Stim2Go and Support for Transcutaneous Spinal Cord Stimulation
Introducing Stim2Go
Stim2Go is a cutting-edge electrical stimulation solution designed to enhance recovery outcomes for persons living with the consequences of a neurological condition such as a spinal cord injury or stroke.
Introduced by Pajunk GmbH, and offered in the UK by Anatomical Concepts, Stim2Go acts as the core of our FES cycling system and allows this widely used type of exercise to be carried out with any model of passive-active bike. In our view, this alone makes Stim2Go a very compelling proposition for many. Stim2go is controlled using an iOS or Android app and comes equipped with more than 30 programme templates that can be customised for individual use.
Stim2Go in action
One of the features attracting a lot of interest is Stim2Go's incorporation of transcutaneous spinal cord stimulation (tSCS) protocols. tSCS is a non-invasive approach that has shown promising results with neuropathic pain and severe spams. Research which is ongoing, is exploring benefits of tSCS for motor function and neuroplasticity enhancements.
In this article, we'll first explain tSCS in general and then Stim2Go's specific approach to tSCS in some detail.
Spinal Cord Stimulation
Stim2Go's implementation of transcutaneous spinal cord stimulation does, as the name suggests, apply electrical stimulation through electrodes placed on the surface of the body. However, spinal cord stimulation first appeared in the 1960s as an implantable device to be applied in cases of severe pain.
Ronald Melzack and Patrick Wall proposed the so-called "Gate Control Theory" in 1965. This theory suggested that non-painful sensory inputs applied to a nerve could, In effect, close the gate to painful signals travelling along that nerve to the brain. According to this mechanism, stimulation of large-diameter nerve fibres (those that carry touch, pressure, and vibration sensations) can inhibit the transmission of pain signals carried by smaller diameter fibres. You've probably heard of TENS units which offer a form of this approach to localised management of pain in a limb.
The first clinical application of Spinal Cord Stimulation (SCS) occurred in 1967 when Dr. C. Norman Shealy first inserted a dorsal column stimulator into patients suffering from cancer pain. The first commercially available SCS system was released by Medtronic in 1968, borrowing technology from their cardiac pacemaker developments.
Since this time, SCS has evolved through several technical milestones. Initially, systems had an external power source with implanted electrodes. By the 1980s, fully implantable systems were available. During the 1990s, programme capabilities and improved electrode designs were the focus. During the 2000s, the emphasis was on various patterns of stimulation and latterly, attempts have been made to integrate artificial intelligence and so-called closed-loop system designs.
A snapshot of tSCS
In practice, SCS has been apploed in cases of Failed Back Surgery Syndrome, Complex Regional Pain Syndrome, Peripheral Neuropathy and spasticity management.
SCS works by generating electric fields between metal contacts placed in the epidural space. These electric fields alter the electrical potential across nerve membranes, particularly affecting the large-diameter myelinated fibres in the dorsal columns. When properly positioned, stimulation causes activation of dorsal column axons, resulting in both orthodromic (toward the brain) and antidromic (away from the brain) transmission of action potentials.
Although SCS, stemming from the gate control theory certainly provided pain relief, we now know that SCS works with more complex, multiple pathways but this is a story for another day.
Recent advancements in SCS, particularly tSCS, have expanded its therapeutic potential beyond traditional pain management to address spasticity and functional recovery in individuals with spinal cord injury. Innovations in non-invasive technologies, such as ONWARD Medical’s ARC-EX System and PAJUNK’s Stim2Go, alongside emerging clinical evidence, are redefining rehabilitation paradigms. There are in fact a number of different types of spinal cord stimulation that are the subject of research and practise. Clearly we still have much to learn about their effectiveness and application.
Transcutaneous Spinal Cord Stimulation
tSCS represents a non-invasive alternative to implanted systems. This approach uses surface electrodes placed on the skin to deliver electrical stimulation to the spinal cord. tSCS operates by delivering electrical currents through surface electrodes positioned over the spinous processes, modulating spinal circuit excitability. Unlike invasive epidural stimulation, tSCS non-invasively targets dorsal roots and interneuronal networks, facilitating neuromodulation of both ascending sensory and descending motor pathways.
SCS devices, primarily inhibit nociceptive signalling via the so-called "gate control" mechanisms in the dorsal horn, making them effective for chronic pain but limited in evoking motor recovery.
In contrast, tSCS employs higher-frequency stimulation (e.g., 50 Hz) to depolarise large-diameter afferents, which primes spinal interneurons and motoneurons for functional task execution. This differential targeting explains tSCS’s unique efficacy in spasticity reduction and motor rehabilitation, as demonstrated by increased EMG coherence and voluntary muscle activation in trials.
A practical starting point for tSCS aimed at pain is 30–50 Hz continuous stimulation with biphasic, rectangular, charge‑balanced pulses of about 0.5 ms per phase (≈1 ms total) at a sub‑motor threshold intensity set around 80–90% of the posterior root‑muscle reflex (PRMR) threshold for 20–30 minutes per session. A large midline electrode is placed over the upper lumbar region (T11/T12–L1) for example, with large abdominal return electrodes to maximise depth and comfort while limiting cutaneous activation.
Why these settings
Moderate frequencies with longer pulse durations are the most commonly used tSCS parameters to engage dorsal root afferents while remaining tolerable, with many protocols using 30–50 Hz and ≈1 ms total pulse width when a biphasic waveform is chosen.
Sub‑motor threshold stimulation is preferred for sensory modulation because it minimises discomfort and has been associated with benefits for hypersensitivity and pain while still modulating interneuronal networks.
Starting protocol
Here's what we might suggest as a starting protocol.
Frequency: 30–50 Hz continuous stimulation (start at 30–33 Hz and titrate toward 50 Hz based on comfort and response).
Pulse width: 0.5 ms per phase (≈1.0 ms total); many clinical protocols treat 1000 μs total as the default for biphasic pulses.
Intensity: Set just below motor threshold (no visible PRM reflex), typically around 80–90% of the current at first reflex; re‑check threshold when posture or electrode impedance changes.
Electrode montage: 5×10 cm midline posterior cathode centred near T11–L1 (or L3–L4 if targeting lower limbs), with one or two large rectangular anodes on the abdomen/iliac crests.
Session length and dose: 20–30 minutes per session, 3–5 days per week initially, monitoring comfort and any change in pain sensitivity.
Ramp/transition: Use slow ramps (≥2–3 s up/down) to improve tolerability at session start/stop and during intensity changes.
Effect of Various Electrode Placements
tSCS can be applied at higher spinal levels, including the cervical and upper thoracic regions, when using appropriate electrode placement and sub‑motor intensities. Cervical tSCS is already used clinically to target arm and hand circuits and sensory modulation, with safety data showing stable blood pressure and heart rate during stimulation when paired with rehabilitation.
Example Placement
Active electrodes are typically centered midline over C6–C7 or C7–T1 to engage upper‑extremity segments, with large return electrodes placed bilaterally over the clavicles or iliac crests to disperse current and improve comfort.
Large surface electrodes and careful midline placement help bias current to posterior root afferents and reduce cutaneous discomfort at the neck during cervical tSCS.
Cervical applications commonly use the same core settings as lumbar protocols: roughly 30 Hz continuous stimulation with charge‑balanced biphasic pulses around 1 ms total width at sub‑motor threshold intensities.
In a large multicenter cohort, stimulation was delivered continuously during therapy with biphasic pulses used in most sessions and amplitudes titrated below motor threshold for comfort and safety.
Stim2Go's deployment of tSCS
The following programme templates are available within the Stim2Go platform
Stim2Go is controlled by an IOS or Android App
Stim2go doesn't just do tSCS.
FES Cycling plus tSCS
Spasticity Reduction 33 Hz
Spasticity Reduction 50 Hz
tSCS Priming
iSCS Priming Double Pulses 100ms
tSCS Priming Double Pulses 50ms
Incorporating tSCS into an FES cycling programme is an attractive proposition for many. Stim2go's 5 channels could be deployed as follows To utilise four channels, with the fifth channel being reserved for tSCS.
Quads and hamstrings bilaterally.
Quads and tibialis anterior, bilaterally.
Quads and gastro-anemias bilaterally.
A short splitter cable can be used to allow the two abdominal electrodes to be placed with the other lead attached to the electrode placed on the spinal cord.
There is the practical question of how to set the current intensity for TS-CS when using the FES cycling programme. The developers of Stim2Go have created the tSCS priming programme for this purpose. With the electrode placement as described above. The TS-CS priming programme is used in a standing or prone position as appropriate. A continuous biphasic pulse train is applied with a pulse width of 1 ms and a frequency of 1 Hz. The current is carefully increased until muscle twitches start to appear in the legs. This occurs at the PRMR threshold, as described above. The current value to be used in other programmes for spasticity reduction or for FES cycling are then set at 90% of this value. You'll note there are two other TSCS priming programmes listed above. These are for research purposes at the moment as they require EMG equipment to be available for the practical use.
Conclusion.
In summary, transcutaneous spinal cord stimulation (tSCS) presents a promising avenue for enhancing neurological rehabilitation outcomes. By carefully calibrating stimulation parameters, such as identifying the PRMR threshold, practitioners can ensure safe and effective application tailored to individual patient needs. While some advanced programmes remain under research, the current applications of tSCS provide tangible benefits in spasticity reduction and functional recovery. Continued research and collaboration are vital to further refine these techniques and expand their practical use in clinical settings.
We have clients at home actively using tSCS as part of their ongoing rehabilitation and taking advantage of the fact that Stim2Go has been first to market with this innovative approach.
By combining this cutting-edge technology with traditional physiotherapy approaches, we are able to address complex neurological challenges more effectively.
To ensure seamless adoption, our training and support systems are designed to equip physiotherapists with the skills and confidence needed to implement tSCS into routine practice. The flexibility of Stim2Go's tools also allows for customisation based on individual patient progress, enabling a truly patient-centred therapy approach. This adaptability has been instrumental in reducing readmission rates and promoting long-term recovery outcomes, aligning with the key success indicators for neurological rehabilitation practices.