Neurostimulation for Chronic Pain: Neuromodulation Using Electrical Impulses and Modern Techniques

Neurostimulation has been recognized as a pain management technique since the late 1960s. Since the 1980s, the method has been routinely used in the treatment of chronic pain.

Chronic pain, in particular, is well-suited for treatment with neurostimulation. Pain is considered chronic if it lasts longer than six months or recurs repeatedly during that period. Common areas of application include

• the back,
• neck,
• arms, and
• legs.

Neurostimulation is also known as spinal cord stimulation (SCS). The procedure involves stimulating nerves using electrical impulses. Pain signals reach the brain via the spinal cord. Neurostimulators influence this process.

Stimulation can occur in both the efferent and afferent directions:

• Efferent: Impulses are sent from the central nervous system to the periphery.
• Afferent: Impulse transmission from the periphery to the central nervous system.

Auricular neurostimulation is a minimally invasive treatment procedure involving the implantation of a stimulation system. This system blocks the transmission of pain signals along afferent nerve branches. This intercepts the sensation of pain before it reaches consciousness. Specialists in neurostimulation include pain management physicians, neurosurgeons, and spinal surgeons.

Neurostimulators inhibit the transmission of signals from overactive nerves using a pulse generator. This electronic pulse generator is known as a neuromodulator or neurostimulator. The device stimulates specific sections of the spinal cord using weak electrical impulses.

The neuromodulator communicates with an electrode. This thin wire is placed in the spinal canal of the patient and transmits the pulses it receives to the nerves of the spinal cord.

Through these pulses, neurostimulation modulates the pain signals of individual nerves before the pain signal reaches the brain. Instead of pain, the patient feels a pleasant tingling sensation in the area where pain was previously felt.

To determine their suitability for neurostimulation, patients are fitted with an external stimulator prior to the planned implantation of a neurostimulator. Following a trial period, if the patient is deemed suitable, the electrode-receiver system (SCS system) can be implanted.

Neurostimulation harnesses the nervous system to intercept pain impulses before they reach the brain © C.Castilla | AdobeStock

Various types of neurostimulators are used in pain management. In addition to implantable stimulators, there are also external neurostimulators.

The stimulator is about the size of a cigarette pack and contains

• high-performance electronics,
• batteries, and
• multipole electrodes.

The neurostimulator supplies the electrode with pulses. The electrode is responsible for transmitting the pulses to the corresponding nerves.

The doctor programs implantable neurostimulators following implantation. Afterward, the patient can turn the neurostimulator on and off and adjust the pulses within limits predefined by the doctor. This allows the patient to adapt the stimulation to their current pain symptoms.

In general, neurostimulation is particularly suitable for conditions such as

• chronic pain in the back, neck, or limbs
• neuropathic pain accompanied by a burning sensation or numbness, or
• minimal pain relief from conventional treatments such as physical therapy or pain medication.

Neurostimulation is thought to trigger anti-inflammatory processes. It also influences microcirculation via sensory pathways.

Clinical studies therefore confirm the effectiveness of nerve stimulation in the context of chronic conditions such as

• nerve root damage (radiculopathies)
• phantom pain and stump pain
• Circulatory disorders
• Zoster neuralgia and postherpetic neuralgia associated with herpes zoster
• incomplete spinal cord injury symptoms
• Complex regional pain syndrome (CRPS)
• Angina pectoris
• (Chronic) back pain caused by conditions such as a herniated disc

As clinical studies show, neurostimulation reduces chronic pain by up to 50 percent. This pain relief enables pain-free movement and thus promotes physical activity. As a result, neurostimulation improves quality of life in patients with chronic conditions.

Thanks to its pain-relieving effect, patients rely on pain medication only minimally or not at all. In this way, neuromodulation using a neurostimulator also reduces the side effects associated with taking medication.

Advantages of Neurostimulation

Compared to other methods, the neuromodulatory treatment using a stimulator offers many advantages. Neurostimulation

• relieves pain,
• reduces the need for pain medication,
• improves quality of life,
• can be tried out during a trial period,
• can be reversed,
• does not permanently alter nerve conduction or the spinal cord,
• can be customized.

Risks and Side Effects of Neurostimulation

Like any treatment, neurostimulation is associated with certain risks and side effects.

• The electrode may shift out of place.
• Pain relief may not occur if the electrodes are placed incorrectly.
• Unpleasant sensations may occur in the stimulation area.

Since the treatment requires surgery, the usual surgical risks also apply. In very rare cases,

• hematomas (bruises) or seromas (fluid collections) may form at the implantation site,
• the spinal cord may be injured during the procedure,
• wound infections may occur,
• or complications may necessitate multiple surgeries.

The treating physician weighs the risks and benefits on a case-by-case basis and thus determines the patient’s suitability for the procedure.

What is neurostimulation?

Neurostimulation is a procedure in which an electrode delivers electrical impulses to nerve structures. The goal of the stimulation is to influence the transmission of pain signals and reduce chronic pain. This method is one of the most important techniques in neuromodulation.

For which conditions is neurostimulation used?

Neurostimulation is used for various conditions, including neuropathic pain, CRPS, migraines, chronic back pain, and leg pain. It may also be beneficial for circulatory disorders, peripheral arterial disease (PAD), and urinary and fecal incontinence.

How is a neurostimulator implanted?

Before permanent implantation, a trial phase usually takes place using an external device placed outside the body. If sufficient relief is achieved, an implantable device is permanently implanted under local anesthesia. The electrodes are precisely positioned in the area of the spinal cord or a ganglion.

How does spinal cord stimulation work?

In spinal cord stimulation, electrical impulses are delivered via electrodes in the area of the spinal cord. These electrical impulses can inhibit the transmission of signals along overactive nerves, thereby providing pain relief. This therapeutic procedure is frequently used for severe chronic pain conditions.

What are the benefits of neurostimulation?

Neurostimulation can improve pain relief, enhance sleep quality, and support pain management when medication alone is insufficient. Procedures such as dorsal root ganglion stimulation, TENS, or nerve stimulation using electrical impulses allow for individualized adjustment based on the location and affected area. This enables targeted treatment of the pain condition and improves quality of life.