Transcutaneous spinal cord stimulation (tSCS) for the treatment of spasticity and gait disorders in multiple sclerosis

INTERVENTION: Intervention 1: Measurement No.1: 50 Hz Measurement No.2: Sham Measurement No.3: 50 Hz Intervention 2: Measurement No.1: Sham Measurement No.2: 50 Hz Measurement No.3: 50 Hz CONDITION: G35 ‐ Multiple sclerosis G35.2 ‐ [generalization G35: Multiple sclerosis] G35.3 ‐ [generalization G35: Multiple sclerosis] PRIMARY OUTCOME: Reduction of spasticity with transcutaneous spinal cord stimulation (clinical assesment with Modified Ashworth Scale) SECONDARY OUTCOME: a) Improvement of MS‐specific clinical functional impairment (Expanded Disability Status Scale); ; b) Extension of the maximum walking distance without aids.; ; c) Improvement of the walking speed in the 10‐meter walking test.; ; d) Correlation of the spasticity assessment in the clinical assessment (Modified Ashworth Scale) with electrophysiological parameters (Hoffmann reflex and tSCS double pulses) INCLUSION CRITERIA: confirmed diagnosis of multiple sclerosis with a moderate to severe spasticity (Modified Ashworth Scale scores of 2‐4)