Noninvasive Peripheral Nerve and Spinal Cord Stimulation

Abstract

This chapter gives a comprehensive overview of noninvasive peripheral nerve stimulation including transcutaneous cervical vagus nerve stimulation (tcVNS), transcutaneous auricular vagus nerve stimulation (taVNS) and external trigeminal nerve stimulation (eTNS), and transcutaneous spinal direct current stimulation (tsDCS). TcVNS, using the gammaCore device, has received FDA approval for the acute treatment of cluster headaches. Clinical studies have shown its efficacy in reducing pain frequency and severity in cluster headaches and migraines. Animal experiments have demonstrated the stimulatory effects of tcVNS on the vagus nerve and its related structures. Studies have also explored the use of tcVNS for ischemic stroke. TaVNS, targeting the auricular branch of the vagus nerve, has demonstrated antiepileptic effects in patients with refractory epilepsy and shows potential in pediatric epilepsy management. This technique has also been investigated for its therapeutic effects on depression. ETNS, which stimulates the trigeminal nerve, has shown promise in the treatment of refractory epilepsy and depression, with clinical studies reporting reductions in seizure frequency and improvements in quality of life. The safety and tolerability of these noninvasive peripheral nerve stimulation techniques have been prove to be generally good, with common adverse reactions such as facial skin irritation. These approaches offer alternative treatment options for conditions such as epilepsy, pain, and depression. TsDCS, which applies electrical stimulation to the spinal cord through surface electrodes, has shown promise in the treatment of various conditions, including spasticity, stroke, spinal cord injury, and restless legs syndrome. Studies have shown positive therapeutic effects on spasticity, walking ability in stroke patients, and post-stroke aphasia. Safety considerations indicate that tsDCS is generally well-tolerated, with minimal adverse effects observed. Overall, tsDCS holds promise as a nonpharmacological treatment option, but additional studies are required to better understand its mechanisms and refine its clinical applications.