Effectiveness of NEUROM and tDCS for Motor Recovery in Chronic Paraplegia

PARTICIPANTS Fifty participants with paraplegia will be recruited from inpatient rehabilitation hospitals. Patients will be treated at Rahma Hospital for Rehabilitation in Tripoli and the Physical Therapy Center of the Faculty of Public Health-I in Hadath.

INCLUSION/EXCLUSION CRITERIA Main inclusion criteria include: age between 18-45 years; diagnosis of chronic spinal cord injury (defined as at least 3 months post-injury); and injury level below T10 with an American Spinal Injury Association Impairment Scale (AIS) classification of A, B, or C. Ethical committee approval will be obtained from the Lebanese University official ethical committee, and informed consent will be obtained from all participants in accordance with the Declaration of Helsinki.

Exclusion criteria include: neuropsychiatric comorbidities; traumatic brain injury (TBI); involvement in any specific program of rehabilitation other than the conventional protocol since injury; and contraindications to tDCS (such as metal in the head or implanted medical devices). Patients with a history of seizure, use of medications containing sodium channel blockers (e.g., carbamazepine), or any substance abuse will be excluded. Patients with severe spasticity (greater than or equal to 3 out of 4 on the Modified Ashworth Scale) will also be excluded.

Prior to the experiment, patients must have received conventional physiotherapy and demonstrated stable lower limb functional scores; performance must not change from the end of conventional therapy until the first baseline measurements.

STUDY DESIGN \& ARMS All subjects will be randomly assigned into three groups:

Reference Group (n=10): Participants will receive a standardized conventional intervention (stretching, strengthening, neuro-muscular facilitation).

NEUROM Group (n=20): Participants will receive the Neural Motor Recruitment Method (NEUROM).

NEUROM + tDCS Group (n=20): Participants will receive the NEUROM protocol combined with tDCS.

All participants will undergo a detailed medical examination, with particular attention to the experimental group receiving tDCS to eliminate adverse effects. Before every session, participants will be prepared for the closed-loop rehabilitation protocol by 20 minutes of static stretching of the lower legs, specifically the hamstrings and soleus muscles.

INTERVENTIONS

Conventional Rehabilitation Program: The conventional control group will undergo therapeutic exercises including: repetitive neuromuscular facilitation, passive and active mobilization, strengthening, endurance exercises, and musculoskeletal interventions (static and dynamic stretching).

Neural Motor Recruitment (NEUROM): Patients in the NEUROM and NEUROM+tDCS groups will receive daily home Motor Imagery (MI) training with 20 minutes of stretching for 10 days. MI training will be individually delivered in a quiet room designed for this purpose. Participants will lay on a bed facing a 43-inch screen located 3.5 meters away, with the center of the screen 1.2 meters from the floor. The screen will display a 5-minute video of two feet repeating large movements of dorsi- and plantar flexion. Instructions will be detailed and read aloud. An audio output will guide the subject to feel the movement (kinesthetic imagery) with the instruction: "Imagine yourself performing the feet movement without actually executing it with your eyes closed."

Transcranial Direct Current Stimulation (tDCS): The combined group will receive NEUROM + tDCS. The StarstimNE non-invasive wireless tDCS neurostimulator (Neuroelectrics®, Barcelona, Spain) will be used. A wireless neoprene cap based on the International 10-20 System will be placed on the participant's head by aligning the central Cz electrode position with the vertex. Small Ag/AgCl gelled electrodes (3.14 cm²) will be used. In all sessions, one electrode will be placed on the left M1 and the other on the right M1 (corresponding to C3 and C4). The montage will alternate: in one session the anode will be on the left M1 and the cathode on the right M1 (AL-CR), and in the next session, the polarity will be reversed (AR-CL). DC current will be increased over 7 seconds to 1 mA and maintained for 20 minutes. During tDCS, the participant will be asked to perform kinesthetic imagery.

OUTCOME MEASURES

Vividness of Motor Imagery Questionnaire (VMIQ): Participants will indicate the vividness of an imagined movement on a 5-point scale (1: excellent/lively as actual performance; 5: no image at all).

Assessment of Movement Attempt (AMA) and Execution: The motor task consists of repetitive alternating dorsal and plantar flexion of the right foot (30°-0°-45°) at a self-paced rhythm. The perceived intensity and frequency of attempted movements will be rated in a structured interview. Answers are noted as qualitative descriptors and rated on a 6-point scale (1: very weak/rare; 6: very high/often).

ASIA Examinations: Motor and sensory examinations will be performed by SCI-experienced physical therapists at baseline, week 1, week 2, and week 4. Five key muscle groups will be assessed (total score /50) and sensation will be recorded for 12 key sensory points (Light Touch and Pin Prick; max score /48).

Visual Analog Scale (VAS): Used to measure introspective perception of movement during the illusion condition. Participants will rate the strength of the kinesthetic illusion from 0 mm (no sensation) to 100 mm (feels exactly like actual movement).

EXPECTED OUTCOMES \& APPLICABILITY Priming the motor cortex to augment functional benefits with peripheral training is a relatively new approach. Research is needed to increase the effectiveness of physical rehabilitation in Spinal Cord Injury. The investigators anticipate that distinguishing between therapies with unequal impacts on outcomes will answer clinical questions regarding non-conventional strategies. The findings may support the hypothesis that modulating excitatory input of the corticospinal tracts combined with motor imagery in a closed-loop protocol is a promising strategy for improving lower limb functions in chronic paraplegia.