Neuromodulation for Chronic Pain – Modern Pain Management with Targeted Stimulation

Neuromodulators can be used to directly and specifically influence peripheral nerve structures or more complex nervous system structures.

The nervous system relies on two mechanisms of action:

• neurotransmitters (biochemical messengers) and
• electrical activity.

Neuromodulation intervenes precisely in these control processes. The therapist can use it to alter (modulate) suboptimal control of the nervous system. In other words: With the help of neuromodulation, pain transmission can be specifically blocked or significantly reduced. In pain medicine, medications are usually used. While they are effective, they act systemically—that is, on the entire body. In addition, they can cause severe side effects.

Neuromodulation targets the desired site of action directly and leaves the rest of the body unaffected. Therefore, side effects are minimal at most.

The disadvantage of neuromodulation: The procedure requires a high degree of specialization on the part of the therapists and thus entails significant personnel and equipment costs.

There are various methods for treating pain with neuromodulation.

Neuromodulation of peripheral nerve structures

• peripheral electromagnetic nerve stimulation (rPMS)
• Peripheral vagus nerve stimulation (PVS)

Neuromodulation of central nervous system structures

 Noninvasive (outpatient) options:

• Repetitive transcranial electromagnetic stimulation (rTMS) of the motor cortex
• transcranial direct current stimulation (tDCS) of the motor cortex or the dorsolateral prefrontal cortex (DLPFC)
• Pharmacological methods (administration of medications via peripheral venous access, e.g., lidocaine and procaine infusions, ketamine infusions, or via spinal catheters, e.g., opioids or baclofen)

Invasive (surgical) options:

• Spinal cord stimulation (implantable electrodes)
• Cerebellar stimulation using patch electrodes for Parkinson’s disease
• Cerebral stimulation (motor cortex stimulation) 
• Mechanical procedures (balloon compression for trigeminal neuralgia)

Neuropathic pain results from damage to or injury of nerve fibers in the somatosensory system. These are nerve structures responsible for transmitting sensations such as

• touch,
• pressure,
• temperature, and
• pain

.

Common symptoms of neuropathic pain include

• sudden, shooting pain attacks,
• burning pain, and
• persistent abnormal sensations such as numbness, tingling, or a sensation of heat or cold without any external cause.

Conditions in which neuropathic pain may occur include, among others:

• central pain (pain following a stroke or spinal cord injury), central pain
• phantom pain
• postherpetic pain and postherpetic radiculopathies
• trigeminal neuralgia
• Migraine
• Tumors that compress or infiltrate nerves
• Back pain caused by degenerative spinal disorders (facet joint osteoarthritis with referred pain), central spinal canal narrowing (spinal stenosis), and neuroforaminal narrowing with nerve compression due to connective tissue structures (herniated disc) 
• Compression syndromes (carpal tunnel syndrome, ulnar nerve entrapment syndrome, thoracic outlet syndrome) 
• complex regional pain syndrome (CRPS Type I and II)
• Morton’s neuralgia

Neuropathic pain can also occur in conditions such as diabetes mellitus or vitamin B12 deficiency. Certain

• medications (e.g., chemotherapy),
• toxins (e.g., alcohol),
• infections, and
• chronic inflammatory diseases such as multiple sclerosis

can also be associated with neuropathies. 

Neuromodulation is an option for neuropathic pain. However, this is only considered if conservative therapies and oral medications have previously proven ineffective. Nociceptive pain results from stimulation of pain receptors (nociceptors) due to tissue damage to the skin and internal organs. In these cases, neuromodulation does not produce any significant effect.

Therefore, a thorough pain evaluation is essential before deciding on neuromodulation. Only then can physicians assess whether the patient is likely to benefit from this procedure. The specialists responsible for neuromodulation come from disciplines that are sometimes distinct and sometimes overlapping. As a rule, the appropriate specialist depends on the specific clinical picture.

The primary specialists for this treatment are

• neurologists and psychiatrists, as well as
• neurosurgeons and
• pain management specialists,
• and often anesthesiologists as well.

The main benefit of neuromodulation lies in the reduction of medication dosage compared to oral administration.

For patients with severe chronic pain, very high doses of an active ingredient are required when using pain medication in tablet form. The associated side effects are often significant and frequently include

• nausea,
• weakness and dizziness, as well as
• severe fatigue or
• confusion.

A medication pump (pain pump) is an effective alternative. It is a type of neuromodulation therapy. A pain pump delivers pain medication directly to where it is needed. This results in far fewer side effects.

In addition, a medication pump can be programmed. This allows you to set times for higher or lower doses of medication. For example, a higher dose at night can help improve sleep quality. During the day, however, a lower dose may be sufficient.

Patients can operate their pain pump themselves to a certain extent, for example, by reducing the dose or temporarily increasing it © catalyseur7 | AdobeStock

In very rare cases, complications may occur. This primarily applies to invasive procedures, for example due to

• mechanical defects in the medication pumps or tubing,
• battery depletion, etc.

Implanted systems carry a very low risk of

• allergies,
• bruising, and
• infections.

Noninvasive procedures, which are also offered on an outpatient basis, are unproblematic. These include infusions of lidocaine and ketamine, rTMS, and tDCS.

rTMS and tDCS are noninvasive stimulation techniques. They were initially used in the treatment of psychiatric disorders, such as

• depression,
• anxiety,
• obsessive-compulsive disorder, and
• depersonalization.

The evidence base here is exceptionally strong. These techniques have FDA approval and have been incorporated into the S3 guidelines. It is a fundamental principle of pain management to incorporate biopsychosocial considerations into the treatment of chronic pain.

This also results in a very broad spectrum of treatment options for pain therapists for all somatization disorders. These include, for example, somatized depression and anxiety. These conditions always serve to intensify and perpetuate pain. Any improvement in psychogenic comorbidity leads to improvements in the pain condition.

Neuromodulation is a proven and effective treatment for chronic pain that has been in use for more than 40 years. It offers significant relief to people with severe chronic pain for whom conventional pain therapy is insufficient.

What is neuromodulation in pain management?

Neuromodulation in pain management is a therapeutic procedure that uses electrical impulses to specifically modulate pain signals in the nervous system. It is primarily used for chronic pain and neuropathic pain syndromes.

For which types of pain is neuromodulation suitable?

Neuromodulation is primarily used for chronic pain, such as neuropathic pain, spinal cord stimulation for back pain, or complex pain syndromes. It can also be used therapeutically for movement disorders or conditions such as Parkinson’s disease.

How does spinal cord stimulation work?

In spinal cord stimulation, electrodes are implanted into the spinal canal to generate electrical stimulation. This influences the transmission of pain signals in the spinal cord and can significantly alleviate severe pain.

Is neuromodulation permanent?

Neuromodulation is generally reversible and can be customized to the individual. The implanted systems can be adjusted, deactivated, or removed if necessary.

What are the risks of neuromodulation?

Possible side effects of neuromodulation include infection, bleeding, electrode displacement, or malfunction of the pulse generator. Overall, the procedure is considered effective and well-tolerated when used for the correct indication.