury as part of the International Standards for Neurological Classification of Spinal Cord Injury. DESIGN: Prospective, multicenter observational study. SETTING: U.S. Spinal Cord Injury Model Systems. PARTICIPANTS: Persons (N=125) with acute traumatic spinal cord injury (SCI), neurologic levels T12 and above, were serially examined at 1 month (baseline), 3, 6, and 12 months postinjury. There were 80 subjects with tetraplegia and 45 with paraplegia. INTERVENTIONS: S3 pressure sensation at all time points, with a retest at the 1-month time point. MAIN OUTCOME MEASURES: Test-retest reliability and agreement (κ), sensitivity, specificity, positive and negative predictive values. RESULTS: Test-retest reliability of S3 pressure at 1 month was almost perfect (κ=.98). Agreement of S3 pressure with DAP was substantial both at 1 month (κ=.73) and for all time points combined (κ=.76). The positive predictive value of S3 pressure for DAP was 89.3% at baseline and 90.3% for all time points. No pattern in outcomes was seen in those cases where S3 pressure and DAP differed at 1 month. CONCLUSIONS: S3 pressure sensation is reliable and has substantial agreement with DAP in persons with SCI at least 1 month postinjury. We suggest S3 pressure as an alternative test of sensory sacral sparing for supraconus SCI, at least in cases where DAP cannot be tested. Further research is needed to determine whether S3 pressure could replace DAP for classification of SCI

COVID-19 and the spinal cord injury community: Concerns about medical rationing and social isolation.

Purpose/Objective: To provide a descriptive account of the impact of the COVID-19 pandemic on the spinal cord injury (SCI) community focused on participants’ concerns about medical discrimination and medical rationing, the impact of the pandemic on access to personal care attendants and medical supplies, and the impact of the pandemic on overall and mental health. Research Method/Design: Cross sectional, observational study among community-dwelling adults with SCI. Data were collected online between May 1, 2020 and August 31, 2020 (n = 187). The online questionnaire included questions regarding medical discrimination and rationing, the impact of the pandemic on access to care and medical supplies, and the impact of the pandemic on overall and mental health. Results: Individuals with SCI have experienced difficulty accessing medical supplies due to the pandemic, and approximately half of our participants (52%) perceived that discrimination through medical rationing was occurring. Furthermore, compared to the general U.S. population, our sample reported that the pandemic had a greater negative impact on their mental health and access to medical supplies. Conclusion/Implications: Our findings suggest that the COVID-19 pandemic has negatively impacted mental health and increased concerns of social isolation as well as access to medical supplies among those with SCI. Rehabilitation psychologists must advocate alongside the disability community to limit health disparities and to conduct outreach, specifically with regard to mental health issues. Future research should focus on the effects of pandemic-related fears and social isolation, as well as resilience in the context of public health care threats

Altered brain morphometry in carpal tunnel syndrome is associated with median nerve pathology☆☆☆

Objective: Carpal tunnel syndrome (CTS) is a common median nerve entrapment neuropathy characterized by pain, paresthesias, diminished peripheral nerve conduction velocity (NCV) and maladaptive functional brain neuroplasticity. We evaluated structural reorganization in brain gray matter (GM) and white matter (WM) and whether such plasticity is linked to altered median nerve function in CTS. Methods: We performed NCV testing, T1-weighted structural MRI, and diffusion tensor imaging (DTI) in 28 CTS and 28 age-matched healthy controls (HC). Voxel-based morphometry (VBM) contrasted regional GM volume for CTS versus HC. Significant clusters were correlated with clinical metrics and served as seeds to define associated WM tracts using DTI data and probabilistic tractography. Within these WM tracts, fractional anisotropy (FA), axial (AD) and radial (RD) diffusivity were evaluated for group differences and correlations with clinical metrics. Results: For CTS subjects, GM volume was significantly reduced in contralesional S1 (hand-area), pulvinar and frontal pole. GM volume in contralesional S1 correlated with median NCV. NCV was also correlated with RD and was negatively correlated with FA within U-fiber cortico-cortical association tracts identified from the contralesional S1 VBM seed. Conclusions: Our study identified clear morphometric changes in the CTS brain. This central morphometric change is likely secondary to peripheral nerve pathology and altered somatosensory afference. Enhanced axonal coherence and myelination within cortico-cortical tracts connecting primary somatosensory and motor areas may accompany peripheral nerve deafferentation. As structural plasticity was correlated with NCV and not symptomatology, the former may be a better determinant of appropriate clinical intervention for CTS, including surgery

A short report: PAMM, a novel antioxidant protein, induced by oxidative stress

Reactive oxygen species (ROS) play a central role in estrogen deficiency-induced bone loss. We previously identified and characterized a novel member of the Peroxiredoxin (PRX) like 2 family that we called PAMM: Peroxiredoxin Activated in M-CSF stimulated Monocytes, a redox regulatory protein that modulates osteoclast differentiation in vitro. In this study, we report increased PAMM expression in H2O2-treated cells and in bones from ovariectomized (OVX) mice 4 weeks after surgery, models for oxidative stress in vitro and in vivo, respectively. We also detected increased PAMM abundance and phosphorylated Akt in OVX mice treated with estrogen. In addition, Wortmannin, a specific PI3Kinase inhibitor and Rapamycin, an inhibitor of the PI3Kinase/Akt pathway, blocked Akt phosphorylation and stimulation of PAMM expression by M-CSF. These results indicate that M-CSF-induced PAMM expression is mediated by Akt phosphorylation. Our data also suggest that estrogen-induced PAMM expression is mediated by phosphorylation of Akt. These findings point to PAMM as a potential candidate for Akt-mediated protection against oxidative stress

Functional deficits in carpal tunnel syndrome reflect reorganization of primary somatosensory cortex

Carpal tunnel syndrome, a median nerve entrapment neuropathy, is characterized by sensorimotor deficits. Recent reports have shown that this syndrome is also characterized by functional and structural neuroplasticity in the primary somatosensory cortex of the brain. However, the linkage between this neuroplasticity and the functional deficits in carpal tunnel syndrome is unknown. Sixty-three subjects with carpal tunnel syndrome aged 20–60 years and 28 age- and sex-matched healthy control subjects were evaluated with event-related functional magnetic resonance imaging at 3 T while vibrotactile stimulation was delivered to median nerve innervated (second and third) and ulnar nerve innervated (fifth) digits. For each subject, the interdigit cortical separation distance for each digit’s contralateral primary somatosensory cortex representation was assessed. We also evaluated fine motor skill performance using a previously validated psychomotor performance test (maximum voluntary contraction and visuomotor pinch/release testing) and tactile discrimination capacity using a four-finger forced choice response test. These biobehavioural and clinical metrics were evaluated and correlated with the second/third interdigit cortical separation distance. Compared with healthy control subjects, subjects with carpal tunnel syndrome demonstrated reduced second/third interdigit cortical separation distance (P < 0.05) in contralateral primary somatosensory cortex, corroborating our previous preliminary multi-modal neuroimaging findings. For psychomotor performance testing, subjects with carpal tunnel syndrome demonstrated reduced maximum voluntary contraction pinch strength (P < 0.01) and a reduced number of pinch/release cycles per second (P < 0.05). Additionally, for four-finger forced-choice testing, subjects with carpal tunnel syndrome demonstrated greater response time (P < 0.05), and reduced sensory discrimination accuracy (P < 0.001) for median nerve, but not ulnar nerve, innervated digits. Moreover, the second/third interdigit cortical separation distance was negatively correlated with paraesthesia severity (r = −0.31, P < 0.05), and number of pinch/release cycles (r = −0.31, P < 0.05), and positively correlated with the second and third digit sensory discrimination accuracy (r = 0.50, P < 0.05). Therefore, reduced second/third interdigit cortical separation distance in contralateral primary somatosensory cortex was associated with worse symptomatology (particularly paraesthesia), reduced fine motor skill performance, and worse sensory discrimination accuracy for median nerve innervated digits. In conclusion, primary somatosensory cortex neuroplasticity for median nerve innervated digits in carpal tunnel syndrome is indeed maladaptive and underlies the functional deficits seen in these patients