INTRINSIC MOTOR NEURONE EXCITABILITY IS REDUCED IN SOLEUS AND TIBIALIS ANTERIOR OF OLDER ADULTS

Age-related deterioration within both motor neurones and monoaminergic systems should theoretically reduce neuromodulation by weakening motor neuronal persistent inward current (PIC) strength. However, this assumption remains untested. Surface electromyographic signals were collected using two 32-channel electrode matrices placed on soleus and tibialis anterior of 25 older adults (70±4years) and 17 young adults (29±5 years) to investigate motor unit discharge behaviours. Participants performed triangular-shaped plantar and dorsiflexion contractions to 20% of maximum torque at a rise-decline rate of 2%/s of each participant's maximal torque. Pairwise and composite paired-motor unit analyses were adopted to calculate delta frequency (ΔF) and estimate PIC amplitudes. ΔF has been used to differentiate between the effects of synaptic excitation and intrinsic motor neuronal properties and is assumed to be proportional to PIC amplitude. The results show that soleus and tibialis anterior motor units in older adults had lower ΔFs when calculated with the pairwise (-0.99 and -1.29 pps, respectively) or composite (-1.65 and -2.26 pps, respectively) methods. Older adults' motor units discharged at lower rates (-2.14 and -2.03 pps, respectively) and were recruited at lower torque levels (-1.50 and -2.06% of maximum, respectively) than young adults. These results demonstrate reduced intrinsic motor neurone excitability during low-force contractions in older adults, likely mediated by decreases in the strength of persistent inward currents. Our findings might be explained by deterioration in the motor neurones or monoaminergic systems, and could contribute to the decline in motor function during ageing; these assumptions should be explicitly tested in future investigations.

Strategies for the recovery of patients with post stroke sequelae in the context of the COVID-19 pandemic

Introduction. The performance areas of post-stroke mention negatively correlated determinants in doing daily activities. The intrinsic motor recovery depends on the primary motor deficit. The functional recovery of patients with post-stroke sequelae is not only based on the remission of the functional deficit, but it also depends on the ability to develop adapted motor strategies.The objective of the study was to point out, for the patients with post-stroke sequelae, the sensitive, motor and cognitive changes in the context of the COVID-19 pandemic. Material and method. The study included a number of 18 patients diagnosed with post-stroke sequelae and was conducted for a period of 5 months in an outpatient department. The recovery treatment included sessions of kinetotherapy and occupational therapy. The evaluation of the patients was made in the beginning of the treatment, at its end and at the control after 6 weeks. Scales were used to assess pain, the static and dynamic balance, the gait and the cognitive function. Results. The obtained results were statistically significant for the patients in the group. The values that were obtained by applying the tests and evaluation scales are consistent with the clinical evolution of the patients in the study group. Conclusions. Given the pandemic period we are going through, it is still necessary to carefully evaluate not only the sensory-motor functions of patients with post-stroke sequelae, but also the cognitive functions that are known to influence in some situations the recovery of these patients. Keywords: post-stroke sequelae, functional recovery, kinetic therapy,

Autonomous Stairwell Ascent

SummaryThis paper documents autonomous multi-floor stairwell ascent by a legged robot. This is made possible through empirically deployed sequential composition of several reactive controllers, with perceptually triggered transitions. This composition relies on simplified assumptions regarding the robot’s sensory capabilities, its level of mobility, and the environment it operates in. The discrepancies between these assumptions and the physical reality are capably handled by the intrinsic motor competence of the robot. This behavior is implemented on the legged RHex platform and experiments spanning 10 different stairwells with various challenges are conducted.

Mixed Lymphangioma and Cavernous Hemangioma Within the Ulnar Nerve: A Case Report

Background: Lymphangiomas are benign lymphatic vessel hamartomas typically found in the skin or subcutaneous tissue of the head and neck. Although mostly seen in a congenital context, acquired forms have been reported. By contrast, cavernous hemangiomas are benign hamartomas of endothelial origin. They can arise anywhere in the body, but are typically described as arising from the central nervous system. Methods: We report the case of a young patient who developed a mixed lymphangioma and cavernous hemangioma within the ulnar nerve. The tumor was removed during an intrafascicular dissection with preservation of all major fascicles. Results: Postoperatively, the patient retained intrinsic motor function and full sensation returned. This is the first published case of this type of mixed tumor occurring in a peripheral nerve. Conclusions: It could not be ascertained whether trauma was the mechanism by which a lymphangioma developed within the peripheral nerve, as has been proposed. Although this is plausible, alternative mechanisms should be considered.