Combined rTMS and tSCS for Upper Limb Recovery in Cervical SCI

Combined Repetitive Transcranial Magnetic Stimulation and Transcutaneous Spinal Cord Stimulation for Upper Limb Recovery in Chronic Incomplete Cervical Spinal Cord Injury: Pilot Randomized Controlled Trial

This clinical trial investigates whether combining cortical and spinal neuromodulation can improve upper limb motor recovery in adults with chronic incomplete cervical spinal cord injury (SCI). Restoring upper limb function is the top rehabilitation priority for individuals with tetraplegia, yet effective interventions remain limited.

The study combines transcutaneous spinal cord stimulation (tSCS), which enhances spinal circuit excitability, with intermittent theta burst stimulation (iTBS), a form of repetitive transcranial magnetic stimulation that increases cortical excitability and strengthens descending motor pathways. While each approach has shown independent promise, their combined use has not been evaluated in a controlled trial.

Eligible participants are adults aged 21-65 with chronic (>12 months post-injury) incomplete cervical SCI (ASIA Impairment Scale grade C or D, levels C2-C8). A total of 24 participants will be randomised 1:1 to either combined iTBS and tSCS plus standardised upper limb rehabilitation, or tSCS plus rehabilitation alone, across 24 sessions over 12 weeks.

The primary outcome is change in Upper Extremity Motor Score from baseline to week 12. Secondary outcomes cover functional performance, independence, spasticity, corticospinal excitability, quality of life, and goal attainment. Assessments occur at baseline, post-intervention, and at 4- and 12-week follow-up.

As a pilot randomised controlled trial, this study will generate the first controlled evidence on adjunctive cortical neuromodulation alongside tSCS-based rehabilitation, while also producing feasibility data to inform the design of a future definitive multicentre trial.

Background: Cervical spinal cord injury (SCI) results in severe upper limb impairment, with restoration of hand and arm function ranked as the highest rehabilitation priority by individuals with tetraplegia. Transcutaneous spinal cord stimulation (tSCS) has emerged as a promising approach for enhancing upper limb recovery. Intermittent theta burst stimulation (iTBS), an efficient form of repetitive transcranial magnetic stimulation, can enhance cortical excitability and descending motor drive. However, the benefit of combining these complementary neuromodulation modalities to simultaneously target supraspinal and spinal circuits has not been evaluated in a controlled trial.

Objective: This study aims to evaluate the feasibility, safety, and preliminary efficacy of combined cortical neuromodulation (iTBS) and spinal neuromodulation (tSCS) versus tSCS alone, each paired with standardized upper limb rehabilitation, for improving upper limb motor function in chronic incomplete cervical SCI.

Methods: This single-center, two-arm, assessor-blinded, pilot randomized controlled trial will enroll 24 adults aged 21 to 65 years with chronic (more than 12 months post-injury) incomplete cervical SCI (American Spinal Injury Association Impairment Scale grade C or D, neurological level C2 to C8). Participants will be randomized 1:1 to receive either iTBS combined with tSCS plus standardized upper limb rehabilitation or tSCS plus upper limb rehabilitation alone. Interventions will be delivered twice weekly for 12 weeks (24 sessions). The primary outcome is the change in Upper Extremity Motor Score from baseline to 12 weeks. Secondary outcomes include measures of upper limb function, independence, spasticity, corticospinal excitability, quality of life, and goal attainment. Assessments will be conducted at baseline, post-intervention, and at 4-week and 12-week follow-up.

Conclusions: This pilot trial will provide the first controlled evidence on whether adjunctive cortical neuromodulation via iTBS produces additional upper limb motor recovery beyond tSCS-based rehabilitation in chronic incomplete cervical SCI. Feasibility data and effect size estimates will inform the design of a subsequent multicenter confirmatory trial.

Inclusion Criteria:

• Chronicity: More than 12 months post-injury at enrollment
• Injury type: Traumatic or non-traumatic incomplete cervical SCI, neurological level C2 to C8
• AIS classification: Grade C or D
• UEMS: 10 to 20 out of 25 on the more impaired side; lower bound 10 ensures sufficient voluntary activation for task training and elicitable MEPs, upper bound avoids ceiling effects.
• Grip strength: MMT grade 3 or higher in finger flexors (C8 myotome) on at least one side.
• Hand function: Able to transfer at least 1 block across the partition within 60 seconds on the more impaired side.
• Sitting tolerance: Able to tolerate upright seated posture in own wheelchair for at least 1 continuous hour without symptomatic orthostatic hypotension or pressure-related discomfort requiring position change.
• Medical stability: No acute medical complications
• Informed consent: Able to provide written informed consent and comply with the study schedule
• Medications: Stable regimen for 4 weeks prior, AND participant plus clinician agreement that dosage (baclofen, tizanidine, botulinum toxin) remains unchanged throughout the 12-week intervention; any change logged as protocol deviation
• Surgical clearance: Cleared by neurosurgeon or orthopedic surgeon for participation in tSCS-based rehabilitation

Exclusion Criteria:

• Seizure history: History of seizures or epilepsy
• Implanted devices: Intracranial metallic implants, cochlear implants, cardiac pacemakers, or other implanted electronic devices. Cervical spinal instrumentation (e.g., posterior rods, plates, or screws at C2 to T1) is not an exclusion for tSCS provided overlying skin is intact; participants with hardware directly beneath planned electrode sites will undergo low-intensity test stimulation during screening, and electrode placement will be shifted by one interspace if current distortion, focal discomfort, or unexpected motor thresholds are observed. Intracranial hardware remains an absolute exclusion for iTBS.
• Prior craniotomy: Prior neurosurgical procedure involving craniotomy
• Pregnancy: Currently pregnant or intending to become pregnant during the study period
• Psychiatric or cognitive: Active psychiatric illness (eg, untreated major depression, psychosis) or cognitive impairment precluding informed consent
• Concurrent neurological disease: Progressive or degenerative neurological condition (eg, multiple sclerosis, motor neuron disease)
• Concurrent trials: Participation in another interventional rehabilitation or neurostimulation trial
• Skin integrity: Skin lesions or breakdown at electrode placement sites (scalp or posterior cervical spine)
• Cortical excitability medications: Medications known to alter cortical excitability (eg, antiepileptic drugs, high-dose benzodiazepines) that cannot be stabilized for at least 2 weeks prior to enrollment
• Severe spasticity: Modified Tardieu Scale muscle reaction grade 4 (unfatigable clonus >10 s) at elbow or wrist flexors on the more impaired side, or spasticity judged by the treating physician as unresponsive to optimised pharmacological management.