This study aims to evaluate the effectiveness of physiotherapy treatment combined with functional electrical stimulation (FES) in a small group of patients with severe acquired brain injury (SABI) of vascular origin and with a clinical and instrumental diagnosis of Intensive Care Unit-Acquired Weakness (ICU-AW). Functional electrical stimulation is a technology that uses electrical impulses, generated by an external device, to reactivate the neuromuscular system through electrodes applied to the skin. In functional electrical stimulation, this process is integrated into physiotherapy sessions, with the active involvement of the patient, through the performance of exercises with the assistance and supervision of the physiotherapist. The rationale behind this is to stimulate neuroplasticity processes by facilitating movement through the application of electrical stimuli and the active participation of the patient in performing a motor task, in an attempt to promote improvement in an impaired function. In particular, the objectives that will be pursued are: improvement of lower limb neuromyopathy assessed clinically using the Medical Research Council (MRC) scale, the Fugl-Meyer scale for lower limbs, the Short Physical Performance Battery (SPPB) scale, the assessment of active and passive Range Of Motion (ROM) of the main joints of the lower limb (hip, knee, ankle) and measured instrumentally by neurophysiological examination and ultrasound examination. After randomization, patients in the control arm will be treated with physiotherapy and speech therapy sessions as per the conventional protocol, and an additional 15 physiotherapy sessions lasting 60 minutes over a period of 5 weeks. Alternatively, patients in the experimental group will receive, in addition to conventional rehabilitation treatment, a treatment consisting of 15 physiotherapy sessions combined with FES lasting 60 minutes over a period of 5 weeks. At the end of the treatment period, baseline characteristics and clinical and instrumental outcome variables will be compared between the two groups using the chi-square test for dichotomous and categorical variables and the t-test for independent samples or the Mann-Whitney U test for continuous variables, depending on whether or not they are normally distributed. In all analyses, a p-value \<0.05 will be considered significant.