The efficacy of two protocols for inducing motor cortex plasticity in healthy humans - TMS study

Stimulation-induced plasticity represents an experimental model of motor cortex reorganization. It can be produced in awaked humans by combining the non-invasive electrical stimulation of somatosensory afferents via mixed peripheral nerves with the transcranial magnetic stimulation (TMS) of the motor cortex. Animal experiments indicate that an application of two converging inputs from various sources in a tightly coupled manner, following the so called Hebbian rule of learning, leads to an increase in motor cortical excitability. The aim of our study was to compare the effects of two plasticity-inducing protocols by quantifying the motor cortex changes using TMS. Plasticity was induced by combining peripheral nerve stimulation with TMS (paired associative stimulation - PAS) and by peripheral motor point stimulation of two adjacent hand muscles (dual associative stimulation - DAS). The protocols were randomly applied in 12 right-handed healthy volunteers. The amplitudes of TMS-induced motor-evoked potentials (MEPs) in the right abductor pollicis brevis muscle were recorded before, immediately after PAS or DAS stimulation, and 10, 20 and 30 min later. Both protocols led to significant and lasting changes in MEP amplitudes, however, a significantly larger increase in MEPs was observed after PAS than DAS. The results indicate that afferent input can differently affect cortical motor circuits and produce variable motor output. Thus, the efficacy of LTP-like mechanisms, presumably involved in Hebbian-like plasticity in humans, varies with the types/origin of the converging inputs. Our findings may be relevant when designing therapeutic interventions for improving motor function after neurological injury or disease

Which clinical variables have the most significant correlation with quality of life evaluated by SF-36 survey in Croatian cohort of patient with ankylosing spondylitis and psoriatic arthritis?

The aim of our study was to assess clinical variables with the best correlation to quality of life (QOL) assessed by medical outcome survey Short-Form 36 (SF-36) in patients with spondyloarthritides, including ankylosing spondylitis (AS) and psoriatic arthritis (PsA). We analyzed the cohort of 54 patients (22 patients with PsA and 32 patients with AS), who filled the Croatian version of SF-36. For each type of arthritis, patients were clinically evaluated using the extensive list of clinical variables categorized into subjective and objective group. For AS patients, subjective and objective variables (spinal mobility measurements, clinical assessment of spinal pain, patient assessments of disease activity and pain) correlated mainly with the physical functioning concept of SF-36. Patients assessments of fatigue correlated with the energy/fatigue subscale, whereas patient assessment of enthesial pain correlated with the pain subscale. Correlations between clinical variables and SF-36 concepts of PsA patients showed more diverse distribution than for AS. Objective variables (spinal mobility measurements, a 76-joint score, clinical assessment of spinal pain) correlated with concepts concerning physical health and pain. Several subjective patient assessments correlated with energy/fatigue, emotional well-being, pain and general health subscales. Both patient and physician assessment of PsA activity correlated with the role limitations due to emotional problems. Bath ankylosing spondylitis functional index (BASFI) had the strongest correlation with the physical functioning concept of SF-36 in both diseases. Our findings provide important information to help selecting the variables with strongest impact on QOL, for better planning the management strategies and achieving better rehabilitation results