Two Levels at Once: Stimulating the Neck and Lower Back Together

tSCSFunctional Electrical Stimulation (FES)

16 Sept

Stim2Go from Pajunk is proving a very popular system for electrical stimulation due to its flexibility. In addition to supporting FES Cycling, it boasts many novel applications and the ability to create custom applications. Amongst its programs, there have been a number of transcutaneous spinal cord stimulation (tSCS) applications. Up until now, these were typically utilised to target severe spasms or pain.

We're getting to grips with some new cervical tSCS programs and two combined cervical-lumbar tSCS programs. These place one electrode on the neck and another on the lower back, and run both in the same 20-minute session. It is in beta testing, available under European and UK medical device rules only, and not cleared in the United States. I want to walk through the idea behind this configuration and what the human evidence shows.

What "two levels at once" actually means

tSCS delivers current through skin electrodes over the spine. At the right intensity, it excites large sensory nerve fibres where they enter the cord, and those fibres wake up the movement circuits at that level. Our introduction for non-clinicians covers the basics.

The two-level programme uses a small oval electrode over the fifth cervical vertebra, roughly the base of the neck, and a larger rectangular electrode over the junction of the eleventh and twelfth thoracic vertebrae, just above the small of the back. Both return their current to a pair of large electrodes over the hip bones. The settings on both channels are identical: one-millisecond biphasic pulses with no kilohertz carrier, at 33 Hz in one version and 50 Hz in the other.

Three details are worth knowing. The neck electrode is less than half the area of the lumbar one, so at the same current it carries more than twice the current density at the (potentially) less comfortable site. Each channel needs its own intensity, set against that person's reflex threshold, rather than matched numbers. And "at the same time" does not mean simultaneous pulses: the Stim2Go has a single current source, so the channels fire in turn, 10 milliseconds apart at 50 Hz. The return electrodes therefore never carry both channels' current at once.

Why anyone thought the neck and the lower back should talk to each other

Watch someone walk, and their arms swing in time with their legs. That coordination is not organised in the brain alone: long fibres inside the spinal cord, the propriospinal pathways, connect the arm circuits with the leg circuits. The stimulation research followed that anatomy. In 2015, Yury Gerasimenko's group stimulated the neck, the lower thoracic spine and the upper lumbar spine in six people without injury, with their legs supported in a frame that removed gravity. The thoracic site alone produced stepping-like movements. Adding the other two sites improved the stepping in five of the six, and switching them off again degraded it.

Two studies from Vivian Mushahwar's laboratory in Alberta clarified the picture. In 2020, Trevor Barss and colleagues found that stimulating the neck alone reduced a leg reflex by about 23 per cent, while the lower back did not. The neck reaches the leg circuits, but the effect was inhibitory. In 2021, Behdad Parhizi and colleagues tested the neck, the lower back, and both together in 14 people without injury. The lower back raised a forearm reflex by 11 per cent, the neck alone did nothing, and both together raised it by nearly 20 per cent. A measure of the pathway from brain to hand moved only when both sites were on.

KEY POINT: The neck and the lower back are connected inside the spinal cord, and driving both at once changes what the cord does in ways that one site does not. But the change is not always facilitation, and every one of these measurements comes from intact spinal cords.

What the human evidence shows

I sort the evidence into three tiers: shown in people with spinal cord injury, indirect support, and reasonable guess.

Shown in people with spinal cord injury. Two studies. In 2022 Soshi Samejima and colleagues reported on two men with long-standing incomplete cervical injuries who did two months of intensive walking training, then two months of the same training with stimulation at the neck and lower spine. Walking distance improved three times as much in the stimulation phase. Two people, no sham, and the phases always ran in the same order. In 2023 Hatice Kumru's group in Spain randomised 11 people with cervical injuries to breathing-muscle training with or without stimulation at the upper neck and mid-thoracic spine. Breathing pressures and lung capacity improved with stimulation and not with training alone. It is a real two-level protocol, though at different levels from the Pajunk programme, and breathing is not among its stated uses.

Indirect support. Neck stimulation on its own has a good record for the hand: Parag Gad's group reported grip force roughly tripling during stimulation after eight sessions, Fatma Inanici's group reported gains in six people that held for months after stimulation stopped, and the 60-person ARC-EX trial published in 2024 found 72 percent of participants exceeded the minimum important difference for strength and function. Trunk control has its own evidence, all from lumbar sites: Mrinal Rath's group cut seated sway from 4.7 to 1.4 millimetres in eight people with lumbosacral stimulation alone. And in 2023, Claudia Angeli and Gerasimenko found that adding neck stimulation in four people with lumbar implants reduced the implant's evoked responses yet improved stepping. Levels do not simply add.

Reasonable guess. That one 20-minute session at two levels does as much as two separate sessions, but I believe no study has compared them. I expect neck stimulation reduces arm spasticity, but perhaps it has never been tested as a primary outcome.

33 Hz or 50 Hz which to choose

Why two versions? The published work splits along goal lines rather than proving one frequency to be better. Around 30 Hz is the setting used to facilitate movement. Karen Minassian's group used it to engage the rhythm-generating circuits during robotic stepping in 2016, and Kumru's breathing study used it too. 50 Hz is the Vienna setting for spasticity. Ursula Hofstoetter's group showed in 2020 that a single 30-minute session of 50 Hz lumbar stimulation reduced spasticity for at least two hours, with the word "temporary" in the paper's title, and the group's 2024 mechanism paper attributes the effect to a short-lived strengthening of the cord's own inhibitory circuits.

So 33 Hz belongs to the facilitation family and 50 Hz to the spasticity family. I found no human study comparing the two head-to-head. Pick the version that matches the goal and hold it long enough to judge. Our previous article on treatment duration and carryover covers how long each family's effects last.

The waveform question at the neck

In May this year I wrote about a paper from Rodolfo Keesey, Hofstoetter and colleagues showing that the kilohertz carrier waveforms in some newer devices recruit fewer of the sensory fibres that drive lasting change, and that the problem is worst at the neck. The Pajunk programme uses the conventional one-millisecond pulse with no carrier, the waveform that paper supports.

There is a nuance in the same paper because its abstract states that lumbar stimulation preferentially recruits sensory fibres, whereas cervical stimulation favours motor fibres, regardless of the waveform used. The conventional waveform is the right choice at both levels, but it does not make the neck channel behave like the lumbar one. The case for the upper electrode is weaker than my earlier article implied.

KEY POINT: The conventional waveform is the right choice at both sites. At the neck, it still recruits a higher share of motor fibres, so the lasting, plasticity-driven gains the lumbar channel is built on cannot simply be assumed for the cervical channel.

Three reasons to go carefully

None of these says "do not try it". All three say measure, and screen.

Autonomic dysreflexia. In 2024 Ryan Solinsky's group studied two people with complete injuries high in the thoracic spine. At baseline, a painful cold-water test provoked no dysreflexia in either. With sub-motor spinal stimulation added, a dysreflexic blood pressure response appeared in every trial. Larger series seem to point the other way and Goutam Singh's group ran neck and thoracic stimulation in seven children without a single episode, and the ARC-EX trial reported no serious device-related events in 60 people. But for anyone with an injury at or above the sixth thoracic level, blood pressure monitoring in the early sessions and a dysreflexia plan should be considered.

Spasticity can go the wrong way. In 2025 Evan Sandler and Edelle Field-Fote's group tested several stimulation arrangements for calf spasticity after spinal cord injury. There was no reduction at the group level, and in people whose spasticity was mild to begin with, the dual-site continuous setting made it measurably worse. That is the closest published warning for a two-site programme: measure spasticity before and after rather than assuming which way it will go.

The one sham-controlled trial missed. The first randomised, sham-controlled trial of this stimulation family for spasticity, by Eira Lotta Spieker and colleagues in 2025, used 50 Hz lumbar stimulation in progressive multiple sclerosis and did not reach significance on its primary spasticity score. The authors include a co-founder of SensorStim, the company that designed the Stim2Go. The most rigorous trial to date came from the group closest to the device. Our plain English guide to spasticity and spasms sets that result in context.

KEY POINT: The two-level programme has a genuine physiological basis and a thin clinical record. The three cautions do not close the door. They imply baseline measures first, blood pressure checks for anyone with a high lesion, and no assumption about which way spasticity will move.

Where it might fit

I would frame these as questions for an assessment rather than as indications. A person with a cervical injury who has both a hand training goal and a standing or stepping goal, and who would otherwise be choosing one. Someone working on sitting balance, bearing in mind that the trunk evidence comes from the lumbar channel. Someone combining stimulation with arm-and-leg cycling, where the same neck-to-leg connections are the whole rationale, as our article on combining tSCS with FES cycling discusses.

How does this compare with the ARC-EX, the cervical-only device cleared in the United States in 2024? That device has a 60-person multicentre trial behind it for arm and hand function, and nothing on the Stim2Go matches that depth for the neck alone. The Stim2Go offers breadth, home use, a lumbar waveform rationale and a lower cost, and the two-level programme extends the breadth. Different propositions, not a contest.

A word for readers with multiple sclerosis. Implanted spinal stimulation was tried in MS as early as 1973, and largely abandoned. The modern transcutaneous work in MS amounts to four small lumbar studies in around 50 people, and the one with a sham control is the Spieker trial above. Nobody has stimulated the neck in MS. It is tempting to think that because MS lesions are often in the neck, two levels cover more of the affected cord. The stimulation acts on the sensory roots under the electrode, not on the lesion, and cervical cord shrinkage in MS is common and tracks disability, so there may be less to recruit there. The defensible reason to try two levels in MS is scope, an arm goal alongside a leg goal, under supervision, with measures before and after, heat sensitivity managed, and the knowledge that in some people no reflex threshold can be found.

Beyond beta test

What we do at Anatomical Concepts is apply electrical stimulation. We look at whether the Stim2Go (and a beta programme like this one) fits the person in front of us, what it would sit alongside, and how the effect will be measured. Our role is to keep the equipment conversation grounded in what the evidence supports and open about what it does not. If you would like to talk it through, for yourself, a client or a service, I am happy to have that conversation.

Two Levels at Once: Stimulating the Neck and Lower Back Together

What "two levels at once" actually means

Why anyone thought the neck and the lower back should talk to each other

What the human evidence shows

33 Hz or 50 Hz which to choose

The waveform question at the neck

Three reasons to go carefully

Where it might fit

Beyond beta test

Further reading

Related articles on our site

Anatomical Concepts.
Every Body Better.

Two Levels at Once: Stimulating the Neck and Lower Back Together

What "two levels at once" actually means

Why anyone thought the neck and the lower back should talk to each other

What the human evidence shows

33 Hz or 50 Hz which to choose

The waveform question at the neck

Three reasons to go carefully

Where it might fit

Beyond beta test

Further reading

Related articles on our site

The Stages of Electrical Stimulation: A History in Seven Turning Points

Anatomical Concepts.Every Body Better.

Anatomical Concepts.
Every Body Better.