Quantitative evaluation of trunk function and the StartReact effect during reaching in patients with cervical and thoracic spinal cord injury

Reproducció del document publicat a: https://doi.org/10.1088/1741-2552/ac19d3
Objective. Impaired trunk stability is frequent in spinal cord injury (SCI), but there is a lack of quantitative measures for assessing trunk function. Our objectives were to: (a) evaluate trunk muscle activity and movement patterns during a reaching task in SCI patients, (b) compare the impact of cervical (cSCI) and thoracic (tSCI) injuries in trunk function, and (c) investigate the effects of a startling acoustic stimulus (SAS) in these patients. Approach. Electromyographic (EMG) and smartphone accelerometer data were recorded from 15 cSCI patients, nine tSCI patients, and 24 healthy controls, during a reaching task requiring trunk tilting. We calculated the response time (RespT) until pressing a target button, EMG onset latencies and amplitudes, and trunk tilt, lateral deviation, and other movement features from accelerometry. Statistical analysis was applied to analyze the effects of group (cSCI, tSCI, control) and condition (SAS, non-SAS) in each outcome measure. Main results. SCI patients, especially those with cSCI, presented significantly longer RespT and EMG onset latencies than controls. Moreover, in SCI patients, forward trunk tilt was accompanied by significant lateral deviation. RespT and EMG latencies were remarkably shortened by the SAS (the so-called StartReact effect) in tSCI patients and controls, but not in cSCI patients, who also showed higher variability. Significance. The combination of EMG and smartphone accelerometer data can provide quantitative measures for the assessment of trunk function in SCI. Our results show deficits in postural control and compensatory strategies employed by SCI patients, including delayed responses and higher lateral deviations, possibly to improve sitting balance. This is the first study investigating the StartReact responses in trunk muscles in SCI patients and shows that the SAS significantly accelerates RespT in tSCI, but not in cSCI, suggesting an increased cortical control exerted by these patients.
This work was developed in the framework of the joint project 'Biomedical signal interpretation to study motor impairment, neurological disorders and novel personalised neurorehabilitation therapies', between the Fundación Institut Guttmann and the Institute for Bioengineering of Catalonia. This work was supported in part by a fellowship from 'La Caixa' Foundation (ID 100010434) with fellowship code LCF/BQ/DE18/11670019, in part by the Secretaria d'Universitats i Recerca de la Generalitat de Catalunya under Grant GRC 2017 SGR 01770, in part by the Agencia Estatal de Investigación, the Spanish Ministry of Science, Innovation and Universities, and the European Regional Development Fund under Grant RTI2018 098472-B-I00, in part by the CERCA Program/Generalitat de Catalunya, in part by H2020-ERA-NET Neuron under Grant AC16/00034, in part by La Marató de TV3 2017 under Grant 201713.31, and in part by Premi Beca 'Mike Lane' 2019—Castellers de la Vila de Gràcia. The authors declare no competing interests.