If you have been reading about the autonomic nervous system — perhaps because you live with a spinal cord injury, or you work with people who do — you will almost certainly have encountered the idea of "autonomic balance." The image is seductive: sympathetic on one side, parasympathetic on the other, and health is achieved when the two sit neatly level, like a set of scales in equilibrium.

It is a useful teaching shorthand. It is also, as modern physiology has demonstrated over the past three decades, an oversimplification that can actually mislead both clinicians and patients.

The fundamental question is this: does the autonomic nervous system ever truly achieve "balance" — and if not, what should we be aiming for instead? The answer has direct implications for how we think about autonomic dysfunction after spinal cord injury and for emerging interventions such as transcutaneous vagus nerve stimulation (tVNS) that aim to improve autonomic regulation.

If you've determined that you need electrical stimulation for denervated muscles, the next question is obvious: which device should you choose? This is where many people become confused — and understandably so. The market is flooded with electrical stimulation devices, most of which cannot help denervated muscles, and the technical specifications can be bewildering even for clinicians, let alone someone navigating this for the first time after a life-changing injury.

In my experience, the confusion isn't really about the number of options. It's about how devices that look similar on the outside — a box, some wires, a pair of electrodes — can be fundamentally different on the inside. A TENS unit from a pharmacy or bought online, and a specialised denervated muscle stimulator may appear related, but they are designed for entirely different physiological purposes. Choosing the wrong one isn't just a waste of money; it means lost time during a period when early intervention matters most.

In this article, I'll explain what features actually matter for denervated muscle stimulation, why most devices on the market are unsuitable, and how to evaluate your options

This article focuses partly on a specific device: the tVNS® system, manufactured by tVNS Technologies GmbH in Germany. This is not a wellness gadget or an unregulated consumer product. The tVNS device is approved as a Class IIa medical device under the EU Medical Device Regulation (EU-MDR) with CE marking—currently the only non-invasive VNS device with this level of EU-MDR approval. It is registered for four specific clinical indications: epilepsy, depression, chronic migraines, and Prader-Willi syndrome. Anatomical Concepts (UK) is delighted to distribute and support the tVNS® system in the UK.

Why does this matter for rehabilitation? Because the same mechanisms that make vagus nerve stimulation effective for these approved conditions—neuroplasticity enhancement and anti-inflammatory action—are precisely the mechanisms that show promise for neurological rehabilitation. The ongoing research into stroke recovery, spinal cord injury, multiple sclerosis, and other conditions builds on a foundation of established science and regulatory-grade engineering.

When clinicians think about pressure ulcer prevention, they typically focus on pressure—the perpendicular force that compresses tissue against a surface. This is understandable. The condition is called a pressure ulcer. Pressure is in the name.

But pressure tells only part of the story. Shear—the force acting parallel to the support surface that distorts tissue layers relative to each other—may be even more damaging than pressure alone. Research dating back to Bennett's seminal 1979 study demonstrated that when shear is present, the pressure required to produce vascular occlusion is reduced by approximately 50%. At shear levels of roughly 100 g/cm², the pressure needed to stop blood flow was half that required when little shear was present.

This finding has profound implications for heel protection. A device that reduces pressure but doesn't address shear may leave the heel vulnerable to the very damage it was meant to prevent.

One of the most common questions I receive comes from people who've had a denervating injury—whether spinal cord injury, brachial plexus injury, or another peripheral nerve condition—years or even decades ago. They've recently learned that electrical stimulation might help preserve or improve their muscle condition, and they want to know: Is it too late for me?

This is an important question that deserves a thorough answer. The research evidence and my clinical experience both suggest that while earlier is definitely better, "too late" is rarely the correct conclusion. In this article, I'll examine what the evidence actually shows about late intervention, which factors influence outcomes, and how to decide whether it's worth trying in your specific situation.

We don't discuss the technical aspects of stimulation. This has been covered in other articles on this site. Recognise, however, that the stimulation patterns are designed to work directly with the muscle fibre and do not rely on an intact peripheral nerve.

Transcutaneous spinal cord stimulation (tSCS) represents a promising noninvasive neuromodulation technique for rehabilitation in spinal cord injury (SCI) and other neurological conditions.

From this article you will gain a clear understanding of how tSCS is used as a priming tool within rehabilitation, the research principles that guide its clinical application, how it is integrated alongside task-specific therapy, and what types of functional improvements and neuroplastic changes clinicians aim to achieve when it is delivered consistently over time.