Surgical treatments for pain

Surgical methods of treating pain syndromes can be divided into three groups:

• anatomical;
• destructive;
• neuromodulation methods

Anatomical operations are represented by decompression, transposition and neurolysis. If indicated, they are often performed at the first stage of surgical treatment and are in many cases pathogenetically directed. It is well known that the most complete functional result of surgical treatment of trigeminal neuralgia is achieved by microvascular decompression of the trigeminal nerve root. In this case, this operation is the only pathogenetically justified one and often allows to completely eliminate the pain syndrome. Anatomical operations have found wide application in the surgical treatment of tunnel syndromes. Such "anatomical" operations as meningoradiculolysis, exploratory laminectomies with excision of scars and adhesions, especially repeated operations of this kind, have been practically not used in developed countries in recent years. They are considered not only useless, but often cause the formation of even more severe adhesions and scars.

Destructive operations are interventions on various parts of the peripheral and central nervous system, the purpose of which is to cut or destroy the pain sensitivity pathways and destroy the structures that perceive and process pain information in the spinal cord and brain.

Previously, it was believed that cutting the pain pathways or destroying the structures that perceive it can prevent the progression of pathological pain. Many years of experience in the use of destructive operations has shown that, despite their fairly high efficiency in the early period, in most cases pain syndromes recur. Even after radical interventions aimed at destroying and cutting the nociceptive pathways of the brain and spinal cord, a relapse of the pain syndrome occurs in 60-90% of cases. Destruction of nerve structures in itself can lead to the formation of GPUK, and, what is more important, contributes to the spread of pathological activity of neurons to higher "floors" of the central nervous system, which in practice leads to a relapse of pain syndrome in a more severe form. In addition, destructive operations, due to their irreversibility, in 30% of cases cause severe complications (paresis, paralysis, dysfunction of the pelvic organs. Painful paresthesia and even dysfunction of vital functions).

At present, in developed countries, destructive operations are used only in a limited number of practically doomed patients with severe forms of chronic pain that do not respond to any other methods of treatment. An exception to this rule is the DREZ operation. It is a selective transection of sensory fibers in the zone of entry of the posterior roots into the spinal cord. At present, indications for DREZ operations are limited to cases of preganglionic rupture of the primary trunks of the brachial plexus. It should be emphasized that careful selection of patients for this operation is necessary, since the "centralization" of pain with the presence of pronounced signs of deafferentation makes the prognosis of such operations extremely unfavorable.

Neuromodulation - methods of electrical or mediator action on the peripheral and/or central nervous system, which modulate the motor and sensory reactions of the body by restructuring the impaired mechanisms of self-regulation of the central nervous system. Neuromodulation is divided into two main methods

• neurostimulation - electrical stimulation (ES) of peripheral nerves, spinal cord and brain;
• a method of dosed intrathecal administration of drugs using programmable pumps (used more often for oncological pain syndromes or when neurostimulation is ineffective.)

In the treatment of non-oncological pain syndromes, neurostimulation methods are most often used, which can be divided into:

• electrical stimulation of the spinal cord;
• electrical stimulation of peripheral nerves;
• electrical stimulation of deep brain structures;
• electrical stimulation of the central (motor) cortex of the brain.

The most common of the above methods is chronic spinal cord stimulation (CSCS). The mechanism of action of CSCS:

1. electrophysiological blockade of pain impulse conduction;
2. production of antinociception mediators (GABA, serotonin, glycine, norepinephrine, etc.) and strengthening of the descending influences of the antinociceptive system;
3. peripheral vasodilation due to effects on the sympathetic nervous system.

Most authors identify the following main indications for neurostimulation:

• Failed back surgery syndrome" (FBSS), which translates as "failed spine surgery syndrome", it is also called "postlaminectomy syndrome", "spent spine surgery syndrome, etc."
• neuropathic pain due to damage to one or more peripheral nerves (after minor injuries and damage, operations, pinching (compression) of soft tissues or the nerve trunks themselves, as well as due to inflammatory and metabolic disorders (polyneuropathy));
• complex regional pain syndrome (CRPS) types I and II;
• postherpetic neuralgia;
• post-amputation stump pain;
• postoperative pain syndromes - post-thoracotomy, post-mastectomy, post-laparotomy (except FBSS and post-amputation);
• pain in the limbs associated with impaired peripheral circulation (Raynaud's disease, obliterating endarteritis, Buerger's disease, Leriche syndrome, and others);
• angina (implantation of a system for chronic stimulation eliminates not only pain, but also its cause - spasm of the coronary vessels and, accordingly, ischemia, often being an alternative to bypass operations);
• in case of pelvic pain, the HSSM method is less effective, however, it is chronic stimulation (of the spinal cord or branches of the sacral plexus) that often proves effective in cases where conservative methods are powerless, and direct surgical intervention on the pelvic organs is not indicated;
• deafferentation pain in the limbs, for example, with postganglionic brachial plexus lesions or partial spinal cord lesions. Pain due to preganglionic rupture of brachial plexus branches, unlike postganglionic lesions, is much less amenable to electrical stimulation of the spinal cord. DREZ surgery remains an effective operation in this case. However, given the above-described shortcomings of destructive interventions, it is advisable to perform it in cases of unsuccessful results of chronic electrostimulation. Further development of neurostimulation methods and, in particular, the emergence of the method of chronic electrical stimulation of the central cortex of the brain has called into question the use of DREZ operations or the ineffectiveness of HSSM.

Currently, electrical stimulation of the motor cortex of the brain can be a non-destructive alternative to DREZ operations. The main criteria for selecting patients are:

• severity of pain syndrome and its impact on quality of life (on a visual analogue scale from 5 points and above);
• ineffectiveness of medication and other conservative treatment methods (more than 3 months);
• absence of indications for direct surgical intervention (anatomical operations);
• positive results of electrical stimulation tests.

The main contraindications to neurostimulation are the following:

• severe concomitant somatic pathology;
• incurable drug dependence;
• a history of suicide attempts accompanying severe mental pathology;
• mental disorders with obvious signs of somatization;
• intellectual disability of the patient that prevents the use of the system for electrical stimulation.

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