Neuromodulation

In Switzerland, around one in five adults suffers from chronic pain. Chronic pain cannot be seen by looking at the person affected. Quality of life and social relationships are considerably limited.


Today there are already many multimodal pain therapy models that consist of medicinal, physical and psychosocial components and are effective in many cases. Despite these multimodal treatments, there are very many patients whose pain cannot be sufficiently alleviated by conservative multimodal concepts. 

 

 

Surgical pain therapy and neuromodulation


Neuromodulation is "the change in nerve activity through targeted delivery of a stimulus such as electrical stimulation or chemical agents to specific neurological points in the body". 

In neuromodulation, state-of-the-art medical devices are used to improve or suppress the activity of the nervous system for therapeutic purposes. These technologies include implantable and non-implantable devices that deliver electrical or chemical stimuli or other active substances to reversibly modify the activity of the brain and nerve cells.


When should neuromodulation be used in the course of therapy?

 

Neuromodulation is most effective when used as early as possible. When selecting patients, it should be ensured that patients cannot be conservatively treated. The treatment algorithms of the current guideline on epidural spinal cord stimulation offer good assistance. Pre-existing depression, addictions or current pension requests should be clarified and are not an absolute contraindication. 


The patient (or their caregiver) must understand the neuromodulation process, be able to operate the system and the goals and expectations must be realistically established. If, during the test phase, the treatment provides a good pain relief of at least 40-50% and the patient wishes to receive the therapy permanently, the entire system can be implanted. 


Neuromodulation therapies for chronic pain include:

Peripheral nerve field stimulation (PNFS)

Subcutaneous nerve field stimulation is used for well-localised pain, for example in lumbar back pain. In patients with local back pain that could not be adequately treated with conservative means, a discussion about surgical therapies, such as stabilisation operations ("stiffening surgery"), often arises. If patients do not want to undergo stabilisation, or the surgical risk of stabilisation would be too great due to significant secondary diseases, subcutaneous nerve field stimulation can be a useful alternative.

 


The operation can be carried out under short or local anaesthesia and is completely reversible. The principle is that two or more thin electrodes are inserted subcutaneously at the site of pain. A neurostimulator emits weak electrical impulses through these electrodes, thereby stimulating the nerve fibres in the painful area. At the point of pain, there is a slight, pleasant tingling sensation in the pain area.


The procedure offers the advantages that it is very effective in positive testing, it can be controlled by the patient him/herself, there is a low surgical risk and, unlike a spinal fusion, it is easy to remove in the event of problems or treatment failure.
 

Peripheral nerve stimulation (PNS)

In the case of pain that originates from a directly irritated or damaged nerve, the patient usually feels pain in a clearly localised area. In such cases, direct nerve stimulation of the damaged nerve may help. 

The procedure

The electrode is placed directly on the damaged nerve. A neurostimulator, which is inserted subcutaneously, emits electrical impulses via these connected electrodes and thus stimulates the nerve fibres in the painful area. This creates a slight, pleasant tingling sensation in the area of pain.
The method offers the advantages that if it is effective in the testing phase, it can significantly improve quality of life, is very easy to test, carries a low risk and is easy to remove in the event of problems or treatment failure.

 

Spinal cord stimulation (SCS)

Epidural spinal cord stimulation is used in predominantly neuropathic and ischaemic pain syndroms. Most neurostimulation patients are treated for radiating radicular pain, with or without previous spinal surgery (failed back surgery syndrome/chronic back and leg pain). Back pain can also be treated well nowadays. It is also very effective for angina pectoris (AP) and peripheral vein disease (PVD).


The most common indications include chronic back and leg pain in spinal disorders, nerve pain (radiculopathies) after decompression surgery, knee pain after knee TEP with correctly inserted TEP without revision indication, polyneuropathy pain, peripheral arterial occlusive disease/circulatory disorders, CRPS.

 

 

The procedure

 

With this technique, an electrode is positioned in the epidural space in a minimally invasive manner. The electrodes are first channelled through the skin and connected to an external pulse emitter. After the therapy has been tested successfully, the electrodes are connected to a neurostimulator, which is inserted into the subcutaneous fatty tissue. It is a completely reversible process. The stimulation system can be switched off at any time and removed if necessary. 

Side effects such as those caused by medication (e.g. upset stomach, drowsiness) do not occur with neurostimulation.

Stimulation of the dorsal root ganglion (DRG)

The Dorsal Root Ganglion (DRG) is an easily accessible structure in the spine and plays a key role in the development and treatment of chronic neuropathic pain. It is a bundle of sensory nerve cell bodies in the epidural space. Each nerve root communicates with the dorsal root ganglion in a way that enables sensory messages from a defined area of the body. Therefore, the use of DRG stimulation can enable focused therapy on a specific area of focus.

 


The procedure


Similar to the SCS technique, the DRG electrodes are inserted into the epidural space in a minimally invasive manner and from there inserted into the intervertebral foramen, in which the DRG is located. Each wire is tipped by four electrode contacts that are arranged above the DRG. In a similar way to SCS, after a successful testing phase the electrodes are connected to a impulse generator (IPG) in the upper gluteal area/lower back or with an extension in the abdominal wall. After the surgery, the electrodes can be programmed to generate stimulation based on the pain pattern.

Continuous radiofrequency (CRF) thermocoagulation or pulsed radio frequency therapy (PRF)

The application of electrical radio frequency (RF) signals to nerve tissue using an RF lesion generator and RF electrodes inserted into the tissue is an established technique. The technique is used to treat pain, movement and mood disorders.

In clinical practice, lesions with radio frequency (RF) current are most often used to treat pain syndromes. Although it is believed that the generation of heat that causes "thermocoagulation" of the nerve tissue is responsible for the clinical outcome, a newer modality of RF application known as pulsed radio frequency (PRF) provides the RF current, without generating destructive amounts of heat.

 

 

The procedure

 

Two fundamentally different techniques are used:


1) pulsed radio frequency (PRF) therapy:
This is a neuromodulation therapy. The nerve is treated with high electrical energy at body temperature, which changes the conduction of pain. This method, in which the nerve is not damaged, is mainly used for neuropathic pain. This treatment is usually combined with drug treatment of the nerve root.


2) Continuous radiofrequency (CRF) neurolysis:
This technique is neurodestructive, i.e. the pain-conducting nerve is treated with targeted heat. As a result, a long-lasting reduction in pain can be achieved in the area to which the nerve spreads.
This treatment cannot be applied to all nerves. In most cases, sensory nerves are treated. Otherwise, complications such as muscle weakness or even paralysis could occur.

Intrathecal drug application (pain/spasticity)

Intrathecal drug infusion with implantable pumps and catheter systems is a safe and effective therapy for selected pain patients with severe chronic pain. It improves pain relief, reduces drug-related side effects, reduces the need for oral analgesia and improves the quality of life in a segment of chronic pain patients whose pain it has not been possible to adequately manage with more conservative therapies. Intrathecal drug therapy has therefore established its role in the treatment of malignant pain, benign pain, and severe spasticity.

In most cases, morphine or morphine-related drugs are administered using a pain pump. Other drugs such as muscle relaxants or novel types of pain medication are also used. The treating doctor can set up the pain pump and therefore adjust the dose, speed and timing of the drug delivery.

 

The procedure


A test catheter is implanted through a small access in the lumbar spine and channelled through the skin. An external pump is connected to this catheter. 

During the test phase:


•    During the test, together with your doctor you monitor how you react to the administration of the drug.
•    Each time the intrathecal dose is adjusted, the dose of oral medication is adjusted at the same time.

If your test phase was successful and your pain responds to the targeted drug infusion, the catheter can be connected to a drug pump. The drug pump is usually implanted on the left side of the lower abdomen. 
Following implantation, the pump is regularly refilled with the drug. This is carried out painlessly through the skin with an injection needle. Individual appointments in the pain clinic are made with the patient to refill the drug pump.