Electroneurostimulation in Treatment of Chronic Pain Syndromes

V.A. Shabalov, E.D. Isagulyan

(Burdenko Research Institute of Neurosurgery, Moscow)

According to data of epidemiologic studies, 64% of the population suffer from this or that type of pain. This index reaches 78% in the aged.

As for the USA and Germany, chronic pain is watched in 20 and 7 million people respectively. Data of native epidemiologic studies show, that chronic pain syndromes (without taking into consideration oncologic diseases) are diagnosed in not less than 40% of adults. This rate tends to constant growth (G.N. Kryzhanovsky, 2003).

Frequent and unjustified use of potent drugs and narcotics results in development of dangerous complications and addiction. Besides, it puts doctors in an unpleasant position in relation to their patients and law enforcement bodies, struggling against narcomania.

When conservative treatment of pain syndromes turns out to be ineffective, surgical methods are used. Today a number of destructive operations, performed in developed countries of the world, is limited. They are made only in doomed cases with severe chronic pain, resistant to other methods of treatment (B.A. Meyerson, 2001).

The report goal is to demonstrate efficacy of chronic neurostimulation of cerebral and spinal structures in arresting severe neurogenic pain syndromes, resistant to drug therapy.

Materials and Methods. There were 8 cases with severe neurogenic pain syndromes, aged 32-62 (mean age - 42.1 years). Mean duration of pain syndrome was 6 years. Persistent severe pain of a neurogenic character, which could not be arrested by analgesics and specific anti-pain psychotropic drug therapy, was an indication for operation.

Pre- and postoperative assessment of pain syndrome severity and its effect on a quality of life was carried out on the basis of a modified visual-analog scale (VAS).

Implantation of electrodes was performed under local anesthesia with mandatory intraoperative test stimulation. Chronic electrodes were implanted into thalamic sensory nuclei in 2 cases. One of them was a male with severe phantom limb pain; the second was a female with severe neurogenic pain syndrome of the right arm, which developed after removal of the radial nerve neuroma at the level of the forearm lower third. As for the patient with severe phantom limb pain, electrodes were implanted into sensory nuclei (1) and a median center of the thalamus (1). Implantation was made in accordance with a standard stereotaxic method.

The rest 6 cases underwent epidural implantation into a lumbar enlargement of the spinal cord. Implantation of epidural electrodes was combined with posterior selective rhizotomy in one female with marked severe spasms in the lower extremities.

There was a positive effect, watched in an early postoperative period in all operated cases (100%). The score of pain intensity (VAS) reduced from 9-10 up to 0-3 in 6 cases (75%), i.e. by 70-100% from its initial level. A dose of analgesics decreased several times in all the cases; some patients gave up their taking.

Catamnesis (1.5 years on the average) was indicative of a preserved positive effect in all the patients. Satisfactory results (reduced pain syndrome) were observed in more than 50% of cases. Life quality improved in 2 cases. There were no poor results in this series of patients.

There was one complication (electrode migration), which demanded reoperation and correction of its position. It was done without loss of the obtained initial result of chronic electrostimulation.

Discussion. Chronic electrostimulation of deep-lying structures of the brain and chronic epidural electrostimulation of the spinal cord can be methods of choice in treatment of severe neurogenic pain syndromes. It is conditioned by minimum invasiveness, reversibility and absence of a destructive effect on organs and tissues. One can increase efficacy of this method. It is achieved by careful selection of patients, intraoperative stimulation, improvement of both implantation technique and systems, used neurostimulation.