Neuromodulation: Specialists & information

What is neuromodulation?

Neuromodulators can be used to directly influence peripheral nervous structures or more complex nervous system structures in a targeted manner.

The nervous system uses two principles of action:

• neurotransmitters (biochemical messengers) and
• electrical activity.

Neuromodulation intervenes precisely in these control processes. The therapist can thus change (modulate) a non-optimal control of the nervous system. In other words, neuromodulation can be used to specifically switch off or greatly reduce the transmission of pain.

Medication is usually used in pain medicine. Although they are efficient, they have a systemic effect, i.e. on the whole body. They can also cause severe side effects.

Neuromodulation reaches the desired site of action directly and leaves the rest of the organism unaffected. Therefore, scattering effects are minimal at most.

The disadvantage of neuromodulation is that the procedure requires a high level of specialization on the part of the therapist and thus a high level of personnel and equipment.

What neuromodulation methods are there?

There are various methods for treating pain with neuromodulation.

Neuromodulation of peripheral nerve structures

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

Neuromodulation of central nerve structures

Non-invasive (ambulatory) 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 procedures (administration of medication via peripheral venous access, e.g. lidocaine and procaine infusions, ketamine infusions or via catheters close to the spinal cord, e.g. opiates or baclofen)

Invasive options (involving surgery):

• Spinal cord stimulation with spinal cord stimulation (implantable electrodes)
• Cerebellar stimulation with plate electrodes for Parkinson's disease
• cerebrum stimulation (motor cortex stimulation)
• Mechanical procedures (balloon compression for trigeminal neuralgia)

Reasons for treatment and common diseases

Neuropathic pain is caused by damage or injury to nerve fibers of the somatosensory system. These are nerve structures that are responsible for transmitting sensations such as

• touch,
• pressure,
• temperature and
• pain

are responsible.

Common symptoms of neuropathic pain are

• sudden attacks of pain,
• burning pain and
• persistent sensations such as numbness, tingling or a feeling of heat or cold without external causes.

Diseases in which neuropathic pain can occur include

• central pain (pain after a stroke or spinal cord injury), central pain
• phantom pain
• Post-zoster pain and post-zosteric radiculopathies
• trigeminal neuralgia
• migraine
• Tumors that constrict or infiltrate nerves
• Back pain due to degenerative spinal diseases (facet joint arthrosis with referred pain) and central spinal canal narrowing(spinal canal stenosis) and neuroforaminal narrowing with nerve compression by connective tissue structures(slipped disc)
• bottleneck syndromes(carpal tunnel syndrome, ulnar groove syndrome, thoracic outlet syndrome)
• Complex regional pain syndrome(CRPS type I and II)
• Morton's neuralgia

Neuropathic pain can also occur in diseases 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 possible for neuropathic pain. However, the prerequisite is that conservative therapies and oral medication have not previously shown any effect.

Nociceptive pain is caused by stimulation of the pain receptors (nociceptors) in tissue injuries (nociceptors) of the skin and internal organs. No significant effect can be achieved here through neuromodulation.

Carefulpain diagnostics are therefore essential before deciding on neuromodulation. This is the only way for doctors to assess whether the patient can benefit from this procedure.

The specialists responsible for neuromodulation come from different and sometimes overlapping disciplines. As a rule, responsibility depends on the exact clinical picture.

Specialists for the treatment are primarily

• Specialists in neurology and psychiatry, as well as
• neurosurgeons and
• pain specialists,
• often also anesthetists.

Benefits of neuromodulation and possible side effects

The main benefit of neuromodulation is the reduction in the amount of medication compared to oral administration.

Patients with severe chronic pain require very high doses of an active ingredient when using tablets as pain medication. The associated side effects are often significant and often include

• Nausea,
• feelings of weakness and dizziness as well as
• intense tiredness or
• confusion.

A drug pump(pain pump) is an effective alternative. It is one of the neuromodulation procedures. Painkillers are administered directly where they are needed via a pain pump. This results in far fewer side effects.

A medication pump can also be programmed. This allows times to be set for a higher or lower dose of medication. At night, for example, a higher dose of medication can improve the quality of sleep. During the day, on the other hand, a lower dose may be sufficient.

Patients can control their pain pump themselves to a certain extent and, for example, reduce and temporarily increase the dose © catalyseur7 | AdobeStock

Complications are possible in very rare cases. This mainly applies to invasive procedures, for example due to

• mechanical defects in the drug pumps or the lines,
• battery exhaustion, etc.

Implanted systems carry a very low risk of

• allergies,
• bruising and
• infections.

Non-invasive procedures, which are also offered on an outpatient basis, are unproblematic. These include infusions with lidocaine and ketamine, rTMS and tDCS.

Special case of transcranial stimulation and ketamine

rTMS and tDCS are non-invasive stimulation procedures. They were initially used in the treatment of psychiatric disorders, such as

• depression,
• anxiety,
• compulsions and
• derpersonalization.

The data situation here is extremely good. The procedures have FDA approvals and have found their way into the S3 guidelines. It is a principle of pain therapy to incorporate bio-psycho-social considerations of chronic pain.

This results in a very broad treatment spectrum for pain therapists for all somatization disorders. These include somatized depression and anxiety. These disorders always have the effect of intensifying and maintaining pain. Every improvement in the psychogenic comorbidity leads to improvements in the pain disorder.

Conclusion

Neuromodulation has been a proven and effective treatment for chronic pain for more than 40 years. It offers significant help for people with severe chronic pain for whom conventional pain therapy is not sufficient.